Bad intake valves: Why?
05-03-2011, 06:26 PM
#1
artselectricinc.com
Platinum MemberThread Starter
Bad intake valves: Why?
Late last year I had my motor rebuilt locally by a reputable re builder. He is not exclusive marine but does a lot of them. It is a stock 502 that was retrofitted to Merc EFI a few years ago. It is in a 42ft Harley and is ran steady between 3400 and 3600pm's and occasionally 3800 if I am in a hurry. WOT is 4400 if I trim the drives up some. The other engine has over 1,000 hours on it and is getting tired but still runs pretty darned good.
The motor in question has approx 40 hours on it now. I noticed it idling poorly so I looked everything over and did a compression test. I found the numbers all over the place. Anywhere from 60psi to 155psi.Did a leak down and found that most all the intakes valves are leaking bad. So I called the builder and asked him if there is anything that I could be doing wrong. He said If I was running too rich it would keep the valves too cool preventing them from seating and eventually cause them to tulip.
The engine is running rich.(I did not tell the builder this during our conversation) but didn't think that it would harm the engine. Is this a plausible explanation? I have never heard of this before, so I am skeptical.
If running to rich caused my problem, then I will send the heads to him to get fixed. If not I will have to do something else. I'm not trying to get anything fixed under warranty as much as not doing the same thing over and over. I take this boat out of state every year and it has to be dependable.
The motor in question has approx 40 hours on it now. I noticed it idling poorly so I looked everything over and did a compression test. I found the numbers all over the place. Anywhere from 60psi to 155psi.Did a leak down and found that most all the intakes valves are leaking bad. So I called the builder and asked him if there is anything that I could be doing wrong. He said If I was running too rich it would keep the valves too cool preventing them from seating and eventually cause them to tulip.
The engine is running rich.(I did not tell the builder this during our conversation) but didn't think that it would harm the engine. Is this a plausible explanation? I have never heard of this before, so I am skeptical.
If running to rich caused my problem, then I will send the heads to him to get fixed. If not I will have to do something else. I'm not trying to get anything fixed under warranty as much as not doing the same thing over and over. I take this boat out of state every year and it has to be dependable.
