Low Compression Problems

(teedub01) · (teedub01) **Join Date: Aug 2007** 08-28-2007, 2:48 PM

I just bought a 2004 Supra Launch in March. A few weeks ago the engine started to run rough and it sounded like it was running uneven, if that makes sense. I took it to a shop and they said that two of the eight pistons are running at 4 and 5 pounds of pressure instead of 170. Anybody have any idea what the problem could be?

(phatboypimp) · (phatboypimp) **Join Date: Apr 2005** 08-28-2007, 3:19 PM

Rings are shot or potentially a blown head gasket. Time for a top end rebuild. Essentially resurfacing the heads, replacing the head gasket and putting new rings on the pistons. Not cheap.

Pre-mature piston ring wear is usually caused by poor maintenance. Although there are a lot of people on this site that know more than I do about this issue.

(wakesetter101) · (wakesetter101) **Join Date: Oct 2005** 08-28-2007, 3:33 PM

I would bet you have a blown head gasket. Are the two cylinders with low compression side by side? If thats the case (and i bet money that it is).
You will need to pull the intake and then the head. Not that big of a deal. Just a pain.

(teedub01) · (teedub01) **Join Date: Aug 2007** 08-28-2007, 3:34 PM

The engine only has 92 hours on it and I know for a fact that the previous owner took immaculate care of the boat/engine with regular tune-ups etc. Plus, I had it surveyed before I bought it and the surveyor said it was in pristine condition. It had been running just fine this whole summer and then this. I am seriously at a loss...

(teedub01) · (teedub01) **Join Date: Aug 2007** 08-28-2007, 3:34 PM

Yes, they actually are side by side

(nasty530) · (nasty530) **Join Date: Aug 2007** 08-28-2007, 5:42 PM

Like Big E has stated, chances are it is a blown head gasket. This is certainly less than needing a rebuild but still not cheap. Take it to a traditional auto mechanic, my experience has been that they are a little less expensive then boat dealerships and there is nothing much different about the engine.

(wakesetter101) · (wakesetter101) **Join Date: Oct 2005** 08-28-2007, 5:51 PM

Are you going to try to tackle this yourself? It could be done on a Saturday. Head gaskets normally run around $50 bucks i would guess.

(teedub01) · (teedub01) **Join Date: Aug 2007** 08-28-2007, 6:09 PM

No, I probably won't tackle it myself. I don't know enough about engines to even go there. Plus, I want it done right. Any guess as to how much this could be?

(malibuboarder75)

Maybe find a guy in the neighborhood who works on engines and pay him to help you.

(teedub01) · (teedub01) **Join Date: Aug 2007** 08-28-2007, 6:42 PM

That actually might be a good idea. I really want to have it fixed before Labor Day weekend and that's probably my best hope. We'll see, thanks for the tip though!

(bob) · (bob) **Join Date: Feb 2001** 08-29-2007, 2:22 AM

If you plan on tackling it yourself, even with an experienced persons help, get the shop manual. Seems to me you need to find the cause to prevent a second blown gasket. Did the warning horn ever come on, telling you that it overheated?

(psudy) · (psudy) **Join Date: Dec 2003** 08-29-2007, 9:25 AM

It could be a burnt valve as well. That happened to my boat, and they just replaced the valve. It wasn't cheap, but nothing a mechanic does to a boat is.

(Message edited by psudy on August 29, 2007)

(teedub01) · (teedub01) **Join Date: Aug 2007** 08-29-2007, 10:38 AM

No, nothing came on that the boat was overheating.