View Full Version : Teflon Tape for Oil Leak?


Tatsuya
08-15-2010, 12:07 AM
My dad's truck has had a slow drip for a while now. We both figured it's the plug gasket. Went to Napa, got the stuff, saw a baaad lookin' white girl wearing a lot of skin on the way home, all is well on a 90 degree day.

Long story short, I changed the oil and everything and hours later there's a puddle. :mad: It's not the plug and I'm pretty sure the threads aren't crossed. Is teflon tape a bad idea? Or maybe cutting the finger off a nitrile glove and using that like tape? Something's gotta be done tomorrow morning. I don't think my dad's in a rush to buy a new oil pan.

Torque1st
08-15-2010, 12:14 AM
Teflon tape will not seal straight threads. You can buy new gaskets for the plug. The metal ones that have a captive rubber washer are the best. Check the threads in the pan and plug to make sure they are not stripped or broken. It is very easy to strip the threads with Teflon tape on them. You can also buy oversize self-tapping plugs.

scbird94
08-15-2010, 12:15 AM
Steel pan? aluminum pan? what kind of truck? These things make a difference. In the long run, if your sure its dripping out of the plug sealing area, you either are using the wrong drain plug (aftermarket?), wrong gasket, or if its aluminum, chances are you may have a crack alongside the threads from overtightening.

Best to replace the pan...

Tatsuya
08-15-2010, 12:53 AM
Teflon tape will not seal straight threads.
Can you explain this to me? Sorry if that's a dumb question. :lol_hitti

My dad got the truck used (brother bought it and gave it straight to my dad) and he said the previous owner had put teflon tape on it already so they might have dickwrapped the threads that way.
Steel pan? aluminum pan? what kind of truck? These things make a difference. In the long run, if your sure its dripping out of the plug sealing area, you either are using the wrong drain plug (aftermarket?), wrong gasket, or if its aluminum, chances are you may have a crack alongside the threads from overtightening.

Best to replace the pan...
It's a steel pan on an '84 Toyota EFI pickup. Put on a 19mm aftermarket plug from Napa. I know it needs a new pan and pan gasket but until then I need a quick fix.

nate379
08-15-2010, 01:01 AM
Drain the oil, pull the plug and clean it off good. Install plug, RTV around it, give it a few hours and put oil back in.

Did this on one of my trucks for a few years till I bought a Fumoto valve. I don't know why, but new plug, new gasket, etc wouldn't stop a small drip. Pulling the pan involves lifting the motor out so I didn't want to mess with it if I didn't have to.

Torque1st
08-15-2010, 01:22 AM
Can you explain this to me? Sorry if that's a dumb question. :lol_hitti
Teflon tape will seal tapered threads (pipe threads) but straight threads do not "wedge" into each other in the same manner.

BTW- Oil pans seal on the pan surface beneath the plug head, not the threads.

Stick
08-15-2010, 02:20 AM
Can you explain this to me? Sorry if that's a dumb question. :lol_hitti
Teflon tape has no sealing properties of it's own. Teflon tape helps lubricate the threads to making them easier to seat properly. In the case of pipe threads, the threads are tapered and seal by wedging against each other. Straight threads aren't designed the same way, so in the case of a drain plug on an oilpan, the sealing surface is the bottom of the plug (a crush washer, o-ring, fibre gasket, etc.)

Torque1st
08-15-2010, 02:26 AM
Teflon tape has no sealing properties of it's own. Teflon tape helps lubricate the threads to making them easier to seat properly. In the case of pipe threads, the threads are tapered and seal by wedging against each other. Straight threads aren't designed the same way, so in the case of a drain plug on an oilpan, the sealing surface is the bottom of the plug (a crush washer, o-ring, fibre gasket, etc.)
Actually the Teflon tape does have the ability to flow into imperfections in the pipe thread during tightening and help seal the leak paths. It also often sheds particles and shredded tape into the fluid which is why one should never use Teflon tape in hydraulic or lubricating systems.

EDIT- Many people think that oil pan plugs must be "gorilla tight" which also causes many problems. Teflon tape just makes that situation much worse because of that lubricating property.

Tatsuya
08-15-2010, 02:28 AM
Ok, that makes a lot of sense. Thanks, Torque, Stick!
Drain the oil, pull the plug and clean it off good. Install plug, RTV around it, give it a few hours and put oil back in.

Did this on one of my trucks for a few years till I bought a Fumoto valve. I don't know why, but new plug, new gasket, etc wouldn't stop a small drip. Pulling the pan involves lifting the motor out so I didn't want to mess with it if I didn't have to.
Ahhh, my dad was thinkin' about doing this too. Thank you for the feedback! I'm pretty sure we'd have to lift the motor out too to get at the pan. We'll likely go with this.

Torque1st
08-15-2010, 02:34 AM
Clean it off real good and put a small amount of black RTV around the hole and then install the plug if you can't find one of those composite rubber/metal washers. Usually they are in stock at the parts store. Put the rubber side against the pan.

It seems leaking oil pan plugs are a real problem in the age of quick-lube places. :mad:

Stick
08-15-2010, 02:54 AM
Actually the Teflon tape does have the ability to flow into imperfections in the pipe thread during tightening and help seal the leak paths. It also often sheds particles and shredded tape into the fluid which is why one should never use Teflon tape in hydraulic or lubricating systems.
I believe we are saying the same thing, but it is still the mechanical action of the threads that does the sealing, not the teflon tape. I know all about not using it in hydraulic systems as well, I followed up after another guy in the shop used some in a machine that had an 8 stack valve body. Needless to say I wasn't too pleased when I tore it down and found tiny particles of shredded tape in the spools. Paste is generally fine, but tape has no place in any hydraulic application.

Torque1st
08-15-2010, 03:07 AM
I believe we are saying the same thing, but it is still the mechanical action of the threads that does the sealing, not the teflon tape. I know all about not using it in hydraulic systems as well, I followed up after another guy in the shop used some in a machine that had an 8 stack valve body. Needless to say I wasn't too pleased when I tore it down and found tiny particles of shredded tape in the spools. Paste is generally fine, but tape has no place in any hydraulic application.
I feel for ya! Did you drown the guy in hot skydrol?

The Teflon tape particles do help seal the threads by filling imperfections even in NPTF fittings. I generally do my best to avoid pipe threads.

Beware the cheap Teflon tape sold in the Home Box stores and other retail outlets that is a plastic film with a coating of white Teflon on it. That stuff is a real PITA and totally worthless.

ddawg16
08-15-2010, 06:08 AM
I'm sure you have confirmed that the plug is the source of the leak? Quite often the leak is actually the back of the pan (rear main seal), oil leaks down the pan right where the drain plug is....

If your sure it's the plug....and you have replaced the washer.....

I would look at the threads....someone posted a thread about 2 weeks ago where they found the threaded nut inside the pan to be cracked......

....... saw a baaad lookin' white girl wearing a lot of skin on the way home, all is well on a 90 degree day.


What? No pics? If you don't have pics then don't even write about it.....it's hard enough for some of us to stay on topic....now some of us are trying to put that image in our head....post pics next time....we may not be able to help you with your problem....but you earn a couple of man points....

Tatsuya
08-15-2010, 03:21 PM
Yeah, it's the plug. Even though the gasket needs to be replaced, the plug's the problem.

And considering how close I was to the center median on a residential road with an oncoming car who probably saw me looking long and hard, it's a good thing I don't have pics.