Bad Compression

[tmfd]

Re: Bad Compression

Are you spraying starting fluid to keep it running? Starting fluid can harm the engine further. Overall, the video is a very good "how NOT to" work on or test an outboard motor.

 

[swick]

Re: Bad Compression

Are you spraying starting fluid to keep it running? Starting fluid can harm the engine further. Overall, the video is a very good "how NOT to" work on or test an outboard motor.

its not starter fluid, and its not to keep the engine running. But thanks for making a dumb assumption. Actually it ran just fine, even better today. Didn't run it long enough to come out the tell, like John was saying, and I did not have the throttle up. This is the first time that this engine was really run in about 2 years. Ran perfect today.

 

[tmfd]

Re: Bad Compression

Well what is it then

 

[swick]

Re: Bad Compression

checked compression again and the bottom stayed at 110 however after a good run the others went up to 180, 180, & 160. I know I should do a leak down test, short of pulling off the head what else should I do or could I do? As of right now I have the engine sitting tilted up with some marvel mystery oil in all 4 cylinders. I'm going to let it sit over night and give it a shot tomorrow looking for signs of progress. Also have a decarb on my to do list. Any other advice?

 

[john from md]

Re: Bad Compression

Before doing anymore, you need to do a decarb to see if the 110 is from sticking rings. Marvel mystery oil is a great penetrant but it has no detergent properties and will not break down carbon build up.

If you had the capability, you could do a differential compression test. This basically does a leak down check of the cylinder. That would give you an idea of if it was the rings or the head gasket.

If you still have low compression after a good decarb and good run, pull the head and take a look see.

John

 

[foodfisher]

Re: Bad Compression

Your compression guage is suspect. 180 is higher than factory new. IMHO

 

[swick]

Re: Bad Compression

I got on a friends compression tester then I went and bought a brand new one and it read exactly the same.