258 knocking!! What a surprise!

[J:UN]

Ok first of I’m new to the board so hello everyone!

And for my first post I’m gonna make a vague and ridiculous question.

I have a 89 yj with the 258. The problem is a slight tapping in higher rpms …I have no power loss and it does it weather or not I’m driving. I have yet to really get into the engine to look at but I was wandering if there would be some general quick things I could look for that you guys would suggest. We’ll thanks for havin me


Jason

 

[erhild]

Hello and Welcome to the board...

Just a quick guess would be a stuck lifter, bend pushrod or leaky exhaust manifold... That is where I would start looking anyhow...

 

[Jeepskate]

With a long handled screw driver or chunk of broom handle you can listen to the lifters and rods to really hone in on the one thats clicking (assuming that's the problem). They also make a mechanics stethescope for the same purpose. Go watch "Mr. Hollands Opus" the deaf kid in the movie does this to tune his Corvair's adjustable rocker arms. It's a good way to get real intimate with your engine without the commitment of taking it's top off... I mean it's valve cover.

 

[brian4.2]

I like the exhaust manifold, my TJ sounds horible for 5 minutes. Quiets right down.

 

[J:UN]

Thanks for the info so far, Seems as though the sound is coming from the lower front of the block...I went ahead and replaced the water pump..still there....so I went and bought a new Timing chain and gears which I'm glad I took care of because the old had close to a 2 inch play!!! ok so as I was cleaning the timing cover I noticed some chain rubbing on what I believe to be some sort of chain guide? Well i didn't have the $ or the transportation to buy a new one and since the new chain was tighter I didn't get a new one...Still taps!! Two days ago I went and changed the oil to a 20w-50 which worked really well on surpressing the noise untill it strats warming up and the tapping starts driving me insane again.

I'm almost to the point to start looking into the cam...Any other suggestions before I start?

 

[judge09]

Well this is my second time replying...my comp is crapping out. So I hope this reply doesnt come up twice. Simple check is the torque on the rockers. But I had a problem like that with this nissan I was working on and the clicking was coming from the A/C compressor. I know most YJs dont have A/C but if you do check it out.

 

[olyeller]

i'm with the judge, even though it sounds like the noise is coming from the lower part of the block, i'd check the rockers (experience talking). i had a ticking sound from my 258 too. i removed the valve cover to reseal it and decided to check the rockers and 2 of them had play in them when there was no pressure from the pushrods. i could wiggle them until they would almost not push down on the valve stem. i used a surface grinder to take some metal off the bottom of the keeper for the rocker and the noise went away.

 

[J:UN]

Ok ....I'm hesitant but it seems like an easy check. I shouldn't have to replace the valve cover seal right?

 

[J:UN]

Nope!! not the rockers or the pushrods.


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