Chevy Cobalt Forum banner

1 - 3 of 3 Posts

·
Registered
Joined
·
157 Posts
Discussion Starter #1
Tonight I made a wonderful discovery of an oil leak from my engine, that up until now had been super dry and oil leak free. I had parked the car after work in the driveway and later moved it to mow the back yard. And there’s a new oil spot right where I had parked.

I had hoped it was just the oil pan or transmission pan gasket. Or even the oil sending unit. But no, it definitely looks like it’s right in between the trans and engine. I even looked to see if the oil filter lid was leaking or the valve cover. So I’m fairly certain. But I think I’ll put it on a lift and power wash it to see where it comes from.

I have taken transmissions out on other Cobalts and GMs with Ecotecs so I know it’s not extremely difficult. And especially with a lift and transmission jack I have at the shop. Although I have not had to replace a rear main seal on them. Looking at the back of a long block, I can see it has a separate lower casting of the block, hoping that’s not the source of the leak. Oil pan itself is dry, the transmission pan is wet, but looked like the oil has leaked on top of it around its edges and probably got spread around by air flow from driving.

Also I have in mind a few things I may do to take advantage of having the transmission out, unless I find out it’s not the rear main seal. One would be to go ahead and replace the transmission front pump seal, it’s cheap and it’s going to be right there. Also the torque converter clutch solenoid and pulse width modulator valve. I have noticed it will act weird when trying to hold speed around 40-45 mph or so. Like it locks and unlocks and rpms will have a slight surge up and down. At least that’s what I have read was a common problem caused by those parts. And last, I still haven’t done a fluid change and it’s due for one. I usually do a filter and fluid change when I buy a used vehicle since I don’t know if the previous owner did proper maintenance. So far I don’t think so with all I’ve done.

On top of the oil leak, I have a bad cooling fan. So I will be picking that up Saturday. So I’ll be able to hit the engine with our power washer while I’m at the shop.

Everything was going so good with this car. Now this. I think I’ll also do an oil change. I used the cheap high mileage bulk oil last oil change. I don’t know if that is why it started leaking. But I’m going to just stay away from it again, seems coincidental. But I almost always use Castrol high mileage semi-synthetic 5W30. Good thing I keep and eye on things. I have so many customers that are oblivious to what’s going on with their cars, it’s unreal. I always like to check oil level every couple weeks. And lift the car up at least every two months, if not more often. It kind of goes with working in a shop I guess. Anyways, the oils leak had to have started yesterday or today. I had just had a look under the car and didn’t see any leaks. Well I guess that’s what I get for having an old car.
 

·
Registered
Joined
·
157 Posts
Discussion Starter #2
So I looked where I park at work. No oil stain. It didn’t leak all day either. But I only drive about 2.5 miles to work, so the car doesn’t get hot. Looked in the driveway at home and I see another spot. I did drive from work to home, then to Whataburger and waited in line, then home. And that gave the car enough time to get hot that time. I guess it’s not a super bad leak, I just hate oil leaks.

I’ll get a better look tomorrow while I replace the cooling fan and give it a wash under the engine. I wonder if while the car was running hot, that it may have caused the seal to expand beyond what it usually does. Hottest it got was 224*f, and not for long. But did get to staying between 208*-214* for about 10-15 minutes until I got home the night I caught the car running hot. It would only run in the higher temperature range when I first got the car, before the t-stat was replaced. Tonight in line at the burger place, it only topped out at 190*.

If I go ahead and replace the rear main seal, I will probably take pics and post them. I haven’t found much as far as pics that anyone else has posted.

Also wondering if I should spring for the fluoroelastomer seal. It’s expensive, but it might outlast the engine. Haha.
 

·
Registered
Joined
·
157 Posts
Discussion Starter #3
I got it power washed. It’s coming directly down right in line with the crankshaft. I was really hoping I’d see it from the oil pan. So crap, I guess it’s going to have to be done eventually. Luckily it’s not leaking enough to leave a huge puddle. But enough to spot the driveway.

I did however check the transmission fluid and it’s really bad. It also looks like it’ll be a good time to replace the fluid pan. Looks like bottoming our with the old bad struts has dented and bent it, although it’s not leaking. I can’t believe how much more the chain stores sell the Dexron-VI compared to the place I just bought my cooling fan. It’s a good $4 more, and the place I went sells the genuine GM fluid for that much less. It’s like $4.50 a quart.

I forgot how cramped the engine oil pan is, so it’ll be a good time to reseal it if I am having to remove the trans out for the rear main seal. I remember doing these and having several bolts be really different to spin out and a pain to get them back in. And on top of that having to use sealant instead of a proper rubber gasket. It was like that on a lot of Honda’s I’ve worked on as well. Similar design actually.
 
1 - 3 of 3 Posts
Top