How to fix exhaust header leak at collector

[swiftdrivr]

My DB-1 has a very noticeable leak from the exhaust header, at the joint where the 4 individual tubes slide into the tail pipe. It may have been there a long time, I don't know, as the header is over 20 years old. I am not sure if this is to be expected at this slip-joint, or if it is a problem. If it is a problem, I don't know if it can be fixed without buying a new header. Anyone got any ideas on this?

[OneWayOut]

Got a photo? My first guess is that there is a small dent in the collector or tubes, leaving a gap.

You can check to make sure everything is perfectly round with a exhaust pipe expander.
http://www.toolplanet.com/product/Ta...Expander-20110

[swiftdrivr]

Took a while to get to the shop. I don't see any dents, but with the engine running, I feel a big leak if I hold my hand near the joint. I should have tested some other cars to see if I felt it on them, but didn't think about it at the time.

[Purple Frog]

Really good muffler shops have "pipe expanders". With patience one could oh very slightly grow the 4 primaries.

In the picture they look like they still have a lot of meat. Might be able to be expanded slightly without cracking.

or... in my shop we would coat the primaries with red RTV and slide the mess together.

[cjsmith]

Like frog mentioned, high temp RTV works well up to +-1000 degrees. I used to use it on the 2 stroke manifold to pipe joint. It sealed the pipe as well as kept the two pipes from rubbing against each other and enlarging the gap. If it gets too hot it will break down and blow out.

[swiftdrivr]

RTV sounds cheaper than a new header, and safer than expansion, which might lead to new a header. many thanks, guys.

[DanW]

RTV sounds cheaper than a new header, and safer than expansion, which might lead to new a header. many thanks, guys.

The expander will get the tubes round again. That may help with fit.

[Charlie Schmidt]

cheap expanders are also available from a lot of places, if you want to tweak it a bit before RTV

I got one at HF, but lots of options

[problemchild]

RTV sounds cheaper than a new header, and safer than expansion, which might lead to new a header. many thanks, guys.

Your question was how to fix it ..... not the cheapest way to make it better without fixing it

[Steve Davis]

Jim,
Not sure how you checked your exhaust, but almost all exhaust systems leak at the collector at low RPM's. Yours might be just fine at speed. Rev it up to ~4000 or so and it should start pulling air INTO the gaps around the header pipes rather than pushing it out. It still affects the way the system works and the less leaks the better, but not as much as it appears at or near idle.

[swiftdrivr]

Greg. point taken. I really don,t like the thought of smearing RTV on my pipes.
Steve. excellent point. THe motor runs fine, and times were good. I may be chacing a red herring. FUrther research seems in order.
I hate typing on my wife's iPAD
many thanks for all the replies

[BLS]

Jim,

My FV exhaust leaked badly at idle, but as Steve mentioned above, it disappeared at higher RPM.

[DaveW]

IMO, exhaust tube expanders can be used with care on almost any exhaust pipe w/o fear of damage as long as you do the process incrementally, and are careful to not make the tube too big. The probability of cracking the tube or making it out of round is very low as long as you expand a little, and then rotate the expander several times during the process to even out the expansion and keep the tube round. Heating the tube a bit during the expansion process will make it more ductile and less likely to crack, but I have not found that to be necessary.

Exhaust-joint inner pipes will always shrink from use over a long period because of thermal expansion during usage. The outer tube is cooled by the air, while the inner one is heated, expanded, and softened by the heat from the exhaust gasses, so it yields a bit. When the system cools, the inner pipe then contracts and may eventually after many, many cycles be too small to fit tightly.

This is more of an issue in mild steel systems. SS systems don't seem to have this issue enough to be a problem.

Another thing to think about is that if it did it once, it will probably have the same issue again, so this fix is probably only temporary.

[rickb99]

Really good muffler shops have "pipe expanders". With patience one could oh very slightly grow the 4 primaries........

We took our 89 Reynard to a serious muffler shop (not one of the chain stores) and they used a pipe expander to fix the fit on our 4 into combiner. We let one of the pros there do it and he hit it right on with only two hits on three pipes and one on the fourth.

[JoePublicVA]

My DB-1 has a very noticeable leak from the exhaust header, at the joint where the 4 individual tubes slide into the tail pipe. It may have been there a long time, I don't know, as the header is over 20 years old. I am not sure if this is to be expected at this slip-joint, or if it is a problem. If it is a problem, I don't know if it can be fixed without buying a new header. Anyone got any ideas on this?

Try a "C Flange Bracket" stopped my leaks. U should chk that flange is flat first or simply remove old wrapped flange. Bracket can b installed without the old flange.

[EYERACE]

Thanks! Y'all might have just given me the idea of how to fix an exhaust fitting leak on the motorcycle........chart I've kept for years shows temps for various RTVs......black = 600 F, copper = 700 F, blue = 500 F, red = 650 F. Where I'm going with this is.....I've used red myself for header/block sealant but I'd care to hear others stories/experiences before I go slap some whatever color on the cycle pipe. At one point I was going to use some JB weld but never got around to it.

[Steve Demeter]

I use red on the header pipe / head joint on a Pinto. But the biggest reason that it works is that it is contained by the pressure on the bolted joint.

Again, something someone taught me,.. Did not figure it out myself.