PTFE rear main seal installed NOT dry

Messages
768
Location
South Carolina
Thread starter
I just put a new clutch in my '86 Ranger, because look at the old one: It needed a new flywheel, and I replaced the rear main seal while I was at it. As usual, I discarded all of the instructions and installed the seal like normal, with a light film of grease so it doesn't get torn up while driving it in. After I got the transmission bolted back up, I found a little piece of paper on the floor from FelPro. It said something like, "PTFE seal, do not lubricate, must be installed dry, I'm a FelPro seal, look at how special I am, PTFE 4LYFE, blah blah blah, etc." This is the first time I've seen an oil seal that wants to be installed dry. So, how long will my greased seal last before it shreds into a million pieces and starts spraying oil everywhere? Oh btw, I will be filling it with Maxlife 10W-40 and servicing the PCV valve, etc.
 
Last edited:
Messages
911
Location
California
You would have got 1,000,000 miles leak free from the rear main seal. Because you greased the rear main seal, you will now only get 999,999 miles with no leaks from the rear main seal.
 
Messages
768
Location
South Carolina
Thread starter
Originally Posted By: Kool1
You would have got 1,000,000 miles leak free from the rear main seal. Because you greased the rear main seal, you will now only get 999,999 miles with no leaks from the rear main seal.
My life is over. I am no longer a mechanic. I will be rolling my toolboxes out to the curb on trash day.
 
Messages
10,000
Location
Waco, TX
Originally Posted By: eyeofthetiger
After I got the transmission bolted back up, I found a little piece of paper on the floor from FelPro. It said something like, "PTFE seal, do not lubricate, must be installed dry, I'm a FelPro seal, look at how special I am, PTFE 4LYFE, blah blah blah, etc." So, how long will my greased seal last before it shreds into a million pieces and starts spraying oil everywhere?
It will leak, though probably not too bad. You can't remove it, clean it and reinstall it... it's already ruined, so just drive the beast. Since you have a PCV, you might be OK. Cummins diesel engines are the same, but no crankcase vacuum of any kind. It's REALLY hard to get them installed right and not leak.
 
Messages
8,925
Location
Marshfield , MA
hmmn, is the PTFE seal the standard for older Rangers? Which engine? Transmission? Freaken Ford and their weirdness. The RMS for the Rat's 4.0 is an lip seal of something but it wasnt PTFE. I go to the Ranger Station forum and after a few yrs of helping out mostly kids. I can get a fairly rapid response from a few genuinely knowledgeable Ford mechanics. grin2
 
Messages
768
Location
South Carolina
Thread starter
Originally Posted By: andyd
hmmn, is the PTFE seal the standard for older Rangers? Which engine? Transmission? Freaken Ford and their weirdness. The RMS for the Rat's 4.0 is an lip seal of something but it wasnt PTFE. I go to the Ranger Station forum and after a few yrs of helping out mostly kids. I can get a fairly rapid response from a few genuinely knowledgeable Ford mechanics. grin2
I think the seal material is whatever the seal maker wants. I have probably put in PTFE seals in customer cars and greased them without knowing they were PTFE, but I never heard a complaint. Who ever reads that little piece of scrap paper that comes in the box? I guess I will find out how important a dry install is, because I'm not taking it apart anytime soon! This Ranger is a 2.0L Lima with a single barrel carburetor and a Toyo Kogyo 5-speed transmission. Nothing fancy. It needs a few more things, and then it should be driving down the road by the end of next week.
 
Messages
4,825
Location
Taiwan
Guessing that the layer of grease MAY provide a leak path and/or prevent the seal mating...er...intimately, with the surfaces, and that a PTFE seal isn't supposed to need lubrication because its, like, made of PTFE. Thats my theory, which is mine.
 
Last edited:
Messages
12,249
Location
Indiana
I would have added oil to OP, don't feel bad. Unless you want to redo the job, the only thing you can do is keep an eye on it. I doubt it'll blow out as your driving is that's your concern.
 
Messages
4,825
Location
Taiwan
Originally Posted By: eyeofthetiger
Originally Posted By: Ducked
How come this is in "off topic"?
Because beer
Beer should never be off topic
 
Messages
718
Location
New York
Was it the outer lip or the inner sealing lip? It sounds like you did the outside, the inside is I think what they mean when they stay install dry. If you did the inner sealing lip, sorry hate to break it to you but it's likely to fail. PTFE seals are special because the sealing lip has PTFE that sort of melts or transfers a little PTFE on to what it's sealing against. This makes the sealing surfaces slide on each other smoothly. Greasing the sealing lip prevents this from happening. There are peculiarities with PTFE seals vs other materials like neoprene or nitrile. For example PTFE seals usually come stretched with a ring you are only supposed to remove when installing (some of them say to use the ring to guide the seal into position). Then you're supposed to wait a few hours for the inner sealing lip to shrink a little. Then you start the engine and it transfers the PTFE over.
 
Messages
768
Location
South Carolina
Thread starter
Originally Posted By: NoNameJoe
Was it the outer lip or the inner sealing lip? It sounds like you did the outside, the inside is I think what they mean when they stay install dry. If you did the inner sealing lip, sorry hate to break it to you but it's likely to fail. PTFE seals are special because the sealing lip has PTFE that sort of melts or transfers a little PTFE on to what it's sealing against. This makes the sealing surfaces slide on each other smoothly. Greasing the sealing lip prevents this from happening. There are peculiarities with PTFE seals vs other materials like neoprene or nitrile. For example PTFE seals usually come stretched with a ring you are only supposed to remove when installing (some of them say to use the ring to guide the seal into position). Then you're supposed to wait a few hours for the inner sealing lip to shrink a little. Then you start the engine and it transfers the PTFE over.
Well, I greased both sides, and I used the plastic ring to guide the lip over the crankshaft. We will see what happens.
 

JC1

Messages
4,731
Location
Oshawa, Ontario Canada
To the OP, I'm guessing it's all back together and running? I'm sure half of us would have done the same thing. As others posted, keep and eye on it and see if it leaks with the maxlife.
 
Messages
24,114
Location
MA, Mittelfranken.de
I have never put a PTFE seal in "wet" only dry, these are buggers to seal and you should use a sleeve if there is the slightest indication of a groove or score or they will pizz like mad. I have a feeling this seal is now using the grease as a false seal and once that is gone it will be a serious leaker. Drive it a while, if it doesn't leak good enough but if it does you may have to buy a new disc and tear it apart again, the only difference between tearing it apart now and after it has been running is the possible cost of the new disc. The Flywheel and plate can all be cleaned with brake cleaner and used again. Reading the instructions is always a good thing to do.
 
Top