My GF has a '99 4wd Jimmy. 4dr. The transmission pulls and shifts strong, but leaks like a sieve. Its pushing 200,000 miles and I was just going to go ahead and give it all new gaskets and seals. The last Blazer tranny I worked on was a th-350 out of a '79 K-5. How are these newer ones different? Are that any tips and tricks should know about before I dive in? I pulled the dash to change the heater core, and didn't research . Three dash pulls later I had heat and a/c..LOL I don't want a repeat!

Also I'm going to have to lube the chassis, it squeaks like an old matteress! What do you guys use, or do you just upgrade the bushings?

Thanks

 

I can answer your question about the transmission. I'm guessing you are doing the input seal? On the outside it's most likely the same principle as far as replacing the seal. The only thing you need to figure out is why the seal is leaking. There are drain holes (I think 2, only problem is I can't remember if they lead right to the pan or if something else can cause resistance) behind the seal that allow pressure to bleed off from the pump. If they become clogged oil will get past the seal. Otherwise there may be a groove worn in the torque converter from the seal. You'll just have to pull the trans and find out which it is. I just wanted you to know about the return holes so a new seal isn't installed and the same problem happens.

Hope that helps a little.

For the chassis, I use generic bearing grease. My thoughts are this: Even the wrong lubricant is better than no lubricant. I would first put the vehicle up in the air and give everything the shake/rock test to see what is worn out if there is anything. Then start greasing and pump grease in until either some starts coming out or until it starts coming out somewhat clean. I like to push all the dirt filled grease out once a year.

 

How do go about checking those holes? Just use a pipe cleaner like with oil holes going through the engine block?

 

To replace the input seal you basically have to pull the transmission out.
Take a tranny mount bolt to your local hardware store and buy the same bolt, about 6" longer. Buy 4 of them.
Once you get the tranny free, use the longer bolts and slide it back as far as possible. You now have to remove the torque converter from the tranny pump, carefull. Pry out the old seal, put tranny fluid ont he new seal and pound it home. lub it again. No lubricant and you could be repeating the whole weekend long process again for another $5 seal.

Now, before you go through the trouble of replacing the input seal, verify your leak isnt coming from the tranny dipstick tube seal. The only positive way to tell the two apart is to pull the torque converter cover/accessory hole covers and look for fluid inside the bellhousing. No fluid your leak is most likely the dipstick tube. Althoug if your tranny is overheating, and/or its overfull. The fluid will leak out the breather tube. The tube is located behind the bellhousing on top of the tranny. Newer models ran the tube a little longer and it hangs within sight. Best to reach your hand up and feel for the tube. See if it has fluid on it.
One last possibility, verify your leaking tranny fluid and not engine oil. Typical for the intake manifold seal to leak on the back of the engine, or the oil pressure sending unit could be leaking, its next to teh distribtor on the back of the engine. Both will have fluid run down and look like th tranny is leaking fluid.

If your tranny is low on fluid, it could also be leaking into the t-case, pull hte top plug ont eh back of the t-case. If you ahve a more than a little come out, you have a lekaing into put seal. Pull the t-case from the tranny and replace. If you let if go, it will work its way up into your vacuum system and screw up your HVAC system. Now your talking money to fix.

Any of it sound familiar?