Is this unusually low compression for blown engine??

[shockerfd]

My brother-in-law to be just bought two 1997 skiis from a friend of his. Sorry, not exactly sure of the model but they have the 787 in them which I'm familiar with. I told him we needed to do a compression test to see what kind of life is left in these engines. One ski had a MAG psi of 150 which is great. The PTO barely registered 4-5psi. Before I got there he got it started and it ran fine although I thought it sounded strange to me when I heard it. The people he bought it from claimed it ran fine last summer. Is 4-5psi typical psi of a blown engine? My once seized engine was in the 50's. I would think with a psi that low it would be extremely hard to start and would not have run at all.

Thanks

 

[mudpie]

oh yeah, compression is bad!!
a engine can and will run on one cylinder, this is probaly why it sounds funny when running or it sounds like a bag of hammers cause the piston is broke
could have burned the edge of piston or siezed a ring, either way it needs to be fixed, so the price of the ski is going down!!!
good luck and be carefull
mud

 

[kustomkarl]

Need to tear it down and check it out if he keeps it.

The ski will start out of the water but it will not start in the water with a load on the engine. Your looking at over $300 bucks if you rebuild the top end with 2 new pistons yourself with oem parts.

:agree: if the piston pieces didn't wipe out the crank bearings, and the bottom end...then it's time to replace the engine or spend lots on a rebuild...

 

[shockerfd]

I definitely think replacing the engine is the way to go. I figured even with psi that low, running out of water would be horrible. We haven't gotten to the other ski yet because the wear ring is chewed up and some corroded wiring has to be fixed. He's called them and they've been going back and forth about what to do about the deal. Things are kind of getting ugly. If the second ski doesn't check out he wants to walk away from the deal, which I can't blame him.

 

[kustomkarl]

Unless he paid a really really cheap price, he should walk away...there are lots of good machines for sale with the way the economy is.

Karl

 

[shockerfd]

Unless he paid a really really cheap price, he should walk away...there are lots of good machines for sale with the way the economy is.

Karl

Technically only partial payment has been made but the deal was for 2 1997skis(3 seater) with tandem trailer for $1500. Great deal for running skis IMO but if both have blown engines not sure it's worth the hassle. One is going to need a new wear ring and both would get carb rebuilds. Rave cap is melted on the other ski yet to be tested, which has me concerned. Hopefully that's a bad oring or most likely too much clearance. So there are a few other little things that need fixed or replaced. They are a little rough around the edges but would serve his purpose for now. I just don't think he has the time or money to drop in a couple new engines if needed, one for certain at this point.

 

[shockerfd]

Engine on the second ski was seized. I can't say I was surprised by the look of things. Two skis and two blown engines. It's going to be no deal!