new boat, some questions on 5.7 mercruiser

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

have the heads pressure tested while they are out. check to see if you have an engine oil cooler. those can leak as well. generally water in oil is bad.

i figured as much, going to bite the bullet and open her up till i find the source


im leaning towards exhaust manifolds/risers since owner stated he reused them from another engine

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

how unlikely would it be for the head gasket to be blown? even compression on all cylinders doesnt really indicate that

one of the spark plugs did have some rust on thread, not sure how telling that is of any problems

last time out on water i did idle around alot trying to set timing and waiting for marina parking

 

[trexbob]

Re: new boat, some questions on 5.7 mercruiser

Hi, since nobody else is replying here, I thought I'd jump in... I'm a long time auto mechanic (not a professional however), kind of new to boat engines though. Water in the oil generally means a blown head gasket in a car, but not necessarily in a boat, as others have said. A compression test won't always give you a proper diagnosis either... it's a good starting point, but has it's shortcomings... was the engine up to temp before you did the compression check? If not, you should re-check with the engine at operating temp. Better yet, a leakdown test would help eliminate the head gasket scenario, or at least make it less likely, if all cylinders are up to spec. Have you identified if you have an oil cooler yet? I'd look there before pulling the heads off.

 

[TilliamWe]

Re: new boat, some questions on 5.7 mercruiser

The number one through about 4 reasons for water in a marine engine are the exhaust manifolds. Check EVERYTHING twice before you pull the heads.

 

[John_S]

Re: new boat, some questions on 5.7 mercruiser

The number one through about 4 reasons for water in a marine engine are the exhaust manifolds. Check EVERYTHING twice before you pull the heads.

agree

 

[skiray6825]

Re: new boat, some questions on 5.7 mercruiser

Keep us posted on your progres. Many of us have the same type of motor and would like to stay aware of any potential issues
.

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

trust me i will, this will be my first experience and i am trying to learn as much as possible so will be posting many pictures for reference for you all reading thru this and wanting to learn as well

will be removing exhaust and possible intake mani if needed today or tomorrow and report back with pics

i dont believe i have an oil cooler though i will double check

 

[Scott Danforth]

Re: new boat, some questions on 5.7 mercruiser

you will have a power steering cooler, you may have an oil cooler.

have you changed oil and re-checked the block for water intrusion?

pulling the exhaust will tell you a lot. if the exhaust ports are clean, dry, and only have carbon then you dont have an exhaust manifold leak. however if any of the ports have rust, you found a water entry point.

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

you will have a power steering cooler, you may have an oil cooler.

have you changed oil and re-checked the block for water intrusion?

pulling the exhaust will tell you a lot. if the exhaust ports are clean, dry, and only have carbon then you dont have an exhaust manifold leak. however if any of the ports have rust, you found a water entry point.

when i removed old oil and noticed water i did not put any new oil, figured it would be a waste until i found the source, especially since ill need to cycle a couple oil changes once problem is solved to remove any remaining water, which ive read "marvel mystery oil" would be beneficial at that point? input?

 

[Scott Danforth]

Re: new boat, some questions on 5.7 mercruiser

if you simply have trace amounts of water after an oil change, it will steam off once the engine is to temp. however since you just bought the boat, I would have put new oil in and run it for about 20 minutes.

 

[Mac525]

Re: new boat, some questions on 5.7 mercruiser

just a thought you said the distributor was loose when you got it and the water could have gotten in that way especailly if your engine cover lets rain water down right over the distributor as mine used to good luck

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

just a thought you said the distributor was loose when you got it and the water could have gotten in that way especailly if your engine cover lets rain water down right over the distributor as mine used to good luck

distributor was only loose enough to turn with a considerable amount of force, doubt much water couldve gotten in but thanks

does anyone have input on the marvel mystery?

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser



doesnt look good to me, first experience with this so maybe im wrong? is this bad enough to have caused the amt of water i had in my oil?

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser



additional pics

 

[Scott Danforth]

Re: new boat, some questions on 5.7 mercruiser

Black socks and crocks.....are you on vacation.....

seriously, looks like your pulling heads and having them tanked and tested. water sitting in the cylinders can wick past the rings and get into fuel. did you do a compression test?

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

Black socks and crocks.....are you on vacation.....

seriously, looks like your pulling heads and having them tanked and tested. water sitting in the cylinders can wick past the rings and get into fuel. did you do a compression test?

yes, all were within 5% of each other, biggest differentiation was maybe 125 vs 120

and haha, nice catch with my footwear :facepalm:

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

and that wasnt completely warm, i would say a semi cold start, i warmed up the motor to do test but i got distracted with some beers

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

anyone have a link or know how to easily test cooling system pressure on this motor? i know to block off exhaust manifold lines but basically an easy way to make an adaptor in order to pressurize....

 

[Bondo]

Re: new boat, some questions on 5.7 mercruiser

anyone have a link or know how to easily test cooling system pressure on this motor? i know to block off exhaust manifold lines but basically an easy way to make an adaptor in order to pressurize....

Ayuh,.... 'bout any hardware store will have pipe fittings, pressure gauges, 'n schrader valves...

 

[idleRelaxation]

Re: new boat, some questions on 5.7 mercruiser

Ayuh,.... 'bout any hardware store will have pipe fittings, pressure gauges, 'n schrader valves...

aha, will take a trip and see what i can come up with

anyone know off the tops of their head if pro-comp makes marine intake manifolds? thats what i currently have on and cant seem to find any marine intake manis from them