My rebuilt V8 - the saga continues unabated!

[ThePinkPanther]

Yep, my 20 year old Ford Windsor 351 V8 had a cracked head and at twenty years of age required replacing or rebuilding.

I took it to a local marine "mechanic" who I know does good work and he said it would be ready in about four weeks. Yeh!

OK, some 14 weeks later it is still sitting on my pontoon, quite useable but overheating badly at moderate RPM.

Starts well, runs smoothly and temp at 3,000 rpm is around 65C being normal but ...................... an extra 2-300 revs and the temp gauge goes full scale, way up to max around 100C and that is way to hot for this marinised motor. And it is instantaneous, no mucking about, you can see the needle peak in about 2-3 seconds and that is weird. Conversely, drop the rpm back by the same amount and the return back to normal is just as fast.

It was the starboard head that was replaced and this side runs very cool whilst the unworked port side gets about 20C hotter but I would imagine that would be normal? At idle bith risers are much the same and it will stay cool as long as you want, even fast idle around 2500-3000 is no problem. Just seems in gear that the issue arises.

Additionally, all exhaust risers and manifolds were replaced on both sides during the refit so there should be no problem with water channel blockages anywhere within.

A new impellor and housing was also fitted.

I have checked these temps using an external IR thermometer and the gauge is pretty well spot on. Replaced the sender unit in the head, removed the thermostat (for one run only) with no obvious difference.

Normal 3200 RPM STBD = 68C PORT 80C @3500 RPM STBD = 72C PORT = MAX

I have removed the intake hose from the water pump very briefly whilst running and it is like a fire hose, huge gushes of water pumping through.

First clue! It has a tendency to backfire on the odd occasion, sometimes at idle, other times at the above 3,000 rpm mark. So, me thinks it is retarded too much and as the mechanic said he "couldn't find the timing mark" it has not been properly tuned but having said that, it runs perfectly, excellent fuel consumption, 25% better than the old donk and idles well, albeit a bit fast as I can't get the return spring on the Holley carby to release properly just yet and it sits at a slightly fast idle in neutral.

But what the hell is causing this instantaneous increase in temp by such a small number of revs? I can't believe the timing would be enough to cause this but I am not an ace in this area and maybe it is the cause?

Like I've got oodles of water inflow, all clean water channels - most of them anyway - motor appears to run and start well and by the immediate decrease in temp I have to believe the impellor is working fine so I'm beat!

Any advices or help much appreciated!

[gazza2006au]

i know nothing about inboards. but i have a question: why did u only service one head? just thinking because there are two separate heads they are still pretty much one component as in u cook one you'll cook both

could the water flow be restricted by a non OEM head gasket on the head u replaced and this is blocking a internal water gallery from circulating between both cylinders?

[gofishin]

Mercruiser leg? Water intake thru leg, or thru hull?

[ThePinkPanther]

i know nothing about inboards. but i have a question: why did u only service one head? just thinking because there are two separate heads they are still pretty much one component as in u cook one you'll cook both

could the water flow be restricted by a non OEM head gasket on the head u replaced and this is blocking a internal water gallery from circulating between both cylinders?

Probably not the best wording re the heads on my part!

The port head was checked under x-ray for any cracks and milled back a touch but I'm not sure how far the guy went to in cleaning out any water channels on the port side of the motor. But it has all new manifolds and exhaust risers so I'm a little intrigued why it is getting so much hotter than the other one? I'll pull of all of the inlet pipes tomorrow just to triple check the water is doing the right thing!

Definitely got the marinised gaskets, I made sure of that and picked them up from Volvo myself.

Thanks for the reply, much appreciate!

[ThePinkPanther]

Mercruiser leg? Water intake thru leg, or thru hull?

It's a Volvo leg actually and the typical stern drive unit with the water intakes being like most outboards having the entry holes down either side of the lower leg. I've stuck high pressure hoses through them but no real benefit. What's got me beat is the immediate increase in temp for just a couple hundred of revs? I'm still betting on the timing as the back firing is definitely not right!

Thanks muchly for your reply!

[gofishin]

It's a Volvo leg actually...Between the universal and exhaust boots there is a hose about 35mm O/D that connects the water circuit up to the transom shield. The leg connection for this hose is an alloy fitting that corrodes, and hence loses its ability to seal properly with the hose.

Above certain speeds, when the water splashing around the hose/boots isn't there anymore, and there is good 'suck' from the motor water pump - air is sucked into the system causing what you describe.

Might still be something else, but I would pop the hose and fitting off and have a good look. Any corrosion on the sealing surface, get a new one. Might just be your problem.

[BM]

Both heads should be more or less the same temp so something is wrong. Cooling circuits can sometimes be different between automotive use and marine use of the sane engine. Mercury dropped the Ford V8 due to overheat/reliability issues. The fact that the replacement head is overheating suggests the problem related to that head. What else was done to the engine?

[aussiebasser]

Some older V8s in cars overheated if the thermostat was removed. The reason was that the coolant was circulating through the system so fast it didn't spend enough time in radiator to cool down. We used to cut the centre out of the thermostat and put the out back in to act as a restrictor. The Windsor V* was a great engine in the early 70s, but that was over 40 years ago and there have been some amazing breakthroughs in design in those 40 years.

[The Woo]

Yep, my 20 year old Ford Windsor 351 V8 had a cracked head and at twenty years of age required replacing or rebuilding.

I took it to a local marine "mechanic" who I know does good work and he said it would be ready in about four weeks. Yeh!

OK, some 14 weeks later it is still sitting on my pontoon, quite useable but overheating badly at moderate RPM.

Starts well, runs smoothly and temp at 3,000 rpm is around 65C being normal but ...................... an extra 2-300 revs and the temp gauge goes full scale, way up to max around 100C and that is way to hot for this marinised motor. And it is instantaneous, no mucking about, you can see the needle peak in about 2-3 seconds and that is weird. Conversely, drop the rpm back by the same amount and the return back to normal is just as fast.

It was the starboard head that was replaced and this side runs very cool whilst the unworked port side gets about 20C hotter but I would imagine that would be normal? At idle bith risers are much the same and it will stay cool as long as you want, even fast idle around 2500-3000 is no problem. Just seems in gear that the issue arises.

Additionally, all exhaust risers and manifolds were replaced on both sides during the refit so there should be no problem with water channel blockages anywhere within.

A new impellor and housing was also fitted.

I have checked these temps using an external IR thermometer and the gauge is pretty well spot on. Replaced the sender unit in the head, removed the thermostat (for one run only) with no obvious difference.

Normal 3200 RPM STBD = 68C PORT 80C @3500 RPM STBD = 72C PORT = MAX

I have removed the intake hose from the water pump very briefly whilst running and it is like a fire hose, huge gushes of water pumping through.

First clue! It has a tendency to backfire on the odd occasion, sometimes at idle, other times at the above 3,000 rpm mark. So, me thinks it is retarded too much and as the mechanic said he "couldn't find the timing mark" it has not been properly tuned but having said that, it runs perfectly, excellent fuel consumption, 25% better than the old donk and idles well, albeit a bit fast as I can't get the return spring on the Holley carby to release properly just yet and it sits at a slightly fast idle in neutral.

But what the hell is causing this instantaneous increase in temp by such a small number of revs? I can't believe the timing would be enough to cause this but I am not an ace in this area and maybe it is the cause?

Like I've got oodles of water inflow, all clean water channels - most of them anyway - motor appears to run and start well and by the immediate decrease in temp I have to believe the impellor is working fine so I'm beat!

Any advices or help much appreciated!

You say a new impeller and housing was fitted.
Did the old impeller lose blades? If so, did you find them? Usually they find themselves partially blocking the heat exchanger or oil cooler, whatever is the first item after the pump. It's been a long time since I've worked on a Ford powered Volvo setup so the layout is escaping me now.
Go methodically through your SALT water cooling side. It sounds like a flow issue. The water sounds like it can get out due to new risers, but there could very well be a restriction elsewhere - often from impeller blades from a failure "years" ago.

[ThePinkPanther]

Both heads should be more or less the same temp so something is wrong. Cooling circuits can sometimes be different between automotive use and marine use of the sane engine. Mercury dropped the Ford V8 due to overheat/reliability issues. The fact that the replacement head is overheating suggests the problem related to that head. What else was done to the engine?


Oooooops. sorry, crappy typist I am!

It's the original head that is heating up much faster than the new one! Not a huge amount, around about 15-20 degrees C. At idle, they are both much the same tough even there it is about 5-6 C higher. That kind of kills my idea of the timing being the culprit as it appears to be something "mechanical" in the "old side of the motor" causing the problem!

Thanks for reply, much appreciated!

[ThePinkPanther]

You say a new impeller and housing was fitted.
Did the old impeller lose blades? If so, did you find them? Usually they find themselves partially blocking the heat exchanger or oil cooler, whatever is the first item after the pump. It's been a long time since I've worked on a Ford powered Volvo setup so the layout is escaping me now.
Go methodically through your SALT water cooling side. It sounds like a flow issue. The water sounds like it can get out due to new risers, but there could very well be a restriction elsewhere - often from impeller blades from a failure "years" ago.

Thanks for that info, nope, the original impellor was in reasonably good shape, no damage to the blades at all, just took the precaution of replacing it while it was out of the water! Today is my tear apart all the hoses day and hope there is some sort of obstruction in there somewhere!

[ThePinkPanther]

Thanks for that, I have tried it with/without the impellor and no difference! Bugga!

[ThePinkPanther]

Between the universal and exhaust boots there is a hose about 35mm O/D that connects the water circuit up to the transom shield. The leg connection for this hose is an alloy fitting that corrodes, and hence loses its ability to seal properly with the hose.

Above certain speeds, when the water splashing around the hose/boots isn't there anymore, and there is good 'suck' from the motor water pump - air is sucked into the system causing what you describe.

Might still be something else, but I would pop the hose and fitting off and have a good look. Any corrosion on the sealing surface, get a new one. Might just be your problem.


That's damn interesting! When the boat was out of the water, the leg was also overhauled and I know this guy does a good job on them, he's done mine before so I'm kind of hoping there was no major corrosion as you say, but ....... this 35 mm hose, not the bellows is it? Think that is bigger than 35 mm but if that is it, a brand new one was fitted.
If it's another hose, can I see it from below the leg when it is tilted up?

Thanks for this info, much appreciated!

[gofishin]

From top to bottom, connections on leg:
1x universal joint bellows
1x cooling water hose and gear cable close together
1x exh bellows
...although it has been ~20yrs since I have worked on one !!

From a quick Google search, see attached. Fitting circled in red, hose behind it. 35mm O/D was a guess, but it wouldn't be far off.

If it is suspect, I would suggest converting to a thru hull water system. Just have to plug/blank the existing system somewhere else you will test out your bilge pump!!

PS. Don't know if your leg is a 270, 280 or 290, or newer. If newer then the above may not help. Don't know about them.

http://images.tapatalk-cdn.com/15/09/21/06582cbcb04dd4cbacf26da29aa2299b.jpg

[ThePinkPanther]

[QUOTE=gofishin;1600327]From top to bottom, connections on leg:
1x universal joint bellows
1x cooling water hose and gear cable close together
1x exh bellows
...although it has been ~20yrs since I have worked on one !!

From a quick Google search, see attached. Fitting circled in red, hose behind it. 35mm O/D was a guess, but it wouldn't be far off.

If it is suspect, I would suggest converting to a thru hull water system. Just have to plug/blank the existing system somewhere else you will test out your bilge pump!!

PS. Don't know if your leg is a 270, 280 or 290, or newer. If newer then the above may not help. Don't know about them.

Mate, that's one hell of a reply, really appreciated! I've put up a new post after I took her for a run today and have some more info to add! That schematic breakdown is fantastic!

[ThePinkPanther]

Firstly, many thanks to everybody for the top replies and suggestions, certainly helps me narrow down the issues!

OK, just to clarify what was done to this motor:

Rebuild of everything internally in the motor, pistons and all their associated bits, new PORT cylinder head, new manifolds and exhaust risers on BOTH SIDES! Hoses etc all replaced and every accessory from salt water pump, starter etc. etc. pulled apart and serviced. Also the Stern drive (Volvo) was thoroughly checked and found in good condition throughout. New bellows fitted, Unis all fine, new impeller and housing and all marinised gaskets fitted throughout! So, to the overheating problem!

Note: NEW = side of donk with new cylinder head, OLD is the other ..........

At idle and up to around 3,000 rpm, temp is normal at some 60-70 C though even at this stage the STBD side is already about 10C higher .......... Increase in power by as little as 300 rpm causes full scale increase of temp on gauge to 100C and that is confirmed by external IR Thermometer. The NEW side maxes at 75C but the STBD - old side) hits the 100!

Out on the water, while the temp was pretty normal, I briefly took off every water pipe from the stern drive intake to the saltwater pump, outlet to the thermostat housing, both outlets to both manifolds and you could put out a fire with the water gushing out of each one (same result with earmuffs and hose at pontoon). In fact jusr loosening the hose clamps had water bursting out of the pipe ends before their removal,

Pushing up the revs by 300, immediate full temp! Conversely, pull them back by a small amount and the temp falls back off the clock! Crazy!

Pulled off the hoses completely off again during high temp reading and ............ water, water everywhere! The inlet hose to the high temp OLD side had more than enough cool water pouring into it!

So, is it just a tight and new motor causing the problem but why would the OLD side be effected so dramatically? The gauge and sender can be ruled out as my hand held IR thermometer confirms the temps are genuine!

Having said the above, is 90-95C too hot for a new tight motor? Maybe it's normal! Don't even want to think why the OLD side is heating up all by itself though!!!

I'm stuffed guys! Over to the experts!

[The Woo]

Did this do this before the rebuild?
Why was it rebuilt?

Is the engine standard rotation? Is it possible a new water circulation pump has found its way on there and suits the wrong rotation?
If the engine features a serpentine drive belt for accessories is it routed correctly and not spinning the circulation pump backwards?

Im not wanting to send you on wild goose chases but weirder things have happened.
Where is the boat?

[scottar]

Just cruising the web there is some talk of both thermostats and head gaskets being able to be installed back to front with both resulting in heating issues. So is this thing purely saltwater cooled or do you have a heat exchanger and a fresh water pump as well?

[ThePinkPanther]

Did this do this before the rebuild?
Why was it rebuilt?

Is the engine standard rotation? Is it possible a new water circulation pump has found its way on there and suits the wrong rotation?
If the engine features a serpentine drive belt for accessories is it routed correctly and not spinning the circulation pump backwards?

Im not wanting to send you on wild goose chases but weirder things have happened.
Where is the boat?

Had a cracked cylinder, scored bore and twenty years old so close to its end!
Never overheated in its entire life, ran for over twenty years at 60-70 C

Yep, standard clockwise rotation, same old water pump with new impeller, nothing altered and is putting out huge amounts of water at all revs. Belt rotation is normal old pulleys and nothing special about the set up, all new belts?

Thanks for suggestions, much appreciated!

[ThePinkPanther]

Just cruising the web there is some talk of both thermostats and head gaskets being able to be installed back to front with both resulting in heating issues. So is this thing purely saltwater cooled or do you have a heat exchanger and a fresh water pump as well?

Thanks Scotar! I've had the thermostat both in and out and the effect is still the same overheating. It's purely salt water cooled via the leg impeller and then the pump itself. Even when it is overheating, the
pump is putting out huge amounts of water to both manifolds though just looking at the water flow I guess doesn't mean it is enough. Same old question though, why does ,and extra 300 rpm have such a dramatic effect? Doesn't make sense! Add 2-300 rpm and the temp gauge goes to maximum!

i can run all day long at around 3,000 rpm and the temp is fine, nudge it up a bit, goes bloody mad!

[Seppo BNE]

Purely speculation and imagination below....
Just thinking - if the rise and fall on the old head is pretty immediate, in the space of a few seconds? Could it be a head gasket/cracked head leaking pressure from the cylinder to the cooling jacket? Are the compressions OK?, is there a way to check for bubbles in the risers/cooling circuit when pressurising the cylinders one by one? Just thinking the thermal mass of water and steel should take more than a few seconds to change a large amount 80-100 deg?. If the water in the head gets blown out enough from leakage from the cylinder, the cooling effectiveness could drop right off. Once RPM is reduced a little, less air is getting pushed in and there is enough water to cool things down again. ??

From a relatively cold engine, what does it do when going up to 3300rpm - does the old side ramp up just as quick as if the motor was already warmed up at normal temp?

Total inboard ignorance below: :) :)
Is there a way to do a test like on old cars, looking for bubbling in the radiator?.. maybe a looped cooling circuit with a tee in it so you can see if pressure is getting forced in ?

[Seppo BNE]

Random thought #2, If the fuel economy is a lot better (25%) than the old, and idles fast etc- could it also be running lean and starting to ping with at higher power?
As for old side being hotter under power - skimmed head = higher compression ratio = more ping chance? --- is there any noticeable difference in plug colour between any plugs - are the plugs running hot or normal colour on the insulator?
Is it an easy thing to richen the mixture a bit to see if there's any difference?
Also for timing - not sure which way would make it run cooler - advance? slightly and see if there is any change? -- does it have a distributor with vacuum advance, is all that working OK?
Wishing you good luck in solving the problems!...
Being off the water, or on the water at less than full power is no fun!

[Noelm]

I guess it doesn't have some sort of bypass/diverter/poppit valve setup like outboards do? Symptoms are very poppit valve like! Failing that, best guess is "something" jammed in the cooling passage, possibly near the temp sensor, letting enough water through below 3,000RPM, but not above.

[juggernaut]

Do a compression test if not already done and see what that shows up. Look at plugs for any differences between each bank.

If base timing is out as in too advanced it could be pinging and increasing the temps and destroying your motor.

Also pressure test the cooling system if you can to ascertain if there is a leak somewhere.

[Greg P]

What type of cooling system is it again? Are the block, heads closed freshwater circuit and manifolds saltwater cooled? Were all the rubber coolant hoses replaced or inspected or original (sometimes issues with hoses loosing shape and sucked in reducing flow at higher rpm ? Where are you measuring the temp? From the original sender or just a heat gun?

[scottar]

Given that it is saltwater cooled, I would almost be inclined to think you have a blockage somewhere either due to an impellor previously failing or simply salt and corrosion build up. I would have thought that an engine that was designed originally to run on a closed cooling system would have a hard time getting hot at all with the thermostat out and cold water continually coming in. You did check to make sure the head gaskets were in the right way?

[ThePinkPanther]

Two things first! I really appreciate the replies from everybody on this issue! The suggestions have been great and have helped me a great deal to try and track down the problem.

Secondly, my apologies for not getting back speedily enough to the replies! Unfortunately I had to make a medical emergency trip to Adelaide that took a couple of weeks but with good results ........

OK, same problem i.e. Overheating of starboard manifold! I have done numerous checks following all the suggestions from you guys and I am 99% convinced this "mechanic" (for want of a better word) has put the head gasket in upside down or maybe the wrong one even! Or there is a serious blockage in there somewhere?

I have pulled ALL the water hoses off one by one at idle, normal 3000 rpm (no overheating) and 3,300 rpm (instantaneous overheating) and the water flow from them all is enough to fight fires! So it seems to me the water from the impeller and sea water pump is more than enough to do the job but it's just not getting to the head properly i.e. Gasket fitted wrong way?

I even - very briefly - blocked off the water intake to the "cold starboard manifold" and the exiting water via the leg was still pretty strong though damned hot as you would expect!

So I'm going to have to dismantle the whole starboard side and see what is going on!

And you may well ask "what is the mechanic doing to help?"

Not a thing! He has disowned the entire problem saying he was only responsible for rebuilding the motor! Other problems weren't of his doing! Any criticism will incur legal action! Not the sharpest knife in the drawer this guy!

So, thanks again and I'll get back with any progress!

[TheRealPoMo]

Take pictures and have a witness. If the gasket is upside down try to leave it attached to the head and take it to him.

[ThePinkPanther]

Got that thanks! Already have a pic of a piece of wire used to hold the throttle linkage to the carby instead of a cotter pin, consequently fell out and left me with no power when I needed it, also fully threaded bolts used to bolt starter motor on. Threads chewed out the alloy holes and the pinion gear moved out of range of ring gear, numerous wires just cut off and left hanging, several gauges not working ........... It's been a ton of fun so far!

[kind_cir]

I know nothing of marine engine cooling but it sounds similar to a car cooling problem where with just a few more revs it overheats. In a car the bottom radiator hose has a spring inside it that stops the hose compressing when engine revs increase. If the spring rusts away or goes missing then the hose compresses reducing flow and it overheats with just a few 100 revs more.

[scottar]

Panther - have a look at a couple of the car sites - there is a tab that indicates the gasket is either in the right way or not.

[ThePinkPanther]

Thanks fir that kind-cir! The marunized 351 is pretty simplistic in the water cooling department. An impeller in the lower leg accepts water forced in by about 12 twelve scoop type holes that are then fed to the water pump that circulates it through the thermostat housing and directly into each manifold block.

I know what you mean by the hose pipe pinching in but I don't think that can happen in my system and I have checked the inflow to the manifold when it starys to overheat and the flow is pretty solid bout nonetheless I'll have a peek at the hoses just to make sure they are not doing as you say, like a semi vacuum effect I guess?

Much appreciated, I'll beat the brute yet!

[Gon Fishun]

Thanks fir that kind-cir! The marunized 351 is pretty simplistic in the water cooling department. An impeller in the lower leg accepts water forced in by about 12 twelve scoop type holes that are then fed to the water pump that circulates it through the thermostat housing and directly into each manifold block.

I know what you mean by the hose pipe pinching in but I don't think that can happen in my system and I have checked the inflow to the manifold when it starys to overheat and the flow is pretty solid bout nonetheless I'll have a peek at the hoses just to make sure they are not doing as you say, like a semi vacuum effect I guess?

Much appreciated, I'll beat the brute yet!

Note square tab can be seen without removing head.

111152

[ThePinkPanther]

Gon Fishin, Mate, that is of incredible value to me! You have saved me from a huge job ripping the head off! Just in time, I had my tools all ready to go!

Yer a legend!

[Gon Fishun]

Gon Fishin, Mate, that is of incredible value to me! You have saved me from a huge job ripping the head off! Just in time, I had my tools all ready to go!

Yer a legend!


Scottar deserves the credit. I just found the pic. It's been 25 odd years off the tools and the memory was jogged.

[kind_cir]

Gon Fishin, Mate, that is of incredible value to me! You have saved me from a huge job ripping the head off! Just in time, I had my tools all ready to go!

Yer a legend!

So is that your problem, or is everything ok with the head gasket orientation ?

[myusernam]

so it was the fault of the rebuild guy? Did you take it back and make him fix?

[ThePinkPanther]

Note square tab can be seen without removing head.

111152

Bugga!! Finding that little bit of the head gasket behind all the plumbing, pipes, fuel filters etc. was soooooo much fun - but I found it and the "square bit" is definitely sticking out where I think it should be according to the pic. It's on the front outer section of the cylinder head and about 10 mm kind of square so I think that's it! Another glimmer of hope smashed down!

So, I'm kind of dun guys! I just have to put it down to a blockage in the guts somewhere as I have exhausted all the suggestions and advices in this post! I think I'll pull the exhaust risers and manifolds off for a looksee but not sure what I am really looking for at this stage!

My only shred of remaining hope is the timing is well out but the donk runs so well and starts fine though it does have that very intermittent backfiring now and then so that is the only hard clue I have to work on! Off to buy a timing light and work out how to do it!

Again my sincere thanks to all you guys for assisting me on this saga! With 36 replies I have found it a bit difficult responding to each one but rest assured I'm going to go over each one yet again to make sure I have checked everything suggested to me!

I'll be back!

[kind_cir]

Bugga!! Finding that little bit of the head gasket behind all the plumbing, pipes, fuel filters etc. was soooooo much fun - but I found it and the "square bit" is definitely sticking out where I think it should be according to the pic. It's on the front outer section of the cylinder head and about 10 mm kind of square so I think that's it! Another glimmer of hope smashed down!

So, I'm kind of dun guys! I just have to put it down to a blockage in the guts somewhere as I have exhausted all the suggestions and advices in this post! I think I'll pull the exhaust risers and manifolds off for a looksee but not sure what I am really looking for at this stage!

My only shred of remaining hope is the timing is well out but the donk runs so well and starts fine though it does have that very intermittent backfiring now and then so that is the only hard clue I have to work on! Off to buy a timing light and work out how to do it!

Again my sincere thanks to all you guys for assisting me on this saga! With 36 replies I have found it a bit difficult responding to each one but rest assured I'm going to go over each one yet again to make sure I have checked everything suggested to me!

I'll be back!

Might want to check the fuel side also. May be a blocked main jet leaning out the mix and causing heat. What carby is it running ?
Backfiring is more likely to be caused by a lean mix more so than timing which can also cause it. Look to see the accelorator pump is working how it should also. I realy think
it's a carby problem. Crap proberly got mixed up or entered the carb when it was off.

25 % better on fuel, you got to ask yourself.... Might be time to get a sniffer in the exhaust pipe and find out whats going on.

leaning towards a lean mix and a lean mix is a hot mix if you know what i lean.

[ThePinkPanther]

Thanks again for that! It's a Holly dual throat CFM600. Costs about $275 for a full overhaul but a new one is only fifty or so bucks more! It's easy to get off so might do that although carbies aren't my strong point I'm afraid. Cleaned up the harmonic balancer with sandpaper and not one wretched timing mark on it! Like where the hell did they go? Only .a vague suggestion of a white mark on it and seems to be set a tad before TODC.

Getting quite depressed with all this crap! Who called the man a mechanic?

[Triple]

Clutching at straws but possible intake leak on that bank causing lean running/over heating and backfire issue??? I would spray some carb cleaner around when running just to eliminate the theory if there is any leaks..


is there any noticeable difference in plug colour between any plugs - are the plugs running hot or normal colour on the insulator?



Do a compression test if not already done and see what that shows up. Look at plugs for any differences between each bank.


Have you done this yet?

[Gon Fishun]

I still reckon you have a water circulation problem. It is about the only thing that will cause the temp to rise so quickly, like instant as soon as fuel is fed to the combustion chamber. I did read somewhere, but can't find it now, that some head gaskets are different and holes had to be drilled into the block? Head? and or the gasket itself to allow water flow.
Does the intake manifold have water jackets and are they allowing the flow of water.

[ericcs]

i can't understand the lean running or timing theory, wouldn't it then affect both banks?

[scottar]

I still reckon you have a water circulation problem. It is about the only thing that will cause the temp to rise so quickly, like instant as soon as fuel is fed to the combustion chamber. I did read somewhere, but can't find it now, that some head gaskets are different and holes had to be drilled into the block? Head? and or the gasket itself to allow water flow.
Does the intake manifold have water jackets and are they allowing the flow of water.

There was some talk on one of the American car sites about "steam holes".

[ThePinkPanther]

Clutching at straws but possible intake leak on that bank causing lean running/over heating and backfire issue??? I would spray some carb cleaner around when running just to eliminate the theory if there is any leaks..

Have you done this yet?

Yep, pulled all the plugs and a nice even looking colour on all of them with no sign of overheating. Good thought on carby cleaner, I'll give that a go tomorrow. Think is she runs beautifully (other than overheating), idles and starts well, excellent fuel consumption, oodles of power......... but the lean running would affect both sides of the donk wouldn't it and it is only the port side that is overheating badly!

[ThePinkPanther]

I tend to agree mate as only ONE SIDE overheating pretty well discounts timing, mixtures, carby issues etc surely?

There is a solid steam of H2O pouring into the hot manifold side via its his but of course, is it getting where it should going?

Im losing it I think!

[kind_cir]

Arr well, time to rip it out and install a Chev ;D

[jamesmcjim]

what type of temp gauge is it electric . if so check the power supply for the gauge and wire from gauge to sender for earthing or bad joins. is the sender in the intake manifold?if so maybe measure temp with gun there to see if you get what gauge is saying.

[stevebris]

Please read the whole thread before making comments such as this. (facepalm)

[Gon Fishun]

Can't help anymore mate. I have little knowledge about these , but you might have a look at these water flow schematics. ???????

https://www.perfprotech.com/blog/articles/fresh-water-cooling