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Replaced the head on the motor...250000 miles on my daughter's 1999 Grand the mechanic says that he hears a knocking under the motor says she should just get a new car. Could the knocking be from something else..he says the oil is black and that means oil pump has gone out..could there be an alternative it too late to replace the oil pump

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Lets review.
Replacing the head at 250k was probably not a good investment.
My advice has always been, if you need engine work at 200k or more, its time for another vehicle because the rest of the parts are still worn out. The normal life of a car or truck in the USA is 200k.

Usually a knocking sound means a rod or main bearing has failed. Which would require an engine overhaul to fix.
Black oil has nothing to do with the pump. The oil should be changed at 500 miles to remove any debris caused by replacing the head. That may fix the problem if there is junk floating around in the oil pan.
If the oil pump has failed, you would have very low oil pressure which would show up on a gauge.
It could cost you more to fix the knock that it did to replace the head.

Posted on Jul 31, 2013


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Yes you have to check your pressure with a mechanical gauge first. If the pressure reading is good replace the oil pressure sending unit. They are known to go bad, and oil pumps going bad is rare. 

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SOURCE: 1999 Jeep Grand Cherokee overheated

You probably messed up a rod or caused piston damage your going to need more than a head gasket usauly when you over heat a car you causing the pistonts to expand more then they need to causing scouring and exsisive piston ware by the sound of it and the year your better off replacing the whole motor or completely rebuilding the old one wich will cost more then a use motor! good luck!

Posted on Sep 12, 2009

Testimonial: "good advice, easily understood, and written very clearly. thanks"

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SOURCE: Have a 2000 grand Cherokee 4.7, car boiled on me

You need to pressure test the cooling system. Unless you had the heads magnafluxed or inspected very carefully, there could be minute cracks causing the problem.

This is the #1 problem with any engine where boiling takes place due to the expansion power that steam has the capability of producing.

The cylinder walls could also have cracks in them, there could also be a freeze plug that is leaking slightly, causing the engine to overheat as it can't build the proper pressure.

sometimes it's a better move to get a low mileage used motor, than to attempt to repair one that has high mileage and this type of suspected damage.

good luck

Posted on Feb 20, 2010

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ABS light on

thundergod hit the nail on the head with the Jan 28th, 2009 post!
I had a similar problem, took my car back to my mechanic and they fixed it for $45!
They had accidentally (I hope) knocked a wire loose when doing a major repair but warning lights don't come on right away they take a few miles of travel to run through the software in our cars computers before showing up on the dash!
This is why I change mechanics every so often!
Like food, I get sick and tired of tasting the same thing over and over again.
I put 25,000 miles on a year, do a lot of maintenance and repair, and most importantly ...change mechanics every once in a while!

Hope this is helpful.

Good Luck!
96f1613.jpg jackiaria

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A very good possibility is a bad trac bar in the front-end, also how old is the front steering damper?

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