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post #1 of 4 (permalink) Old 10-10-2018, 07:07 PM Thread Starter
Join Date: Oct 2018
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Cobalt Strange Oil Leak?

hey all thanks for having me.

Call me crazy and yes I have worked on cars in the past. I loved the Pontiac brand before they foolishly got rid of such a solid car line. Obviously this is not about the other makes/models since this forum focuses on only one type of car.

I am helping a friend fix her car; it’s a 2007 Chevy Cobalt with the 2.4l auto in it. There seemed to be an oil leak from the oil pan, so my first thought was to change out the oil pan gasket. Problem with leaks is they can end up coming from anywhere and not just the spot we think it is originating from.

What I did was do a quick check under the car, which was pooling oil at the pan. We had limited access to the undercarriage so I used a floor jack and did the best I could. When she finally got some ramps we made a date and ordered the gaskets and some sealant for the repair.

When I got under the car the first thing I noticed was that some idiot had JB Welded the oil drain plug into the engine. I told her only way I knew of getting the oil out was to drop the pan. We dropped the pan and thankfully the weight of the oil broke the seal and for the most part it all drained into the oil pan on the garage floor. We then proceeded to carefully scrape the old sealant off the oil pan and then inspected the old gasket, which was not damaged as you can guess. We then applied permatex to the pan and pressed the new gasket on and let it setup for an hour. After we replaced the pan and torqued it off starting from the center. We refilled the oil to about 4.5 quarts and went to bed. In the morning the oil was again pooling under the engine.

Here is where it gets strange. When she took the car out that day the transmission starting acting up, and she couldn’t even go anywhere, she made it to a garage and they told her that she had NO ATF in her car. Wtf we drained the oil, not the ATF right? To my knowledge cars have oil and ATF but they do not share one reservoir. Did I miss something anyone anyone?

They put two quarts of ATF in her car and she came back home. My issue is if we drained the ATF and NOT the oil then wouldn’t the car have like 8 quarts of oil in it, and be smoking like hell? Shouldn’t that reservoir have overflowed everywhere? As far as I know every car I have ever seen uses separate fluid containments. I have never heard of a car sharing oil and ATF.

I inspected the fluids that came out of her car (See photos) one cup had the NEW oil in the container, the other has the “oil” we dropped from the pan that night, and the other photo is the oil that is collecting under the car.
Obviously we did not try to pour any of these liquids back in the car as I AM NOT a mechanic; I just did my best to help a friend who was low on cash. If any of YOU are trained and know what that fluid is feel free to chime in.
BTW when we dropped that pan the “oil” that drained FILLED the pan under the car (the pan is the black one you get at auto stores btw for anyone who is wondering) and I swear it was OIL not ATF Fluid, which is usually red and has a sticky sweet smell to it.

Aside from this we still did not know where the oil was coming from, so I put the car on ramps again and this time used a pressure washer to clean the entire underside of the engine, then I put on some bright lights and waited. Sure enough THIS TIME I spotted the real leaking areas (See photos) and I think it’s the SIDE of the engine that abuts the transfer case. I thought the bolts might just be loose but when I took the bolts out no oil came out of the hole, but was still dripping from the seam in the engine. This to me looks like a bottom end rebuild and could be a MAJOR repair. Since you guys love your cobalt’s and know more than I do I thought I would get some opinions.

BTW we did not change the filter because also unlike other cars it requires a special wrench (32mm socket) and not the standard strap wrench on most cars.

So my questions are
1. Where are the leaks REALLY COMING FROM
2. Was that ATF fluid we dropped and if so why was it in the oil reservoir

Any thoughts?

Thanks everyone

Photos coming soon, the links are acting weird!

Last edited by charlis07cobalt; 10-10-2018 at 07:23 PM. Reason: forum not showing all the icons (possibly buggy)
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post #2 of 4 (permalink) Old 10-14-2018, 11:00 AM
Join Date: Jul 2018
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Did you happen to check the oil level prior to pulling the pan? If it's leaking at the mating surface of the engine/transaxle, it's possible it's the pump seal on the trans side leaking ATF, rather than the pan gasket or rear main leaking engine oil. Depending on mileage, ATF may appear dark enough in color to pass as oil, though a quick sniff of the fluid should make it easy to differentiate.

I'm not familiar with the A/T in the Cobalt, but other trouble spots for leaks on automatic transaxles are the seals at the end of the CV and the trans cooler lines, if equipped.
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post #3 of 4 (permalink) Old 10-14-2018, 04:59 PM
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All first picture show transmission oil. When you thought you were fixing the oil leak at the engine you may have missed the boat. Not saying the engine wasn't leaking oil but obviously your transmission was, these are known to leak at the transmission cooling line fittings. My guess is you just need new lines like my wife's G6 2.4l.

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post #4 of 4 (permalink) Old 10-14-2018, 09:50 PM Thread Starter
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Hey guys, thanks for the replies,

Coby7 in answer to your reply, the transmission was never leaking. We just accidentally attended to the wrong area. Good news is it has a brand new gasket, bad news it never needed it.

I suspected that was AT fluid when I smelt it, very sweet smell.

It would seem we never fixed the original issue, and HDcornercarver the areas your talking about all seem to point to MAJOR repairs.

I am convinced the fluid leaking from the ENGINE parts is in fact oil, however I am unfamiliar with this type of car, so again not sure "what part" of the engine it is actually coming from.

We checked the oil yesterday as when she pulled out from the garage there was at least a quart on the garage floor, however the dipstick still shows it as past the full line, my guess is the car is purging through the leak area the overfilled oil.

Again remember we cannot get the drain plug off (since someone JB Welded it on) to even drain the oil.

Its a mystery but the car is running fine, even though its pissing oil.
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