93 gmc yukon

my yukon is making a thumping noise when i first turn the engine on (about 12 to 20) thumps,and then again when i shut the engine off.there is also a oily leak coming from under the dash on the passenger side, have any ideas?

Maybe engine and transmission mounts for the thumping, the oily leak could be coolant coming from the heater core. The oily substance could be anti-freeze.

You may also want to take a look if the exhaust system is secure. They made a Yukon in 93?. Do you have AC? the oily stuff could be AC oil from a leaking evaporator. I have never seen this though. I can’t even picture a 93 yukon.

Yep. Check it out on here on the car research link. Right back to '92.

Thanks for the input!Figured it was the heater core, but didn’t know what was making the thumping noise.
I will have it checked out this wknd. I do appreciate you guys tremendously.
Thanks again

Going to have the truck looked at this wknd.
Yeah a 93 2door yukon. They are great looking trucks! Check 1 out.
Thanks for your reply so quickly!