Hi All,

Really hoping for some feedback on this!

Every once and a while, usually after I've been driving on the expressway for about 20 minutes (home from work), after I accelerate from a complete stop, i get 3-5 knocks and can feel them easily under my feet. If i accelerate harder it seems a bit harder and loader. I'm not a mechanic, but I know a little, and I've crawled underneath and cant seem to notice anything out of the ordinary.

I have a 97 XJ Sport... Any ideas? Again its usually only after getting off the express way (has happend other times), and accelerating from a complete stop. It doesn't do it all that much. Ujoints seem solid, and from what i can tell, the bushings look good.

Thanks!

 

Does it seem like it's coming from the engine?

What oil pressure are you seeing at hot idle, cruise, and under acceleration (when you hear/feel the knocks)?

What coolant temp are you seeing when you feel/hear the knocking.

Are you using gasoline from a different gas station than what you have been using?

Is your oil level okay.

What oil and oil filter are you using? When's the last time they were changed?

What engine is in your XJ?

 

If it happens when you hit bumps you may want to check on the exhaust mounts, my pipe doesnt run under my feet but I still feel the exhaust pipe rattle.

 

All my gauges read fine. It definitely doesn't sound like its coming from the engine. Some of those questions seem irrelevant... oil level is fine. 97 sport, 4.0 I6.

It sounds and feels like it's right under my feet, and it doesn't happen while going over bumps. It only ever happens when i take off from a complete stop, and it does it right away, 3-5 quick knocks. It only happens maybe 25% of the time (if even that), and usually after I get off the expressway after about 20-25 minutes on my way home from work.

 

Do you by chance have a manual ? I had an 88 that would do that and the hose to the slave was bent and would hit the floor under the right conditions

 

Try greasing your front drive shaft slip yoke. Check for slop in the front drive shaft u-joints.

 

Check to see how close your exhaust pipe is to the transmission crossmember. I recently had a very similar issue and the trans mount had collapsed. New mount fixed the problem.

 

Have you closely inspected the motor mounts and transmission mount?
I agree with other responses about the exhaust knocking on the crossmember. Bad mounts can cause this.

 

This^^.

 

Hey! That's my pic you thief.

 

Why, yes it is. Did I ever thank you for that? LOL...

 

 

I'll have to take a look. From what I could tell the motor mounts in the engine compartment looked fine. I just figured it wouldn't be the exhaust hitting the cross member since it doesn't happen over bumps or anything. But I'll take a look.

I was thinking it was the drive shaft slip yoke possibly, I haven't greased that yet.

Also, no, I don't have a manual.

 

Poke your noggin under it and see. Figuring don't count.

 

Poked my noggin under there, and the mount looks fine, no play.

Any chance this could have anything to do with the transfer case linkage? Before I bought the jeep, it seemed to go into 4 wheel fine, but didn't notice if the light came on (me not paying attention). The other day I went to put it in 4W and noticed the light didn't come on. Wasn't exactly sure if it went into it or not. I did it fairly quick once I noticed the light didn't come on.