Troubleshooting a transmission

[cam7002]

Hi, everyone. I read some posts about transmission problems (i.e., "Loss of Power" post), but I was hoping someone could give me a rundown on the proper soup to nuts, by-the-numbers way to do a transmission troubleshoot.

One of my M1009s is reluctant to take off, but it works fine once warm. I am not sure I would call this a "slip", but I suppose it could be categorized as such. It's more of a "reluctance" to do work. I am hoping/praying to hear something other than the standard AAMCO answer to every transmission problem -- "Yeah, you need a new transmission." I am praying it is something like a transmission fluid pump, a filter, a torque converter or perhaps some other not-so-expensive repair that I might be able to do.

Also, I understand that there is more than one option for a replacement transmission, should that be the ultimate repair need. Can anyone tell me what my options are, and what the benefits of each option is?

All your thoughts and experience are appreciated.

Thanks!

 

[Bobert]

Mine had that problem, it got bad enough where it wouldn't go at all. I just got a rebuilt one and new TC for 650 at a smaller shop.

I was thinking about doing a 700r4 but it turned out to be a bit more work than I care to do right now. Mine had a kind of whine to it like maybe the pump was bad. And you could smell the clutches burning up so we just did the whole thing.

Another option to get some get up would be some axles out of a gas blazer from the junkyard with 3.73s. I'm considering doing this especially since that "gov lock" doesn't do a darn thing for me.

 

[Westech]

your pump is going south... mine is that way also. I just added some "snake oil" and let it warm up before I drive it. I know I will have to replace it someday but I hope to do that when I get home and out of the Army.

 

[SmokeyDod]

Unless you have already done this, the FIRST thing I do when I get any of the trucks or blazers from GL is pull trans pan and check the filter. When these vehicles sit for long time even if they don't have lots of miles (20K or less) I have found on several of mine that the filter like "glazes over" and forms a seal that the fluid will not flow thru freely. I always replace filter & fluid even if vehicle seems to drive okay. I had 2-3 of them barely pull on flat ground but when I do above they are like new. If you run it much at all slipping the clutch friction discs in them-- then you will need to have a rebuild. If it starts slippling even 2 miles from home, I have rather pull over and get it pulled home rather than try to force it.

 

[HAWKMAN]

 

[Goatwerks]

There is no escape from aging seals. It is cheaper to pull it out and do a soft overhaul and replace the pump bushing before other damage occours.
Rubber turns to plastic over time with heat , so unless fluid warms the seals till they are supple, they leak resulting in failed clutch packs.
The average overhaul hit for a TH400 or 700r4 is around $85-$150.
That is all the seals, gaskets, clutch plates and bands.
The internet is your friend...........................

 

[motormayhem]

I just re-cased mine. It is not that hard to take apart and put back together yourself. The TH400 is a pretty simple machine.

 

[cam7002]

Thanks for the pointers. I have never cracked open a transmission before, although I did help install a junkyard one when I was a kid. I think I have been a little more intimidated by it than I should be.

Another thought however .... someone posted that, when dropping the pan, I should go ahead and put a drain plug in the pan.

Question: Why would I do that? Is changing the fluid in a tranny not like changing the oil in that one should change the filter at the same time? As such, everytime I change the fluid, I would need to take the pan off anyway to swap out the filter and take a look in the pan for anything peculiar? Or is this just a thing in case someone were to overfill the tranny with fluid?

 

[Westech]

done that too.. it really works its not a joke. the brake fluid will swell the seals and away you go.

 

[cam7002]

Very interesting and creative. I think before I go the brake fluid route, I'll drop the pan and take a peek. I would hate to sell one of the two having done that. I would be a total pikey to sell one that seems to be running fine after doing a "repair" like that.

 

[papercu]

put a drain plug in the pan

Because it is a VERY messy job to drain the oil by just loosing the transmission bolts. If you can find one, the transmission cover for the HMMWV has the drain plug and will fit. Wayne

 

[cam7002]

Ahhh, very clever! Why aren't all pans generally made with one?

 

[Goatwerks]

The short answer is the added cost per unit . However some years there was an option code for the pan with a drain plug.