TH400 problem

[acmunro]

I have a TH400 transmission in a new to me M1031 giving me problems. It appears to have a gov't rebuild tag up around the bellhousing. I got the truck ready for PA inspection. It was running and driving good, but when I started to pull a long steep hill it started slipping in third gear. I just hit a level spot so I pulled over and checked the fluid. It was full but looked like it had air bubbles in it. It seemed to work good on the level, I don't know if it is because it really isn't pulling hard on the level or if going up an incline has something to do with it. I have it parked in the garage now. Any ideas ? Thanks in advance.

 

[optitrader66]

Pull the pan and check the filter and pickup tube,I have had two m1009' s that the filter had fallen down and that allowed the pickup tube to fall down and then it doesn't get enough fluid to pull. on these two a new filter and o-ring on the pickup tube and they were running smooth again. about $15.00 for a filter kit
Hope it works for you

 

[beanman1]

mine did the same thing and it was the filter and pickup tube that optitrader talked about

 

[Bobert]

My m1009 is doing something similar. Does the 1-2 shift get softer when it warms up also? Mine has a bad vacuum pump that I will replace when I get around to it. If that fixes it I'll let you know.

I will have to try the pickup tube thing next.

 

[tm america]

fluid level was probably low making it suck air on the hill.that will airate the fluid and make the level show higher than it actually is. check the fluid level again after letting it sit several hours that way the air will settle out of the fluid. fluid will grow to over twice it's size when it is airated

 

[kadetklapp]

I had a late-model chevy blazer that dropped it's filter just after getting serviced and while I was actually full of fluid, it couldn't build enough pressure over third gear to shift.

 

[acmunro]

Thanks all. I went to my garage and dropped the pan. The filter must have dropped. The o-ring on the plastic tube seemed pretty loose as the plastic tube about fell out of the transmission. On this truck the filter was retained by a bolt and a spacer. Should the bolt have a washer where it contacts the filter and then the spacer between the filter and the transmission ? I removed the pan from an old junk transmission I had and it had two washers between the bolt head and the filter. I don't think that is correct. The filter should move a bit shouldn't it?

Also I stopped at the auto parts store to get a new o-ring for the plastic tube to transmission connection. They had a o-ring assortment. I picked up a couple of candidates. Is this o-ring anything special or would an o-ring from an assortment be ok. Thanks again.

 

[tm america]

put two orings on there it will help but it is imposible for the filter to fall of of the tube with the pan on .the pan holds the filter on to the tube. the shouldered bolt and pipe spacer is all that comes on there from the factory. you can put some washers on there if you want.put one on the top and one on the bottom of the filter. i have been rebuilding transmissions for almost 20 yrs. trust me i have never seen a filter that was able to fall of the tube with the pan on .when you get your filter there are two type one is a filter the other is a screen make sure you put the filter type back in it as the screens are for use with manual valve bodies and trans brakes they dont stop the small stuff that can make your governor stick

 

[Coal Cracker]

Thanks all. I went to my garage and dropped the pan. The filter must have dropped. The o-ring on the plastic tube seemed pretty loose as the plastic tube about fell out of the transmission. On this truck the filter was retained by a bolt and a spacer. Should the bolt have a washer where it contacts the filter and then the spacer between the filter and the transmission ? I removed the pan from an old junk transmission I had and it had two washers between the bolt head and the filter. I don't think that is correct. The filter should move a bit shouldn't it?

Also I stopped at the auto parts store to get a new o-ring for the plastic tube to transmission connection. They had a o-ring assortment. I picked up a couple of candidates. Is this o-ring anything special or would an o-ring from an assortment be ok. Thanks again.

Any o-ring should work as long as it's the same size/diameter, if you have a problem getting the right one, call Transtar in Lancaster, Pa. and tell them what you need, that's where I get my parts from, they'll ship it to you, you should have gotten a new o-ring in your filter kit.

 

[acmunro]

Any o-ring should work as long as it's the same size/diameter, if you have a problem getting the right one, call Transtar in Lancaster, Pa. and tell them what you need, that's where I get my parts from, they'll ship it to you, you should have gotten a new o-ring in your filter kit.

I didn't see an o-ring with my filter kit. I'll have to look again. The o-rings I purchased are a bit thicker than the one that was in there. As long as I can get it in there it should make a better seal. The o-ring that was in there was way looser than the the one I pulled from my junk transmission.

 

[tm america]

any trans shop will have the filter tube o rings .they dont come in a filter kit just the filter with seal and a gasket.i put two o rings on the tube as it helps it seal and stabilizes the tube too.why pay shipping on a o ring that most any shop would just give you for free. transtar doesnt usssually sell to the public and they are not gonna want to break a overhaul kit for one 5 cent o ring