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Engine Compression Readings

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USCG1968

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"Engine Compression Readings

"Engine Compression Readings

In getting ready to sell my old 1992 Evinrude 125 (140) hp I did a compression test on each cylinder. Each cylinder read out at 115 psi with the right lower read out at 135 psi. I tested it out with two different gauges and both time it came out the same. Why would a cylinder read out much higher then the other three? I can see under the 4 th cylinder reading much lower but higher? Ever since I had the 1992 125 hp one of the plugs would foul up after towing another boat. I would just clean that plug and it would be ok. Any ideas? Thank you. ……. Fred

[email protected]"
 
One of my neighbors who works

One of my neighbors who works on outboards on the side did the test. We cranked over the engine over fast and once at a time we took one spark plug out and screwed in a compression tester. He was very surprised to see the one cylinder running high when the other three were exactly the same. He was going to buy my engine until he saw the readings. Since he had two compression testers he wanted to test it twice.

What my neighbors does is he get an older Boston Whaler and McKee’s and re-do them like new. Then he installs an older engine that still has life and sells the package with a “For Sale” sign on his front driveway. After testing the first three cylinders he made me an offer for the engine. Then the last reading came in high (135) and he took the offer away. Oh well. The funny thing is last summer I was using that same engine all summer.
 
Remove all of the spark plugs

Remove all of the spark plugs before doing that compression test. Did this make any difference?
 
The plugs must be in except th

The plugs must be in except the cylinder you want to test to get a reading.
 
My mistake. Joe told me he had

My mistake. Joe told me he had all the plugs out when he did the test.
 
"Well it was cold in New Jerse

"Well it was cold in New Jersey; the engine is in my cold garage out of the weather. Having said that we still have the problem of 3 cylinders with psi 115 and the last one is 135 psi. Can you send me your e-mail or your number and I will give you a call..... [email protected] Thank you"
 
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