Engine cause tranny failure?

[Citizen Rider]

I bought my blazer in feb of last year, and from feb to august, i went through about 3 rebuilt transmissions. The tranny that is in it now i got from Mattk here on the boards, he had a very similar setup to what i have, and he never had any troubles. It was rebuilt just over a year ago. It seems to be on its last leg, and its barely been driven, and has not been offroad while in my rig.

So im possibly going on 4 blown TH350's in less than a year. 1 was a sprag broke and would lock up the tranny in 2nd. Another it just exploded everything inside the case.

My question is, could there be something internally wrong with my engine that would cause ANY transmission that has been installed on my blazer, blow itself up within a couple months of very short driving and little wheeling?

 

[CDA 455]

How about the drivers' driving habits? Incorrect installation?

Disclaimer: This is just a WAG !

 

[Col_Sanders]

How is the rest of your drivetrain?

Have you pressure tested the tranny when you install it? Maybe your cooler is clogged?

 

[Chaddy]

Has your torque converter expanded?

 

[Leper]

If the main bearings are worn, and the crank is walking back and forth, it will cause tranny problems by mashing the TC into the trans.

 

[diesel4me]

X2!..

Yes,if the thrust bearing surfaces on the crank or main bearing that controls the amount of end play in the crankshaft wear ,it lets the crank push on the converter,which usually ruins the pump in the tranny first..but the main cause of thrust bearing wear comes from the torque converter,when it "balloons" due to clogged cooler lines, or other internal causes,or lugging the truck under heavy loads constantly,as when towing uphill...

In general, a poor running engine can cause tranny failure--low or eratic vacuum affects the modulator,causes line pressure in the tranny to be too low,and can cause slippage of the clutches..it also heats the converter up more if the motor is running poorly..

But I have swapped good engines in place of bad ones in many vehicles,and the tranny still worked fine--better in fact,than they acted with the poor runner bolted to them..I'd suspect you have other things on your truck adding to the tranny's problems.(big tires,high gears??)..its rare to pop 3 in a row,with similar failures,unless they were on their way out before you installed them..

 

[koldsimer]

Hey! Did you hear that? I could of sworn I just heard something.

































465/205


I knew I heard something.

 

[Citizen Rider]

First 2 trannies it didnt help i had 10bolts, 3.08 gears, and 38's, although it actually had decent amounts of power and movement.

Now i have a transmission that came out of a 79 blazer with 4.56's and 37's with no problems and a rebuild just over a year ago. I run 4.56's and 38's. Tcase came out of a running truck, axles came from a running truck. My engine has had slight problems here and there, but im really wondering if theres more than the eye can see that is wrong.

 

[MattK]

Hey! Did you hear that? I could of sworn I just heard something.

































465/205


I knew I heard something.

the power of the granny compels you!

 

[JEBSR]

I have a silly question for you. Did you flush the lines and cooler or are you recirculating metal through the new tranny's from the old? I have seen this happen on a few occations. We had a TH400 in a friends car that kept going out and when we finally asked him this question he told us he was just pulling old out and putting new in. When we flushed his system we filtered it and you would be amazed how much metal was in the system. Flushed it and reinstalled 10 years ago now. Still running strong.

 

[JanneB]

And the converter, flushed or replaced?

 

[Citizen Rider]

Each time exept for the one in it, the converter was new. I reused the converter from Mattk's setup.

Also everytime the lines have been flushed. I also now run a perma-cool inline filter/temp guage. So through the filter, into an after market tranny cooler, and back to the tranny.

 

[koldsimer]

You gotta get this figured out man. We must wheel soon! Based on others suggestions, i'd say it's either excessive crankshaft play or something with the TC. Hmmmmm.

 

[Citizen Rider]

I have no clue where to start from here. I cant stand having it sit infront of my house.

 

[JEBSR]

If you have a dial indicater, you can measure the endplay at the flexplate. Look in a good repair manual and see what the endplay should be, gently pry the crank forward, set the dial indicator and zero it, pry the crank back and see what the reading is. It would have to be very excessive to damage anything other than the pump though IMO.