1988 3.0 130HP Merc No compression

[Bruce San]

I'm trying to help a friend long distance. He's had the boat for 10+ years and is allways very meticulous about winterizing. He took it out of storage for the season. Did what ever you do to get it ready to run and took it out. It ran OK but lacked the power he was used to at top end. Had it tuned up and went out again. According to him it ran "like a scaulded dog" he was very happy with the performance. Ran around for an hour or so at verying speeds/RPMs without a hitch. Shut her down to make a phone call. When he went to restart it would turn over but not start. Had to get towed in.

He started by checking spark, OK. Fuel is new. verified fuel pump is working.

Checked compression and got 0 on all 4. pulled off valve cover and distributor cap and rotor is turning, valve train is moving. pulled timing cover and timing gear looks OK.

Any ideas?

 

[licketdsplit756]

Re: 1988 3.0 130HP Merc No compression

i would get another compression gauge.as long as the rings are ok there would be no reason for you to not get compression..you can feel it bye sitting your finger over one of the plug holes..even if a head gasket was bad. you would still have some compression. im sure the valves cant all be stuck open.

 

[Don S]

Re: 1988 3.0 130HP Merc No compression

I find it hard to believe that he has 0 compression on all 4 that easily.
My guess is his compression gauge is dead.
Have him put is finger over a plug hole and crank the engine and see if there is actually any compression.

 

[Bruce San]

Re: 1988 3.0 130HP Merc No compression

compression tester was good. Turned out to be a blown head gasket. The head is out getting a valve job now.

 

[Don S]

Re: 1988 3.0 130HP Merc No compression

I'm sorry, but a head gasket does not blow all 4 cylinders down to zero all at one time.
Something else is going on that we don't know about.

 

[Bruce San]

Re: 1988 3.0 130HP Merc No compression

That's what I thought too. We'll see. It ain't over yet. I'll keep you posted.

I wish I was there to actually see what is going on and get my hands on it.

 

[Dante04SRT]

Re: 1988 3.0 130HP Merc No compression

Any new news?

 

[Bruce San]

Re: 1988 3.0 130HP Merc No compression

Yup. Head is back on with a valve job and new gasket. Desciption of compression is as follows: "Not quite zero. Fluctuates from 0 to 25 then it may go to 100 and back to 0. Back and forth up and down, but no where near 140 where it's supposed to be."

He says his next step is a leak down test.

 

[cheburashka]

Re: 1988 3.0 130HP Merc No compression

He should verify the timing before he runs it again. From the "running like a scalded dog" and the blown head gasket, I wouldn't be surprised if somebody had set the timing wrong, with too much advance.

 

[Don S]

Re: 1988 3.0 130HP Merc No compression

Timing isn't going to change the compression. BUT, have him check the engine oil. Is the level over full? Is it aireated? Could be pumping up the lifters with aireated oil.

 

[cheburashka]

Re: 1988 3.0 130HP Merc No compression

Timing isn't going to change the compression. BUT, have him check the engine oil. Is the level over full? Is it aireated? Could be pumping up the lifters with aireated oil.

What I meant was that if it is indeed a blown head gasket, advanced timing could be the culprit. I'm with you in doubting that a head gasket could cause all four cylinders to lose compression, but assuming he's right and that it was a blown head gasket, too much advance could have caused it.

 

[Dante04SRT]

Re: 1988 3.0 130HP Merc No compression

So was it truly a blown head gasket or what? Were there any other problems as well? I'm in the same boat right now.

 

[Bruce San]

Re: 1988 3.0 130HP Merc No compression

Leak down test performed last night. Air whistling out of many passages leading to crankcase. Even with oil applied to cyls. 1 and 4 wouldn't hold squat. 2 and 3 were poor at best. The old boy has thrown in the towel and is sending it out for rebuild.