Exhaust flange blew out again this morning

[RickB]

It seemed like I had it all installed right, everything was tight. It worked OK for a week, then yesterday on the way home it sounded like there was a leak. I looked under and found gray material on the side of the motor.
This morning it blew out when I turned it over.

I can get more gaskets, but what else can I do to assure a good seal?

My downpipes are rusty, but not rusted through.

It did seal for a week, but then it blew out. Is there anything I can put on there to make sure I get a good seal next time?

Anything worth doing once is worth doing over and over. /bcforum/images/%%GRAEMLIN_URL%%/nopity.gif

 

[jlaird]

Dumb question, just how can it blow a seal/gasket out when it has a 2" hole going to the rear.

What is blocking your flow out the exhaust pipe?

 

[RickB]

I don't know Jack, when it was working it had lots of exhaust coming out the tailpipe. I know that's totally subjective, how much is enough? How do you tell how much back pressure there is?
I'm just wondering if the top of the downpipe is too rusty and the metal has gotten too thin to make a good seal?
The gaskets slipped right on, should they be very tight or should they slip on & off?

 

[jlaird]

I have no clue on a B. Just seems that you must have a bad flange or too much back pressure or both. How is the inside of the mufler, cat. converter on there?

 

[RickB]

Maybe the flange is too weak, rusty.

I'm tempted to just buy a header and be done with it.

The outside of the muffler is rusty, I assume the inside is rusty too. Like I said though, there was plenty of exhaust coming out the tailpipe.

 

[jlaird]

Durn if I know what to say. Has Tony got a header?

 

[RickB]

Good question, I have a growing list of stuff with Tony.
Maybe he does, I'll ask him.

 

[RickB]

I'm looking at this one on Ebay:

 

[PeterC]

Rick, Do you have the support bracket strap[ assembly that goes to the transmission in place? That has to be there, otherwise all of the exhaust and engine movement is working on the gaskets. The front pipe should move solidly with the engine, and the rest of the system should be rubber mounted.

Had it happen to me several times until I replaced that stuff.

Peter C.

 

[ronzi]

My experience with my B with std. cast iron manifold & std exhaust downpipe is that it took a couple of whacks at it to get the donut to really seal. Any cocking of the two flanges & it may seal for a little while but after a few heat cycles it starts leaking.
Access to the joint is of course a pain, and the tendency was (for me anyway) to not get the nuts tightened equally, thus cocking the flanges, and eventually generating a leak.
Ultimately I had to loosen the downpipe at the downstream end so I could wiggle it around and keep it straight as I tightened the flange nuts.

 

[RickB]

Peter, I will check about the strap to the transmission.
I don't remember seeing it, but I wasn't looking for it.

Ronzi, thanks. I'll be trying again this weekend.

 

[Tom_Fisher]

My experience with my B with std. cast iron manifold & std exhaust downpipe is that it took a couple of whacks at it to get the donut to really seal. Any cocking of the two flanges & it may seal for a little while but after a few heat cycles it starts leaking.
Access to the joint is of course a pain, and the tendency was (for me anyway) to not get the nuts tightened equally, thus cocking the flanges, and eventually generating a leak.
Ultimately I had to loosen the downpipe at the downstream end so I could wiggle it around and keep it straight as I tightened the flange nuts.

I just installed a new exhaust system last weekend. The two flange connections you're talking about are very difficult to get access to. I think it helps, also, to use 3/8 extensions and rachet along with your 1/2 " socket (instead of the 1/2 extension and rachet) - the "skinnier" one affords a little better access.

Anyway, once you get the 6 nuts and washers in place and tightened down, then you take the old girl for a good spin.
Definitely enough to thoroughly warm her up - and then some.

After she cools down (the next day, at least), get back under the car and check those nuts again - I found that they all needed re-tightened, considerably.

I suspect you just need to replace the gaskets and do like I said.

 

[ronzi]

"I think it helps, also, to use 3/8 extensions and rachet along with your 1/2 " socket..."

And a u-joint and a looooong extension to get the ratchet down below the bend in the downpipe. Trying to tighten the nuts with about one tooth of arc on the ratchet is, well, trying.

 

[PeterC]

I also like to use a jack to hold he pipes tight rather than make the nuts pull it up.

Peter

 

[RickB]

I probably got it in there cockeyed.
I have a small jack I can use, I will try that next time.
Yes on 3/8 & extensions and deep well sockets etc...
I wouldn't even try putting my 1/2 inch stuff up there!

What about some kind of goo to goop the stuff up when installing the things?
Is that just a bad idea?

 

[PeterC]

I used furnace cement..... once. It certainly sealed it, but made reuse and later removal, ummm, nasty.

 

[Tom_Fisher]

What about some kind of goo to goop the stuff up when installing the things?
Is that just a bad idea?

Some people do that. What I did was put the nut (without the washer) on that I could get to the easiest. Do that on both pipes. Then, draw those nuts down which will pull the flanges up. Then put the nuts and washers on the remaining bolts. Then go back and take off the plain nuts without the washers. Now put the washers on those two and then put on the nuts. I found it helped to use an extra nut in the socket to act as a shim. It takes some doing but it can be done!

 

[Scott_Hower]

I'd pass on that header. I tried to fit the exact same thing years ago and the head flange was warped. I also had to grind the welded mounting "flats" down to get it even with the intake flanges.

I had a stock exhaust manifold refurbed with new studs and it fits perfectly.

Use brass nuts and plenty of anti-sieze.

 

[RickB]

Thanks Scott - I'll likely not go that way in that case.
I don't need more troubles!

This makes me wonder if I have other issues - is the part that bolts up to the manifold supposed to be loose fitting around the pipe? Mine is very loose.

I assumed this should be fitting like a compression fitting in plumbing - the ring that bolts up to the manifold presses against the gaskets that should squish a bit and make the pipe fit tight.

Is this correct?

 

[Tom_Fisher]

This makes me wonder if I have other issues - is the part that bolts up to the manifold supposed to be loose fitting around the pipe? Mine is very loose.

I assumed this should be fitting like a compression fitting in plumbing - the ring that bolts up to the manifold presses against the gaskets that should squish a bit and make the pipe fit tight.

Is this correct?

Yes - there are two of these loose fitting flanges. Each one is triangular with a hole for the bolts at the apexes of the triangles. They are very loose fitting when they come out of the shipping box. On each pipe goes a donut gasket and then the flange is bolted on which draws the assembly together (mates it with the exhaust manifold).

Here's a view of this "flange pipe" assembly (disregard the mufflers):

https://www.mossmotors.com/Shop/ViewProducts.aspx?PlateIndexID=37207