New engine! Dead after 10 hours!

[ckraker]

:facepalm: got a 1989 4 winns for free! Of course there's a catch, the engine was junk. So i bought a rebuilt engine online that only had 10 hours on it. I heard it run, but we all know used engines are a gamble. Sure enough after about One hour on the lake poof... 30 psi on two rear starboard cylinders. I suspect the head gasket. Thoughts? Any idea why a gasket would fail so quickly? She ran great for an hour. Thanks

 

[alldodge]

Maybe mention what engine?

Anything is possible, it could have over heated, timing could be off or carb running lean and detonation started, or could be the motor had a problem and the prior owner put a band-aid fix, and now its yours

 

[ckraker]

It's the 4.3. sorry

 

[Rick Stephens]

If you don't want to do a quick disassembly, the only way to get an idea what happened is to do a leak down test.

 

[JASinIL2006]

After only 10 hours, I'd be thinking about trying to get my money back...

 

[Scott Danforth]

I would suggest a leak down test

 

[Benny67]

I bought one of those borescopes from amazon for like $20 Before you start tearing the engine down, maybe get one and see what's doing inside the cylinder with it. It may save you some time.

 

[Bondo]

Ayuh,..... My WAGuess is there's water, 'n crap in the boat's fuel system that caused a lean condition, 'n detonation killed it,.....

 

[stonyloam]

Low identical compression on two adjacent cylinders says the head gasket blew between them.

 

[Benny67]

Low identical compression on two adjacent cylinders says the head gasket blew between them.

Indeed...I'd agree on that diagnosis

 

[Scott Danforth]

without a leak down test we are all guessing. a leak down test will tell you where its leaking.

if its the head gasket and it was run for any length of time, it could have fire-slotted the block and/or head

 

[ckraker]

[No message]

 

[ckraker]

This is how my day started.. trying to figure out why it runs cold. :nono:

 

[alldodge]

Hope it didn't hurt the heat so much it cannot be repaired
Ebay would be best bet
https://www.ebay.com/itm/Mercruiser...193163?hash=item443c48ffcb:g:cDAAAOSwFmtcx2jJ

Could also think about a redesign and use newer (but not newest) style thermostat

https://www.mercruiserparts.com/bam/subassembly/31486/1599/125

 

[Scott Danforth]

now you have to determine why the head gasket went.

use a quality straight edge and feeler gauges to check the block and head

 

[ckraker]

Everything is still flat. Nothing over. 004. I'm nervous about this, thinking it's going to happen again.

 

[jimmbo]

Post pics of the block and head where the gasket failed

 

[alldodge]

Measure the block as well and note were the variations are in the block and head to determine if they will increase any gaps

 

[Evinrude Boater]

I was also interested in the overcooling situation since I’m having the same condition. I thought rust flakes from the t-housing got lodged in it, but no. I hope the blown head gasket and overcooling aren’t related. Looks like your T-housing froze.

 

[ckraker]

Nope it didn't freeze, i was trying to remove that plug to make sure nothing was plugging that passage behind it. Busted it myself. 200 dollars later a new one is on the way. I doubt the two issues are related. But I'll keep you posted. I am wondering if the overly cold engine somehow led to the blown gasket.