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Alright, looking to source some ideas from everybody. I recently finished up a head swap along with new rockers and pushrods. Everything seems to be running pretty well except I’m getting this odd squeaking noise when the engine is up to temp and idling. Above idle it seems to go away and it doesn’t happen when cold.
At first I was worried the pushrods might be misaligned or not oiling but I’ve double checked them and clearances and oiling seemed to be fine after running it with the valve covers off. The odd thing is the noise didn’t happen with the covers off and it also goes away when I’ve got the covers back on and the dipstick pulled. This makes me think it might be a small vacuum leak but I’m not sure why it’d be missing when cold or revving if so. I’ll still be running that down.
Just curious if you guys have anything else you think I should be checking?
If the noise goes away when you pull the dipstick out you should pull it all the way out and put your thumb over the hole to feel for suction.
There’s definitely a vacuum in the block/crankcase and pulling the stick relieves it. Do you think it’s too much maybe? Would that be a problem with the pcv valve?
I switched over to a mini ram intake but I’ve retained the original pcv routing. Intake to valve cover on the passenger side and then on the driver’s side I’ve got the pcv valve in the cover routed through a catch can and then back into a port on the back of the intake.
I guess it could just be a whistle through the filter in the catch can. I’ll check for that.
Thinking about it, maybe I need to move the pcv intake line to between the throttle body and MAF instead of after the throttle body to reduce that vacuum?
Not sure how the PCV routing is on a mini ram. You could have stuck PCV valve. check to see if it rattles when you shake it.
I'd clamp off or block the PCV hoses on each side. You should then feel some pressure at the dipstick tube depending on the amount of blow by. If there is still vacuum with the PCV system blocked it could be a manifold leak.
So I just slapped a filter on the pcv intake on the passenger side and capped off the port it was being fed from and, voila, no noise. I think it must’ve been sucking too hard on something.
I’m going to be switching over to a MAP sensor here in the near future so I’m less worried about unmetered air making it in. May just call this one solved.
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Speaking from around valve covers
