No reverse when cold

[frehol]

Hi,

My Blazer will not reverse when cold. Reverse does not engage. As it is warming up it reverse slowly with alot slippage. (I tried this once, but do not dare to do it anymore as I guess it might destroy something in the tranny)

It works fine in the forward gears.
The first 500 yards I drive(forward) after startup there is a bubbeling sound from the transmission, like air in it.
When transmission has warmed up it reverse fine, with no slippage.

I just changed filter and fluid to see if it helped, but it did not.

I guess the reversecluth does not engage when cold, but why?

Info: Blazer -95, VIN W, 4x4, 4L60E, NP233

/Freddy

[MT-2500]

It is usually about rebuild time when reverse goes.
But do a little testing first.

Any metal or clutch stuff in oil pan or filter when fluid changed?

Fluid level showing full when hot engine running in park?

Correct depth filter and pickup tube seal?
Bubbling sound could be reverse clutch seals blowed or air sucking in filter intake.
Seal blowed can be tested with a pressure gauge on reverse apply port.
Seal leak more could is why it works less cold.

[frehol]

Originally Posted by MT-2500

It is usually about rebuild time when reverse goes.
But do a little testing first.

Any metal or clutch stuff in oil pan or filter when fluid changed?

Fluid level showing full when hot engine running in park?

Correct depth filter and pickup tube seal?
Bubbling sound could be reverse clutch seals blowed or air sucking in filter intake.
Seal blowed can be tested with a pressure gauge on reverse apply port.
Seal leak more could is why it works less cold.

Thank you for quick reply!

No clutch stuff in oil pan, but magnet was covered in metalic dust. (see pic)

Fluid level is ok, but need to be checked often because fluid disappers. No visible leaks but transfer case gets overfilled and need to be drained down to its normal level. Must be TC input seal blown... will replace it soon.

The filter I put in was same size as the old one, seal looked right as far as I can tell...

Bubbling sound is heard in forward gear, not reverse - but I will test tomorrow if it bubbles in reverse when cold.

Reverse apply port? Where? Do I need to remove valvebody to access it?

/Freddy

[MT-2500]

Pressure ports are on side of transmission.
Or you can pull valve body and pressure test clutch packs.

If fluid level and filter is good it is time for another or transmission rebuild.

[frehol]

Originally Posted by MT-2500

Pressure ports are on side of transmission.
Or you can pull valve body and pressure test clutch packs.

OK, I'll check pressure on outside ports.
What should it read?

Originally Posted by MT-2500

If fluid level and filter is good it is time for another or transmission rebuild.

Thanks, that was what I did not want to hear

[frehol]

Today's update: Started it up and put it in reverse, no movement. Put it back in Park and rev'd it 'till it stopped bubbling (about 3 sec.), put it in Reverse again and now it worked as normal. Guess I had to get the air out to get it to work.

But as MT writes it needs a rebuild. Something is broken inside

Now I have to try to find a good tranny to put in or find another blazer to buy cheap. Love the blazer but don't know if it's worth the money to rebuild the tranny, work cost is high here in Sweden... Maybe it can be a project for me to try to rebuild it myself.

What differs from my -95 model year and later years? Might be hard to find a -95 in OK condition here...

(Or maybe I buy a Lada Niva, they are cheap!)

/Freddy

[MT-2500]

Originally Posted by frehol

Today's update: Started it up and put it in reverse, no movement. Put it back in Park and rev'd it 'till it stopped bubbling (about 3 sec.), put it in Reverse again and now it worked as normal. Guess I had to get the air out to get it to work.

But as MT writes it needs a rebuild. Something is broken inside

Now I have to try to find a good tranny to put in or find another blazer to buy cheap. Love the blazer but don't know if it's worth the money to rebuild the tranny, work cost is high here in Sweden... Maybe it can be a project for me to try to rebuild it myself.

What differs from my -95 model year and later years? Might be hard to find a -95 in OK condition here...

(Or maybe I buy a Lada Niva, they are cheap!)

/Freddy

Reverse pressure is always higher than forward pressure.
With out looking it up in transmission book I would say it should be 200 PSI or more on reverse.
You need to stay with or real close to the same year.

A salvage yard interchange book will tell you what will interchange.

[blazes9395]

The '95 model year was a unique year in that it does not interchange with any other year. The '95 was the first year the TCC was PWM controlled. The '93-'94 were electronic and looked identical to the '95, but had an on/off TCC control. The '96 and up were also different. The older trannies('93-'94) can be converted to work with the '95 but its usually easier just to find a '95 model year tranny.

[frehol]

Originally Posted by blazes9395

The '95 model year was a unique year in that it does not interchange with any other year. The '95 was the first year the TCC was PWM controlled. The '93-'94 were electronic and looked identical to the '95, but had an on/off TCC control. The '96 and up were also different. The older trannies('93-'94) can be converted to work with the '95 but its usually easier just to find a '95 model year tranny.

Blazes, do you have any idea what is different with the '96 and up?
I think I read somewhere that it just was the cooler line fittings, but from your post I guess there is more...

/Freddy

[blazes9395]

There were a few things that were different. The '96 4l60 started using the bolt-on bellhousing. This was the same time the 4.3 was revised to the SFI(sequential fuel injection) from the CPI(Central posrt injection) and was equipped with the cast aluminum oil pan, which is integral, and bolts up to the new bellhousing of the revised transmission. This alone will make it not bolt up properly with the older '95. The '95 was a one piece tranny, with the bellhousing cast together with the transmission body. Also the aluminum convertor/flywheel cover used in these trucks served a purpose and must be reinstalled, along with the brace(s) on either side. Other changes included the 3-2 downshift solonoid was changed in 96' making it incompatable with the '95. There were also valve body revisions too. Thats all I can really remember, there are more I am sure.

Another common problem that is missed, and doesn't really concern your question, but I'll add it here, is the different convertor clutch material used through the years. The '98's and up and some '97's used woven carbon material whcih is designed and used with different lock-up stratgies used thoughout the years. The '95, '96, and maybe some '97's used composition carbon which is a different material and cannot hold up to the torque apply stratgies used in the newer trucks. Now the rest of the transmission will work pretty much from '96 and up but if the wrong convertor was used it would eventually burn up and potentially take out the rest of the transmission. So just in case someone needs this info, here it is too.....

Hope this helps.