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Mike S.
Mike S., Mechanic
Category: Car
Satisfied Customers: 5060
Experience:  25+ years experience as an auto mechanic.
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2007 Jeep Wrangler: Hi, we just put in a long block on this

Resolved Question:

Hi, we just put in a long block on this truck. it ran fine for about 1000 mi. then began to run rough. It pulled a number 5 cylinder misfire code. We did a compression check and a leak down check. It failed the leak down pointing to exhaust valve. We removed the valve cover and the number 5 exhaust rocker had destroyed itself. I was in touch with the warranty guys from NAPA and he sent me new rockers and pushrods. We put it on and ran new compression and leak down. 165 psi cold and no leaks through the valves. The issue is this, I am an old time backyard mechanic and used to seeing oil every where when I start the engine w/o rocker cover on. The valves we a little noisy at first but in within a minute at idle the engine sounded normal and seemed to function OK but I can't see any evidence of oil anywhere except a few drops here and there. I read your great site and see that at idle the pressure is only 5psi so after warming we ran it to 2000 rpm. sounds OK but still not much oil. Removed the long bolt in the Rocker Shaft and ran borescope in. Saw that the hole was not plugged. Poured Marvel Oil in and it flowed through. I am worried about no visible indication of oil since it is a new engine and it has already destroyed one rocker. Is it normal on new cars not to have lots of oil splashing everywhere? Thanks, XXXXX XXXXX man, or Frank, which ever you prefer.
Submitted: 1 year ago.
Category: Car
Expert:  Mike S. replied 1 year ago.

Did you check to see if the exhaust valve hit the piston?

Do you think the rocker failed because of a lack of lubrication? Any signs of that? Was the lifter or valve train tapping before? Does the rocker look blue or is there any small metal shavings laying around?

Did you check that the new push rod does squirt out oil when running?

Actually I am getting ahead of myself. After I typed this I continued to read and see you had already answered some of these questions.

Ok, no or little signs of oil? Is that both sides or just the one? I assume you did run the engine without the valve cover and look. Have to checked the oil pressure?

What weight of oil are you using? Did you add any STP to the oil originally when doing the longblock for breakin? If so, is it still in there? Have you changed the oil filter yet?

Expert:  Mike S. replied 1 year ago.
These are the specs I got, 5W-20 Motor Oil, 5 psi at idle, 30-80 psi at 3000rpm.
Customer: replied 1 year ago.


OK, I originally suspected that it may be a valve hit. I put the borescope down the cylinder after we poured Marvel Oil in the cylinder to see if it would leak through. (this is what the warranty tech told us to do) the marvel oil ate some of the carbon off the piston and I discovered a notch that looks manufactured and not a valve hit. It is wedge shaped and has very clean lines. None of the other cylinders has the same mark that we can tell. This worries me but the tech said they may put in different pistons. He couldn't come with a picture of one. I have never seen such a thing but I have seen valve strikes and this doesn't look like that. As I said we did a leak down compression test and there is no sign of exhaust valve not sealing. The rocker failed because the pushrod came out from underneath it. The rocker shaft was badly gouged on the bottom so I don't know what happened first.


Now we are getting great compression and a good leak down.


I only have the one rocker cover off. I can not see if the push rods are squirting any oil but the engine sounds normal. We did not use any STP for the break in. Have not checked oil pressure but no light is on and engine sounds normal . I just don't trust the no oil thing.

Expert:  Mike S. replied 1 year ago.

Different pistons? Do you believe that?

Well, so the exhaust valve isn't bent, that's good.

I don't think the oil light will come on untill it's under 1 psi, you should check the oil pressure.

Customer: replied 1 year ago.

I don't believe that but I also don't know what to think when we have good compression and the leak down doesn't show a bad valve or rings etc. I guess I will check the oil pressure and go from there. I was hoping someone would say "hey old man, we build tighter more efficient engines these days and they don't spray oil all over the place with the rocker cover off. Thanks, XXXXX XXXXX help.

Expert:  Mike S. replied 1 year ago.

Yeah, check that oil pressure.

Mike S., Mechanic
Category: Car
Satisfied Customers: 5060
Experience: 25+ years experience as an auto mechanic.
Mike S. and 15 other Car Specialists are ready to help you

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