1994 Jeep YJ Engine Knocking

RICH S

MEMBER
1994 JEEP WANGLER YJ
4 CYL
4WD
MANUAL
121,000 MILES

My wrangler has out of the blue started knocking. I have kept up on all routine maintenance since I have owned it for the last 10,000 miles. It is still running very strong and the performance does not feel hindered. I did notice that there seems to be water dripping out the exhaust and it is running a little hotter than normal. The radiator coils are falling off (flaking) so I bought a new one but have not installed it yet. However, I don't think this will fix the knocking. This is a project jeep and I eventually want to put a 350V8 in it but money is a little tight right now. Any suggestions?
-Rich

6 Replies

MMPRINCE4000

MECHANIC
8,548 POSTS

Check the oil, if it is a chocolate color, you may have a head gasket failure. Coolant in the oil will wash the main bearings and cause a spun bearing and many other bad things

Perform a compression test to see if the headgasket is the problem.

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Saturday, December 6th, 2008 AT 10:41 AM

RICH S

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4 POSTS

I checked my oil and it was clean as a whistle and it has been 1,300 miles since I changed it. That is a good thing right? My next question is how much should I expect to pay for a compression test? Also, could it have anything to do with my exhaust?

Thanks,
-Rich

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Sunday, December 7th, 2008 AT 11:33 AM

RICH S

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4 POSTS

I was just tinkering and I noticed that the base of the fan where it goes into the engine has a slight wobble and the sound seems to be coming from there. It is a constant knock/grind sound even when I rev the engine up. What do you think?

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Sunday, December 7th, 2008 AT 11:50 AM

MMPRINCE4000

MECHANIC
8,548 POSTS

I think you are on to something. If it is not an engine knock (and the oil sounds good), then it could be an assy. Like the fan, or bearing in a pulley.

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Tuesday, December 9th, 2008 AT 12:07 PM

RICH S

MEMBER
4 POSTS

Well I replaced the water pump, thermostat, and bought a used radiator that appears to be in good shape. The knock is completely gone and it actually sounds better than when I bought it! (After I had to return the first water pump since it has a reverse rotation.) However, it is over heating. There are no leaks, I sealed the gaskets, and the radiator is filled. Is it possible that I have bought a bad thermostat. I checked the upper hose and it seems to have pressure and is heating up along with the engine so I don't believe it is stuck shut. Any ideas?

-Rich