Antifreeze leak on header flange

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Frnknsteen

Frnknsteen

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Ok,.... Strange question....

I was replacing my leaking back up light switch on the 833 transmission in my '67 barracuda last night. I was reinstalling the inspection cover that I removed to clean where the leaking lube got between it and the trans, when I brushed across the pass side header collector flange and noticed it was wet.

I had been noticing a small puddle of antifreeze here and there, but only if it sat for a while. I started looking and it seems to be coming from the back right corner of the head, and actually looks like it is coming from the header flange to the head. I immediately started thinking "Great,... I've got a bad head gasket or something", but something occurred to me this morning.

Do the exhaust bolts go into the water passage on 906 heads? I swear that years ago I remember antifreeze coming out of some of the bolt holes when I was changing header gaskets on the 440 in my Charger. Seems to me we put a little high temp RTV on the bolts when we put them back in.

Is it possible I have a loose header bolt and antifreeze is slowly seeping out when it sits for a while? I will have to take a look at it tonight and see if the header bolts are tight.
 
yes, the bolts go into the coolant passages. in the past I have used Teflon tape with good results on the header bolts.
 
Thanks guys. I will check into that tonight if I get time. I have an appointment with the tax man right after work, but I may have time to go mess with it afterwards.

Thanks again. What a relief if that is all it is!!
 
yep, only the 4 corner holes go into water jackets. Those were originally studs instead of bolts. Tight wouldn't stop a leak. They'll need some sort of sealant on them.
 
Yeah I was going to say that this is not the best place for RTV, there are better products out there and I think all small blocks have the same problem.
 
leblanc said:
Yeah I was going to say that this is not the best place for RTV, there are better products out there and I think all small blocks have the same problem.
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So should I use some sort of sealant like Indianhead, or #2 Permatex that others mentioned? or go with Teflon tape as Vitamin suggested? The nice thing about Teflon tape is I could just remove the bolt, dry it off, wrap it in Teflon tape and put it back in.
 
I use that silver powder that you find at the counter of most parts stores... It 'melts; in the coolant when it's hot, then collects in the leak and stops it.... Works great for threads.... Just use about 1/4 tube in the radiator, then run it for 30-40 minutes and the leaks will stop...
 
vitamindart said:
yes, the bolts go into the coolant passages. in the past I have used Teflon tape with good results on the header bolts.
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Is it a good idea to use Teflon tape on that? I’ve always been worried about that so I never did it.
 
I like teflon tape works as does silicone. I would get some high temp silicone that will stand up to the heat from the manifolds. You should probably drain the coolant and dry the hole(s) if you use silicone. When you unscrew the bolt or stud it will pee out coolant for quite a while. You might be able to unscrew, dry off the bolt, wrap with teflon, and screw it in without loosing more than a gallon.
 
I've used hi temp RTV on clean dry parts without a problem. Most chemical sealants do require clean and dry. Teflon tape properly applied would be worth a try.
 
I have in the past used RV sealant and worked, same sealant I used for the water pump/ timing cover bolts. I started using Teflon tape on the exhaust bolts with good results. I have found it easier to remove the bolts/studs using the tape. I think there is a trick in using the tape, I wrap the bolt making sure the tape tightens when bolt goes in. And I increase the number of wraps as you get closer to the head of the bolt.

The RV works great, but the threads must be absolutely clean and dry, no residue antifreeze left overs. Carb cleaner and air gun works if I can get to area it needs to be. They do make a liquid form of the Teflon tape, I have never used it.
 
Dicer said:
I have in the past used RV sealant and worked, same sealant I used for the water pump/ timing cover bolts. I started using Teflon tape on the exhaust bolts with good results. I have found it easier to remove the bolts/studs using the tape. I think there is a trick in using the tape, I wrap the bolt making sure the tape tightens when bolt goes in. And I increase the number of wraps as you get closer to the head of the bolt.

The RV works great, but the threads must be absolutely clean and dry, no residue antifreeze left overs. Carb cleaner and air gun works if I can get to area it needs to be. They do make a liquid form of the Teflon tape, I have never used it.
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Absolutely,... Teflon tape needs to be wrapped in the right direction. Looking at the end of the bolt (threaded end), you need to wrap it clockwise. That way as you insert the bolt and tighten it, it lays down on the bolt. If you wrap it the other way, it will bunch up while you are threading it in and typically leave you with a ring of tape around the bolt right where it goes into the threads. People tend to use too much of it too. I am a process development engineer who designs manufacturing lines, so we are always building new equipment and tooling. We teflon tape all our threaded air connectors to reduce air leaks.

Teflon tape is PTFE Teflon, which has a working temperature of 500+ degrees F, and a melt temp of 620 degrees F. Considering the ends of the bolts I would be putting this on are protruding into the coolant passages as it flows by, I wouldn't think it would EVER hit those kinds of temperatures. I will tape up that bolt soon as I get a chance and see if that takes care of it. That way I don't have to worry about getting it "Dry and Clean" for the sealants to stick.

Thanks!
 
As long as it's feasible, I'd use permatex #2 on a STUD with a brass nut. Then if you tighten the fasteners later, you are not disturbing that thread sealer's seal.
 
Well... Got home a little early so I took a look at it. Headers have studs on all but one place on header flange. Second from back is a bolt. Checked them and everything is tight.

Could it still be leaking out of there if they are tight? I felt around under there and it definitely feels like that is where it is coming from. It was wet under flange at the back bolt.
 
Frnknsteen said:
Well... Got home a little early so I took a look at it. Headers have studs on all but one place on header flange. Second from back is a bolt. Checked them and everything is tight.

Could it still be leaking out of there if they are tight? I felt around under there and it definitely feels like that is where it is coming from. It was wet under flange at the back bolt.
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sure it can leak if there was no sealer on the threads and/or the threads are damaged.
 
Frnknsteen said:
Agreed, but all of a sudden? It never leaked until recently.
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it's possible. Thread sealer can deteriorate. Heat cycles can stretch the fasteners. gaskets can compress, and/or fret.
It happened to me on a 400. I wasn't surprised though, because I knew the thread was a little iffy.
 
Well,... Guess I'm pulling off the header to try to fix that leak. Good thing I ordered a full set of gaskets to be able to remove the drivers side to put the new steering box in. Guess I will be using both sides now! :lol:
 
TEFLON TAPE.......Never sets or hardens, and the bolts are not gonna rust in place
 
Ok, so dumb question,.... What's the easiest way to get the studs out? I don't have room on the stud to double nut them with the headers on, so I am assuming I need to pull the headers off, double nut them and hope they come out ok?
 
rustycowll69 said:
As long as it's feasible, I'd use permatex #2 on a STUD with a brass nut. Then if you tighten the fasteners later, you are not disturbing that thread sealer's seal.
Click to expand...
This should be gospel. Those old studs were there for a reason, to seal up the water jackets and not have to disturb them. How many times have you had to extract these becasue they broke or you bent them in transport? Plenty.....
 
I had a small bock do the same thing on passenger side, I used permatex thread sealer and it did the trick.
 
Frnknsteen said:
--Agreed, but all of a sudden? It never leaked until recently. --
Click to expand...
-- I had a similar situation on My 408. It turned out to be a warped, aluminum, head. -- I hope that this is not the case.
 
Well, I hope not. Heads on it are stock iron 906 heads and the car hasn't been hot. Leak just showed up and it hasn't been driven since last fall (so it hasn't been overheated).

Trying to decide if I should throw a can of Bars Leak in it, or tear it down to see what's leaking and fix it. I hate dumping stuff like that into it when it should just be fixed. Don't get my wrong,... I've used it before on beaters when I didn't feel like messing with them, but hate to do it on this. Problem is, with the studs in it, I looked at it and don't know if I can squeeze the header out between the ends of the studs and the fenderwell.
 
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