2000 Johnson 175 Compression

[cjr]

I am contemplating buying a boat with a 2000 Johnson 175 on it. The compression ranges from 102 to 105 in all cylinders. This seems a little low to me, is this acceptable? The dealer claims the engine only has 71 hours on it. For such a new and lightly used engine should the compression be higher than this? It is a positive sign that there is little variation between cylinders, but I guess I expected the actual compression values to be higher. Any thoughts?

 

[jim dozier]

Re: 2000 Johnson 175 Compression

There was a posting just a few days ago about compressin readings, you might try a different gage and see if the readings are higher, you're right that the important thing is they are all close to each other.

 

[Brew]

Re: 2000 Johnson 175 Compression

cjr,<br /><br />Although my 140hp Evinrude is quite a bit older (1986), I thought you might appreciate knowing that compression all four cylinders is at 110 give or take a pound. So... your 102-105 might not be that abnormal.<br /><br />I'm no expert, but I do recall reading in previous posts that anything above 100 and within a 10% variation between cylinders is perferctly acceptable.<br /><br />Good luck!<br /><br />Cheers,<br /><br />Brew

 

[clanton]

Re: 2000 Johnson 175 Compression

Do a decarb and try a new sears gauge, you might find 115/120 psi.

 

[Sand Bass]

Re: 2000 Johnson 175 Compression

cjr, I read a post from Joe Reeves stating that after 1993 OMC lowered compression ratios on the V6's because of gas quality. Might try a search here and see if you can find his previous post.