Hylomar as oil pan gasket
 

Anyone tried this?

I was reading this page today for work-related activity and it occurred to me that this joint has many places where slight shifts can and do cause shearing of the dried sealant and a leak path.

I'm very tempted to try Hylomar, which if you've never used it before, is a non-hardnening sealant that will reform if the joint shifts slightly. It certainly would be cheaper than reinforcement plates and stud kits.

David

the right stuff is yur fried ...black ...that thing u have to pry off .. every time u take off the pan ... if applied properly it wont leak ...

It'd be fine for use there. I ride Russian motorcycles and use it to seal the drive shaft splines to prevent oil migration and slobber out the seals (among other uses on the bike). Good stuff. There are other "more modern" types of the same stuff out there...easier to find and cheaper. If you hop onto Amazon.com and search for Hylomar, sometimes you can find some NOS Permatex Hylomar for cheap. After Permatex stopped carrying it and Hylo went solo...the prices tripled on the stuff.

But, like the fella says above...black RTV does just as well for most applications.

Hylomar has long been recommended to seal machined metal surfaces on quick-change racing gearboxes. I tried to use it many times on my gearboxes, but, even following the instructions to a "T", it ALWAYS wound up leaking in a week or two. And that was in areas that have much less flex than our oil pans. Its best quality is that it cleans off with solvent, making the cleanup between gear changes easy, as compared to cleaning off RTV. As a result of the leakage problem, I use Permatex Ultra-Blue (soft, but not gummy) on my gearbox, and never have a leak.

Bottom line, I would stick with the "Right Stuff" or a close equivalent. Almost any RTV sealant has plenty of flex to deal with our oil pan. The problem is having enough shear strength and adhere well enough so a leak path doesn't develop. That's where "Right Stuff" type sealants excel.

EDIT: My comments relate only to the "original" Hylomar, which may not be typical of other sealants in the Hylomar line, so YMMV.

Dave

I used Hylomar with no gasket the first time i did a motor build and it did leak. I was not impressed at all with how it turned out. I used red RTV the next time and i had no leaks. I'm sure it being my first build had something to do with why it leaked but none the less....

peanut butter works better than Hylomar..

I used Permatex the right stuff gasket maker and the Banzai Racing oil pan brace with the studs and I haven't had 1 drop of oil leak in 3 months, and I drive my car everyday and all over the place.

the right stuff is the right stuff to use.

if you look at it, the right stuff seems mostly like regular old RTV (it comes in black and grey forms) but the applicator must have some propellant like a spray can. therefore it comes out evenly and is easy to control, instead of the frustrations of squeezing a tube. i used the black right stuff on my oil pan with the banzai brace and so far it's fine

We use Hylomar in sealing the faces of industrial gear drives at work. They don't leak. Hylomar is the gold standard with a few decades of history. Dave, I believe my company uses the tried-and-true original formula called Hylomar Universal Blue. I see that Hylomar also has Racing formulas and other stuff that I have no experience with.

The difference between Hylomar and other sealants is major and fundamental: Hylomar does not solidify. It's a thick tacky goo that has a consistency like chewing gum in spite of extended exposure to solvents/oils and elevated temperatures. If the surfaces shift it flows with it. In some cases you can pull apart the joint and put it back together and it will reseal. (Not that it's wise, but the stuff will do it.) In this application the painted surface of the oil pan should probably be wire brushed off to allow it to adhere to the metal. This point and the many sections of a rotary engine housing are why I'm curious about it.

Silicone, RTVs, The Right Stuff, etc all solidify. They adhere to the surfaces but if you shift the surfaces the bond breaks loose and a leak path is formed. I am resealing an oil pan on a rebuilt engine this week because the original sealing job using The Right Stuff leaked. FWIW I found an untorqued bolt at the leak area a few days after sealing, so it's quite possible the problem was that I missed torquing that bolt and torquing the bolt sheared the bond. I haven't given up on The Right Stuff yet.

On my car I will need to drop the subframe shortly to change out my suspension bushings and motor mounts, so I'm planning to also reseal the oil pan and install helicoils where the pan bolts into aluminum. Since it's my car I'm free to try out whatever I'd like and I might try it.

David

As you said it is your car and you can try it, however I have tried it years ago and it failed miserably. Car started leaking immediately at start up. Hylomar is great for sealing the coolant seals and the housings together as they are machined surfaces. The oil pan is not machined it is stamped, this makes hylomar not a very good choice for this application.

I just came up with the same thing.

This is found on the UK Hylomar website:
http://www.hylomar.com/index.php?opt...d=90&Itemid=75

This document explains the surface finish requirements, which are fairly narrow. Not hard to design a new product around, but in this case the oil pan face, bolt spacing, mixed materials, and scratches/housing splits are all an issue.

Another note I saw of interest is that Hylomar will not cure if used on a surface that has seen a Silicone RTV before. (!). I think you'd need to wire wheel the faces first.

So I'll be passing on hylomar for this.

Interesting! That may explain why it never worked in my gearbox application with machined surfaces - I HAD used RTV previously!

Dave

The reason why the metal surfaces must be perfect is twofold:
1) Hylomar works with ions in the metal to achieve a bond
2) It also relies on the chemistry of the metal to cure.

If RTV was/is on the surfaces it interferes with this process.

Dave

Thanks, Dave.

It's always nice to understand why something that many people say should work didn't work for me. Now I wonder whether if I do a VERY thorough surface cleaning that the Hylomar will now work on my magnesium/aluminum gearbox joints. I may try it just out of curiosity.

Thanks, again,

DaveW

On the subject of pan sealing, I suspect the pan in question leaked because I sealed it without the trans in place. So when the trans was bolted up it pushed on the back edge of the pan and sheared the bond.

I will absolutely confirm that The Right Stuff is tenacious stuff. Took some doing to get that pan off.

Won't work with synthetic?
 

This is a link to a thread on a different forum about Hylomar:

http://www.apexspeed.com/forums/showthread.php?t=35067

I use synthetic - maybe that's why it won't work for me.

Dave

I would just use RTV to seal the oil pan gasket.

To clarify - I'm talking about the gearbox racing application discussed in the other thread. Sorry for the confusion.

Dave

Not true. We use Hylomar at work and have no reservations whatsoever about our customers using synthetic gear oil with it. If there was any concern you bet we'd protect ourselves by using another sealant or forbidding synthetic.

I wonder what kind of gear oil this guy was using?

Dave

I wondered about that, since almost everyone uses synthetic now. Thanks.

The mystery deepens... :scratch:

Dave

hylomar is good but i wouldnt use it for a daily driven vehicle.

The notes on Hylomar and previous RTV usage did not refer to Hylomar Universal Blue, which is what I think is being discussed in this thread.

Use the right stuff and a pan brace with no gasket and you will never have a leak

Hmmmm. I'll have to remember that the next time I board an aircraft equipped with turbine engines--an application where Hylomar sees a bit of use. :lol: