I need a auto trans guru to help with this oddball!!

Transmission, drivershaft, and rearend.

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I need a auto trans guru to help with this oddball!!

Postby powerhungryv8s10guy » Tue Nov 07, 2017 8:57 pm

I was going 40mph headed to school this morning, I never touched the column shifter, and BAM!! full on trans brake at 40! Motor died, rear tires locked up. I pulled into a parking lot, threw it in neutral and restarted the engine, put it back in drive and it seemed fine. Then it did it again in the parking lot. I moved the truck back and forth in the lot, and anything over 10-15mph and it just shifts into reverse on it's own. I limped it home 10-15mph and it would keep doing it. I did put it in 1st gear and it seemed to help. I could get it up to 20mph with less noticable "transbrakeing" 98 s-10 extended cab 4 cylinder 4l60e. I do know these transmissions are known to have issues of not enough line pressure that causes clutch slippage, and a mechanic I know put a stiffer spring in it to boost line pressure and it cured the slippage when the previous owner had the truck. Any Help??
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The Milkshake a 92 short bed reg cab, 3/4 static drop, 92 5.7L TPI/700r4, with a 2000 blazer floor shift center console, and buckets, and lots, lots more!!
Mutant-X a 96 4X4 blazer to be converted to AWD 6.0L V8 lowered to look like a 2wd and Xtreme body kit. Stay tuned.

Craig
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Re: I need a auto trans guru to help with this oddball!!

Postby 91Blazer2WD » Mon Nov 13, 2017 10:45 pm

Hi Craig. I'll see what I can do to help.

As a GM tech the first thing I need to ask is: Are there any aftermarket mods done to the vehicle? Such as: component swaps, aftermarket programming, any accessory plugged in to the DLC? Sorry, had to ask. You would be amazed how often the vehicle gets blamed when it is actually something that has been added or changed even if on the surface it doesn't appear it should be related.

Is the Check Engine light on (SES light)? Even if it is not, do you have any history powertrain codes stored? Although it is not impossible, I would be a bit surprised to have a dramatic failure like that and not set some kind of code. Any codes might help narrow down what area or component to test.

Based on your description, I believe you are having an issue with one or more of the shift solenoids or their corresponding circuits. One way to test the solenoids is a resistance check which can be done from the pass-thru connector (this will help check the wiring inside the trans as well. Keep in mind the resistance values will change with transmission temp. Shift solenoid resistance should be 19-24 ohms at 20*C (70*F ish) or 24-32 ohms at 100*C (212*F). Check for a short to the transmission case as well. Resistance reading from the solenoids to the case should be over 250K ohms.

Just out of curiosity, have you tried to drive the vehicle since it cooled back down. If the problem only occurs when it is hot I would definitely suspect a solenoid winding is either doing open or shorting. If the problem is intermittent or temperature related you may need to duplicate those conditions to get accurate test results.

I hope this helps.
Jeff
1991 S10 Blazer 2WD, full Beltech suspension, ZQ8 swaybars and steering box, 3.42 gears with Eaton Tru-Trac, 4-wheel C5 Corvette brakes w/parkbrake (in progress), SBC swap going in Spring/2018 with Camaro ZL1 NPP mufflers.

1990 Camaro IROC-Z, 350/5 speed, Holley Stealth Ram, Ported Vortec heads, Comp Cams XFI-268, 1 3/4" stainless headers, 3.5" single exhaust w/Dynomax muffler, full tubular suspension, circle track springs (1000lb front/250lb rear), C6 Z51 brakes 13.4" F/13" R, 2017 Camaro 20x9.5 rims, 3.70 cone posi 9-bolt (Tru-Trac to go in 2018).

Jeff
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Re: I need a auto trans guru to help with this oddball!!

Postby powerhungryv8s10guy » Tue Nov 14, 2017 8:07 pm

No add ons or aftermarket equipment or modifications. I did drive it again and same symptoms even cold. I know it involves 2nd gear. 1st gear I can take it to redline, reverse I can take it to redline. I stopped and put it in 2nd gear and it acts just like a trans brake. you can load up the converter and the truck sorta lunges backwards but no forward movement, then when you let of the throttle it sorta lunges forward a bit and still locked up. back to drive and overdrive when it shift into 2nd gear, it locks up.
ImageImageImageImageImage
The Milkshake a 92 short bed reg cab, 3/4 static drop, 92 5.7L TPI/700r4, with a 2000 blazer floor shift center console, and buckets, and lots, lots more!!
Mutant-X a 96 4X4 blazer to be converted to AWD 6.0L V8 lowered to look like a 2wd and Xtreme body kit. Stay tuned.

Craig
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Posts: 2008
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Location: Southwestern IL

Re: I need a auto trans guru to help with this oddball!!

Postby 91Blazer2WD » Tue Nov 14, 2017 8:23 pm

OK, that is a bit of a strange one. Being able to narrow down which gears are affected should help in the diagnosis.
Are you able to scan the truck for codes at all?
If there are no codes it may be more of a mechanical issue or hydraulic leak inside the trans/valve body.
I'm going to talk it over again with the trans specialist where I work and get back to you.
1991 S10 Blazer 2WD, full Beltech suspension, ZQ8 swaybars and steering box, 3.42 gears with Eaton Tru-Trac, 4-wheel C5 Corvette brakes w/parkbrake (in progress), SBC swap going in Spring/2018 with Camaro ZL1 NPP mufflers.

1990 Camaro IROC-Z, 350/5 speed, Holley Stealth Ram, Ported Vortec heads, Comp Cams XFI-268, 1 3/4" stainless headers, 3.5" single exhaust w/Dynomax muffler, full tubular suspension, circle track springs (1000lb front/250lb rear), C6 Z51 brakes 13.4" F/13" R, 2017 Camaro 20x9.5 rims, 3.70 cone posi 9-bolt (Tru-Trac to go in 2018).

Jeff
91Blazer2WD
I found rocker arm monkey's on ebay!
 
Posts: 15
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Re: I need a auto trans guru to help with this oddball!!

Postby powerhungryv8s10guy » Wed Nov 15, 2017 8:55 pm

i don't have a code scanner
ImageImageImageImageImage
The Milkshake a 92 short bed reg cab, 3/4 static drop, 92 5.7L TPI/700r4, with a 2000 blazer floor shift center console, and buckets, and lots, lots more!!
Mutant-X a 96 4X4 blazer to be converted to AWD 6.0L V8 lowered to look like a 2wd and Xtreme body kit. Stay tuned.

Craig
powerhungryv8s10guy
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Posts: 2008
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Location: Southwestern IL

Re: I need a auto trans guru to help with this oddball!!

Postby 91Blazer2WD » Thu Nov 16, 2017 1:13 am

Is the 'Check Engine' light on? Even if it is not it may be worth your while to get a code reader. You should be able to get one for less than $100. Since you are able to duplicate the problem consistently scanning for codes 'should' enable us to verify there are no obvious electrical issues. After giving your description of the problem more thought I'm thinking you are more likely to have a hydraulic issue rather than an electrical one. However, because the electrical portion would be the easiest to inspect and diagnose, I think we need to eliminate that as a potential cause first.

The general consensus among the techs I work with is, if there are no codes, you likely have a hydraulic leak that is allowing 2nd and reverse to be applied at the same time. Reverse gear is controlled by the manual valve and is mechanically not electrically connected to the shifter. This means the only time reverse should be able to engage is when the shifter is in the 'R' position. In your case it would appear hydraulic pressure is leaking from the 2nd gear apply circuit into the reverse circuit.
This could be caused by (listed from most to least likely): damaged separator plate gasket between valve body and trans case, damaged seal on valve in valve body, worn separator plate not allowing check ball to seal, crack in valvebody or transmission case.

Although there are pressure tests that can be done, I'm not sure how useful they would be other than to confirm what we already suspect (that there is a leak). At the end of the day someone would still need to dig in and figure out WHERE the leak is.
1991 S10 Blazer 2WD, full Beltech suspension, ZQ8 swaybars and steering box, 3.42 gears with Eaton Tru-Trac, 4-wheel C5 Corvette brakes w/parkbrake (in progress), SBC swap going in Spring/2018 with Camaro ZL1 NPP mufflers.

1990 Camaro IROC-Z, 350/5 speed, Holley Stealth Ram, Ported Vortec heads, Comp Cams XFI-268, 1 3/4" stainless headers, 3.5" single exhaust w/Dynomax muffler, full tubular suspension, circle track springs (1000lb front/250lb rear), C6 Z51 brakes 13.4" F/13" R, 2017 Camaro 20x9.5 rims, 3.70 cone posi 9-bolt (Tru-Trac to go in 2018).

Jeff
91Blazer2WD
I found rocker arm monkey's on ebay!
 
Posts: 15
Joined: Sat Nov 11, 2017 7:02 pm
Location: BC, Canada

Re: I need a auto trans guru to help with this oddball!!

Postby powerhungryv8s10guy » Thu Nov 16, 2017 6:42 am

I barely have 2 plug nickles to rub together while I go through truck driving school. I've asked 3 different people now, and have got 3 different answers. Trans guy just wants to rebuild it, mechanic says something welded itself together in there, and now what I suspected was a leak in the valve body. Oh, And a friend said a broken sprag gear.
ImageImageImageImageImage
The Milkshake a 92 short bed reg cab, 3/4 static drop, 92 5.7L TPI/700r4, with a 2000 blazer floor shift center console, and buckets, and lots, lots more!!
Mutant-X a 96 4X4 blazer to be converted to AWD 6.0L V8 lowered to look like a 2wd and Xtreme body kit. Stay tuned.

Craig
powerhungryv8s10guy
Subscribed Member
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Posts: 2008
Joined: Wed Sep 22, 2004 8:09 pm
Location: Southwestern IL

Re: I need a auto trans guru to help with this oddball!!

Postby powerhungryv8s10guy » Thu Nov 16, 2017 6:42 am

no check engine light.
ImageImageImageImageImage
The Milkshake a 92 short bed reg cab, 3/4 static drop, 92 5.7L TPI/700r4, with a 2000 blazer floor shift center console, and buckets, and lots, lots more!!
Mutant-X a 96 4X4 blazer to be converted to AWD 6.0L V8 lowered to look like a 2wd and Xtreme body kit. Stay tuned.

Craig
powerhungryv8s10guy
Subscribed Member
Subscribed Member
 
Posts: 2008
Joined: Wed Sep 22, 2004 8:09 pm
Location: Southwestern IL

Re: I need a auto trans guru to help with this oddball!!

Postby 91Blazer2WD » Thu Nov 16, 2017 9:26 am

It's interesting how when you go to some transmissions shops the solution is 'it needs an overhaul', no matter what the original complaint was. :roll: Although this would likely fix your problem and allow the root cause to be determined, I'm not yet convinced it is the most cost effective solution right now. Just out of curiosity, how much mileage is on the vehicle/transmission?

Although I work for a GM dealership and the guys I have been discussing this with do these transmissions all the time, I'm open minded enough to consider other ideas that we may not have thought of. Especially since we have not seen this specific problem before. I'll mention the other opinions you mentioned and see what they say.

Do you have any way to borrow a scanner/code reader? I know some auto-parts stores have tool loaner programs. I don't know if this would include a code reader.
I would just hate to have you tear into the transmission only to find out later that you had a code and the problem could have been fixed by replacing a solenoid or repairing a wire.

I'm not sure of your skill/comfort level or your access to special tools but I see some form of transmission surgery in your future. Even if all you do is remove and inspect the valve body, I would recommend you have a detailed manual (library reference section?) on hand as there are likely going to be some loose check balls that come out and bolt length and torque is important when re-installing the valve body.

If this were my truck this is how I would proceed:
1) Double check the basics (fluid level, linkage adjustment, trans electrical connector installed correctly, motor/trans mount condition).
2) Scan for codes. If there are related codes, diagnose them first. If no codes proceed to step #3.
3) Remove trans pan and inspect for debris (some fine sediment is normal, any chunks or excessive metal flakes indicates hard part failure) If no obvious problems proceed to step #4. If hard part failure indicated, proceed to step #5.
4) Remove and inspect valve body (check for damaged separator plate gaskets, check balls worn through separator plate, damaged seals or valves inside valve body).
Test solenoid resistances. Repair as needed or if no problem found proceed to step #5.
5) Remove and disassemble trans. Repair as needed or possibly replace with new/used complete transmission.
1991 S10 Blazer 2WD, full Beltech suspension, ZQ8 swaybars and steering box, 3.42 gears with Eaton Tru-Trac, 4-wheel C5 Corvette brakes w/parkbrake (in progress), SBC swap going in Spring/2018 with Camaro ZL1 NPP mufflers.

1990 Camaro IROC-Z, 350/5 speed, Holley Stealth Ram, Ported Vortec heads, Comp Cams XFI-268, 1 3/4" stainless headers, 3.5" single exhaust w/Dynomax muffler, full tubular suspension, circle track springs (1000lb front/250lb rear), C6 Z51 brakes 13.4" F/13" R, 2017 Camaro 20x9.5 rims, 3.70 cone posi 9-bolt (Tru-Trac to go in 2018).

Jeff
91Blazer2WD
I found rocker arm monkey's on ebay!
 
Posts: 15
Joined: Sat Nov 11, 2017 7:02 pm
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Re: I need a auto trans guru to help with this oddball!!

Postby 91Blazer2WD » Thu Nov 16, 2017 9:33 am

Or, depending on time/money constraints it may just be easier to skip to Step #5 and install a good used trans and get you back on the road ASAP.
1991 S10 Blazer 2WD, full Beltech suspension, ZQ8 swaybars and steering box, 3.42 gears with Eaton Tru-Trac, 4-wheel C5 Corvette brakes w/parkbrake (in progress), SBC swap going in Spring/2018 with Camaro ZL1 NPP mufflers.

1990 Camaro IROC-Z, 350/5 speed, Holley Stealth Ram, Ported Vortec heads, Comp Cams XFI-268, 1 3/4" stainless headers, 3.5" single exhaust w/Dynomax muffler, full tubular suspension, circle track springs (1000lb front/250lb rear), C6 Z51 brakes 13.4" F/13" R, 2017 Camaro 20x9.5 rims, 3.70 cone posi 9-bolt (Tru-Trac to go in 2018).

Jeff
91Blazer2WD
I found rocker arm monkey's on ebay!
 
Posts: 15
Joined: Sat Nov 11, 2017 7:02 pm
Location: BC, Canada

Re: I need a auto trans guru to help with this oddball!!

Postby powerhungryv8s10guy » Thu Nov 16, 2017 6:20 pm

I don't have a problem yanking the pan and valve body, the problems I have are time and money. I'm currently in school for my CDL-A. I have my permit, and I'm getting hours of driving in everyday. I get home when it's dark, and I'm hoping I can get a part time job before I get done with school. Sat I will be getting my last running truck put back together so I can drive that and give my moms car back to her and get her off my ass. I can't borrow the scan tool from the parts store. I know this because I used to work there. I've barely got enough money to get through school let alone money to just diagnose the problem. I won't have excess money til after the new year and I'm caught up on bills.
ImageImageImageImageImage
The Milkshake a 92 short bed reg cab, 3/4 static drop, 92 5.7L TPI/700r4, with a 2000 blazer floor shift center console, and buckets, and lots, lots more!!
Mutant-X a 96 4X4 blazer to be converted to AWD 6.0L V8 lowered to look like a 2wd and Xtreme body kit. Stay tuned.

Craig
powerhungryv8s10guy
Subscribed Member
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Posts: 2008
Joined: Wed Sep 22, 2004 8:09 pm
Location: Southwestern IL

Re: I need a auto trans guru to help with this oddball!!

Postby 91Blazer2WD » Fri Nov 17, 2017 4:03 am

Sorry if I seems like I'm obsessing about scanning the truck but I have my reasons.
I am a drivability/electrical technician. That is all I do 40 hours a week. I try to approach every problem in a logical way basically proceeding from the easiest to diagnose/most likely causes to the harder to diagnose/less likely causes. What I have found is if you skip the basics and assume 'it's ok, I don't need to check that', it can come back to bite you in the a$$. There are few things more frustrating than spending hours trying to diagnose a problem only to find out the cause is something simple you overlooked.

Having said all that, the general consensus here is that you have a hydraulic/valve body issue. Dropping the pan and valve body will just cost you a couple hours plus gaskets and fluid. If that doesn't reveal a cause it would appear you are looking at tearing down the rest of the transmission. So, even if it does end up being a hard part failure like someone else had suggested, it makes sense to start by inspecting the valve body first.
Keep in mind what I said earlier though. If you remove the valve body there are likely going to be a few check balls that fall out and go rolling around (some are above the separator plate, some below). You will need some reference in order to re-install them in the correct locations (usually use some trans assembly grease to hold them in place during assembly).

Let me know if there is anything else I can do to help.
1991 S10 Blazer 2WD, full Beltech suspension, ZQ8 swaybars and steering box, 3.42 gears with Eaton Tru-Trac, 4-wheel C5 Corvette brakes w/parkbrake (in progress), SBC swap going in Spring/2018 with Camaro ZL1 NPP mufflers.

1990 Camaro IROC-Z, 350/5 speed, Holley Stealth Ram, Ported Vortec heads, Comp Cams XFI-268, 1 3/4" stainless headers, 3.5" single exhaust w/Dynomax muffler, full tubular suspension, circle track springs (1000lb front/250lb rear), C6 Z51 brakes 13.4" F/13" R, 2017 Camaro 20x9.5 rims, 3.70 cone posi 9-bolt (Tru-Trac to go in 2018).

Jeff
91Blazer2WD
I found rocker arm monkey's on ebay!
 
Posts: 15
Joined: Sat Nov 11, 2017 7:02 pm
Location: BC, Canada


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