please help 502 water problem
 

hi all sorry for the long winded first post

bought a new boat couple of months ago with a blown engine a volvo 8.2 gsi . stripped it down had alot of water in it and rust. it had a full rebuild a couple of years earlier also , so decided as i got it fairly cheap and everything else looked in good nik would just put a new base engine in and check everything else as we put it back together.
my engineer mate didn`t like the imco sound advantage set up as he didn`t think there was enough downward run on them but spoke to the boat builder and imco and they checked out ok so decided to go with it
everything seemed fine for the first couple of weeks until one day would not start, took the plugs out and they were wet but only three on one side took riser off and there was water sat in the manifold on one side
we decided to pressure test manifold and risers as they were only 2 years old with light use came back fine. changed the oil there was some milky ness in the filler cap but not in the oil changed plugs took the imco out and ran it straight out the transom tried it again then took off risers still water, so put new manifols and risers on but sadly still getting water in and seems to be getting worse checked the other side again there was a slight dribble in there also but nothing like the other side.

engine is stock with volvo manifolds and risers
oil coolers was pressure tested when rebuilt 2 years ago
have flapper valve and flaps in tips

any help would be great trying to resolve the problem before it goes away for the winter.

in my case it was a cracked head. good luck - jeff

i hope not, mind you the engine is brand new straight out the gm factory might get some come back

did you have exactly the same symtoms

my engineers thinks it must be something to do with exhaust he thinks we never solved the original problem just stuck a new block in but doesn`t know what it is

Pressure check the block.

I'm not familiar with Volvo engines. Is that a high hp engine? If it is, maybe you're getting reversion from the short risers on that Imco exhaust. A good way to check is to run it at idle for a few minutes, not letting it get hot, and then pull a riser and check inside for water.

excuse my ignorance what do i have to do to pressure test the block i`m not an engineer and the guy i use is away for 3 weeks is it something i can get somebody to do easily ie with engine as it is in the boat

done a compression test all cylinders fine + plus checked inlet pressure with diagnostic tool not hot though

volvo is 415hp
going to put another set of gaskets on tomorrow put the imco back on and run it through the drive only will this elliminate the reversion idea

thanks for your responses

If reversion is your problem running your exaust through the drive wont solve it.
You need to take the water away from the risors with a bypass hose. run it at an idle for a short time and remove and inspect the problem then.:cool:

If you are still using the stock Volvo exhaust manifolds, they are a wet riser flange type where the water has to travel between the base manifold and the riser via a gasket flange with four large water passages. It is very common for these to leak at this gasket joint or from the riser itself. I would recommend getting some new exhaust manifolds that are of a dry joint riser type where the water transitions between the base manifold and the riser via an external hose, like those made by Dana, Stainlesss Marine. Eddie Marine, Imco or others. Stock 8.1L 496 -fuel injected engines do not have reversion problems from camshaft size, etc.
When you pressure check the base manifold you cannot also pressure check the riser installed because the water dumps through passages inside the riser directly into the exhaust tube and it cannot be plugged to check both manifold and riser as well as the gasket flange at the same time.
Hope this info helps.

Best Regards,
Ray @ Raylar

can i just take the hose of that runs into the manifold and run it like that boat is now on trailer. if i get no water in there does this mean it is reversion and is there a cure keeping my origanal exhaust system or would it have to go. my engineer thinks i need to heighten the risers for more drop.


have looked at lots of performance manifolds and risers would love to have a set but i really need to know this is definitly the problem before i buy simply because i now have 3x volvo manifolds and risers 1 brand new 2 nearly new at the cost of £500 each and this project is already serously over budget

One of the best in the business gave you good advise. Read his post again and again if needed:eek:

There is nothing cheap about boating:drink: