replacing exhaust bj8

[nicko]

Hi all !
I have been reading the forum for a while now and have found the advice given really excellent.
This is my first posting , so please be gentle!
I have managed to sort out quite a few small things with the car (I'm not a mechanic but practically minded).
However, after a small hole in the exhaust has got bigger,and is sounding like a tractor , I thought it would be a simple job to replace the two pipes from the manifold to the fist silencer. (the rest of the exhaust is fine).
Getting the exhaust off was the easy bit but found that the studs into the manifold were rusty and needed replacing.
This is where the problem lies ! How do you get them out?
Is there some special tool to remove them or is it as I think,
that I need to remove the carburettors ?
If so, is it a case of struggling and patience to get the bolts out, or does somebody know better ?
Advice gratefully received,
Yours frustatingly,
Nicko.

 

[stevebn2bj7]

This is a very common problem on any old car. The extreme solution would be to remove the manifold and work on a bench to get the old studs out. Have the studs broken off? If so, is there any amount sticking out? There are stud removal tools out there. You would likely need a welding torch to heat the manifold up to get them free, then retap the threads for new studs. Another solution is to grind them flush and then drill out the rest of the studs, a bit smaller than the hole so as to not srew up the threads and then tap it out to clean up. You need to be pretty precise though when drilling the holes as the flanges on the exhaust are not adjustable. This can be done when it is in the car but it will be a challenge.

 

[Keoke]

Hi yes asnoted a torch or drilling the old threaded portion of thestud out will work. Similarly, there is aproduct Called PB Blaster which is apenetrant that with a little time and patience may desolve the rust and allow you to remove the rusted studs. In any case when you get them out and replaced with new be sure and use bras snuts on the studs this time to avert what you just went through.--Fwiw--Keoke

 

[John_Progess]

Another excellent penetrating fluid is Kroil. It is available on line or usually at your local beaing house. Have a good day!

John

 

[Bob_Spidell]

I've been working exhaust issues for awhile now, so I'll chime in. First off, just because the studs are rusty doesn't mean they're unserviceable (you didn't say you had trouble getting the nuts off or that the studs broke off). I suggest you try cleaning the stud threads with a thread chaser ("die") before you go any further (they're 5/16" fine, 24tpi IIRC). If the threads clean up and you can get proper torque on the nuts then you'll be OK until you remove the manifold for other reasons (maybe even longer). Of course, be careful starting the die.

Second, I dutifully used new brass nuts for years but gave up because I couldn't get a good, lasting seal (the studs will rust regardless). I attribute this to not-perfectly-flat surfaces on both the manifold and pipe flanges and the mickey mouse gasket materials being used since asbestos became illegal. I finally gave up and started using steel nuts with lockwashers after applying plenty of antiseize paste to the studs. I now have a good seal and don't have to tighten the nuts every thousand miles or so. Be careful not to over-torque the nuts; 20ft-lbs should be about right (you'll have to convert to one of those goofy metric values :wink:

Third (probably should be first), invest in a good set of (SAE) taps and dies; you'll need them. Also, get in the habit of using antiseize paste pretty much everywhere. Just be mindful that since it's a grease required torque will be a bit less.

Just my $0.02.

 

[nicko]

Thanks guys for your prompt responses.
In reply to stevebn2bj7 , yes the studs are still there. I have some new studs and brass nuts. I have put the new nuts on but this just keeps stripping the threads.
The suggestion by Bob Spidell of using a thread chaser to clean them , is this possible in situ or will I have to take the manifold out?
I also have the problem of the "goofy metric sizes" out here.
Anyhow I will try the local garage as he sometimes fixes american tractors and lawnmowers, which are imperial measurements.
Thanks for all your advice and I will keep you posted.
Cheers,
Nicko

 

[Patrick67BJ8]

As an alternative to a torch, I suggest that you consider using a piece of dryice on the studs. It will shrink the studs significantly and a shot of PB Blaster will penetrate easier. I use dryice a lot to free up frozen bolts/nuts. Install stainless steel studs fron dunrite tool company and forget about anymore problems with these studs.
Patrick

 

[Bob_Spidell]

Yes, you can chase the stud threads in situ--from under the car--with a die and 'crescent' wrench. Are the nuts stripping, or are the stud threads stripping? If already stripped, the studs may or may not be serviceable. The brass nuts strip easily, even on clean stud threads (another reason I went with steel nuts).

 

[tahoe healey]

The manifold is somewhat fragile so do be careful (the down pipes, not the intake manifold). The are getting hard to replace which translates to expensive. Get good gaskets from British Car Specialists. Most of the others don't last.

 

[anthony7777]

Hi yes asnoted a torch or drilling the old threaded portion of thestud out will work. Similarly, there is aproduct Called PB Blaster which is apenetrant that with a little time and patience may desolve the rust and allow you to remove the rusted studs. In any case when you get them out and replaced with new be sure and use bras snuts on the studs this time to avert what you just went through.--Fwiw--Keoke [/quote ]................... keoke, fine advise as always, i also use a similar product for removing rusted hardware here on the "east coast " its called "BP" blaster, guess its some kind of markiting guise,...

 

[anthony7777]

nicko, a word of caution, if you decide to go the removal of the intake manifold/carbs method you will probably find the studs that go through the top of the intake manifold and pass down into the top of the exhaust manifold to be troublesome as well...

 

[Johnny]

Nicko, I have to agree with all above. However, I didn't see where anyone suggested removing the studs by first screwing on 2 nuts. Lock the 2 nuts tightly together then using a suitable wrench start trying to ease the stud out. You may have to use a torch of some sort. Please be very careful working with a torch in this area as the gasoline from the carbs is so very close.
Good luck,

 

[nicko]

Thanks everyone.
In reply to Bob Spidell,
it's the nuts that are stripping and also you mentioned the size of the threads being ( 5/16" fine, 24tpi IIRC).
I can't seem to find threads this size online.
Johnny mentioned screwing on 2 nuts and undoing it with the top nut.
The only metric nuts I've got are the brass ones which keep stripping !
Anyway if I can get a die I'll try cleaning the threads with it.
If not I might have to strip it down.
As Anthony 777 says you're right about the two studs that go through the top of the intake manifold , in preparation I tried to see if they would loosen off.
One came out completely and the other one snapped off halfway down the shaft.
More problems!
But as we say in France Pas de problemes, que de solutions,(no problems , only solutions!) Well let's hope so...

 

[Bob_Spidell]

Assuming your studs are stock/original, the nut size should be 5/16" fine (24tpi). They're common here in the States, but maybe not so much in the Metric Zone.

https://www.amazon.com/gp/product/B000DEMA60

 

[Keoke]

Well you have a job now. So you better get some PB Blaster Or KROIL to soak all the rest of the fasteners with prior to trying to loosen them. I still suggest as a final assembly at the exhaust to down pipe joint that you use brass nuts. If Brass nuts were not capable of maintaining a good seal here I wonder how they have survived for the past 40 years or so holding the exhaust manifold to the engine???---Keoke. :laugh:

 

[nicko]

Yep,
I agree, it looks like I'm going to be busy, I will put brass nuts on but as the good weather is likely to be on its way out , I'm going to have plenty of time to sort it.
Keep you posted.
Cheers,
Nicko.

 

[steveg]

If a stud is broken, imho you'll be better off removing the manifolds and doing the stud removal in a vise.

The machine shop guy who removed a stuck one on mine used a combination of Kroil, gripping with vise-grips and wiggling it back and forth ever so slightly over a period of a day or two. He didn't like the torch method as he said it made the manifold even more brittle.