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Discussion Starter #1
I need to redo my thermostat because the Stant unit is leaking at the housing (NOT the O-ring tubes)

I'm also going to be doing my Valve Cover gaskets and while i can get Drei Bond 1209 from a dealer @$22/tube I would like to just get Loctite & Permatex equivalents

for the Thermostat housing I know we're not supposed to use a gasket maker, but i prefer to apply some around the outer most edge in order to avoid future leaks

so this is what I've got so far

Thermostat housing:
Valve Cover:
 

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Been riding permatex ultra black for two years now, no leaks.. no issues. When I first installed the stant it failed the vacuum test, which I figured it would after seeing it was nearly flush in the housing. Took it back out and added a very small amount around the perimeter of the thermostat (~3/32 bead), and removed any excess. The quality of the unit itself makes this worthwhile.
 

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You realize that when you get to sealant-snobbery and particularly RTV-snobbery it really is the end of the line :eek: hiha
 

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Discussion Starter #8
if you can't get the drei bond use #2 permatex on the valve covers, no sealant should be necessary on the t-stat housing.
i think i'm actually going to get the drei bond so that's one done

any idea of shelf life after i open it?

You realize that when you get to sealant-snobbery and particularly RTV-snobbery it really is the end of the line :eek: hiha
:7: rao my participation in oil threads is just the tip of the iceberg

i'm going to pick up a tube of RTV blue and i'll decide what to do after i test fit the behr stat i ordered
 

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on the valve covers i use drei bond or hylomar witch ever is closest to my hand
 

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I used some gasket maker when I replaced the thermostat housing and water pump on my 740il to make sure I had a good seal and the damned thing is leaking coolant.
Shouldn't have used that stuff!
 

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i think i'm actually going to get the drei bond so that's one done

any idea of shelf life after i open it?



:7: rao my participation in oil threads is just the tip of the iceberg

i'm going to pick up a tube of RTV blue and i'll decide what to do after i test fit the behr stat i ordered
I was replacing a Behr every 4 months a couple years ago (low temp / sticking) until I switched brands. Hopefully the product run is better these days.. If you ever decide to go back to the Stant, you could use an oring or shim of perhaps .010 inch under the thermostat in the housing rather than using sealant on top of it, thereby avoiding it altogether in this application.
The Behr rubber surround is much thicker and obviously designed for our cars, but I got tired of the changeout routine. Maybe it was a bad batch and it was a couple years back.
 

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Discussion Starter #12
I was replacing a Behr every 4 months a couple years ago (low temp / sticking) until I switched brands. Hopefully the product run is better these days.. If you ever decide to go back to the Stant, you could use an oring or shim of perhaps .010 inch under the thermostat in the housing rather than using sealant on top of it, thereby avoiding it altogether in this application.
The Behr rubber surround is much thicker and obviously designed for our cars, but I got tired of the changeout routine. Maybe it was a bad batch and it was a couple years back.
i'm taking out the stant because it rides on the 78C/79C border vs the 82C/83C it's supposed to (but i'll save it in case the behr unit is faulty). i'm also not applying the gasket maker to the thermostat, but to the housing
 

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there a right way to do things and a wrong way, right tools to use and wrong ones. the right stuff to use on valve cover gaskets is drei bond or #2 permatex, not regular silicone. i've seen numerous leaks from valve covers due to the wrong sealant being used. you don't put sealant on any gasket unless the bmw repair instructions call for it, you're asking for leaks. i've used oe, behr, and whaler t-stats and never had a leak with any of them new. make sure you clean all the corrosion off the both sides of the housing, especially the upper part where the t-stat seats in the housing. only leaking issue i ever had with a t-stat was re-installing one that had been in there for probably 30k mi. removed it to do the lower separator hoses. when i put it back together it leaked, tried silicone, permatex, indian head shellac, leaked every time. replaced the t-stat, used no sealant, no leaks. the rubber seal is the issue and unfortunately afaik you can't get it separately.
 

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i'm taking out the stant because it rides on the 78C/79C border vs the 82C/83C it's supposed to (but i'll save it in case the behr unit is faulty). i'm also not applying the gasket maker to the thermostat, but to the housing
Actually that is what I did. The aluminum perimeter of the thermostat cover, not the rubber on the thermostat itself. Started out with a small bead and then carefully worked and around all the bolt holes until it had the appearance of a "flat black gasket". Then let it skin for about 15min. When you do this, very little squeezes out and you have a good seal. Sorry if I wasn't clear on that..
 

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I agree with using the right tools, and also agree that there is a place for gasket maker/instant gasket (what we call it over here sometimes) in the sense where it is particularly called for, as opposed to using it as a "top up" to a regular gasket in order to cure a leak/weep that shouldn't be there in the first place.

However, although i'm with you on regular silicone, instant gasket is instant gasket. If its made by a manufacturer specifically for that application in the sense that its an automobile aimed product that seals and resists oil/fuel, and is labelled as such, then IMO you can use it to your hearts content.

People on here get so choosy when it comes to it, because TIS says "use dreibond" everyone is scouring the earth for it as if using any other branded gasket maker is going to make only the e39 M5 leak oil all over the place as opposed to any other car where its used.

I used a regular £3 a tube instant gasket when i replaced my vanos spring plates, on both the front upper timing covers and on the portions of the valve covers where you are supposed to and nearly 2 years later its still oil tight and dry as it should be.

TIS says remove the engine to replace chain guides, yet we know it can be done easily enough, engine in car. We all ignore that advice as we know its plain wrong (who thought TIS could be misleading! SHOCK HORROR!).

Many choose wildy different grades and makes of oil (hell BMW still seems not to be able to make its mind up over that one) and ignore whatever oil BMW are deciding to recommend at this time without a second thought, and yet plenty take it as the word of God when TIS says choosing what gasket maker brand like its the be all and end all!!!

I'm sorry, don't regular gasket makers meet compatibility standards with the outer spaced sourced alloys on the S62 compared with pretty much every other engine?

ROFL!
 

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there are im sure other sealants ie gasket maker etc that may also work fine on the valve covers. but #2 permatex is available everywhere and is proven to work. basically what you want to use is a non hardening sealant.
 

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Discussion Starter #17 (Edited)
SIDE NOTE:

my BEHR stat came in today, one note is that the STANT unit has a little play in the spring/wax-tube which you could hear click if you shook the thermostat

the BEHR unit is solid and has no such play and/or noise

not sure if this explains the thermostat riding on 78/79C vs. 82/83C

will update on BEHR stat late in december
 

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I went the no sealant route, with a Stant, and you're right, the rubber seal is lower... buttoned up, had my wife start her, and my car started crying... that made me cry... now Im onto the extreme core workout part deux, and I don't think my back and hamstrings will work tomorrow, but I hope my car does..

So, I've learned the hard way with this entire process... here's what I learned, YMMV...

If the seal in the housing looks good, feels rubbery, leave it alone.
Maybe the Behr would have been a better idea.
The o-rings, and housing tubes uninstall/reinstall is a lot easier with the plenum off. In fact, smooth as silk... IMO, just take it off... no question. It's actually easy both in and out with that off... I know because the second time in I tried to bypass that, and it was fine on removing, but reinstall would have marred, cut the gasket maker, so I just took the plenum off.
If the seal is no good, just buy a new housing... or the special tools... for both removal and reinstall. Maybe that costs less, maybe it works... and maybe you buy all that, still mess up the housing, and still leak... just saying, it occurred to me that might have been better.
With the stant, perhaps I should have used a sealant the first time, and I bought it because my gut said to... IDK about the blue RTV, because I've never had to use it, but if that fails, then I'm going to be buying a new housing, a Behr, and having BMW put the shi... together. Because I can install it, but I'm not interested in damage to another housing from that seal.
After its not leaking, I'm taking it somewhere to have the coolant flushed... because the consequences of screwing up this work on the S62 appear dire... even the potential, is not good.

Currently... I'm on day two, my back is broken, and it's apart... When I put it back together, maybe I find out that the "variables" from pure OEM parts and processes really matter, and if you do use stant, and change the seal, and possibly scar the housing, well... don't... I thought I was prepared... lots of different info on the Internet though. Some work, some apparently don't.

This replacement seems fairly straightforward, and the wrench turning is easy... but you can turn a non-leaking car into a leaking one... it looks easier than it is, potentially... if your Day Job is not BMW Tech related, and you're doing this, with home garage tools, best of luck to you... be very careful... I sure hope the RTV holds...
 

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I've done 2 thermostats on M5's and both times used a Stant tstat. One was on my car and the other was on another forum member's car.

I use Permatex's waterpump and thermostat sealant that I found in Pepboys. I put a bead around where the thermostat would sit in the housing, and also a bead on the housing's mating surface too. I've never had any leaks doing it this way.
 
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