Mercruiser flushing help please.

[rocksberg6]

I have just purchased another boat and it has a 454 magnum mercruiser fitted, As i have never owned an inboard before,the question was asked when i picked it up ,How do i flush this thing? The dealer said just put on the ears an let er rip! Not much help at all really. I have been told i have to tape up some holes at the front of the gear box and make sure there's heaps of water pressure,but all this sounds a bit of a pain in the arse! Can anyone tell me if this is the right way to do this. If not how?:-/

[Noelm]

all of the ones I ahve seen are just flushed as if it was an Outboard, earmuffs and a hose, but of course there may be some others that need some sort of "special" stuff, but I have not seen them!

[Dirtysanchez]

I heard somewhere that you have to start the motor 1st, then turn on the water tap, because pressure inward from the hose can blow a seal or something like that?

Suppose you could use a big bucket of water, lower the leg into it and then turn it on, to be safe, because this is really just replicating the leg in the water when you are out boating.

Did you get any users manuals for the boat / motor ?

[rocksberg6]

Thanks DS, But now i am really confused! Tried the putting the leg in the half 44 gallon drum thing but all it did when i started the big bugger is blow the water and soluble oil clean out of the drum, straight across the yard,and over the missus's clean washin on the line!:o :-[ :-/ ;D So i don't reckon i'll be doin that again!

[frankgrimes]

I have just purchased another boat and it has a 454 magnum mercruiser fitted, As i have never owned an inboard before,the question was asked when i picked it up ,How do i flush this thing? The dealer said just put on the ears an let er rip! Not much help at all really. I have been told i have to tape up some holes at the front of the gear box and make sure there's heaps of water pressure,but all this sounds a bit of a pain in the arse! Can anyone tell me if this is the right way to do this. If not how?:-/

Best bet would be to contact the manufacturer of the engine - Im sure they'll be happy to tell you the correct way to flush it.

[TOPAZ]

When I took delivery of my Mercruiser in 2003, I was told it needed a particular type of earmuffs.
These have a stainless steel rod (more like wire) which passes through the inlet grille on the leg, and the other side of the muffs clips onto this, clamping the whole thing tightly onto the leg - much more so than spring type muffs.

I was also told to NEVER EVEN turn the motor over for a second, without water running through the muffs, as it would damage the water pump.


Richard

[BM]

Fresh or raw water cooled???

Bravo 1,2 or 3 drive I wouldd expect? Too much hp for an Alpha drive.

Water pickup (depending on leg) will be either in the leg (pickup only and no leg operated pump) or a fitting on the hull with a scoop that protrudes below the hull to draw in water.

You can make a fitting to suit a hull based pickup by moulding a piece of pvc pipe or if its a leg pickup a traditional set of muffs will work also.

HOWEVER, you will not get sufficient water into the seawater pump to adequately cool the engine so only run the engine at idle and keep an eye on the temp gauge as it will heat up as you run it.

Keep the temp needle out of the red and no harm will be done.

The above will apply to fresh or seawater cooled engines.

Cheers

[marlin71au]

I also have a big block Mercuiser with Bravo 2 leg. I've had it for 3 years and I just use the ear muffs with no problem. I always turn the tap on first before starting because it is not a good idea to run it dry as the pump impellor is rubber (or similar) running inside a bakelite housing and it gets hot with out water passing through it and can damage the impellor. The pump runs off a belt down beside the engine and has some 1 inch inlet and outlet hoses off it (there is no pump inside the leg). The only thing I have always been weary of is you have a good water supply from your hose as the pumps on the big blocks are large and pump hi volume water compared to most outboards but becuase we are just at idle flushing the engine the garden hose seems to be able to keep up with the flow on mine anyway. Hope this helps.

[rocksberg6]

Thanks guys, You have been more than helpful,Should have posted this before i stuffed the washin hey!::) What about the blocking of the holes in front of the gear box? Will this help with water pressure in the pick up where the muffs go on? I know i'm worrying to much about something thats pretty straight forward but i don't want to know how much one of these engines would cost to replace.:o :o

[Dirtysanchez]

Mate that is a classic about the washing ;D

So I had it ar$e about face then, turn the tap on 1st.. I will remember that if I ever get the bucks to buy a new boat.. I was looking at some big tinnies recently that have stern drives in them, which is interesting.

Hope you enjoy the boat and that flushing is now not so stressful

[BM]

These holes in the front of the gearbox that you speak of.

If they are holes with hydrodynamic grooves cast into their leading edge they are the holes for your water pickup.

So a conventional set of muffs will cover them.

Do you have a watewre pickup attached to your hull?

Cheers

[rocksberg6]

Thanks BM. The holes that i am talking about are right on the front of the gearbox facing the transom. When the muffs are on the leg (just like an outboard) the water pisses out of these holes, this is why i have been told i may have to plug them up for flushing, but i don't want to if they are part of the intake for the cooling system! The engine is raw water cooled, with no pickup on the hull.

[Mac_Attack]

Thanks guys, You have been more than helpful,Should have posted this before i stuffed the washin hey!::) What about the blocking of the holes in front of the gear box? Will this help with water pressure in the pick up where the muffs go on? I know i'm worrying to much about something thats pretty straight forward but i don't want to know how much one of these engines would cost to replace.:o :o
Hey Rocksberg6
My friend has a mercruiser and which is about a year old and all he does is wake a pair of earmuffs on turn the hose on and kick it in the guts. But NEVER ever rev it when you have earmuffs on it not even to get it going.
Hope thats some help.
Cheers Nick 8-)

[BM]

Rocks,

Perhaps I'm not reading it right but those holes you speak of ARE your water intake, so to plug them would result in no water flow.

Can you post a pic to clear the confusion?

Cheers

[Mrs Ronnie H]

Hi rocksberg6
We have mercruiser inboard and just flush it like a normal outboard. We don't turn the hose pressure right on or anything just make sure you have a good flow and you will be right.

I have a phone number etc if you like where you can pick up good workshop manuals cheap--- is a good read if you have not owned an inboard before.

PM me if you like and i will post link or give you the number. Manuals are half or more below normal price if yo are interested.

Ronnie

[Wahoo]

Thanks BM. The holes that i am talking about are right on the front of the gearbox facing the transom. When the muffs are on the leg (just like an outboard) the water pisses out of these holes, this is why i have been told i may have to plug them up for flushing, but i don't want to if they are part of the intake for the cooling system! The engine is raw water cooled, with no pickup on the hull.


Hi Rock

yes them holes your talking about need to be blocked, the Verados have the same thing and must be blocked when useing earmufs, you can order them as i did from a Merc dealer, its just a small rubber bucket about 40mm Dia with a strap



Daz

[rocksberg6]

Wahoo! THANKS MATE THATS WHAT I'VE BEEN LOOKING FOR!;D ;D ;D .Thanks to everyone thats helped out,now i should'nt have any problems.:D

Barcardi 2 and Jess.
VHF 73
Mooloolaba.