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Oil Leak

OIL LEAK QUESTION EMAILED TO CAR TALK

12-15-08





I listen to your show every chance I get and if missed on Sat morning I try to catch it on Sun nite - too informative and too much fun to miss!

I have a 6 cyl 1992 Mitsubishi Diamonte SOHC with 135,000 miles. Runs great and well maintained - trans fluid changed every 40k miles, oil and filter changes every 3-4k miles, timing belt, tune ups, hoses, belts, new tires, front end and rear suspension parts including struts, tie rod ends, etc.

It has been leaking a little oil on garage floor in a few places at front area of car. Now after doing the repairs described below, I have to add up to a half to three quarters quart about every 200 to 500 miles. I use Valvoline or similar 10w30. It was recommended by an auto repair chain in St. Louis MO that I replace both valve cover gaskets which I had them do at cost of around $450. Still leaked so they said it was the circular seals (4 of them) one each at both ends of each of the two valve covers - they replaced all for another $450 or so.

Seems to leak worse and they checked saying that no leaks are evident from what they did.

Then they said it might be the head gaskets or something else and that it “made no sense to start chasing down leaks”. I cannot argue whether the leaks are still from what they did, and don’t want to spend another $900 or more they said it would cost to replace the head gaskets and possible other seals.

Is there any product that actually may work to stop leaks without doing potential harm to the engine? As I said, the car runs real well getting 19 to 23 mpg in the city and 23 to 26 on the highway.

Thanks, Jack

If I interpreted you correctly, your oil consumption is about 1 qt per 1000 miles. Many manufacturers consider that normal for their vehicles that are much newer. I would invest in a drip pan, monitor my oil consumption, consider using a high mileage oil if you haven’t already, and let it go.

You can buy a lot of oil and a really nice drip pan for the money asked to attempt the repair. I would monitor my oil consumption every 1K miles and see how long I can forestall the repair.

The comments you get here aren’t coming from Tom and Ray, just for the record.

Thanks for the advice. I have tried this and find that the oil loss is mostly from leaking on the ground at the more accurate rate of around 1 quart in 500 or so miles and is evident at every location I stop even for a minute or so - street, others driveways etc. Also, the smell of oil burning and some smoke from the far front of the engine compartment is evident most of the time especially when just starting up and when at a stop.
The drip pan works to collect drips in my garage but elsewhere is a problem along with the smell and some smoke.
Any other suggestions especially about possible valid Stop-Leak products would be appreciated.
Thanks, Jack

I’d steam clean the engine, put a UV tracer dye in it, run it for a day, and check with a UV light (“blacklight”) to see where it’s leaking from before making any assumptions.

Thanks, I’ll try that.

This is a bit of a guess, but I’d take a close look at the oil pressure switch/sender. Easy to replace for less than $20, and known to be an issue with some Mitsus.

Clean the engine off, then run it and see if you can catch it dripping. The UV stuff mentioned earlier can be helpful. Oil blows all over the place when you’re driving, so it’s hard to spot exactly where a leak might be coming from sometimes unless you clean off the old gunk.

Don’t dump any mouse milk in the oil.

Also, get a new mechanic. “Chasing leaks” is sort of part of the job description, you know…

Thanks, I’ll have a different mechanic check the oil pressure switch/sender as you mentioned. That would be a great cause and remedy!
I would still like to know if ANY of the Stop leak products are legitimate and if so, for which type of leaks might they work and if any may do harm the engine if just tried. Also,is it added to the oil after the full amount of oil is replaced in an oil change bringing the total above the line on the dip stick or is room left for the product to make up for the total oil volume in the oil change?
Thanks

I agree that you should find another mechanic because it sounds like these guys are simply throwing darts and hoping.

They charged you 450 for valve cover gaskets? Too high.
They charged you 450 for valve cover circular seals? That should have been part of the original valve cover job.

With oil loss that heavy valve cover leaks are not a guess. It should be very apparent.
I also agree with the oil pressure sending unit diagnosis. The senders often give up with age and the onset of cold weather is often the final straw. Since the senders are tied directly into an oil pressure port it would become a steady drip.

While I don’t normally bash a shop since the entire story is not often known, I will here.
These guys are clueless, crooks, or a combination of both.

exactly and good helpful info here.

My Rav4 just started losing oil so I started it up and it has a steady drip from the oil pressure switch.