2002 Jeep Wrangler Bown Rod

BDEEDS

MEMBER
2002 JEEP WRANGLER
6 CYL
4WD
MANUAL
40,000 MILES

Bought a used jeep recently and noticed oil pressure was not holding after it warmed up. I took it to the shop had it serviced and had an oil pump put on. When I picked it up, it held fine 30-40#. The day after, I took the jeep on a four hour round trip, on the way home the oil pressure dropped to 0 a couple of times. Once I returned home I checked the oil to find it was 2.5 quarts low. It does not leak oil or smoke like it is burning it either. The oil in the engine was dark black and seemed burned so I changed the oil and filter again, After about a week of driving, I had a rod blow. Would the low oil be the cause for the blown rod and is the shop at fault?

2 Replies

JACOBANDNICKOLAS

MECHANIC
109,731 POSTS

Hionestly, I can't answer that. If they replaced the oil pump, there was already a problem. Actually, the pump isn't responsible for how high the pressure is. The pressure is determined by rod, main, cam. Bearings. When the tolerances are within the mfg's specs, the pressure will be where it should be. If the pressure dropped to 0, that tells me one of 3 things. The oil pump, oil sending unit, or the engine are worn and need repaired or replaced.

As far as oil consumption, if you used 2.5 quarts that fast, wither it burned it or leaked it. That much doesn't disappear without some warning.

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Tuesday, November 10th, 2009 AT 1:42 PM

CLIVERASA

MEMBER
1 POST

The excessive oil consumption you are experiencing is probably due to the oil being burnt off. I agree that the internal components are probably out of manufacturing tolerances. Possible worn bearings and/or piston rings. The burning engine oil has left heavy residue, varnish or shellac on the cylinder walls and MAY have caused the ring to stick leading to the breaking of a connecting rod. It is possible, but I am guessing, that a faulty oil pump, in the first instance, lead to oil not being circulated in the fine galleries which subsequently lead to the premature wearing down of the said components. Or it may be that residue or deposits in the fine galleries prevented proper circulation of oil. If too thick an oil was used all along, like say a 20w50, then this may have contributed to the improper circulation of oil, subsequent formation of residues and deposits, blockage of fine channels and galleries. In California some new cars specify 20 weight oil to keep within emmisions laws! Using a 40 weight oil or a 50 weight oil would be disasterous in such an engine.

They may have put a thinner grade of oil along with the new pump but it may have been too late, such that the new thinner oil burnt off because the rings are so worn.

I wouldn't say that it is the shop's fault for the blown rod but you could seek to go halves with the shop for a rebuild?

If you say you saw the oil pressure drop to zero while driving, you will be asked why you did not stop to check the oil level.

Hope this helps.

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Wednesday, November 18th, 2009 AT 9:52 PM