5niner98

ok, this is my first post so I hope Im doing it right. I have a 98 gcl 5.9 with a really loud obnoxious engine squeak. It starts when the motor gets up to running temperature, only at low rpms. anything over 1500rpms and its gone. i originally replaced the belt, a few pullies, water pump, harmonic balancer, timing chain, power steering pump and alternator..alot of un needed spending on my part, but it was driving me nuts. after all of that, still no change. i was reading a post last night about a sqeak in a newer srt and it got me thinking...i let the motor run until it heated up and made the noise, went to take the oil cap off while the motor ran and there was ALOT of pressure released from the engine. right when the pressure started to release, the noise went away! put it back on..noise came back and so on. i checked the pcv valve and hose and it was working properly...and other suggestions on what will remove some of that pressure? its killing me, i know it must be something stupid. sorry about the novel, but i hope i made myself clear.

aa7kn

wow, that's really odd...when you opened the oil fill cap pressire came out and the noise stopped ? try leaving the cap on, and follow the PCV valve or other breather hose and don't did connect it at the valve cover, try removing the hose at the other end...maybe you have a plugged hose and it is not letting the engine breath...that is wild...Hope you get it fixed and let us know what it was.

dave1123

There are 2 hoses in the crankcase vent system. One goes to the air filter housing and is supposed to let fresh clean air enter the engine. The other one goes to the throttle body or intake manifold thru the crankcase vent valve (CCV/PCV). The CCV pulls in vapors from the crankcase using engine vacuum.

Unless BOTH hoses are plugged OR the rings are worn badly, there shouldn't be any pressure in the crankcase. Usually when you've got bad rings, the air filter housing will be wet with oil. The question in my mind is what's squeaking? And why is it squeaking only after it warms up? This is going to require some thought. Maybe another member has some idea. I've never heard of this problem before.

Does the engine run smooth with no oil smoke? Try running it with the oil fill cap off and rev it up. Does it smoke from the filler when you do that?

Oh, BTW, welcome to CF!

5niner98

It's funny that I'm getting replies because this post is from 5 years ago haha. I appreciate both of your responses. It turns out that the day I sold my Jeep (because of this darn noise) I figured out the problem. When I removed the hose from the cold air intake that connected to the valve cover, the noise went away. The port and hose were too small. The issue immediately gone. I wasn't too upset though, I ended up with a 94 Mustang Cobra with all the bells and whistles to replace it. Thanks again for the responses.

dave1123

It must be aa7kn was trying to find something to post.

I'll bet that was more of a whistle than a squeak.

Nateoffroad

I have a '98 Jeep Grand Cherokee, 5.9 w/ a K&N intake kit. I was ready to spend some money trying to get this thing fixed until I read this thread mentioning to take off the oil cap. Sure enough, bunch of pressure built up in there so I traced the PVC valve and bingo. It took 2 minutes with a 5/16 drill bit. Apparently the K&N intake kit never had the Port that runs the PCV valve drilled. Thank you!