transmission problem-no reverse

[rtreptow]

2000 Blazer 4wd 88K miles

My wife calls me when she gets to work today and said the blazer was shifting really funny on her way to work. In her words, it was really jerky. Then at one time she said she heard a loud clunk noise, but continued to work with the truck still not shifting right. On her way home the service engine soon light came on and the truck was still shifting strangely. When I got home I went to move the truck over to the other garage and there was no reverse. It certainly isn't shifting right, seems to stay in gear too long reaching higher than normal rpm's before shifting. Did some searching on the site, sounds like maybe the "sunshell gear"? I'm hoping not. She talked to a mechanic at work and he was thinking it might need a tranny fluid and filter change. Hasn't had one in a long time. But at the time, she didn't mention the loud clunk and was not aware that she had no reverse gear. What's the verdict?

[blazes9395]

Check for tranny oil level, makes sure it is full and inthe right range.

In my opinion, I hate to say it, but it sounds like the common sunshell going out.

Whats the milage on the tranny?

[rtreptow]

88000 miles on transmission. I was afraid you would say sunshell. As I mentioned, the SES light is on, will a reader specifically say sunshell gear?

[blazes9395]

No it won't, it will probably give you the P1870 code - transmission component slipping code. Thats what gives you the hard shift because the computer is noticing the slipping and is trying to reduce any damage by sending full line pressure to the tranny to reduce/avoid slippage.

[rtreptow]

so basically I need a transmission rebuild? Any idea on cost for something like that? I definately do not have the skills or will to tackle that project. I also did some more research and heard that this sunshell gear is thin or faulty in this type of transmission and to make sure when it's rebuilt that they don't stick in the same kind or I'll be looking at the same problem down the road? Do I need to make sure and tell my repair guy that or is he going to be aware of this?

Also, I noticed my radiator fluid is low. None in the over fill and a few inches low in the radiator, when hot. I was going to replace my cap because I heard these are poor on the blazers. I'm afraid this could cause more problems from a few threads I read here. Also, could this have caused my trany to overheat and lead to the sunshell gear failing....or is this sunshell gear just something that eventually wears out on these blazers? Thanks.

[MT-2500]

Originally Posted by rtreptow

2000 Blazer 4wd 88K miles

My wife calls me when she gets to work today and said the blazer was shifting really funny on her way to work. In her words, it was really jerky. Then at one time she said she heard a loud clunk noise, but continued to work with the truck still not shifting right. On her way home the service engine soon light came on and the truck was still shifting strangely. When I got home I went to move the truck over to the other garage and there was no reverse. It certainly isn't shifting right, seems to stay in gear too long reaching higher than normal rpm's before shifting. Did some searching on the site, sounds like maybe the "sunshell gear"? I'm hoping not. She talked to a mechanic at work and he was thinking it might need a tranny fluid and filter change. Hasn't had one in a long time. But at the time, she didn't mention the loud clunk and was not aware that she had no reverse gear. What's the verdict?

Reverse gone and shifting problems unless it is low on fluid it is a dead duck.
One of the best rebuilt transmissions is a dealer rebuilt transmission.
3 years or 50K parts and labor warranty.
MT

[rtreptow]

I have one guy saying it might be fixed with changing the fluid and filter. That just doesn't seem right because the problem happened rather quickly. Although after talking to my wife more, she said that she noticed the truck was hesitating occasionally for the past couple weeks. She would try to give it gas and it would take a second or so before it would go, the engine would rev, but no movement....still thinking new transmission though? FYI, we've had the vehicle since 40K, it's at 88K now and never had a trany fluid and filter change, shame on me!

[MT-2500]

Originally Posted by rtreptow

I have one guy saying it might be fixed with changing the fluid and filter. That just doesn't seem right because the problem happened rather quickly. Although after talking to my wife more, she said that she noticed the truck was hesitating occasionally for the past couple weeks. She would try to give it gas and it would take a second or so before it would go, the engine would rev, but no movement....still thinking new transmission though? FYI, we've had the vehicle since 40K, it's at 88K now and never had a trany fluid and filter change, shame on me!

Reverse and and one forward gear gone points to sun shell.
Slipping or slow to go could be low fluid or filter stopped up.
Check fluid level and make sure it is full transmission hot.
You can Pull pan and check the filter and if any metal or clutches in the transmission pan.
It is transmission repair or replace time.
Good Luck and let us know how it goes.
MT

[mdrush]

Originally Posted by rtreptow

so basically I need a transmission rebuild? Any idea on cost for something like that? I definately do not have the skills or will to tackle that project. I also did some more research and heard that this sunshell gear is thin or faulty in this type of transmission and to make sure when it's rebuilt that they don't stick in the same kind or I'll be looking at the same problem down the road? Do I need to make sure and tell my repair guy that or is he going to be aware of this?

Also, I noticed my radiator fluid is low. None in the over fill and a few inches low in the radiator, when hot. I was going to replace my cap because I heard these are poor on the blazers. I'm afraid this could cause more problems from a few threads I read here. Also, could this have caused my trany to overheat and lead to the sunshell gear failing....or is this sunshell gear just something that eventually wears out on these blazers? Thanks.

No sure about overheating the tranny, but low coolant could mean the transmission cooler in the radiator has ruptured and is leaking dexcool (or green stuff) into the transmission. Better check the trans fluid...just ask BlazerLT.

[blazes9395]

Originally Posted by mdrush

No sure about overheating the tranny, but low coolant could mean the transmission cooler in the radiator has ruptured and is leaking dexcool (or green stuff) into the transmission. Better check the trans fluid...just ask BlazerLT.

Could very well be true, if ther is any doubt, just get a new rad when your transmission is done. If it is leaking just a little, you will loose your tranny eventually again.

Like MT said, pull your tranny pan and take a look inside, if there are metal pieces, or a lot of clutch material at the bottom of the pan, you in for a rebuild. Either way, IMHO, I hate to tell ya, you probably need another transmission.

AND yes if you decide to rebuild yours, or get someone to build it for you, there are better, more stronger sunshells that are avaliable to buy. These wil eliminate that weak point in the transmission. Any good tranny shop are using the better sunshells too.

[silicon212]

This is what a broken TH700R4/4L60/4L60E shell looks like - notice the hub sheared right off. When this breaks, you lose reverse, 2nd and 4th.


This is an SPX/Filtran Beast sun shell. It is heavy duty. TCI also sells the same shell.

The broken shell above came out of my car. I rebuilt the transmission using the shell below. As for pulling the pan and searching for metal - this may or may not tell you if you have a broken shell. My transmission had no metal in the pan after the shell broke.

[rtreptow]

Couple more questions....Do I have my transmission rebuilt, or buy a used rebuilt one? Any benefit of one over the other? Also, when changing a transmission, they should do a tranny flush, correct? Shouldn't they be able to tell if there is a hole in the tranny cooler then? If if have my transmission rebuilt, won't this take longer than getting a used rebuilt one? Thanks for all the help. There aren't any repair shops open over the weekend and I just want to get as much info as possible to mull over when I call a few on Monday. Thanks again.

[silicon212]

Advantages of rebuilding the transmission you now have, if it is the original transmission, is that it's exactly what your car came with. They do small tweaks to the transmissions over the years, and a rebuilt, ready-to-install transmission may not be exactly the same as what's in your vehicle now. Another advantage is that your VIN will be on the transmission, so the 'numbers will match'.

If you do go the way of a rebuilt, ready-to-install transmission, get the GM rebuilt unit. You then get exactly the transmission spec'ed out for your vehicle. Sure, it costs a little more, but you get what you pay for - especially with transmissions.

And yes, any transmission rebuilder/installer worth his salt will flush out the cooler lines - if for nothing other than to reduce costs (RMA/warranty repair costs money).

[Blue Bowtie]

If the transmission started to slip some miles ago, the reaction sun shell hub is probably not sheared off, but has no spline teeth left to it, like this:


I would normally suggest using the factory replacement part, but in this instance I would disagree. Any factory remanufactured or new transmission will invariably have the SAME REACTION SUN SHELL. AFAIK, GM has YET to address the real problem that the rest of the industry has known since 1983 - These things are plain CRAP! Mine went at 61K. Further, the factory reman will likely have a five- or six-disc clutch stackup in the 3/4 clutch, whereas a quality rebuild will have EIGHT discs with full-thickness steels. The same thing happens with the factory low/reverse clutch and direct (forward) clutch.

Further, do not use your original torque converter unless it has under 45K and can be flushed completely. Even 45K miles is a push if the vehicle has been used for hauling/towing or driven harder.

If it were mine, I'd rebuild it myself and select the components individually to make it as durable as possible. That would probably include a five-pinion planetary set, and maybe the low ratio planetary set (2.66:1 first gear) in a higher performance application.

[silicon212]

I thought GM addressed the sun shell issue with the 4L65E - at least that's what some local transmission shops around here (AAMCO and Cottman, to name two) have told me.

I'd still go with a Beast if at all possible.