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OK my turn for advice, 350 mercruiser inboard ski boat

kghost

kghost

Silver Medal Contributor
Ok so it is my turn for some advice,


My friends boat, 1996 ski boat 20 ft (fresh water lake, no salt water)

rebiult motor installed by me and carb rebiult by me in 2001, No issues for the last 10 years.

Last week (been in use for the last month) was using boat and started hearing a wierd noise, sounded like pinging as he descibed.

I advised to stop using and do some diagnostics

I had him take the spark plugs out, change the oil as he said there was some water in the oil and crank the engine over and give me the information on what the results were, ( I was away last weekend so could not be there myself).

(these guys have very limited mechanical skills)

They did as i asked and the resultes were,

Water from # 1,3,5 cyclinders and 6. Oil was normal amount for the most part so water was a result of what ever the issue is so I ma confident it is not a cracked block.

I was there yesterday and I confirmed water comming out of 1,3,5 and 6

3 is the cyclinder with the most water shooting out of it.

I was attempting to do a compression check but developed a secondary issue with the starter I believe as the starter is 15 years old (rebiult unit installed by me in the late '90's) so I could not get enough cranking speed to get accurate compression.

Boat has been pulled and brought to my house for furrther diagnostics on cranking issue and to identify and hopefully repair the wate issue.

So my question to anyone would be

So what are your oppinions as to why water would be comming out of cylinder 6,

If blown head gasket I could see one bank having water, but the fact the other bank has one is troubling.

Could this be a intake manifold issue???

Maybe both exhaust manifolds/elbows crapped out?? (this set up has only the water feeding from the bottom of the manifold up and thru the elbow. NO water directly to the elbow).

Ok I would appriciate any suggestions.........before I tear into this beast........
 
Quoted from the merc service bulletin#2001-13

Water on top of pistons
If water is found only on top of the pistons,the most likely way it got there is through the intake or exhaust valve Rarely is it caused by a crack in the cylinder head or a bad cyl.head gasket.look for signs of water entering the carburetor or throttle body then going into the intake manifold.the most common cause for water entering the engine this way is rainwater drainage into the carb or throttlse body. There is more info on this subject if you need it I can e-mail you the info, I found this bulletin and kept it because I had my engine hydrolock and it was rainwater getting into the carburetor....
 
Last edited:
OK UPDATE:

I tore into it last night,

What I thought was a worn out starter (which I installed 12-13 years ago) turned out not to be the problem.

I removed both exhaust manifolds and elbows. I proceeded to do a compression check........water was pouring out of number 3 and 5 spark plug hole and exhaust port on the head.....


So I tore it apart.

Cyl side 1,3,5,7,.........head gasket WAISTED, one of the worst I have ever seen.....

Cyl side 2,4,6,8..........in better shape but showing some weird stuff.

Owner is on VACA this week and has picked up the heads to deliver to a shop.

New head gaskets, head bolts, intake and exhaust gaskets need to be ordered (did not like the look of the middle row head bolts on 1,3,5,7 side..something was up with them....


Hopefully we get a quick turn around on the head work and have it back together in less than two weeks.....


Boy my age is catching up with me............I was beat after all that yesterday afternoon.............lol

motor was a rebiutl installed by me in 2001, 11 solid years of running with no issues.

Internals, roller cam, .040" over bore and pistons.......All I got for now.
 
No, The 2,4,6,8, side was in much better shape but for some reason there was some water comming out of cyl 6 ???? not 100% sure on that yet.
I am not saying the head gasket was perfectly clean it was not, But considering the exstent of the other side I see it as it was inevadable on the 2,4,6,8, side also.

Your opinons????

The head gasket between 4 and 6 was on its way out, not sealing very well you could see excessive heat/burnish transfer. I would say this is most likely due to heat.......

I know they had a (onboard water pump impellor) issue last year and replaced the entire housing vs just the impellor. They "said" they caught it before it got toooooo hot...........????

I think this and not winterizing it the correct way (MY WAY) all contributed to the failure.

The head shop said heads may be ready Monday. But I do work a regular 40 hr job so the reassembly is when I get to it...........
Still have to clean the block, intake, chase a bunch of threads yada yada......


Getting all fell pro marine gasket sets from NAPA........this is due to it being a rebiult motor and no longer OEM......
 
I'm curious are there any problems as to being .040 over on the block. and your going with a thicker head gasket..?
 
No standard replacement.

Got the heads back today!!!!! they went to work on them right away!! good shop!!

Milled flat, two cracks cold welded (special process by a local) heads held 40 psi after cold weld also may known as stiching.

All gaskets and hardware will be in by 2:00 this afternoon.

Looks like sunday afternoon if all goes well the boat will be back on the water.........One week out of the water.

No a bad turn around for this time of year..........bring it to a marina and I wonder how much and how long?? I suspect over $1500.00 and 3-5 weeks..........


So far total cost for head work and all parts and accessories to this point, ~ $650.00. No labor charge from me yet...........


Based on the final analysis,

1. over heated bad enough to cause head gasket issues and the heads warping,
2. Cracks from improper winterizing technique. Cracks were on the top of the head ~ 2 inches long near the valve springs.


They will be shown how to do it correctly now. Lucky they got away with it for so long...........Still dont understand why they did not listen to me years ago..........oh well some believe myth over reality............spend and learn.............
 
Remanufactered 1996 350 heads @$175.00 each, fel pro top gasket set $150.00 hope the deck is square...your fast dude.:rolleyes:
 
boat_tech said:
lol, kghost, Shouldn't this be covered under installers warranty.:p:D:cool:

Just teasing with you, Good luck.:)
Click to expand...


Well when I did the engine swap 11 years ago, reman motor was $1700, total cost to my friend was $2400 total for the entire job, you do the math I would call that warranty...lol

I would imagine this will be a similar "extended waranty".........lol

I am sure he will through me some cash but I normally do not take much, just enough to cover a few weekends beer supplies.....


Head work including repair of the two cracks was $400, I consider this a reasonable price considering 24 hr turn around


Gaskets set all fell pro marine thru NAPA, complete head bolt kit Thru NAPA, 15 quarts of oil and filters, rags, paint for heads, ~$250.

In the big picture if this works anything under $1000 and a running boat for the rest of the summer it is worth it.

He lives directly on a lake, He water skies almost every day and has a couple of kids and there friends that are always bieng towed on skie or tubes.......

I do not think one who lives on the water can put a price on sitting on shore watching everyone else have fun during the summer while your boat is laid up being repaird......

He does have a pontoon boat also but that is for cruising.


We shall see how all this works out, As far as the deck sruface.......not much I can do about that. Is what it is.......Good cleaning and back toegether it goes........cross fingers and pray to the lady of the lake...........
 
Got the motor all back together yesterday afternoon, went to fire it up and the ignition sensor died........no fire.

Willl have a new on today or tomorrow.....

What a dissapointing way to end a hard days work.

Uploader isnt working so no picks............What is up with this site!!
 
Not a bad turn around, boat at my house Monday 6-18-2012

Boat back in the water Tuesday 6-26-2012

would have been done two days ago if not for the bad ignition sensor............
 
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