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1997 Jeep Grand Cherokee Base 4dr Laredo

1997 Jeep Grand Cherokee
Trim Info:
Rear Wheel Drive, 4 Door, Special Purpose Vehicles
16 mpg city / 21 mpg hwy
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September 28, 2012, 8:35 pm

Tammy A
 

Question: Jeep grand cherokee loud engine knock?

My brother was going to put an oil sending unit on my 2002 jeep grand cherokee laredo 4.0i. He has just started school to be an auto mechanic and assured me it was a simple fix. He misunderstood the location of the unit and took out the oil supply drive instead. He took it all the way out of the block. He realized it was wrong so he put it back in and plugged the cam sensor back in. When he started it to make sure it was ok it ran bad, and made some clanking noise. Then it wouldn't start. After talking to a few people we realized he had thrown the timing off. So with instructions he realigned the oil supply drive. After that he went ahead and changed the actual oil sending unit, did a complete oil change, and charged the battery. It was dead from trying to get it to start. When the jeep finally did start the oil pressure was good but now there is a loud knock coming from what seems like the top of the engine. It's definitely not lifter knock or tick because I know that noise, it's an actual knock. The service engine light is on as we'll. it will start and run for a few minutes with the loud knock but then runs bad and dies. He feels terrible can you please give me some suggestions? Any help would be appreciated.


October 5, 2012, 6:00 pm

Ron W
Expert Mechanic

Have the code checked to see what it is. It probably is a misfire code. It should tell you which cylinder is having the issue.

Unfortunately it sounds like he may have damaged something in the engine internally. If it was in my shop, I would take the valve cover off and run it for a moment to see if the rockers are all moving. If one isn't , that is where I'd start. It could be a bent valve if the timing was incorrect.

Your best bet is to have a shop look at it as this point. If you are mechanically inclined, you could do some checking yourself, but I wouldn't recommend running the engine as SEVERE engine damage can happen (if it hasn't already).

And you can tell your brother from me (an ASE Master mechanic and Automotive Instructor for over 20 years), ALL mechanics go through this learning process. And we all make mistakes, sometimes BIG ones.

If you want to learn this craft, that just goes with the territory. Be patient and forgiving of yourself. In 5 years, none of this will matter, so just let it go, and stay focused on getting that car repaired. Everything is fixable, and if he stays at it, he will get it fixed.


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