I'm new, hope this is in the right section and I'm fallowing all the rules.

I'm working on a 99 buick park ave. 3800, Just did the UIM normal fix, car runs good. I Didn't touch the LIM.

I test drive the car for about 10 miles to really heat it up, witch was hard being that is 12deg. here. bring it back and let it idle for about 30 min to check for leaks.

I got about a dime sized drop of coolant coming from the dust shield that covers the converter bolts, took the cover off and it has evidence of a vary small leak been there for along time. with some new wet coolant.

I took the UIM back off, and took the LIM off, the top of the transmission bell hosing is dry bone dry.

Is there any way the LIM gaskets would leak into the bell housing? Doesn't make sense to me.

Or is there any freeze plugs on the back of the block that would end up inside the bell housing area?

Has there ever been a reported leak in this area?

Thanks ahead of time!

Evan

Welcome to Bonneville Club, Evan.

That is an uncommon area for a coolant leak. I can't remember any freeze plugs (?) on the back of the block, but I have an L36 sitting on a stand in my very cold garage as we speak. If someone with a better memory doesn't get back to you first, I'll go out and remove the flex plate, and rear seal carrier and have a look.

In the meantime, are you absolutely sure the coolant is not dripping from above? Leaks from the throttle body gasket are pretty common. When you say the "normal fix for the UIM," did that include a new UIM and throttle body gasket? It is also possible that coolant is trickling down from LIM bolts. When the LIM gasket fails coolant can wick up the LIM bolts. Those possibilities seem more likely.

I replaced the UIM and all the gaskets. that included the throttle body. I was watching this thing like a hawk with a vary bright flashlight while it was idling and didn't see any thing dripping.

There is no coolant on top of the transmission bell housing at all.

looking up into where the dust cover goes there is residue dried up and even hanging from the edge of the oil pan. I can see that its been thrown around a bit also by the flex plate. This was wet after about 10 min drive and 30 min idle.

I can take pictures and post them if that would help.

If you could take a look at that block it would be vary helpful to me. I want to make sure theres a possibility of a leak there before I pull the transmission.

Thanks again

Evan

Not good news. :( The seal carrier which positions the lip seal for the crankshaft, also seals two big diamond-shaped openings into the water jacket of the block, as well as a couple of oil passages. So, there is a source for coolant leaks behind the flex plate. I don't know it is possible (it would seem at least very difficult) to remove or get behind the flex plate so that you can get a 10mm or 3/8" wrench onto the 10 bolts that hold the carrier in position. If the gasket for the carrier is OK, maybe just tightening the bolts (if you can get to them) would stop the leak. Otherwise, either the engine or the trans is gonna have to come out to take care of it.

When I have an engine or trans out of the car, I seriously consider changing out the rear crank seal and carrier gasket on the engine, and the pump (front) seal on the trans for just this reason.

[edit: twelve, not ten, bolts hold the carrier in place.]

Thank you so much for the information! I'll most likely have to pull the transmission. i dont belive there is any way to get to any of the bolts let alone 10! LOL

thanks you so much!

Evan

You are welcome, Evan. Here is a photo of the apparent source of your leak:



Here is an image of the seal carrier. You can see where the coolant and oil passages are sealed.

Hi Evan:

Did you ever pull the transmission to determine if this was the issue? I suspect my Bonne may be doing the same thing. A small leak from the rear engine block area, small drips from the transmission flywheel dustcover area. Thanks.

Dan in MN