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Help! Replacement Transmission Filter Interfering with Pan

DS75

Member
Joined
Dec 31, 2010
Messages
15
Location
Millersville, MD
Corvette
1986 Coupe, Auto, Metallic Red
I am in the process of replacing my 1986 C4 transmission filter and gasket (the car has the 700R4 auto). The gasket was baked to the pan and crumbled away, probably explaining most of my fluid leakage. I think it was original or close to it. Anyway I bought an AC Delco TF235 kit (filter and gasket). I think the gasket is cork based on the looks. When I compare the new AC Delco filter with the one I removed the new filter looks like it is taller (i.e. the distance from the bottom of the filter to the top of the neck above the seal). Sure enough when I put it in place and try to put the pan back on the pan hits it up front. The pan does not look warped or bent.

This was the part identified for this year with the 700R4 transmission. Any suggestions? I tried pushing pretty hard but resisting really hammering it in as it didn't seem right given how easy the old one came out.

Also, as this is my first gasket replacement - does the gasket have to be immaculately clean on install? I was having a hard time keeping the gasket perfectly aligned on install and ended up having to use my greasy fingers to re-align it with the bolt pattern. I've seen some people on the forum recommend using RTV along with the gasket to make sure the seal is good (and as fun as this has been if that means I get a better seal and reduce the chances for doing this again in a few weeks when the fluids shows up on my driveway, I'm for it). Are there any downsides to this?

Thanks.
 

toptechx6

Well-known member
Joined
Apr 26, 2006
Messages
404
Location
south florida
Corvette
1993 Coupe, Bright Aqua
Are you sure the filter o-ring was removed with the filter? The old one frequently sticks in the valve body and must be carefully removed with a hook type tool. If it is not the new filter will not seat properly. Never use any sealer on a cork gasket, even small amounts of RTV can cause the gasket to squeeze out of position when the bolts are tightened, clean and dry is best.
Correct torque of the pan bolts is critical and will insure a good seal (97 INCH lbs.). Try inserting a couple of bolts through the gasket to hold it in place, the holes are usually snug enough to secure the bolts until they can be started by hand.:thumb
 

DS75

Member
Joined
Dec 31, 2010
Messages
15
Location
Millersville, MD
Corvette
1986 Coupe, Auto, Metallic Red
toptechx6, thanks. I'll stick with just the gasket and proper torque. As for the filter seating, I took a look and it turns out there wasn't the old oring left behind. Either the new filter came with an extra long two piece seal (one reddish orange and one black) on the filter stem or when I first tried to insert it the old oring seated on the new filter stem and came out with it when I removed it after failing to get it to seat properly initially. Once I removed the second piece (the black which was higher up on the stem) the filter seated properly. The remaining seal length on the stem was still 1/2 to 3/4 inch so I think that was all that was intended. I couldn't finish the job though as I got clumsy while wiping some grime off the new cork gasket and tore it. I'll have to go get or order another and maybe then get this job done. Since I don't need the filter too this time I'm free to just pick up the gasket - is cork the right choice or should I go with a different material if I can find it? Thanks again.
 

toptechx6

Well-known member
Joined
Apr 26, 2006
Messages
404
Location
south florida
Corvette
1993 Coupe, Bright Aqua
toptechx6, thanks. I'll stick with just the gasket and proper torque. As for the filter seating, I took a look and it turns out there wasn't the old oring left behind. Either the new filter came with an extra long two piece seal (one reddish orange and one black) on the filter stem or when I first tried to insert it the old oring seated on the new filter stem and came out with it when I removed it after failing to get it to seat properly initially. Once I removed the second piece (the black which was higher up on the stem) the filter seated properly. The remaining seal length on the stem was still 1/2 to 3/4 inch so I think that was all that was intended. I couldn't finish the job though as I got clumsy while wiping some grime off the new cork gasket and tore it. I'll have to go get or order another and maybe then get this job done. Since I don't need the filter too this time I'm free to just pick up the gasket - is cork the right choice or should I go with a different material if I can find it? Thanks again.

Sounds like the old o-ring remained in the bore and was removed when you pulled the new filter back down, easy to confirm if the old filter is still available and the o-ring is not on the tube. I like cork gaskets, many do not, but they often make the mistake of applying some additional sealer, that is the kiss of death in my experience. Clean and dry torqued to specs always works for me, if you use a rubber gasket instead the same rule applies. Note that the torque spec is in INCH lbs. if you mistakenly use a ft. lb. wrench you WILL strip the threads out of the case guaranteed.
 
Joined
Jul 7, 2011
Messages
74
Location
Clinton Indiana
Corvette
1993 coupe
Sounds like the old o-ring remained in the bore and was removed when you pulled the new filter back down, easy to confirm if the old filter is still available and the o-ring is not on the tube. I like cork gaskets, many do not, but they often make the mistake of applying some additional sealer, that is the kiss of death in my experience. Clean and dry torqued to specs always works for me, if you use a rubber gasket instead the same rule applies. Note that the torque spec is in INCH lbs. if you mistakenly use a ft. lb. wrench you WILL strip the threads out of the case guaranteed.

I agree with all he said. Other than the gasket. And its only by choice i prefer rubber. And as stated dont use sealent!... I would kinda like to know though as i have had many cars i kept for a long period of time. I always have heard that rubber swells more with the magik additives to stop leaks. I have used the magik stop leak stuff before and it will help "some" for me to make it through a summer and repair durring the winter. But i have been wanting to test out cork type tranny pan seals since you would think there is alot more room for expansion with those :confused:
 

DS75

Member
Joined
Dec 31, 2010
Messages
15
Location
Millersville, MD
Corvette
1986 Coupe, Auto, Metallic Red
Update

the local advance auto parts (nearest my house) only had a rubber one. Got an earful from the guy behind the counter on the evils of cork when I just mentioned it. the rubber went on fine and no leaks so far. My new confusion is on filling. I put in what the shop manual calls for after a pan/filter replacement -5 qts. I ran the engine and cycled through all the transmission stops/positions. When I check the dipstick there is nothing there. Just tonight I added another qt, a little bit at a time. After 10 minutes of running and the coolant temo up to 220F already I still didn't see anything on the dipstick. Prior to starting at all tonight (at which point I had only put back in 5 qts) the dipstick read the level above the cold mark (second dimple). Am I missing something here? I expected the flid level to rise as the engine heated up. I'm hesitant to add more as I don't want to overfill and have to drain.


I agree with all he said. Other than the gasket. And its only by choice i prefer rubber. And as stated dont use sealent!... I would kinda like to know though as i have had many cars i kept for a long period of time. I always have heard that rubber swells more with the magik additives to stop leaks. I have used the magik stop leak stuff before and it will help "some" for me to make it through a summer and repair durring the winter. But i have been wanting to test out cork type tranny pan seals since you would think there is alot more room for expansion with those :confused:
 

LT4man

Well-known member
Joined
Jun 25, 2003
Messages
2,214
Location
Chicago
Corvette
96 Collectors Edition LT4
You might have to have between 7-8 quarts by the time you are finished.

Just add the oil a little at a time.

Engine/trans must be HOT to check the fluid accurately.

If you overfill just a "tt" bit, I would not worry at all.

Many transmission rebuilders like to run auto transmissions up to a quart over.

Before anyone "flames" me for saying that: THEY like to run them over "Full". Not me.

While driving your Vette, please be sure to SAVE the WAVE! :w
 

DS75

Member
Joined
Dec 31, 2010
Messages
15
Location
Millersville, MD
Corvette
1986 Coupe, Auto, Metallic Red
Close Out

Just to wrap this up I finally got some time to finish this earlier this week and 7.5 qts was the amount it took. Thanks to everyone who offered help/input. On to the next project/repair...



You might have to have between 7-8 quarts by the time you are finished.

Just add the oil a little at a time.

Engine/trans must be HOT to check the fluid accurately.

If you overfill just a "tt" bit, I would not worry at all.

Many transmission rebuilders like to run auto transmissions up to a quart over.

Before anyone "flames" me for saying that: THEY like to run them over "Full". Not me.

While driving your Vette, please be sure to SAVE the WAVE! :w
 

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