My apologies if this is the dumb question of the day... I don't have experience with red Loctite. Is it regularly used for applications inside engines/transmissions?
Can I trust it to hold onto a nut on the inside of a diff cover? I'm trying to get an oil cooler line mated to the cover without welding, tapping the hole, or special fittings. It's a low-tech affair -- we're using fittings from an autotragic cooler.
Should hold if you are using some sort of bulkhead fitting.
NEVER SHOULD Loctite be used internally unless specified.
Brian
Red Loctite can be defeated but not easily.
For internal applications like a bolt you don't want flying around inside your transmission, I use blue "Service Removable" Loctite. Keeps the little bugger in place but can be removed for service.
If I understand your purpose, you want to hold a nut inside a diff cover while you run a bolt through it from outside and don't want the nut to spin while it tightens up, that about right?
If so, Loctite isn't the answer.
Dan
When parts are cleaned with loctites cleaner and primed with there green primer red will need 300+ deg heat to come loose. It's used all the time inside spinning engines but why on a diff cover can't you use a bulk head fitting with nut on the outside?
44
Thanks for the suggestions/advice, guys.
We don't need the Loctite to hold the nut while we tighten it -- we'd be tightening it before installing it. We just don't want to be nervous that it's going work off and wreak havoc.
We've got an aftermarket aluminum diff cover for a Saab 900 transaxle, which is a north-south oriented lump of metal that bolts directly beneath the engine and is weak at its tail, where the diff is:
The diff cover stiffens things up, which is good because the gearbox now has 100% more LSD. We've chosen to use banjo fittings from an automatic transmission for the oil cooler because they were free and because we can run the cooler lines away from the cover parallel to it (this is all happening right by the steering rack/firewall; it's kinda tight). On these cars, when run hard, the gear oil gets so hot that it can affect the engine temps because the 'box doubles as the engine oil sump. Of course, the gearbox isn't too happy about the heat, either. Add the LSD, and things get cookin' fast.
A bulkhead fitting seems like a smart, safer approach. I didn't know that such a thing existed, but I will bring the fittings to the hydraulic shop and see if they've got some that are threaded for them.
I remember using it on a VW transmission and it worked well. I believe that the Bentley manual called for it.
In reply to procainestart:
contact Jerry Sweet in New Jersey. Throughout the 90s Jerry ran many of the east coast rally (Sandhill SC comes to mind) with his SAAB 99 that had been updated, modded, and strengthened
Anyway, Jerry can offer you all kinds of tried and true mods for that assembly to hold up.
http://www.saabnet.com/tsn/faq/service/nj.html - near the bottom of the page
I'm not a Saab expert, but the one's I've built seem to have more than enough meat around the diff that you should be able to drill and tap a small hole in the casting. I don't know how much flow you need, but I have done some where I drilled a 1/4" hole the whole way through, then countersunk something like a 1/2" bit part of the way through so I could tap it for 3/8 NPT fittings.
but if you want to put them in a steel cover, a bulkhead fitting would be grand. Red Loctite would work. A lot of times people are concerned about pieces breaking off, but if you read and follow the directions, the amount of loctite you are supposed to use is so small that even if it all broke off your biggest concern would be that a speck of polymer dust happened to reduce your oil filter flow by .000435%. Not a big deal.
I personally prefer the paste loctite in the lipstick tube thing... not for any other reason than its super easy to use and stays in place under more conditions than the liquid stuff. Its also more shelf-stable, so 5 years from now it will still be paste instead of the liquid stuff being like cold chewing gum.
Of course, if its a steel cover, why not tack weld a nut inside?
curtis73 wrote: Of course, if its a steel cover, why not tack weld a nut inside?
The aftermarket diff cover we have is aluminum. All the other ones I've seen are steel (I actually have a steel one on one of my cars). Saab put them on their 99/900 rally cars for years, so plenty of people have made copies for their own cars. Saab 900 Turbos had engine oil coolers under the LH front corner, and, some years, identical automatic trans coolers on the RH side. So the autotrans cooler is a bolt-on $10 pull-a-part re-purposed 5-speed cooler. 
@oldskewltoy -- thanks for the tip. I wonder if he's over at saabrally.com?
having a 900 myself.. I find the pictures of the gearbox interesting...
Just out of curiosity.. how did saab plumb the auto's cooler lines?
mad_machine wrote: having a 900 myself.. I find the pictures of the gearbox interesting... Just out of curiosity.. how did saab plumb the auto's cooler lines?
c900 automatics had two cooler types, depending on year. The air-to-oil type, which I described in a post above, is plumbed from the front end of the automatic (RH side, IIRC), directly to the cooler on the RH front corner of the vehicle, below the bumper. The cooler dimensions are approx. 1.5"x4"x12", and the cooler itself is housed in a protective steel shroud that bolts to the car body from below (same as the Turbo oil cooler). (Turbo oil and automatic trans coolers, though they appear identical, are NOT interchangeable on account of the angles used for attachment tabs inside their respective shrouds. Saab changed connector types at some point, too, so not all turbo coolers are compatible with all turbo hose fittings. I don't know if the same is true for auto. coolers, though.)
IIRC, the later automatic coolers (90+??) used an oil-to-water cooler comprising a heat exchanger shroud that was positioned at the lower radiator hose, which passed through the exchanger.
If it's aluminum, tack an aluminum nut inside.
Curtis, your liquid loctite will stay good for years after it's opened if you keep it in the shop refridgerator, next to the beer.
Last year with the UAH Moonbuggy we had some problems with some parts in the axles so we red loctited that E36 M3 together at the last minute and it broke lose on the first bump and the wheel made a break for it.
The trick with locktite is: the parts need to be CLEAN for it to work best. I've used red successfully on a number of applications: heat REALLY helped it come apart, and it was something of a swine to loosen w/o heat.
Nathan
procainestart wrote: c900 automatics had two cooler types, depending on year. The air-to-oil type, which I described in a post above, is plumbed from the front end of the automatic (RH side, IIRC), directly to the cooler on the RH front corner of the vehicle, below the bumper.
Ah. I was hoping you could have used an easily accessable plate to mount your cooler lines.
Have you considered using the drain and fill plugs?
Drain plug is on the bottom and wouldn't work. (BTW, 91+ doesn't have a drain plug; diff cover has to come off to change gear oil, or suck it out.) Some Saab rally cars had the draw from the fill plug side; we might still do that. But we want to put the return flow at the ring gear, only accomplished via the diff cover.
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