4T65 Pressure Control Solenoid

[sciphi]

It looks as if the pressure control solenoid on my 99 Buick LeSabre's 4T65 is dying. It is shuddering on hard launches, and sometimes refuses to go. I can get the shudder on command now by stomping the gas from a dead stop.

Has anybody replaced one of these, and what should I look out for when replacing it? I'm looking to do the work myself, which I know will be a royal PITA to do, although not impossible.

 

[mechtech2]

This could be the problem, but so could so many other things.

 

[sciphi]

I'm taking it to a local AAMCO tomorrow for their free diagnostic. We'll see what they say.

 

[elgalante]

Originally Posted By: sciphi
It looks as if the pressure control solenoid on my 99 Buick LeSabre's 4T65 is dying. It is shuddering on hard launches, and sometimes refuses to go. I can get the shudder on command now by stomping the gas from a dead stop.

Has anybody replaced one of these, and what should I look out for when replacing it? I'm looking to do the work myself, which I know will be a royal PITA to do, although not impossible.


Get ready for a rebuild or replacement.

PCS cost mucho $$$s in labor to have someone else to do and is a PITA to do oneself.
Spending $$'s replacing PCS on a '99 4t65 subject to the treatment you admited to above... well..

If you are talking going to AAMCO for their diagnostic something tells me you are not serious either about doing the work yourself

What do you expect AAMCO to tell you? They will ask ~600$ for PCS+ labor alone and highly recommend a full rebuild ~2300$
The treatment you are subjecting your worn 99 4t65e (let alone the mileage and age) guarantees a tear down and need to replace several known problem wear parts.
At this stage it is pointless to save a few $$ and one would go with the full overhaul.

You might not like this part but consider the age and remaining condition of the car. Is it worth the $$'s for a rebuild? Maybe could spend the $$s the rebuild would cost and drive off with a similar vintage 4t65e + 3800 series II car in better working condition that your current?
At least consider it.

Also I would shop around and find that local place that knows the 4t65e well and takes pride to show you their facilities and all the fixes they will perform for an upgrade.
You can do better than AAMCO. Not saying they can't do the job but it's like buying a Fram oil filter without considering what else is out there

Just looking to be helpful not an *ss having seen many go through the same.

 

[T-Keith]

The solenoid can be replaced in the car by taking off the drivers side axle and possibly dropping the cradle a few inches. It's not for the novice, but I'll be doing it to our Park Ave. one of these days. I did have some luck on another car with AutoRX, it might be worth a shot.

 

[sciphi]

Elgalante, I drive very conservatively. Hot-dogging my car doesn't happen very often. I don't launch it hard except when I need to, or about once every 2 weeks. I'm relating a symptom I have observed repeatedly over the past few months. Also, the transmission has 80k mostly highway miles on it, and spent ~90% of that time with the TCC locked up in 4th gear. It has not been abused or neglected, having had its 3rd flush this past December with Dex-VI. It also has a large auxiliary cooler and a Magnefine. I've had the car since 30k miles when I got it ~2.5 years ago. Do the math. The engine is mechanically perfect, and the rest of the car is fairly solid. It's in much better mechanical and interior shape than many younger cars.

I just want to play dumb and see what AAMCO says to persuade the SO that me spending a weekend getting my hands dirty ripping into the transmission happens. I've researched the issue to death, and the PCS sounds like it. Plus, getting a second opinion never hurt, especially transmission related.

We'll see what they say. If they say PCS, great. If they say something else, more research needed.

 

[sciphi]

AAMCO says they can't find it, come back when it's doing it.

Sure enough, it didn't.

Forgot to mention the transmission received an Auto-RX dose about 150 miles ago.

 

[elgalante]

Did you scan for transmission codes? Any P1811 (long shift, max adapt) stored? Ever hear like a whining sound on acceleration after driving some? (similar to a power steering whine)

Find someone with a good scanner that can record PC commanded pressure and shift times and report back some #'s for baseline pressure, peaks and shift times. If this is not an option find a local trans shop that knows the 4t65e and can check this.

If AAMCO cannot find it because it's not doing it, I would not return there.

Considering you indicated you already have a 1-2 3-4 accumulator shim kit installed and you are seeing shudder, yes are likely to be looking at least at the PCS.
As others said, you will need remove the drivers side axle and unhook the cradle and drop the engine to get into the side cover.
It's a PITA job. If you have dropped the bottom pan yourself before for filter change in the car and are feeling brave go for it.
If dropping the pan was an undertaking, let someone else do it.
You will need wood blocks, flat ground, breaker bar, gaskets for the side cover, etc.
Also it could be tricky to ensure you get the right PCS for your particular vintage 4t65e. 97-02 is different than later years.
Some recommend the Borg Warner saying they have proven much more reliable than the originals. There are different ones floating around. Replacing the PCS alone is sorta not that helpful either. You should prob look at a kit such as the Sonnax 4T65E Boost Valve and Sleeve set to address wear in the PCS valve seat/bore.

Sounds like the rest of the car is decent, you also profile the cars entire driving history and maint. ,but only had it for last 30k ?

Have you considered a rebuild book if you are committed to do the research and possible the work. Such as the ATSG General Motors Techtran Manual for the 4T65E.
If nothing else there are lots of good online step by step rebuild efforts with pics online at the 4t65e car forums.

4t65e is not a particularly problematic transmission beyond the PCS but there are other wear parts that could be right around the corner for replacement. Consider also that fully rebuilt 4t65e are cheap if you want to tackle the labor.

On a personal opinion, if you want to keep the car long term, I don't believe in replacing only the PCS. I would find a local place that knows the 4t65e well and all upgrades and have them rebuild. If the rest of the car is good it is a good investment.
AAMCO would not be my choice.

Good luck!

 

[sciphi]

Originally Posted By: sciphi
since 30k miles


AAMCO scanned it, and couldn't find any codes. No mention of long shift times or anything.

Of the 80k miles on the car, I've put on 50k of them. And a family member gently put on the first 30k. The car's history is well-known.

I was considering yanking the engine and transmission to have more room to work in. Dropping the pan was no sweat. I've removed transmissions from other cars before, so I'm fairly comfortable doing the work of removal. Monkeying beyond replacing a solenoid or two is not something I'd feel comfortable doing.

I'd be replacing all the solenoids in the valve body with the Borg Warner ones, and likely doing some other easy fixes, like the boost valve. I know where there are detailed pictures of a 4T65 being ripped apart, and can easily contact folks who have done just that before.

Now it's the question of where to go from here.

 

[Whitewolf]

I had a Buick not long ago and it shuddered on launch but it also didn't want to stop! It turned out to be the TCC solenoid. May not be related to your issue but I thought I would share.

 

[sciphi]

Thanks! It may not be, however, if it's in the valve body, it'll be done on general principles.

 

[sciphi]

Bringing this back from the dead...

I worked around the PCS issue by installing the springs and spacers from a TransGo shift kit into the shift accumulator, and flushing with new ATF. It greatly diminished the shuddering on hard launch, well enough to where replacing the PCS is not necessary. The car has just under 92k miles on it now, 12k of those miles with the TransGo shift kit installed.

Before some folks go off for me not fixing this the "right" way, I know, it's not the right way. It's a shade-tree mechanic solution that happens to work.

I'm waiting for the 4th gear input shaft to strip before doing anything else with the transmission, beyond changing the Magnefine on there. Once that goes, it's rebuild time.