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Edward
Edward, Service Technician
Category: GMC
Satisfied Customers: 2869
Experience:  20 + years experience on various makes and models.
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I have a 2008 Yukon SLT, 2 WD 5.3. I have a leak under the

Customer Question

I have a 2008 Yukon SLT, 2 WD 5.3. I have a leak under the truck. It's only happened 3 times. The previous 2 times was after it had sat parked for 2 days. I park on an incline and always engage the emergency brake. It isn't oil. It was slick, not sticky and had a slight hint of maple. It was also a reddish color. I thought it might be transmission fluid or coolant since both are pink/red. I was a quart low on transmission fluid so I added stop leak and dexron VI. This morning when I backed up, there was a leak. I drove to get the transmission up to temp and checked it - it was in the normal range -midway or higher on the crosshatches. Help!
Submitted: 4 months ago.
Category: GMC
Expert:  Edward replied 4 months ago.

Hello and thanks for your question. My name is ***** ***** I will do all I can to help.

Expert:  Edward replied 4 months ago.

Have you had to add any coolant to it at all recently?

Customer: replied 4 months ago.
I have not added any coolant. There's coolant in the reservoir at the proper level. One thing I didn't add previously is the leak seems to be near the center of the vehicle maybe a little more toward the front.
Customer: replied 4 months ago.
I'm not adverse to adding coolant lol
Expert:  Edward replied 4 months ago.

If it's leaking towards the front. Then I do not believe it is transmission fluid.

Expert:  Edward replied 4 months ago.

transmission is located basically from the drivers door back, Where did you see this leak occur in relation to position of the truck? is it leaking more towards the front? engine compartment? or very front like radiator/grill area?

Customer: replied 4 months ago.
It isn't near the radiator. It's more like the engine compartment - close to being under the console between the front seats-that general vicinity.
Expert:  Edward replied 4 months ago.

Alright, it's possible it could be the transmission then in that case. Have you taken a flashlight yet and looked at the transmission pan yet to see if there was any drip forming on the pan or the back of the tailshaft where the driveshaft goes into the transmission yet by chance?

Expert:  Edward replied 4 months ago.

It's going to look like this, this is the transmission pan and the gasket can and do leak over time.

Expert:  Edward replied 4 months ago.

If you see the transmission pan is wet, or there are any drips on the transmission pan bolts, it would likely need just a pan gasket which is no biggie.

Customer: replied 4 months ago.
ok going to go check it - i'm at work. this thread stays open for a bit correct?
Expert:  Edward replied 4 months ago.

Yes it does, take your time and just reply later and it will send me an alert.

Customer: replied 4 months ago.
Thanks!
Customer: replied 4 months ago.
what I ended up doing was placing a large piece of cardboard underneath while at work. When I left yesterday there wasn't any sort of leak anywhere. Would it be fair to say that since i park on a hill it's likely the rear seal?
Expert:  Edward replied 4 months ago.

It's possible, and if that is the case, then it's likely the transmission, because transmissions can and tend to leak more depending on positioning of the vehicle and coolant leaks usually aren't that way. try the cardboard under it on a hill and see if that will show any signs of leakage, and Also, where the driveshaft comes into the back of the transmission, it may be wet there if you take a flashlight and look. Whether it's a pan gasket or a driveshaft, you should be able to get either one of those fixed for 150$ or less in my opinion. Let me know if you have any further questions. Thank you.

Customer: replied 4 months ago.
it leaks on a hill because i can see it on my driveway! if i back in I don't have a leak. Thanks for your help it's going to be taken care of today.
Lisa
Expert:  Edward replied 4 months ago.

I follow you, then most likely that is either pan gasket or rear tailshaft seal. Thank you! Let me know if I can help any further.

Expert:  Edward replied 4 months ago.

Hello Lisa, did it wind up being the tailshaft or pan gasket?

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