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

[1999montana]

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.

Trans was serviced at 183,000.

Anyone care to guess how long it will run?

[FishFind]

any check engine light

[FishFind]

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.

[procaddytech]

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.

[1999montana]

Originally Posted by FishFind

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.

[1999montana]

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/for...p?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.

[1999montana]

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.

[1999montana]

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!

[procaddytech]

Was the 4th clutch shaft stripped on the end?

[1999montana]

Originally Posted by procaddytech

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.

[1999montana]

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.

[1999montana]

Originally Posted by procaddytech

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.

[danielsatur]

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

[Tech II]

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.....

[procaddytech]

@ 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!