CarTalk.com Best of Deals Car Reviews Repair Shops Cars A-Z Radio Show

2000 Jeep Wrangler- Oil overfill

Went to oil change service an 5 miles later my 4 cylinder engine in my 2000 model Jeep started knocking really bad . So checked the oil an it was at least 1-1/2 quarts to much oil in the engine. So called the shop an the owner had a mechanic that he took the Jeep to that took two days to get back to me an said that the piston wall was broke on one of the pistons , an said that it was not because of the over filling of the oil ? Any feed back on this ? Before this day there was no knock or ping or anything that would say I had a preexisting problem.

A quart and a half overfill could cause the problem but so could the 19 years the Jeep has been in service with xxx,xxx miles - you don’t say. Could be a leaking head gasket putting coolant into the oil, too. An engine teardown is the only way to even attempt to answer that question and even then causality will be tough to determine.

Good luck proving your case to the oil change place. If it were me, I’d just scrap the thing and go get another vehicle.

I have always hated oil overfill after changes. The guy who works on my cars now changes it and it ZACTLY on the high-level mark. Every time. I asked him how he does that and he said “Because I care.”

Overfilling the oil can destroy the engine.

If the level is too high where the crankshaft lobes dip into the oil while the engine is running, this action whips air into the oil causing aeration of the oil. If to much air gets whipped into the oil, the oil pump can’t pump oil throughout the engine. This starves the engine of oil, the engine starts knocking, and something breaks inside the engine.

Here’s an example of oil aeration.

Tester

I have seen several, possibly over a dozen cars that were belching white smoke out the tail pipe and had blown the dipstick out of its tube with the oil severely over the mark and none ever had any mechanical damage result directly from the oil. It’s likely that the catalytic converters took a beating none had any new noise or driveability problem once the oil level was right and the cars were driven a few miles. In particular an Isuzu pickup was more than 4 quarts over filled and got lost in a cloud in front of the shop waiting for the chance to turn in.

It’s my camp ride , it’s not a everyday driver , but update oil company agreed to pay to have the repairs made , its in shop now . Hats off to him for doing the right thing, had three mechanics give there thoughts on it an all said that the extra oil in the small 4 cylinder put added pressure on the bottom side of the pistons an instead of vapor locking it just broke the cylinder wall , so I’m not a mechanic but everyone agreed , it could an most likely did cause the damage.

1 Like

Great news on the shop taking care of this. The 4 banger in the Wrangler has a thin wall between pistons and at about 100k miles not unusual for this type of failure