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Cracked exhaust manifold and ATF leak = fire!

2767 Views 5 Replies 2 Participants Last post by  corksil
Hello, trying to fix a 99 Sienna for a friend.

Friend was towing a trailer and pulled over to find fire under the vehicle.

Towed it to my house and after looking under it, I find ATF (red) all over the bottom of trans/differential and lots of soot from where things were burning/smoldering.

I removed the exhaust heat shields directly below the engine and find that the exhaust manifold has a massive Y-shaped crack in it as if someone ran the vehicle up on a pile of rocks. Exhaust is certainly leaking out of the crack at idle.

I find catalytic-converters and exhaust systems on rockauto for 350 delivered, but that still won't fix my ATF leak.

What is a common source of ATF leak under these vehicles? I removed the inspection plate and the backside of the torque converter looks dry so I'm hoping it's not the rear main seal of the transmission.

Please help, I can post pictures if needed.
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ATF leaks aren't common in Siennas. Since the manifold was cracked by a possible "traumatic event" maybe that's why there's a tranny leak. The only ATF leaks you'll find mentioned here would be from the oil seals (at the drive axles) or around the pan gasket. Sure hope is not a rear main...
The axle seals did not appear to be leaking and I changed the pan gasket and filter behind it.

Was definitely still leaking a little bit afterwards -- I took off the inspection plate and looked at the back of the torque converter but it seemed dry up in there. However, very hard to tell.

Vehicle is no longer in my care -- but if someone was towing something heavy and ran low on fluid, or somehow overheated the torque converter due to heavy towing on a steep hill, could this cause the rear main seal to fail?

I'm still trying to get to the bottom of this.

It was wet and red around the differential, and I saw orange RTV as if it had possibly been apart by a previous owner who tried to re-seal it and failed.

Any other ideas?
Maybe that RTV is a clue!

How about maybe the point where the dipstick tube enters the unit?
Yes. In hindsight I'm thinking that for some reason someone tried to seal the differential case with RTV and it didn't work.

I've split a fair few many automatic/manual transmission cases in the past, so I'm somewhat experienced with the process --- but has anyone ever removed the differential case cover on a sienna?
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