Trimatic Oil Leaks

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Originally submitted by T:

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An Oil Leak from this Bolt Hole was fixed with a new Bolt and Alloy Washer (oldwbute). Photo by Crocky. Click to Enlargen.


Oil Leaks:

There are a number of causes of Oil Leaks from Trimatics.

Pan Gasket:

The Pan Gasket can shrink due to exposure to the hot oil it holds in and simply need re-torquing. 9 ft/lbs is all the pan bolts need. The rear pan bolts can need re-torquing more than the other pan bolts because the oil tends to collect towards the rear.

Or by Hydraulic (high pressure) thread sealant (Arsewipe). Photo by Crocky. Click to Enlargen.

new bolt, new washer,

Hydraulic (high pressure) thread sealant

Oil Filler Neck:

Also known as the Dipstick Tube. The gearbox end of the Oil Filler Pipe is sealed by a Grommet. Over time the Grommet can become hard and an Oil Leak can appear there. Make sure you have the correct filler tube.

UC Tailshaft Yoke showing leaking Welch Plug. Click to enlargen. Photo by T.
 
 
UC Tailshaft Yoke showing leaking Welch Plug. Click to enlargen. Photo by T.
 
6 Cyl Trimatic with Commodore Bellhousing and nearside Selector Lever. A trail of Transmission Fluid shows the path a leak would take if the Front Seal had failed. In this case simply removing the Torque Converter produced the stream.  Image by David Nye. Click to Enlargen.
 
Tailshaft Yoke showing the Welch Plug. Click to enlargen. Photo by HQSS.
 
Trimatic Front Seal. Photo by T. Note the Lip (rightmost) sets the installation depth. Click to Enlargen.
 
Trimatic Front Seal. Photo by T. Note the Lip (uppermost) sets the installation depth. Click to Enlargen.
 

 

Early style 6 Cylinder Bellhousing fitted to a Commodore Trimatic (nearside Selector Lever). Front Seal replacement is made easier with the early style removable Inspection Cover. Image by merc9112006. Click to Enlargen.
 
Here is an image of the reverse side of the Bellhousing
showing the installed Seal bottomed out. Image by Crocky. Click to Enlargen.
 
Has the Torque Converter Seal area become scored? This could have caused the Seal to fail.. Image by SleakVH. Click to Enlargen.
 
Also the Converter Housing Bush may be worn out which is causing the leak. Check for wear. The Converter Housing Bush is shown in the centre of the Bellhousing here. Image by Crocky. Click to Enlargen.
 
The red Arrow shows the Line Pressure monitoring Bolt.  It may be that a Line pressure Bolt can plug the Top Gear Switch Hole. Photo by Qute. Click to Enlargen.
 
A thin Seal exists between the Bellhousing and the Trimatic Casing. Image by merc9112006. Click to Enlargen.
 
The Selector Shaft is shown on the right hand side of the image. Photo by merc9112006. Click to Enlargen.
 
The Photo shows the Detent Retainer Pin to the Right Hand Side of the Modulator. Note the Kick Down Solenoid has been secured by a Bolt to prevent the Wire from being damaged. Photo by T. Click to Enlargen.
 

Blue/Black motor Trimatic filler tubes do not enter the case correctly if installed in a red Trimatics and vice-verca.
The difference lies in the thickness of the bosses at the bellhousing bolts. Red motor bellhousings are thinner
which causes the tube to lean too far forward.
Unstoppable oil leaks are assured if this is the case.
The only thing you need for a good seal on the proper tube is the O-Ring.

===Oil Pipes:===Oil pipes send oil to and from the radiator. Periodically these can need retightening.

Modulator Leaks:

The Modulator should be tightened down using a special spanner. Since conventional spanners are too thick to fit between the case and the Modulator's diaphragm some mechanics use a stilson wrench on the outside to fit or remove the unit. This a sure way to damage it. Sometimes the unit hasn't been tightened enough and a drip can result.

Detent Leak:

Hidden beside the Modulator is the Detent Valve. The Detent Valve is sealed by a rubber O-ring that can go hard and cause a leak. The leak can cause the gearbox to slip out gear or not shift up properly. Note that the Detent O-ring can only be replaced with the Pan removed from the gearbox.  The Detent Valve is held in place by a simple Pin that twists in and out of place.
The Pan itself keeps the Securing Pin in place.

Front Oil Seal:

The Seal is a straightforward replacement after removing the Trimatic from the Car. The Torque Converter is then removed to expose the Seal. There is no need to remove the Bellhousing from the Trimatic. Any removal of the Bellhousing requires aligning pins and a centring Tool (or the spout of a Torque Converter) when replacing it to ensure that the Oil Pump doesn't get out of line and score the Wear Plate. There is mention of a Special Tool for removing the Seal and another for installing the Seal.  The removal tool hooks onto the rear of the Seal and the Seal is pulled out. The Installation Tool has a hollow centre to allow it to fit over the Shaft. This Tool taps the new Seal into place. The Seal can be removed by Tapping it out of shape then pulling it out with your Fingers. The new Seal has a Lip to prevent it entering the Housing too far. A Taper on the outer edge of the Housing makes fitting the new Seal easy by tapping it in with an Hammer and Drift.

Selector Shaft Seal:

The Selector Shaft Seal is tiny and replacing it can ruin the gearbox's casing. The seal should be removed and replaced using a special tool only.

Tailshaft Seal:

Straightforward replacement. Remove the tailshaft. Tap the seal out of shape by tapping the seal's outer edge towards the shaft using the same method as with the Harmonic Balancer Seal. The seal can easily be removed once it is bent out of shape.
Check that the tail shaft yoke does not have a groove worn into it by the Rear Seal. If it has, the yoke will have to be replaced and new universal joints fitted. The Extension Housing Oil Seal recess has a tapered edge which makes fitting a new Seal very easy.  Glue the outer edge of the new Seal with No.3 permatex then tap the new Seal into place using a light Hammer and Drift.  An example of Seal installastion is here Harmonic Balancer Seal.
Refit the tailshaft.

Tailshaft Yoke Welch Plug:

Submitted by v8slrtorana on Fri, 23/03/2007 - 09:59.
HQ to WB, LH to UC, VB to VK all have them.
Any gearbox factory fitted to these models has a welch plug in the tailshaft yoke.
Can create a very hard to find leak, especially with autos as the oil is much thinner.
End of submission by v8slrtorana.  Yoke Leak Thread

Breather Leaks:

Oil weeping from the breather, after the car has been run in reverse, indicates a worn front plate inside the Trimatic. While the gearbox can continue to operate
with this leak it will ultimately involve a full rebuild to fix it. A Car that has been high Towed can also show evidence of Oil emerging from the Breather, but this is not necessarily a fault.

Top Gear Switch:

The plastic in the centre of the switch can come loose from the metal outer case
and develop a leak. The plastic used in the switch is thermosetting meaning that is shrinks and gets harder with heat causing the leak.
Replace the switch
or;
auto transmission aces sell a plug with allen key drive which can block up the hole.

Speedo Drive:

The O-Ring inside the Speedo Drive Insert can go hard and allow oil to leak past it.
Ensure that the Speedo Cable is unhitched and is in a gentle loop before unbolting and withdrawing the Speedo Drive and replace the O-Ring. Failure to make a gentle loop will result in a kink in the Speedo Cable which will cause the Speedo Display to jump and the Driving and Driven Gears to strip.

Dipstick Tube Leak:

There is a rubber O-Ring at the base of the Dipstick Tube that can go hard and cause a Leak. Replacing the O-Ring will stop the Leak and is easily done by unbolting the offside top Bellhousing Bolt and pulling the Tube from the Trimatic Case.

The Wrong Dipstick Tube:

Note: Using the wrong Dipstick Tube will result in an unstoppable Leak that a new O-Ring will not fix. The incorrect Dipstick Tube will not enter the Trimatic Case at right angles which is the cause of the Leak. Half Bellhousing Dipstick Tubes are made for thin Bellhousing Bosses. Full Bellhousing Dipstick Tubes are made for thick Bellhousing Bosses. Interchangement will cause the Dipstick Tube to lean forward in Half Bellhouse case. Interchangement will cause the Dipstick Tube to lean backward in Full Bellhouse case.

Removing the Modulator using the Special Tool. Photo by T. Click to Enlargen.
After removing the Pin with Pliers the Detnet Valve (red) can be eased out about 0.5", just far enough to replace the O'Ring. Photo by T. Click to Enlargen.
The O'Ring will most likely need to be cut with a Razor Blade to remove it without damaging the Detent Valve. Smear ATF over the new O'Ring to help it fit on and smother the O'Ring again with ATF so that it will pop back into the Case without tearing. Photo by T. Click to Enlargen.
Trimatic Selector Seal Remover/Replacer Tool. Photo by T. Click to Enlargen.
Trimatic Selector Seal Remover/Replacer Tool. Photo by T. Click to Enlargen.
Trimatic Selector Seal Remover/Replacer Tool. Photo by T. Click to Enlargen.
Trimatic Selector Seal Remover/Replacer Tool. Photo by T. Click to Enlargen.
Selector Shaft Seal. Trimatic and Powerglide are similar. Photo by John (Arsewipe). Click to Enlargen.
Trimatic Front Seal installation. Photo by uca78t. Click to Enlargen.
Trimatic Front Seal. Photo by uca78t. Click to Enlargen.
Trimatic Front Seal installation.  Photo by uca78t. Click to Enlargen.
 
 
Trimatic Rear Seal.  Photo by uca78t. Click to Enlargen.
 
Removing Trimatic Rear Seal.  Photo by uca78t. Click to Enlargen.
 
Installing Trimatic Rear Seal.  Photo by uca78t. Click to Enlargen.
 

 

Trimatic Dipstick Tube.The O-Ring is 19mm Outside Diameter, 14mm Inside Diameter. Photo by BIJ. Click to Enlargen.
Shot of Trimatic from the rear. The yoke welch plug is visible.  Photo by uca78t. Click to Enlargen.
 

 

Trimatic Dipstick Tube can be a source of Oil Leak. Photo by BIJ. Click to Enlargen.
 

 

Trimatic Trans Pipe Oil Leak. Best tightened by using a Pipe Spanner. Photo by BIJ. Click to Enlargen.
 

 

Front And Rear Seal Replacment:

Submission by uca78t:
For those who haven't the done it as you can see in the piccys there is no science to it.
You just simply pry out the old seals & then very gently tap in the new one.
Cheers Shane

Links:

Using The Selector Seal Remover and Replacer Tool

Selector Seal Remover and Replacer Tool

Oil Pump Bolt Leaking Thread

Terms:

Terms

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