Thread: throwing elbows

Throwing elbows is a mosh pit reference, ha ha.

Man, I know I been around here long enough to know all about heater hose elbows but I have to replace them every few months now and I don't understand.

Mainly I don't understand how the design was expected to work in the first place. They move. It can't.

So, before I set about re-engineering something... talk to me. I could rattle off all that I have tried, and I think I have read it all but I have some questions.

Anybody tap the engine side for NPT threads?

Anybody block the holes with a freeze plug?

Anybody add a second O ring?

Anybody try something else I haven't thought of?

I am tempted to pack a rope seal of some kind in behind the O-rings.

I would like to try hose clamping the elbows to a bracket attached to the nearest available bolts. Just to avoid movement during thermal cycling. But the design leaves me wondering if the elbows are intended to move a little to avoid something else.

This is just a way way way too often repair. Two oil changes means elbow change. Is there hope or is this just my life now?

Thanks for any fresh input.

you could by pass the alt bracket by tapping the holes like you said. the aussies have a factory bypass they use iirc.

have you cleaned them holes out real good? 100 grit sand paper can help, mine had some kinda varnish looking crap in them that i had to chip out with a pick, then i sanded smooth. never leaked. also lubed them o rings up before i pushed em in. you also need to make sure the top elbow is square to the bracket and lim as you tighten the alt bracket bolts down.

Originally Posted by Scottydoggs

you could by pass the alt bracket by tapping the holes like you said. the aussies have a factory bypass they use iirc.

have you cleaned them holes out real good? 100 grit sand paper can help, mine had some kinda varnish looking crap in them that i had to chip out with a pick, then i sanded smooth. never leaked. also lubed them o rings up before i pushed em in. you also need to make sure the top elbow is square to the bracket and lim as you tighten the alt bracket bolts down.

Aussie bypass? More info please.

I clean them holes out real good every time. Gently. Inspecting with a mirror, cleaning with wire brush on Dremel and patiently scraping away deposits with a wooden tool. I would think that 100 grit on aluminum would knock off enough metal to cause a leak mighty quick

At least the top elbow can be grabbed and wiggled and moved, so it is not binding. Every set of elbows has always sealed when new.

Theres a normal black O ring under the goo. They don't morph states of matter, thats a sealant which scrapes off. It did what it is supposed to do.

Everyone must have missed the part about rattle room. Mine wiggle once installed. But I kept hearing you gotta watch that angle, wiggle going in. Yeah, naw. I ain't quite that green, boys. RTV=solved

I have driven these 3800s over 150K miles now, had the GT ten years and the P for 6. Started out using a thin swipe of RTV and plastic GM elbows and they lasted as good as any. Joined here, started doing the way way way too frequent metal elbow dance sans sealant. I drive junk and issues I have are not believable.

I'm sure tapping or using freeze plugs would work. I haven't really had an issue on mine. My old purple car I put metal elbows in and even though lots of people say not too I load those things up with grey rtv. I did the same when I put the engine in my Buick. It's only been about 9K but hasn't leaked a drop. Same deal. Just loaded them up with rtv.

Originally Posted by PurpleGuy

I'm sure tapping or using freeze plugs would work. I haven't really had an issue on mine. My old purple car I put metal elbows in and even though lots of people say not too I load those things up with grey rtv. I did the same when I put the engine in my Buick. It's only been about 9K but hasn't leaked a drop. Same deal. Just loaded them up with rtv.

I have tried RTV when I was still daily driving the GT. Can't say it made much difference in time until leakage but it adds a great deal of fuss and potential for damage when cleaning and replacing.

I am just about fed up enough to use RTV and plastic elbows, although the metal ones are never in there long enough to corrode and break off. What type RTV have you used that seems to be working?

Tim, my thing about that is this: How to determine date of manufacture on an O-ring? Is the one on the elbow older or the one in the parts store's assortment bin? Or is a whole bag of them off the web older? No one can know. The ones on the elbows were made to fit, factory installed in the groove, and have a sealer coating. I can't think of how to beat that unless its using fatter rings. But then will the elbows install to the intended depth and stay squarely seated?

So the answer is yes, the ones that are pre-installed. And I have pics of all the bores but the one I showed was the only one appearing flawed. And honestly I ain't wanting to act snotty or bag on anybody but it kinda comes out that way. Frustration of having a great car with one ridiculous limitation that nobody else seems to have is where I am at and where any fussy tone comes from. My life just kinda runs that way overall so that don't help but I am used to it. King Workaround.

RTV is the only way I can think of, to put it together only once and be a success for any length of time. As I said, I never had a new elbow leak not using RTV. But they fail quickly. So to me, playing around swapping rings is the desperate hobbyist move more so than RTV. I believe that any reasonable person would anticipate this application needing a little of it. For whatever reason, mine don't stay stationary. Three engines, same. This car had 196K when I got it so theres no way for me to know if somebody in it's history hogged the bores out with a sandpaper drum or something while cleaning them.

I am past it. Its one of those situations where further expert advice is pointless because I reached a point of having to become my own expert, to my own satisfaction and thats all there is. I am used to that too. My sheetmetal abilities have ascended to a point of freaking some people out a little, including me, but I have not found a way to be anything short of an idiot when doing mechanical on non-V8, non-carbed cars. But somehow I just managed to pass the twenty year mark with my 455 GP and put as many miles on it as the two FWDs.

There are just things humans don't get to know, and in the grand scheme of things how important is it? To what great lengths can I justify going, to just be included in the no RTV crowd? Pfft, none. There ain't no way in hell sealant ain't part of this job and people are free to think what they will. I haven't made enough pay in the last decade to play with cars. Only manage damage and chase maintainence but I love my job. Its something a few guys would give a gonad to do but my former mechanical ability has gone sour without any fun projects. Driving heaps is just the best I can do.

Just about have that Model A roof insert welded in. The other day I needed to set down a cardboard template for a sec and was going to stick it in the trunk gap. Wouldn't fit! Anywhere. This, on a car whose doors originally overlapped at top and rear. Damn thats good. I can move metal mountains or make new ones but can I overcome simple elbow sealing? Maybe if I stick a 400 in it.

I'm with Scotty, ....again dang it. I think you have corrosion in there. Clean it until it's smooth as a snakes ass. Also, double check the o-rings on the elbows. I remember seeing people state that the o-rings were cut on their new ones. I think the o-rings are the weak link, as they can come with cheap ones. Then just a smear of Vaseline before you install them.

Only other thing I can think is you have a deep scratch where the o-rings seal. Might need a new alt bracket and/or LIM.

Originally Posted by bandook

I'm with Scotty, ....again dang it. I think you have corrosion in there. Clean it until it's smooth as a snakes ass. Also, double check the o-rings on the elbows. I remember seeing people state that the o-rings were cut on their new ones. I think the o-rings are the weak link, as they can come with cheap ones. Then just a smear of Vaseline before you install them.

Only other thing I can think is you have a deep scratch where the o-rings seal. Might need a new alt bracket and/or LIM.

Haven't found corrosion, been in there with dentist's mirror and maglite every time, every hole. It is not just one trouble spot, it is random which spot leaks.


I have found a twist in an O-ring once. I rank metal elbows according to how long they last for me... Dorman worst, GM better, Napa best. I did a burnout at Napa yesterday, they were closed at 6:15 yesterday and don't open Sundays.

I would probably rather install my spare 135K engine than swap the timing cover. I don't recall that spot ever leaking though. Buying new parts is pretty much out of the question but I realize that would be GM's solution.

My experience timing cover is to thin to tap directly, it was thickened with tig and tapped again.


20170605_174114 by Corey S, on Flickr

20170618_144702 by Corey S, on Flickr

Originally Posted by ItHurtz

My experience timing cover is to thin to tap directly, it was thickened with tig and tapped again.


20170605_174114 by Corey S, on Flickr

20170618_144702 by Corey S, on Flickr

Money shot! Thank you for this bit of info and pics. That is exactly what I suspected. I don't own a TIG nor have much faith in welded castings but again, thanks.

So, not one of you thinks that holding the elbow still with a bracket could help?

Iron Pontiac V8 heads use a stamped barbed nipple which is driven in like the dust cap on a tapered roller wheel bearing and they don't leak or require sealant. If the existing bosses could be drilled to remove taper from the O-ring bore about a half inch deep, I could make barbs. If theres enough metal to withstand threading an NPT barb in enough to seal, it can withstand tapping a sheetmetal nipple in. IMO. But I don't have the access or the drill bit.

I will just have to venture into the garage and experiment. Seems the only way to win is to buy stock in coolant and elbow manufacturers.



Next questions:

How to get a thermostat that works as well as those made last century? Without ordering a robertshaw one online.

How to get a good radiator cap? Last one I bought for it didn't even fit onto the radiator.


Much obliged to you gents for your input so far. Think good thoughts.

Originally Posted by idrivejunk

I have tried RTV when I was still daily driving the GT. Can't say it made much difference in time until leakage but it adds a great deal of fuss and potential for damage when cleaning and replacing.

I am just about fed up enough to use RTV and plastic elbows, although the metal ones are never in there long enough to corrode and break off. What type RTV have you used that seems to be working?

I just use ultra grey. Ultra black would be fine as it's more oil resistant but the grey looks nicer when it's done. I smear it on the o rings, shove them in. Then once they're in I try to push some in.

Originally Posted by idrivejunk

Next questions:

How to get a thermostat that works as well as those made last century? Without ordering a robertshaw one online.

How to get a good radiator cap? Last one I bought for it didn't even fit onto the radiator.


Much obliged to you gents for your input so far. Think good thoughts.

I've always used Stant or Gates. Never had an issue yet. I put a 180* stant in my old purple car and that was in there for about 80K miles and never had an issue. It did overheat cause the rad was crap but that wasn't related to the thermostat.

Didn't there used to be a way to edit a post? Typo at and of last post. Posting from phone so theres typos every other word.

Alright then, thanks guys. I made a bracket to hold the leaking elbow still. Hose clamp, strap to intake bolt. I'll see if that makes a difference.It was leaking air on cooldown the other day but stopped when I pushed on the elbow. So maybe.

Originally Posted by GTPpower

I always run a bead of red rtv around the orings. I've never had one leak in the 15 years I've been doing that.

So you have done one elbow replacement in that time?

What is red RTV?

I guess thats the trouble. I used RTV a time or two but stopped because of what I read here. Been replacing twice a year ever since. Just plain bad info causing me lots of hassle. The trust is gone, RTV is in.

Driving the GT until I get another paycheck or two and can solve the problem. Without further input. Thanks.

Yep, the cap could be bad. Thermostat also. Water pump too. Not pouring coolant out now though, nor overheating. I always thought cooling system pressure would be a good gauge or lamp to have. But then I wonder why you can't buy a beef, egg, and cheese biscuit for breakfast. Seems like that ought to be a thing but I don't have to understand why it ain't. I think I was the only one suggesting I am slipping. You'll get old and trip out first time it hits you that you ain't as sharp as you once were. The ability to communicate with youngers slips away even faster. Me, I just stopped the leak and am back to not worrying just keeping gas, tires, and oil up to snuff.

But man o man, theres maybe the biggest nail biter task yet at the shop waiting for me to pull some kinda magic stunt on and that certainly affects my demeanor at times. Among other things. I know it so I post less nowadays.

As far as I am concerned, all is well. With the GTP elbows. The GT is acting up a bit and hollering about maintainence but the GTP is overdue for oil again. I have to spread my inclination pretty thin over my own junk.