A few months ago I had the engine (350) and transmission (TH350) out for some work (replacing engine freeze plugs). As I was bolting the transmission to the engine, I don't think I had the torque converter installed all the way onto the transmission before trying to bolt it to the engine. I knew that the TC had to go on there to "two" stops...and I thought I had it all the way, but as I was tightening the bolts I found that they were very hard to tighten. Then when I went to rotate the TC to align the holes to the flywheel, it wouldn't move. I took the transmission back off and started again, and found that I could get the converter on farther, and everything went together just like it should have.
Now, I knew that this was probably bad...but I re-installed the engine and transmission anyway because I figured there's no way to know what happened until I get it back in and run it. Sure enough, the transmission leaks from the front. It seems to drive and shift fine...but it does really leak from the front. It doesn't pour out...but it does have a steady leak. If I leave it for a couple days in one spot...there will be a 10"-14" spot under the car.
I don't have a lot of knowledge on transmissions. I did replace the front and rear seals while I had the transmission out before, so I'm thinking that it's not those that are leaking. I am going to do some work on the front of the car over the winter (body panel alignment stuff). It's probably a good time to also address this issue. My question is...what did I do, and is it possible to fix yourself?
I seem to recall that not having the TC installed all the way before trying to bolt to the engine could cause some damage to the pump in the transmission. Is that fixable?
Anyone with any advice on what I may have done, what I should check, and what the prospects are for fixing it?
Or, is this a situation where the only real option is to take it someplace to be rebuilt?
10" to 14" spot...but its not filled up anything? I call that pretty normal...I had my th350 re built 6-7 yrs ago...still leaked...bought another used unit ,had it rebuilt...leaked even worse, redid the original then it leaked a little less, still leaking...note I didnt do the re building two different shops did.....bugs me, but every two three weeks I just pour a bit more in...clean up the pan under...
Thanks...that's a little re-assuring. I may have been understating the puddle a bit. Meaning it may be a bit larger than that. I left it for a few weeks once and it formed a little "river" that went to the floor drain.
I have a lot of cars that leave little spots here and there...that's to be expected. But this one is a bit much. I figured since I was going to have the whole front of the car apart anyway for some panel fitting stuff, it might be an easy time to pull the engine and trans to address the problem. But I don't know exactly what the problem is...or where to look for it.
Yep, those both leak a little too. So does the speedo cable port. And so does the rear seal (that I had replaced). Seems that if it can leak, it does on this thing. The vast majority comes from up where the torque converter meets the transmission. There are some bolts on the front face of the transmission (I think those are for the pump?) and that seems to be where the majority of the leak is coming from.
I have one just like it in my son's hot rod. I'd swear it leaks from the seal around the tq conv but it's hard to tell. It may be coming from the front pump seal. I'd pull it out if it wasn't such a pain. I'll be interested in hearing what you find the main issue to be.
As for your install issue, if it works OK, it's not likely the cause of your leak. Is it leaking from the front seal? Is the torque converter new (not grooved)? How did you install the seal? My first guess (if it's leaking from the front seal) is that either the seal was bad or the install was. Did you oil the TQ before you slide it in? A dry seal can get ruined pretty fast.
I did lube the front and rear seals before putting the converter on, and the driveshaft yoke. I don't think the front leak is coming from the seal (as far as I can see). I do get a leak from the rear seal...and I think that perhaps that driveshaft yoke has a groove worn in it. I'll be replacing that at some point.
I found a stock photo online and marked it up where the leak seems to be coming from. It seems to be coming from where the pump mates to the transmission housing (where the black meets the silver in the picture). I don't know if the trans in the picture is actually a TH350...but it shows the area well enough.
Is it easy to pull the pump and replace the seal? Or does that open up a whole can of worms that I don't want to get into?
IIRC, the pump just slides out after you remove the mounting bolts. I think there is a gasket or maybe an O ring, I can't remember. It's been a lot of years since I did it.
Double check and redo the pan seal. I had a new 200r4 trans and had the pan on and off a few times at install (marking new dipstick etc) and mine also seemed to leak where your arrows point. It was bad enough to blow back and get on exaust and make a mess. It would blow around the TC and was hard to tell where exactly leak was coming from. (Drip from TC cover)I dreaded pulling trans back out after finally getting car back together. I Bought a new pan gasket and no more leak. Now I just notice the oil pan drips a bit from the rear main... never ends.
Also the trans came with a plastic TC cover and it was universal and didnt fit that great, it kind of got in the way of getting the pan on, so i'd remove it and reinstall after your pan is on and not leaking. hopefully this may be your issue. Good Luck
