HELP Required ..Water in Oil,,..mercruiser 4.3

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hondajohn

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Hi all,
I have a Searay with a 4.3 mercruiser engine ( first boat ) . I WAS having a problem with high water temp at tickover, but okay while running. Local marina owner suggested new impeller,,, they changed that and the bellows and bellows housing. Temp now okay at idle,,,seems like problem solved.
BUT,,, Since they did the work,,, i Now have water in the engine oil. (Engine runs fine and tickover perfect,,all temps and prssures seem normal.)
Marina owner says 3 possibilities,,,cracked block,,,cracked head,, blown gasket.
Seems like a hell of a coinicidence that i have cracked a block or head the minute they completed the impeller work.
Am i Jumping to conclusions ?? ,,, Could it be a temporary problem that may clear itself with a few oil changes,,,or am i being too optimistic ?...being new to boating/engines and Not knowing whats exactly involved in changing impeller/bellows,,, i`m not sure if the work they did could have caused the water in oil problem. is that possible ? or even Probable ?.
Would appreciate any suggestions ? ,,,thanks,,, John <span style="color:blue"> </span> <span style="color:blue"> </span>
 
Thanks ges,,,appreciate that,,,,but it still seems a hell of a coincidence that the manifolds corroded or failed on the very day the impeller work is done, plus, engine is running ( at the moment anyway ) like a dream,no misfires,, nice tickover, etc... I think i`m clutching at straws and just looking for the easy answer. thanks,,john
 
It could be that the old impellor wasn't capable of pushing water around much, and the manifold/riser gaskets could just about hold on with the lowered pressure.

Now you've fitted a shiny new impellor, the coolant is being pumped through at full pressure, and the gaskets are leaking.

It's not a coincidence, it's chasing the problem further down the chain!

dv.
 
Thanks S28,,,, I`m not trying to pull down your reply at all,, ( I really appreciate it ) ,,but,,,,, The Water was circulating fine ,,,all normal temperatures, even when throttle opened right up. if the water wasnt getting through properly,,,wouldnt it have overheated at high throttles ??, The temp only used to raise up at tickover,,,,,soon as you revved it up in neutral , the temp came down. thanks again,,john
 
That is a bit odd - overheating often happens at high loads/high rpm.

It could still be though, that the root cause of your problem is leaking or blocked risers and / or manifolds.

Water in oil not good! Either way, needs to be sorted out asap, or you'll end up going engine shopping.

dv.
 
...Bearing in mind i`m a complete novice,,,,,,(,,,,, So a blown manifold gasket is a much better problem than a cracked block or head,,, i assume its not that big a job ?? is there any way to check other than paying the marina owner a bloody fortune to find out ??.... any way to test ? or to narrow it down ? thanks again guys
 
It seem to make sense to me when the marina guy said,, the impeller worn, so not quite drawing enough water at LOW revs,,but all okay at high revs or when running ( higher revs,more water ).
 
I’m also on my first boat and if in the same position as yourself would bite the bullet and get my local marine mechanic to start investigative works asap and try and locate source of ingress. May and hopefully will save a lot of money in the long run. Good luck
 
You need to get that water/oil out of the engine asap or you will be looking at a new motor, it will corrode everything that normally has oil oil on it.
If its not excessive change the oil a few times, but first you need to find the cause, First check the plugs to see if one bank or the other has rust/water on the plugs to narrow things down a bit.
Then I would pull off the risers and check for leaks around the gasket and down into the manifold/cylinders.Replace as req'd.
If they are bone dry then you need to get the heads off to check the head gaskets,
Its unlikely the block or head is cracked as these engines are pretty well bulletproof.
 
Thanks sb99 and thanks spannerman........ Will make some enquiries. I missed a bit off the original posting,,,,,,after he`d done the impeller work,,, i then asked him to give it a bit of a service and general checks,,,, this is when he found the water in oil problem. I remember him saying after he changed the oil and drained it again,,that he put 4 Litres in,,,and got 4 and a 1/4 Litres back out.
Not sure if that is what you would call excessive ?
Obviously NO water is best. thanks again chaps
 
How did you detect that there was water in the engine oil? Is the oil turning milky colored?

There must be an oil cooler in that engine that uses raw water for cooling. I've got three of them, one for the engine oil, one for the transmission oil, and one for the vee-drive gearbox. Since you have an I/O drive, you probably only have one oil cooler. These coolers can corrode through, causing seawater to get into the oil. Normally they aren't repairable. You just have to replace them.

You can remove the cooler and have it pressure tested.
 
Thanks QE too,,,, I didnt detect,,the marina guy did, as he was doing a service. But,.., (as previous post ),, This was immediately after changing the bellows/impeller/housing.
Just seems a hell of a coincidence to me that the water in oil appeared a couple of days after the impeller work was done,,,boat hadnt even been taken out since new impeller. and yes,, oil milky in dipstick hole and filler cap. He said he put 4 litres oil in, and drained 4 and a quarter litres back out.
So he investigated further and confirmed water in oil.
Thing is,,, we checked dipstick a week previous and all was fine,,, was only immediately after he changed impeller that water occurred.......thats whats making me think he may have disturbed something during impeller change. ive no idea whats involved with an impeller change so i can only guess , Just seems a hell of a coincidence.
thanks,,,john
 
There is no engine oil cooler on Merc petrol engines only a power steering cooler, so its going to be exhausts or head gaskets leaking.
 
Thanks again,,spanner,,,,, Ive read something about "static line " ... water level line ?,,,
could anyone explain in leymans terms ?? ( bearing in mind i`m completely naive on boat engines as you may have already guessed. ( I spent 20 minutes looking for the Brake fluid resevoir !!!! ) ( only jokin )
and could that have anything to do with ingress of H2O ? ,,thanks again
 
Me and a friend have plans to whip the risers off and check gaskets this weekend as spanner suggests,,, ( if i can find out what they look like ) ,,,, thanks again chaps
 
Milky colored engine oil means you have a serious problem. I guess I should have asked first whether the engine is raw water cooled or has a fresh water cooling system installed. If it's raw water cooled, then Spannerman is correct about there being no heat exchanger. In that case the water almost has to be coming through the head gasket, from the manifolds, or a crack in the block. In either of the first two cases case, the water must be getting into the cylinders. If this is the case, I would think you'd notice ignition problems. Try inspecting the spark plugs with the engine cold. I once had an exhaust manifold water leakage and first detected it by a routine inspection of the spark plugs. I could see beads of water on the inside of the plug.

However, I can't imagine that a manifold leak could introduce enough water into the engine oil to turn it milky. If you've had a severe engine overheat due to the impeller wearout, you may have a cracked block, which would explain the water-into-oil leakage. Hope it's not that bad.

It's also possible that the old impeller shed bits of rubber that clogged up the cooling passages somewhere. I've had to clean out bits of rubber form one of my heat exchangers.
 
Thanks again QE ,,, we`ll get the plugs out and inspect this weekend,,,,, but like i said previously,,it IS running fine,,, It starts first time,, runs like a dream,,,ticks over like a dream,no misfires,, nothing.
I`m certainly no expert,not even close,,,,but i would have thought if plugs were wet,it wouldnt run that smoothly ?? .
anyway,,,, plugs out for inspection on sunday,,,, will keep you all informed,,,thanks again chaps
 
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