PTFE vs Ultra Grey on Protruding Bolts

kz6fittycent

I realize that back in the 80's the common method OE manufacturers used to seal bolts that protrude through water jackets, oil passages, etc. However, one of the benefits of PTFE (liquid) is that it is specifically designed to seal in situations like this - and do it for a very long time, basically permanently.

I am about to do some work, and replace my flywheel, clutch, etc. I know that @MazdaMitch used some Ultra Grey sealant on his crank bolts, and I am not at all opposed to doing that. However, I have always used PTFE for situations such as this, without any issues. In fact, many manufactures specifically call out the use of PTFE on bolts, plugs, etc.

I'm just wondering if anyone else has used PTFE on their crank bolts and it leaked. I can't see why it would, but again, maybe someone DID have it leak.

So, I guess I'm asking for opinions. Just to be clear, mine stinks, and so does yours 😛

P.S. To be clear, I am very likely to go w/ PTFE because of my experience, but I'm still willing to listen to others experiences.

Axel-Breaker-Earl

Good question!

I grew up working on old school engines and we always used RED LOCTITE on the flywheel-to-crank bolts, simply to keep them from loosening until you're ready to loosen them. Both the crankshaft threaded holes & the flywheel bolts need to be clean from any oil or grease and DRY before applying the Loctite in order for it to work properly.

I have done this on engines where the crank threaded holes don't extend into the crankcase AND on engines where they DO.......like the Mazda engine crankshafts. I still do it this way.......the bolts stay put, and there is no oil leakage ever. I'm sure the Mazda factory service manual calls for a SEALER on the threads also.......the red Loctite adds a locking feature to those bolts, and it is the main reason why I use it. I would not use BLUE Loctite there either........just my 2 cents.......but it has been working for many years now.

MazdaMitch

I had to order 6 new crank bolts for my red truck when I was building that motor.
The previous owner, not sure what happened but all the heads on the crank bolts had hit the pressure plate and were rounded off a bit.

Anyways the new bolts had a red goo on them that was reminiscent of rtv and these were factory bolts.
When I was rebuilding this motor, I did a quick and dirty rebuild and it didnt suffice.
I had to have the block bored over so I rebuilt this motor TWICE.

On the second go round these crank bolts, the red goo was done. So after some research I discovered that it was fine to use the Permatex HI TORQUE grey rtv.
I have done this on 2 trucks, no issues.

kz6fittycent

Hey, check this out! Seems it does both things (thread locker and sealant) in one shot. I didn't know it existed.

Cusser

Loctite was a sister company to the one I worked for 2004-2016. They make excellent products, but I only got a few for free.