mercury 150 blackmax compression

[EBENZER]

guys i just got a 87 merc 150 blackmax . it has been sitting for 2 years.First thing i did was check compression. the numbers were as follows: left bank 118-118-117 right bank 108-110-108..is it ok for bank to have a difference like these..thanks for help

 

[rabeck5792]

Re: mercury 150 blackmax compression

yes,it is normal for 1 bank to have about 10 psi difference,due to rotation & piston rock-over.

 

[EBENZER]

Re: mercury 150 blackmax compression

so are these number ok for a healthy engine..

 

[rabeck5792]

Re: mercury 150 blackmax compression

they seem to be,because not all compression gauges read the same.you should really use a leak down tester.

 

[CharlieB]

Re: mercury 150 blackmax compression

Cold engine, hasn't been run in a couple of years?

With these numbers it should be safe to go ahead, clean the carbs, invest in a new impeller and gear oil, fire it up on the hose and run it 10 minutes at a moderate idle to fully warm up then retest for a much more reliable reading.

It may be just fine for a long time yet.