Coolant leak from engine and transmission mating surface

Hello ladies and gents,
I am new to this forum I came on here to see if anyone had the same issue I am having. I currently am leaking coolant from where the transmission and engine mount together. There is no wetness on the top of the transmission. It is only coming from the bottom. At first I thought it was a rear main seal, but after lifting the truck up and checking my fluid levels, it’s my coolant. Has anyone else had this issue? I’m guessing imma have to drop the transmission. Which I have yet to do (young buck here). Any tips or tricks? This is an Ohio truck so she is rusty! I really appreciate!

 

You sure it's coolant and not trans fluid?

 

Make sure it's not coming from up higher somewhere. Maybe blowing back from the fan or something.

 

The few times that I have dealt with leaks coming from that area it was caused by a crack in the rear of the engine block and corroded engine block core plugs ( commonly referred to as freeze plugs though that's not what they are there for).

 

I am sure that it is coolant and not transmission fluid or oil. I do have a leak from the (correct me if I’m wrong) pulley housing plate. (Something like that, not hard to reach. I did just re-seal my housing for the thermostat and manifold, there is coolant that leaks on the block, underneath the intake. I did take it to the local mechanic shop, to get their opinion. He did mention something about the freeze plugs. I have never heard of that before, nor know where they are located. I know that it is a pretty active leak. I’m just gonna assume if the block is cracked I’m screwed. The truck does have 265,xxx on her. I really appreciate the help.

 

its rare on these, but it can happen... theres 2 freeze plugs on the back of the engine. one for each bank, you can see one in this picture, if it springs a leak it'll leak coolant where your describing, other posibility is the rear heater hose leaking, but you said the top of the trans is dry.

 

So I’m going to drop the transmission. While I do that I’m sure I should just change the rear main seal. Should I go ahead and get a new fly wheel? Also are the bolts for the fly wheel re-useable or are they the one time use?

 

Never heard of getting a new flywheel just for the hell of it, on a manual you might resurface one. Don't know about the bolts, I've never pulled a flywheel on a tundra, I always reused flywheel bolts on other vehicles though.

 

Bolts are reusable. I use red loctite on the bolts. The flexplate is reuseable. Yes I would do the rear main because your there.

 

Yes I mean flex plate not fly wheel I apologize! Thank you all for the advice! I will let you know what I find!

 

Interesting. I use anti-seize on most bolts

 

Mine had coolant leaking out of the coolant valley on the head. I placed a new seal and no more leak. The coolant would drip down one the backside of the engine where it met the transmission.

 

Make sure its not coming from the rear water bypass gaskets leaking, which are in that area. Pics here:

https://forum.ih8mud.com/threads/front-water-bypass-solved-with-write-up.1027084/

I had a coolant leak dripping off the bottom of the tranny (originally thought it was tranny fluid). Took it to the shop and the guy got an endoscope camera under the manifold and we found that the water pump was leaking onto the block and out the weep holes in the back and eventually dripping off the bottom of the tranny. Turns out previous owner had used a paper gasket on the water pump instead of the metal crush which of course eventually started leaking.

Moral of the story, I would find the leak source before dropping the tranny. I also like typing tranny.

 

Bingo. Assume you replaced the water pump seal?

 

Well Seth 419 I really hope your right, I just took the housing for the thermostat and manifold line then resealed it with some RTV from O’Rileys. Then after a week of driving she (my truck, her names Betsy) started leaking real bad. I noticed that she was leaking on top of the block, underneath the intake. The only question is she leaks a good amount. So do you really think it would leak that much from the weep holes?

 

Sorry if I worded it wrong, but they are not weep holes on top of the block, more so just drain holes. The top of the block has a depression in it and they are there just to let any water drain out. My leak was actually coming from the water pump leaking onto the block and then through those drain holes. You could definitely have a pretty good leak if the water pump gasket is bad.

 

Hey everybody! I know it’s been a while since I have came back on! Well I took the advice of checking my water pump first. What would you know it was the water pump putting coolant on top of the block. I didn’t know it was ran by the timing belt! So that came as a surprise! Took a minute to do everything! The water pump took me about 14-16 hours to do, with a lot of running to the parts store for stuff, luckily had some pneumatic tools to get the job done! Thank you everyone for the help! New pump, new idler and tensioner pulley, new timing belt! Recently I have also done the sway bar and links, ball joints and tie rods! Still need to get an alignment but the truck is up to date.

 

I’m late to the party here but I just had the separator case swapped and the engine valley resealed and my coolant leak onto the tranny is still occurring. I think I’m going to try to change the water pump and gasket based on your advice. Thanks, wish me luck

 

Forgive me if I'm missing something @Underdogg , but this isn't a case of the transmission pass-thru on the radiator causing your problem?

If the seals go out where the transmission's radiator pass-thru enters, you'll have coolant in your transmission fluid and vice-versa.

This is what fails, what it looks like, and why. That pass-thru tube runs through the radiator coolant pool at the bottom of the radiator.

 

As I understand it, on the Gen 2 Tundras there is a separate heat exchanger that runs coolant and ATF against the same metal but I don’t think they can likely mix together to avoid the pink milkshake scenario from a busted radiator part.

And the leaking coolant isn’t milkshake like. It’s running down the top/back of the transmission. Had the shop change ATF last year and didn’t get any mention of coolant contamination in there.

In this thread though, someone said they have the same symptom of coolant leaking from above the transmission because of the water pump and gasket. I’m praying this ends up being the fix because I can at least do that myself. I’ll swap the radiator while I’m at it so let’s hope there’s no ATF in there somehow

 

Keep in mind this is a 1st gen thread for a totally different engine.

 

Ah damn it. Thank you. Just searched "coolant leak" but should have read the rest of the post

 

I miss the old spartan kick to the grill for these infractions

 

How did you clean the coolant out the top motor