Cooling System Warning Alarm

[Spaniard_King]

Dug up a pic for ya

[Roughasguts]

Oh yeah you do. The water pump or impellor is just under the cav plate above the prop, But hold out on the water pump for a while.
Sure it will need to be done but, but i'm not convinced it's a water pump problem at this stage.

Sit back and wait for some ideas, Chimo hows your theory on this, would your Mod work.

[Roughasguts]

Nice one Spaniard King. Looks like the culprit, and first call of service to me.

[BaysideMarine]

Smelly, your waterpump is located at the top of your lower unit (leg).

When you remove your leg it will be immediately apparent sitauted around the drive shaft.

Undo the retaining bolts/screws and take the top cover off. Often on top of the top cover there will be a broad o-ring that sits on top of the top housing of the pump.

The impeller is a rubber star shaped device that fits inside the housing and is held in place by a "key". It runs inside an outer cup of stainless steel typically and has a stainless plate above and below it. The impeller is the major wear component however, over time the stainless sections
of the housings wear also.

I wouldn't be replacing thermos in my customers engines every 2 years as that would be rather excessive. Thermos only need replacing when the rest of the cooling system is ruled out and there is an overheat issue remaining. And even then it would be a guess between thermos (first check item) and clogged cooling channels around the head/s.

Yep, RAG I have had many of these apart.. From baby donks of all brands to the big donks.... Only thing I haven't had apart is a V8 OMC donk. They only made them for a couple of years and whilst ok on the race circuit (rebuilt every race) they were a serious liability on the recreational market).


Cheers,



Nicholas

[Smelly]

Well done King. Extremely well-laid schematic!

I presume Item 2 is our stat cover...shown in pics prrovided on Page 3 of this thread..

Where are the pressure valves located - it says I have to service these as well.

So, here is the plan so far.. Replace:
stats
pressure valves
sensors
switch maybe

Judging by the extreme salt build up I saw upon powerhead removal, it seems this engine has not been serviced for many years - if at all! (original paint still on screw/bolt heads on powerhead). Iff this is the case, extreme makeover I guess is the wayt to go..

Remember - this boat/engine has been sitting for at least 12 months - without use.
I bought it in Jan this year and has been in storage up until Sept this year.
Have not taken it out fishing yet..becuase I want ot be confident of the rig first.

I have already done plugs, filters, head clean...
WHen I started it again this morning - it sounded quite OK.

Smelly

[Smelly]

BM - how do i remove the sensors from the heads please?

[Smelly]

SO, guys, what is the plan - what should I do first?

[Chimo]

Hi Spaniard King and others and of course Smelly

Thanks for the Cross Flow V4 engine pic SK

Assuming there is an overheating problem which there seems to be, based on Smellys comments, and the thermostats themselves are not US / buggered and the water pump impeller is operating but probably needs renewing this OMC could be suffering the same problem that mine and a week ago # Big Puff Daddy http://www.ausfish.com.au/forum/YaBB.cgi?num=1164593063 #Vee 4 115 HP also appears to have suffered from.
Based on the parts and system shown in the picture the problem I and others have had may be relevant here too.

In the later model V 4 engine '97 115 HP (mine) which is different BUT appears to have the basic principle of thermostat operation after much hassel I found that the cause of my overheating problem in one head ie one side was the result of part no 5 Grommet which is housed in valve body part 4 having different hole diameters to the grommet in the other side.

Therefore one head got hot while the other did not. #This may or may not be the case here but #too small a holes in the two grommets may also be a problem particularly due to the impact on flow with too high a spring pressure as well.

Sounds petty and verging on BS #but I fixed this overheating in one side of the motor which caused the horn to go off and activated the Engine Management Unit which cut the revs and made the motor run like a chaff cutter by making the holes in both the grommets #the same diameter. #

One way is to remove and fit new grommets. #My bushy method in the later model motor was to enlarge the small hole with a vee shaped stone on a variable speed drill and then file a dozen small cuts into the grommet to replicate the rough surface that permits the main cooling water flow to start passing around the outside of the thermostat #when the volume of water pumped by a "good" water pump impeller causes the springs that hold the thermostats into the gromets to compress to allow the high volume cooling flow to cool the engine.

What Rough As Guts otherwise known as RAG mentioned earlier in this story about the windscreen wiper stainless steel is the final piece in this bushmans outboard modifiction / overheating repair. #

The spring pressure on the thermostat into the grommet is increased if the grommet hole is small because the spring has more tension on it than originally intended / designed. #

As a result the thermostat cannot pass far enough into the grommet therefore the water pressure required to compress the spring to allow the thermostat to move back to allow the water flow through cannot be achieved by a water pump impeller other than a very new one and even then this is not a certainty.

My solution is to compress two coils of the thermostat holding spring (part 10 ) and make two clips from the stainless steel band found in windscreen wiper blades to hold two spring coils together. #This shortens the spring, reduces the spring tension and so allows cooling water flow to be increased with lower pressure needed from the waterpump.

In my case, on one of my motors with this grommet #and spring problem evening up the the cooling has also allowed that motor to now idle and run much smoother from cold. #

Prior to the mods it would not run smoothly from cold until it had warmed up. #This meant I had to start and restart the motor a number of times while the other one idled more smoothly and didn't stall even when cold. #This modification therefore is a way to get rough idling motors to run smooth and I doubt you will find it in the manual!

I am not sure with out seeing this motor in the flesh (which isnt going to happen) if this modification will do the trick but for what its worth I'll share my experience and hope it helps.

Cheers

Chimo

[Roughasguts]

Smelly, Not discounting what the othe guy's say on this motor, geez I didn't even know where the thermostat was.

I think I would remove the thermostat housing and check out all the salt build up, that thermostat is in a funny spot and probably sits in salt water most of it's layed up life. So like the rest of the motor I think it would be packed in salt build up, and theres no way that thermostat could open. So pull it out drop the lot in hot water, then clean it up maybe a bit of grease for the moving bits.

I get the feeling the pressure valve is No 6 in the diagram, no real need to pull out the sensors after all there working.

But listen to the other guy's that work on these motors, they have the knowledge, I'm just feeling around in the dark.

[FNQCairns]

Smelly, time to get a manual, Ebay has them on CD rom?, you have the OMC, V4, 110hp bubbleback looper, they are good engines dont wreck it.

Good luck with the thermo changeout, I think the factory manual states removal of the powerhead to change/inspect it, although I know it can be done without all that drama (fiddly... UUHHH!), just eye the above diagram and be very patient.

Some people who have owned bubblbacks in the past , drill a couple of holes to access screws on the cowling and blank of with solid grommets.

IMO go with the recommendation above and check out the impeller OR do what I would do and back it down the ramp to see if it pumps - it very well might, have someone feeling the heads as you rev up to 1600 no more, if still not pumping let it cool for 20 minutes then push it into the water start it and go like a scalded cat to 4500rpm then shut down if not pumping- it proably will be pumping but I have not read your history - did you start it dry?

Actually I would do the last one first but political correctness and all that, but I would have had some idea of history first - go the impeller.

cheers fnq

[Smelly]

Great insight people - OMC, V4, 110hp bubbleback looper...what sort of name is this for a motor ?

Why does this the donk have a good reputation ?

I htink this thread will be invaluable to the next person who needs help in this area.

I now certainly have a clearer understanding of it all!

I have had boat/motor for nearly 12 months now - have not put in water yet

I have not started it dry but who knowswhat the previous owners did??

Chimo - I htink your email got lost in space - no worry..I know you were reading an waiting your turn to summarise today's events...well worth looking into!

Personally, I think it may be the impellor/stats because it has sat for so long - already I replaced a few perished items on the motor..

I still wonder how to replace/remove the existing sensors...?

[Roughasguts]

Smelly the temp sensors are probably just push in, mine are retained by a rubber gromet and retaining screw.

If you pull the brown wire off, then earth the wire to the engine with the ignition on you will get the warning sound.

All they are is a bi-metal strip contained in something that looks like a watch battery, they are pushed in to a blank hole in the head.
No water contact just pushed in with white lithium grease.

When there set Temp is reached the bi-metal strip deforms and makes contact and earths out sounding the buzzer.

Not sure but might be able to get them out with pin nose pliers, very gently though.

[Chimo]

Hi Smelly

If it was my motor i think I'd be leaving the sensors alone at least untill the last thing. They seem to be working what causing the alarm!

There are other more likely rubber perishing things to fix first. (impeller) thermostat grommets maybe?

Again my experience only, but I have found I get a better understanding of problems by doing as little as possible ie one thing at a time and checking the impact / result before doing more.

This way I think its possible to get a better knowledge of cause and effect .

Similar analogy with your "boss"----------- saying sorry dear, its my fault can lead to better Saturday nites whereas a lot of extra action / discussion can result in no Saturday nites and ultimately the worst possible outcome for a fisherman / boater ie the most expensive thing ever bought (divorce). "Smelly and I know what we are on about the rest of you lot don't worry about it"

Cheers

Chimo

[Smelly]

THanks for chiming in CHimo!

SHe's a tough nut to crack but I'll try and make her 'SMELLY' tonight....

ANyway, when I take the leg of for the impellor change out, what else should I change or look out for when I have the leg off - what further gasket kits do I need, etc..

Smelly

[Chimo]

hi Smelly

I reckon FNQ is right with his suggestion that you invest in a manual / service book for the motor. Would be handy to say the least.

The other suggestion which I made to you earlier, to is to get the motor serviced by an OMC BRP master Technician and be there when he does it and ask questions.

If he is worth his salt he will not object to you being there. I would not take your motor, or any motor for that matter, to "a bloke who does Jonhsons too" If you going to pay you might as well get what you pay for.

It would pay to give the Master Tech who does the work for you whatever history you have as well; ie "the motor has sat for at least the last 12 months"

As someone else said ealrlier, they are a good motor so don't stuff it by taking short cuts at this stage.

I didn't answer your question about what else to look for when you pull the leg off cause I reckon you could be better off chasing up a recommendation for a good OMC man in your own Point Cook area, probably someone reading this may be able to drop a few names too.

Hell, I'm doing the GOM thing; sorry.

I hope it all comes together for you including the Smelly Saturday nite


Cheers
Chimo