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Low even compression on twin evinrude 150 Ocean Pro engines

J

Jcomach

New member
Hi, good day.

I am new to the boating world. I just bought a 1986 2500 Pursuit Tiara. It came with twin Evinrude 150 Ocean Pro 2 stroke engines with 724/738 hrs.

I had the engines checked by a reputable Johnson mechanic. Everything came back good. The engines looked brand new and were taken care of all it's life.

The problem is that the boat was owned by an older gentleman that let it sit for 5 years. Recently (Jan 2020), the family had the same Johnson mechanic do a full service, including rebuilding the carbs, changing the water pump and impeller, and general service.

I had a compression test done, and all the numbers came back low. Lowest at 74psi highest 81psi across both engines. Now I could understand if one or two cylinders are low and the rest are high but what will cause all the cylinders on two different engines to have such low compression?

I am looking to see what you experts have to say on this. Any help will be much appreciated.023CDABA-C9F0-4332-86BF-0257117275DF.jpegB4CDDCA9-4149-4759-A51C-85F14975CEF6.jpeg
 
Jcomach said:
Hi, good day.

I am new to the boating world. I just bought a 1986 2500 Pursuit Tiara. It came with twin Evinrude 150 Ocean Pro 2 stroke engines with 724/738 hrs.

I had the engines checked by a reputable Johnson mechanic. Everything came back good. The engines looked brand new and were taken care of all it's life.

The problem is that the boat was owned by an older gentleman that let it sit for 5 years. Recently (Jan 2020), the family had the same Johnson mechanic do a full service, including rebuilding the carbs, changing the water pump and impeller, and general service.

I had a compression test done, and all the numbers came back low. Lowest at 74psi highest 81psi across both engines. Now I could understand if one or two cylinders are low and the rest are high but what will cause all the cylinders on two different engines to have such low compression?

I am looking to see what you experts have to say on this. Any help will be much appreciated.View attachment 25136View attachment 25137
Click to expand...
A faulty compression gauge.
 
He actually had two gauges. It happen to him before. He tested one cylinder twice. Both were within 2psi of each other.
 
When we took the boat for the sea trial, they started easily and ran fine no sign of hesitation on both. We did do the compression test about 2 hrs after the sea trial.
 
Those are 60° motors and about 95-100 psi when new at cranking. Your gauge could be low reading so spray some OMC Power Tune in the motors following can directions and add some Carbon Guard to fuel. Also since it sat I myself would drain and flush oil tanks in boat and refill with quality TWC3 oil.
 
faztbullet said:
Those are 60° motors and about 95-100 psi when new at cranking. Your gauge could be low reading so spray some OMC Power Tune in the motors following can directions and add some Carbon Guard to fuel. Also since it sat I myself would drain and flush oil tanks in boat and refill with quality TWC3 oil.
Click to expand...
Thanks. Will try to drain and flush the oil tanks.
 
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