AQ130c Compression Readings

[pcmpete]

I am getting serious blow-by and loosing alot of oil. Little smoke from the exhaust but alot of oil around the engine, especially the front. Can the blow-by effect blow gaskets and seals.

At idle, when I remove the oil filler cap the rpm would increase by approx 100rpm.

The dipstick level would go from full to nearly off the stick in a 4 hour trip (25% of time in No-Wake zones to pulling tubes and general WOT)

I finally got round to taking a compression test, results below.
From these results and the blow-by can I safely say that my piston rings are shot?

Or is there something I should be looking for.

AQ130c Aug 2009
Compression Test Results

Dry Cylinders (psi)
1. 125
2. 150
3. 150
4. 140

10ml Oil in Cylinders (psi)
1. 150
2. 175
3. 180
4. 175


Thanks for your time.

 

[captmello]

Re: AQ130c Compression Readings

The book says compression should be between 170 and 200.

So it seems your engine is a bit tired. However, The fact that the compression only went up 25 psi when wet makes me think your valves may need adjusting. Have you adjusted the valves recently.

The oil filler cap thing is interesting. I've never taken the cap off my boat or a car for that matter while it was running.

Sometimes I think what we think is blowby is condensation evaporating out of the oil.

Maybe your crankcase isn't venting properly and building up a little pressure causing the excessive oil leak.

You need to identify where the oil is leaking from and fix it. Do a valve adjustment and see what the compression numbers do.

Are you thinking of rebuilding it this winter?

 

[pcmpete]

Re: AQ130c Compression Readings

The Valves were adjusted and set within the last month, and since then the oil loss has increased, (not sure they that would be related or not)
The motor is 34 years old, so it just could be suffering from too many birthdays and needs either a rebuild or put out to pasture.

It is hard to pin-point there the oil is coming from, I have cleaned the engine the best I could and then after a good run on the water the engine is covered from the Valve Cover & Under the Air Box right down to the oil pan. Could it be alot of blow-by not being able exit the dog house and settling back down on the engine, the inside of the dog house gets covered in oil too.

Thanks for your replies.

 

[ENSIGN]

Re: AQ130c Compression Readings

With that much blowby it sounds like its time for a rebuild