Rebuilding a 4T65E-HD - Part 1 reference material - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat

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Old 05-05-2008, 12:01 AM   #1
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Default Rebuilding a 4T65E-HD - Part 1 reference material


Kinda grimy when picked up:

The -HD diffy parts were first to come out; the differential looks good and checks out as per planetary play spec in the FSM:

Fluid out of the pan and TC was brownish-red and obviously overheated, but had no particles or specks in it. The pan had no metal bits, and the magnet had only typical fine gray "clutch mud" stuck to it.

Pan removed:

Cracked open the filter with a hammer and chisel:

Only some fine clutch mud, no metal particles. The third pic shows some black "flakes" stuck between the felts...I know what that is already, but I'd be getting ahead of myself

I'm getting help from Dave at to make sure I get the right overhaul parts for my year and anticipated power level.


OK, so I'll go through the book step-by-step, with my inspection notes and pics on the dismantle.

Torque converter: JTFM 258mm TC. Looks OK on the outside and in the teeth, but the bearing has some nicks in it. Probably best used as a core for a reman.

Reverse Servo: OK.

Forward Servo: OK.

Pan: OK; cleaned up great. May investigate getting a drain plug welded into it. Two M6 bolts missing, but threaded holes in case all OK, and can get $2 replacement bolts from Intense. Pan Gasket in excellent shape after cleaning, and can be reused.

Oil filter: No alarms; see previous post(*).

Accumulator assembly and 2-1 Band Servo: OK. After I get new piston seals out of an Overhaul kit, I'll probably swap this unit in it'* entirety into the current trans and swap in the current trans' unit with Thrasher shift kit already installed.

Control Valve Body Cover (Side Cover): OK. Very grimy, but cleaned up fine. Gasket in great shape after cleaning, and can be reused. Had a W-body specific mount bolted to it, will probably give away or sell mount.

Wiring Harness: Screwed that puppy up; all the little plastic retaining clips to the solenoids were very brittle, and as careful as I tried to be I broke every last one of them:

This harness will find use as part of a solenoid test apparatus. I bought a replacement used 14-pin harness for $15 shipped from an EBAY seller I have bought good parts from before; it checks out OK.

Oil Pump: Removed but not yet disassembled for inspection:

Control Valve Body Assembly: Removed and prepared for inspection:

Checkballs, case cover pin, separator plate, pressure switch, etc. bagged and tagged.

NOTE: The valve body can be a potential budget-buster, depending what I find inside…stay tuned.

Oil Pump Drive Shaft: Teeth at pump end OK, but teeth at TC end are badly worn:

Vehicle Speed Sensor: OK.

Output Shaft / Differential / Extension Housing: OK; discussed in earlier post.

Manual Valve Link, Oil Dam, Input Speed Sensor: OK.

Case Cover Removal: Rounded off one of the bolts

But got it out with some reverse drill bits:

Found replacement M8-1.25 50mm grade 10.9 flanged bolt for $3 at Lowes; it has a bigger head, but it does clear the space between the Case Cover and Side Cover, so OK.

Fourth clutches and thrust washers came out with the case cover:

Two locating pins:

Manual valve OK. Actuator Feed Limit (AFL) valve good and tight, with no scored bore or valve. (This was a potential project killer, as the AFL valve fix from Sonnax requires special tools and machining and is muy expensivo:

Drove Left axle oil seal out from behind with hammer and screwdriver. Axle bearing looks good. Pump shaft sleeve looks good.

TC relief ball valve seat is a bit chewed up:

Sonnax makes a $5 fix for that:
This could definitely have been a contributor to the seller’* TC lockup dropout issue.


Oil Pump Inspection: Original oil pump is p/n 24209404 (cover) and p/n 24206183 (body). This is '97 to '98 style pump, based on my research.
Taken apart.

The vane rotor with my cryptic Sharpie marks to make sure reassembly is right:

Pump slide has some concentric grooves in it:

Vanes have corresponding ridges:

Is this groove and ridge thing normal? I frankly don't know.

Spare pump I bought is p/n 24213197 (cover) and 24210098 (body). My research indicates this is the mid-98 to '02/'03 style pump update, before GM went to some kind of 3-piece pump.

I note that the pump slide in the spare pump does not have any grooves, nor do the vanes have ridges. I also note the newer pump cover has a "bypass" groove cast into it, which I like.

I can interchange pump covers; however, pump slides/vanes/rotors are not interchangeable because they are factory matched to the depth of each pump body coming off the assembly line.

These pumps seem to be worn similarly otherwise. Both are probably just fine, but I'll likely go ahead and use the spare pump.


Valve Body Inspection:

There are 11 separate bores for solenoids and/or valves.

1. Line Boost Valve and Pressure Regulator Valve:

The line boost valve and reverse boost valve ride inside the boost valve bushing:

The inner bore of the aluminum bushing is clearly worn, and these valves are rattling around inside too freely. This is a common problem, and leads to slow / sloppy shifting. Sonnax makes a drop-in fix (about $45):

2. 1-2, 3-4 Shift Solenoid and 1-2 Shift Valve: Solenoid clicks when 12v applied; will probably replace anyway (about $20) to be safe. Shift valve and bore OK.

3. Electronic Pressure Control (EPC) Solenoid and Torque Signal Regulator Valve: This solenoid clicks, too; however, it is always recommended to replace this one (about $50) on a rebuild. This solenoid is year specific (97-02, or 03+). Regulator valve looks good and the bore is fine.

4. Line Pressure Relief Valve: All OK.

5. Torque Converter Control / Pulse Width Modulator (TCC/PWM) Solenoid and Torque Converter Control (TCC) Valve:

Solenoid clicks, but again, always replace this one on a rebuild (about $40).

TCC valve is quite worn and loose in the bore (though the bore looks OK):

This is a common problem also, and could be the cause of the TC lockup dropout issue. Sonnax TCC valve drop-in fix (about $25):

6. TCC Regulator Apply Valve:

The valve and bore are OK; good thing, because the Sonnax fix for this require special tools and machining and would be a budget buster:

The end plug looks worn on one side, as if it was being "canted" somehow:

The Sonnax TCC valve fix referenced above includes a new teflon sealing ring for this end plug. Also, I could order a whole new end plug (p/n 24208635) from GMPD for about $5.

7. 2-3 Shift Solenoid: Solenoid clicks when 12v applied; will probably replace anyway (about $20) to be safe.

8. 4-3 Manual Downshift Valve and 3-4 Shift Valve: All OK.

9. 3-2 Manual Downshift Valve and 2-3 Shift Valve: All OK.

10. 1-2 Accumulator Valve:

The valve is slightly scored, but seems tight in the bore:

If I can find a p/n for this valve, I'll consider replacement, but I think it'* OK as-is.

11. 2-3 Accumulator Valve and 3-4 Accumulator Valve:

Like the 1-2 accumulator, these both show some light scoring:

But both are tight in their bores. The bushing the 2-3 rides in looks fine, and is tight in its VB bore. Again, if I can find p/n'* for these valves I might consider it, but I think these are OK as-is.


Checking out the channels in the VB, I found only this minor chip:

I'm not worried about that.


One thing I need to find out more about...

I found three "mystery clips" like this one:

That are not referenced in the manual. They are smaller than any of the valve or solenoid end / retaining clips.

One was found in this location on the torque signal regulator valve (blue arrow):

One in this location (blue arrow) on the TCC control valve:

And the third I think was in this location (black arrow) on the TCC regulator apply valve:

There'* a TSB about "extra clips in the valve body" on 4T65E'*, but noone can seem to pull it up for me:

My intuition tells me that these "extra clips" were used to temporarily hold in valves during manual assembly (to keep the springs compressed while the end caps / retainers were installed further down the assembly line). Their locations do not affect the operation of the given valves.

Perhaps they were supposed to be hand-removed at the factory after the VB was assembled, but were not. Or were not removed because they don't affect operation.

I'd really like to get my hands on that TSB to know for sure


All in all, I didn't see anything in the valve body that I'd consider a project killer.


Good news! I got confirmation that those "mystery clips" I found are indeed temporary assembly clips and can be removed during the rebuild:

So, on to other things.

Case Cover Inspection:

I found only one small nick in the fluid channels:

Nothing to worry about.

The area near where the axle goes in had a gouge in it, looks to me from maybe a prybar or something used to remove the axle. I filled it with epoxy:

At the same spot, where the side cover goes on, there is a chip in the cover:

It'* outside where the sealing ring is, so I'm not worried. I filed off the sharp edges of the chipped area.

3-4 accumulator looks OK.

So, overall the case cover checks out OK (once I take care of the TC relief valve fix).


See Part Two
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