F134 Upper Engine Noise

[crscrkcj]

The more I drive my CJ5 and work to eliminate the noises, the more noises I hear. Recently noticed that when the engine is warm it has a small tap. or knock. I have checked it out while in the driveway and it appears to be a upper engine noise as vs crank. It only makes the noise when engine rpms are increased. When steady rpm, I don't think it is tapping at all. I believe the engine block has had the deck planed when last overhauled. I'm thinking that we could be very near to critical tolerances with piston - valve clearances. It has very few miles on it since rebuild. Does anyone have any experience with such? If so how was it detected? Other than pulling head what can one do to confirm minimum or less clearance? Visually?

Thanks

 

[gert]

Well I hope the pistons arent hitting if they are the motor usually likes to go boom I was going to say check on adjusting the valves but your valves are under the head. I dont know if you can adjust em

 

[CJ]

Is it a deep, or hollow or a tinny sound? Depending on that - we might help.

The big problem is that without actually hearing it - it could be anything!

One thing, I heard a an old CJ engine noise that baffled me for a long time! It ended up being the water pump - the bearings were gone and as you reved it, 'it clunked'...

It could be just about anything...

 

[crscrkcj]

Well I hope the pistons arent hitting if they are the motor usually likes to go boom I was going to say check on adjusting the valves but your valves are under the head. I dont know if you can adjust em

Intake valves are in the head, exaust in the block. Sort of half overhead valve.

 

[crscrkcj]

Is it a deep, or hollow or a tinny sound? Depending on that - we might help.

The big problem is that without actually hearing it - it could be anything!

One thing, I heard a an old CJ engine noise that baffled me for a long time! It ended up being the water pump - the bearings were gone and as you reved it, 'it clunked'...

It could be just about anything...

CJ,

New water pump and alternator. Alt was bad and was making so much noise you couldn't hear the exhaust noise.

The sound is not tinny. It sounds more like a peck with a small dowel or wooden hammer handle. Could it be a piston slap. I know nothing of what was done during the overhaul. The engine starts great and has no exhaust blow-by. When you are accelerating it makes the noise, but when it gets to speed and you shift it level off it runs smooth as butter. Probably best running at lower rpm such as 1500-2000 in 2nd or 3rd gear.

I'm concerned about how much you can take off the block since the serial number has been completely removed from the front boss. Thats got to be at least .020-.040" . Unless there was never a number stamped? Ever heard of that?

 

[Old Dog]

the only way I know off to check piston clearance is to pull the head and put puddy on the piston, put the head back on and turn the motor over, pull the head back off and check the marks left in the puddy. A lot of work but it will tell you the story.
If that much has been taken off the head, you now have pretty high compression, could you be hearing engine ping? Maybe try running premium gas and see if it goes away.

 

[crscrkcj]

Premium gas got most of it. I've got to get a compression tester. No telling what the compression is. But it must be close to 10:1. 91 octane didn't do it all. Also, I'll adjust timing.
Thanks Old Dog

 

[Old Dog]

Well since you are old enough to remember, reg. gas use to be at least 91 octane, so you might need to run that and add a can of 104 octane boost. A lead additive might be a good idea for your valve train also.
As you said make sure your timing is not to far advanced. Good luck.