Lost Overdrive but 1,2,3 still working, anyone?

Current Mileage: 218,500 Kms

Accelerating to get on the highway from a speed of 60 Km/h, I heard a high pitched squeal for a few seconds and then it was gone. Sounded like a belt slipping, but wasn't.

Trans shifted a little hard as it downshifted, and when it finally 'wanted' to shift into overdrive there was nothing. Tach was fluctuating between 2500 RPM and normal 1800 to 2000. However, when we started downhill, the Tach dropped off to about 1000 RPM (@ 90 Km/h).

I was only going a short way, so shifted into 3rd and left it there. Works fine otherwise. Guessing that the overdrive clutch hub is now stripped.

Van is not worth a trans rebuild, so I guess we'll drive it in 3rd gear until it gives up entirely. :uhoh:

Trans was serviced at 183,000.

Anyone care to guess how long it will run?

any check engine light

could just be a solenoid but it would throw a code. TCC lockup solenoid going bad will cause no over drive and hard 1-2 shift.

Yep. The 4th clutch shaft is most likely stripped. Common problem. If it's not worth the repair, put it in D3 range and go. Of course you will be running at a higher rpm, no teling how long the powertrain will last. Good luck.

any check engine light

Nope, no codes or CEL.

I managed to override the PCS max pressure issue with a shift kit, Lucas trans conditioner and in-line trans cooler about two years ago. Got about 45,000 Kms further with it until this problem cropped up.

It could be a lockout issue, as it was hot today and the trans is more susceptible to max pressure from the PCS when it's hot. Oddly, when the pan was dropped two years back there was nothing I would have considered abnormal, just normal wear after 160,000+ Kms.

Van has developed other issues, like a rocker panel that rotted out a foot forward of the right rear wheel, and a rack and pinion that is getting lazy in the morning, and sometimes when it's hot. Mechanically, I've fixed everything else to get a few more miles out of it. Re-sale value is probably less than $1,500. Drive it until it quits.

Wondering if the power train will burn up at highway speeds in 3rd though. Of course mileage will suck by about 20% too.

I read somewhere on a Bonneville web site that the 4T65E Trans can experience a TCC lock out due to a bad ground in the chassis, a bad brake light switch, or a code stored in the ECM.

http://pontiacbonnevilleclub.com/forum/viewtopic.php?f=23&t=12868

Interesting reading. The power train is the same (less the 3800) and knowing these vans and their wiring and grounding issues it is a possibility.

Going to find a good trans shop for an opinion, but I think we will dump the van if the cost to do a band-aid fix is more than $500.

Took the van to a really good, recommended shop yesterday morning. Not sure what the code was in the ECM, but the owner of the shop scanned the ECM, and then we took the van for a test drive with the scanner attached.

Trans / ECM is calling for lock-up (4th gear) at highway speeds, but the diagnostic info and the Tach confirm that the 4th gear clutch is not engaging. Mostly, the problem is confirmed as a mechanical problem as no feedback is received from the Trans saying I am now locked up in fourth gear. Apparently a common problem with the vans. $2000 to R&R, not worth it.

He says we could probably run it around town for years without doing anything, but I need a car that can highway 50% of the time.

So, I guess we will say goodbye to the van shortly, or perhaps find a mechanic who understands the problem, can fix it, and is interested in owning a van that has everything fixed on it, but needs some Trans work.

Thinking of an '08 or '09 Ford Escape or Edge as our next vehicle. The guy behind me bought two about two weeks ago wholesale from a used dealer for $8000 each with low mileage; - sold them both for $10,000. Would have been a steal to get one! They retail for about $16,000 average up here in the Great White North.

Decided to get it fixed, lesser of two evils and drive it a while longer. New rack and pinion too. Only thing left is the alternator or a rear wheel bearing, everything else that can be replaced has been!

Was the 4th clutch shaft stripped on the end?

Was the 4th clutch shaft stripped on the end?

Hi, we won't know until they pull it down a week from Monday.

Although the ECM was calling for lockup on the highway, the tach confirmed that it did not lock up; - was hunting between 2000 and 2500 rpm at 65 mph suggesting that the hub was slipping, or splines were stripped.

Trans guy has re-built hundreds of these and he tells me he normally installs a steel shaft and hub to eliminate the problem entirely. Think later model 4T65e-HD's use a steel on steel design too.

Safe to say that the original shaft was not hardened as in later build 4T65e trans. Not sure if just the shaft or the hub is aluminum though either.

Will keep the post updated as information becomes available.

One more repair out of the way soon.

Decided since the sub frame will be lowered enough to remove the trans that this might be a good time to replace the rack and pinion (getting lazy in the morning and popping on left and right turns when the spool shifts inside).

Boy, I love GM junk! (or is that Got a Mechanic Coming)?

And here's the irony, the reman parts I've replaced are better than the OEM's GM installed new.

Was the 4th clutch shaft stripped on the end?
Yep, clean as a whistle! 4-th gear clutch pack was worn, but might have been serviceable. The one and only band in the trans was also worn and friction heat was evident.

They replaced the channel plate with a reman one and new oversized pistons, PCS, and TCC solenoids, 4-th clutch hub and clutches, driven sprocket and a new hardened shaft. Gaskets and seals. The gasket on the side cover is apparently the most expensive (supposed to be re-useable, but almost always breaks taking the case apart).

Also had the rack and pinion installed at the same time while the sub frame was lowered and saved about 3 hours labor to R&R.

Alignment tomorrow.

You can use it for local city driving, or POD!

Glad you found out the problem....

Just to clear a few things up, 4th gear is not lockup, it's overdrive gear....the TCC solenoid locks the tranny in 3rd and 4th gear.....

@ Tech II, It's crazy how many people think TCC lockup is overdrive isn't it. This car did not have OD of course but I get alot of people saying their car will not go into overdrive. And you have to ask, "Do you have all the gears but no TCC lockup?" They usually still don't get it but lockup is usually available in 3rd and 4th gears, sometimes 2nd. I think they wait for that last drop in rpm and if it doesn't happen they assume OD is gone. I try to tell them 3rd gear is a 1:1 ratio. 4th gear is 0.70:1 which is actually overdrive. TCC is just a clutch to engage trans to flywheel to save gas and keep trans temp down.
Now with these 6 speed autos we have 2 OD gears and no 1:1 ratio. Crazy!

@ Tech II, It's crazy how many people think TCC lockup is overdrive isn't it. This car did not have OD of course but I get alot of people saying their car will not go into overdrive. And you have to ask, "Do you have all the gears but no TCC lockup?" They usually still don't get it but lockup is usually available in 3rd and 4th gears, sometimes 2nd. I think they wait for that last drop in rpm and if it doesn't happen they assume OD is gone. I try to tell them 3rd gear is a 1:1 ratio. 4th gear is 0.70:1 which is actually overdrive. TCC is just a clutch to engage trans to flywheel to save gas and keep trans temp down.
Now with these 6 speed autos we have 2 OD gears and no 1:1 ratio. Crazy!

Good point and I hear you. I probably shouldn't have referred to it as a true 4-th gear. It is exactly as you describe, a direct connect between the crankshaft and the output shaft of the transmission, or direct drive.

My '78 Dodge has a lock-up torque converter in it too, but you only experience lock-up above 40 MPH. The rest of the time below 40, it is in 3-rd gear or 1:1 with torque converter slippage. I thought the Van was the same.

Didn't think the 4T65e could lock up in 2nd, but might explain how it stripped the splines clean. Interesting, although the shaft is splined for a good 1 and 1/4 inch, the lockup hub only uses the first 1/2" of the shaft to engage.

Some applications will start applying TCC in 2nd gear, not all. You described your problem very well. No overdrive is what you said and overdrive is what you didn't have. You even called the stripped hub in your first post! 4th gear is overdrive and the 4th clutch hub was stripped. Wipes the splines clean off smooth doesn't it? If it wasn't for all of the gaskets and fluid that need to be replaced along with the shaft, the repair wouldn't be bad at all. The other common problem is the forward band breaking. Let's hope that doesn't happen because it is all the way in the back of the trans. Can be overhauled with trans in vehicle, but let's just be glad you are on the road, completely functional.

i have an 01 montana with 117k experiancing similar problems. the guy my mechanic recomends charges 1000-1300 for total rebuild. is it worth it? only if i am sure that is the problem. how can you be sure? see eaglehawk post on 9/23. what diagnostics are available?:confused:

i have an 01 montana with 117k experiancing similar problems. the guy my mechanic recomends charges 1000-1300 for total rebuild. is it worth it? only if i am sure that is the problem. how can you be sure? see eaglehawk post on 9/23. what diagnostics are available?:confused:

The investment is only feasible if:

* engine has had Lower Intake Manifold gasket failure repaired and solved so as not to lose the engine due to internal coolant leaks
* body is sound and not in need of major rust surgery
* all other components are in good shape: - shocks, ball joints, tie-rods, and suspension parts

I literally went through the entire front end this year and replaced everything that could wear out including the rack and pinion.

If the engine had started knocking or worse, I would not have considered doing the trans rebuild at all.

Value of these vans is about $1,500 to $3,500 depending on year, and overall mileage and condition. So an investment (in your case of $1,100 to $1,300) might be warranted, as long as you know what you have to work with and that it will last to gain benefit from the re-build.

Basically its one of those should I or shouldn't I things. If you like the van and know it will run longer with the re-build then the choice is yours. Beats depreciation on a new one or even a good used 2008 or 2009 vehicle.

There were no specific diagnostic codes for what was happening to my trans because as long as shifts are timed and occur when they should, the trans can not report back that it has any issues.

Originally it exhibited the max line pressure code which caused it to shift hard in 1,2 and 3. But this was masked by the installation of a shift kit that caused the trans to shift faster thus eliminating the max pressure or PCS syndrome. Problem was that although it fooled the ECM, the trans was still slipping a bit, but it did run another 50,000 Kms before a major failure occurred.

Then just recently it lost 4-th and would not lock up in 3-rd either due to a stripped input shaft that attached to the 4-th gear clutch assembly.

i have an 01 montana with 117k experiancing similar problems. the guy my mechanic recomends charges 1000-1300 for total rebuild. is it worth it? only if i am sure that is the problem. how can you be sure? see eaglehawk post on 9/23. what diagnostics are available?:confused:

You would be a lot luckier than I was at 1,000 to $1,300 for a re and re. Mine ended up costing just over $2,000; - ouch!