Compression 1987 Evinrude XP 150

[muchco]

I'm looking at purchasing a 1987 Evinrude XP 150. Cosmetically it looks in great shape. I asked the shops mechanics to do a compression test on the engine. The test came back at 85 psi on all 6 cylinders. This appears to be low. I asked the Mechanic and was told that for the year and model of the engine this was normal and the fact that the cylinders are even is a better indicator than the 85 psi. I was also told that the V6 crossflow is a low or lower compression engine than the V6 loopers. Is this true? The engine appears to run fine. Model #E150STLCUR.

 

[Dhadley]

Re: Compression 1987 Evinrude XP 150

Welcome!!<br /><br />Your guy has it backwards. Its not unusual for loopers to have slightly less static compression because of the aggressive port timing, port area etc. 85 seems a bit low but even is good. Static compression has a lot to do with what heads are on it and which head gaskets it has.<br /><br />See if you can get the casting numbers off the heads and we'll see what heads are on it.

 

[muchco]

Re: Compression 1987 Evinrude XP 150

Ok, I will see if I can get the head casting numbers. If it's even and runs fine should I still be wary? Also would giving it a good De-Carboning with Seafoam or a like product possibly raise the compression? Thanks for the response.

 

[Dhadley]

Re: Compression 1987 Evinrude XP 150

Possibly. A good decarb job cant hurt -- well, OK it can if you leave it in the motor too long. Just follow the instructions on the can. But thats a good idea.

 

[muchco]

Re: Compression 1987 Evinrude XP 150

Thanks for the input, I will try the de carboning

 

[farginicehole]

Re: Compression 1987 Evinrude XP 150

Dhadley, what damage can be done if you leave the decarb product in the motor too long, and how long is too long? Just curious because it seems like it says on the can of Sea Foam Deep Creep that it can also be used as a fogging oil. Maybe this is a different product than others? Thanks!

 

[Dhadley]

Re: Compression 1987 Evinrude XP 150

It could be different, I've never used it. I use OMC / BRP Engine Tuner. Its pretty potent and if you leave it in too long it will actually dry out the oil on the sleeves. Then the cylinder that has the exhaust ports open can start to get surface rust. Then ring wear etc. Only seen it twice. <br /><br />I'd just follow the instructions on the can youre using. If the Sea Foam is used as storage oil then it must be OK.

 

[farginicehole]

Re: Compression 1987 Evinrude XP 150

I see. Thanks!

 

[muchco]

Re: Compression 1987 Evinrude XP 150

To Dhadley, I have had a chance to decarbon the engine and that raised the compression from an even 85 on all six to 95 on all six cylinders. In an earlier posting you had mentioned to get the head casting number to see which heads this engine had on it. Would you be able to tell me wehre to locate the casting number on the head? Thanks.

 

[CATransplant]

Re: Compression 1987 Evinrude XP 150

Good news, muchco. I had the same 85 compresson on my old 35. Decarbing and running for a while brought it up to 105. As long as they're even and the outboard is running well, I'd have no worries. Test it again at the end of the season, and I'll bet it goes up a few more psi.

 

[muchco]

Re: Compression 1987 Evinrude XP 150

Thanks for the response, that Seafoam is amazing stuff. I live in Canada, couldn't find it anywhere up here. Was able to have some brought in from North Dakota. I will be stocking up for the future. These forms are a great thing for the do it yourselfers. Have a good day.