Exhaust leaks

[AUSMHLY]

What performance problems could exhaust leaks cause?

I did a leak test today by attaching a leaf blower to the tail pipes and spraying soapy water to the entire muffler system. More leaks than I thought.

I'd appreciate advise of how to repair them and with what products without having to replace the pieces, if possible.

1) Both leak at the manifold. Brass nuts are tight. Hopefully new gaskets will fix.
2) Leaks in the middle of the flex area of the down pipe. Can sealing muffler tape be used?
3) Leaks under the clamps at the front and rear where the pipes join the muffler.
4) Leaks, pin size, where the pipe is welded to the muffler.

Any recommendations of what products to use?

 

[Bob_Spidell]

1) Both leak at the manifold. Brass nuts are tight. Hopefully new gaskets will fix.
>>> New gaskets with high-temp sealant: https://www.aircraftspruce.com/cata...MIyLO7_qTh5QIVD8ZkCh13owxSEAQYBSABEgLSzfD_BwE

2) Leaks in the middle of the flex area of the down pipe. Can sealing muffler tape be used?
>>> Tape probably won't work; weld up the leaky area (if you can find it)

3) Leaks under the clamps at the front and rear where the pipes join the muffler.
>>> High temp sealant (see above)

4) Leaks, pin size, where the pipe is welded to the muffler.
>>> Grind the area a little, then JB Weld

Note all 'fixes'--except the new gaskets with sealant--are probably temporary.

 

[steveg]

re #3) Versachem works well if you clean the joints first. 1000*F continuous, 1500 intermittent:

These types of clamps work best - you really have to tighten them to prevent leaks. (Examples aren't necessarily the right sizes):

 

[Bob_Spidell]

I should have mentioned that both the downpipe and exhaust manifold flanges are notorious for being warped (the downpipe flanges appear to come pre-warped from the manufacturer these days). Since you have to take the downpipes off anyway, be sure to flat file the flanges as best you can; no amount of gaskets and goop will seal a warped joint for long.

Steve, that looks like good stuff, but it has a couple really negative reviews; I guess it worked for you? I'm still searching for the blue stuff Edd China always used on exhaust joints; if it's good enough for Edd ...

 

[HealeyRick]

Steve, that looks like good stuff, but it has a couple really negative reviews; I guess it worked for you? I'm still searching for the blue stuff Edd China always used on exhaust joints; if it's good enough for Edd ...

The interwebs seems to agree this is the stuff Edd uses: https://mossmotors.com/hylomar-exha...MIrqbm05zi5QIVBL3ICh1K8AItEAkYASABEgK8nvD_BwE

I think if I was going to remove the downpipes to do the gaskets, I'd bite the bullet and replace the downpipes entirely. That metal in the flex joints can be thin and resist efforts at repairing.

 

[Michael Oritt]

No one addressed the initial question: "What performance problems could exhaust leaks cause?"

 

[steveg]

...Steve, that looks like good stuff, but it has a couple really negative reviews; I guess it worked for you? I'm still searching for the blue stuff Edd China always used on exhaust joints; if it's good enough for Edd ...

Bob - I'm still looking for the perfect goop. Maybe one of these is better.
Google searched for "best exhaust sealant":

One thing about the Versachem is it comes in a larger tube than the Permatex.

 

[HealeyRick]

No one addressed the initial question: "What performance problems could exhaust leaks cause?"

I can't see it would cause any performance issues at all. There is, however, a danger to the driver from carbon monoxide leaks.

 

[AUSMHLY]

Would having exhaust leaks affect carburetor tuning?
Might air leaks affect this reading?



Leaks will not affect power or gas mileage?
Seems I've never been able to get the mileage other BJ8 owners say they get.
It sure would be swell if low mileage was as simple as addressing exhaust leaks.

 

[AUSMHLY]

I should have mentioned that both the downpipe and exhaust manifold flanges are notorious for being warped (the downpipe flanges appear to come pre-warped from the manufacturer these days). Since you have to take the downpipes off anyway, be sure to flat file the flanges as best you can; no amount of gaskets and goop will seal a warped joint for long.

Steve, that looks like good stuff, but it has a couple really negative reviews; I guess it worked for you? I'm still searching for the blue stuff Edd China always used on exhaust joints; if it's good enough for Edd ...

Ok, not the first guy to ever ask this question, so feel free to school me.
If the flanges are warped, would having a thicker gasket help? Being they come in only one thickness, double the gaskets?

 

[Bob_Spidell]

The interwebs seems to agree this is the stuff Edd uses: https://mossmotors.com/hylomar-exha...MIrqbm05zi5QIVBL3ICh1K8AItEAkYASABEgK8nvD_BwE

I think if I was going to remove the downpipes to do the gaskets, I'd bite the bullet and replace the downpipes entirely. That metal in the flex joints can be thin and resist efforts at repairing.

Thanks, Rick. Hylomar makes a paste that might be good for plugging holes:

http://hylomar.com/hylomar-product-range/exhaust-products/

 

[Bob_Spidell]

No one addressed the initial question: "What performance problems could exhaust leaks cause?"

Not performance, per se, but leaks can cause excessive 'farting' from the exhaust, esp. when coasting in gear.

 

[Keoke]

HI TH

I use plain pld RTV on mine works a charm.

As a matter of fact the flex jont on one of my pipes got damaged somehow , so I simply sealed that hole with RTV.

You will have a problem dismantling it later but a torch will ease the pain.

 

[steveg]

If anyone uses the Hylomar EAP5, would like a followup on how well it works and whether the small tube is enough for the typical exhaust system.

 

[kozelding]

I have an older Falcon SS exhaust that has always been a pain to seal, especially between the downpipes and the mufflers. This year I tried these:
https://retrocycle.com/products/11234_wide_aircraftstyle_chrome_exhaust_clamps

And they work great (if a little shiny). They're wide enough to cover the full length of the slits in the down pipes, and tighten in such a way that the pipe ends seal.