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Author Topic: Exhaust Manifold Blowing  (Read 6707 times)

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nixoro

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Exhaust Manifold Blowing
« on: 14 November 2006, 09:33:36 »
Having had abit of time spare on sunday I managed to have a look at my exhaust and have confirmed my exhaust manifold is blowing.

You can hear a tapping noise coming from that area.

I am looking to remove the exhaust manifold on saturday to rethread a couple of known knackered stud threads. Looking to get a tap and die set on saturday to sort this problem.

I was thinking what is the recommended to use for refitting the studs loctite or something similar also I am looking to change the gasket if it knackered what sort of sealant is recommended as I have some proper exhaust sealant but not sure its ok to use on the manifold to head join.

I assume that if any of the current studs have snapped its going to be a bugger to drill them out.

This job has been needing to be done for a while and so looking to get it sorted.

Any tips for removal or refitting would be much appreciated.
« Last Edit: 14 November 2006, 09:33:53 by nixoro »
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omegaV6CD

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Re: Exhaust Manifold Blowing
« Reply #1 on: 14 November 2006, 09:54:53 »
Quote
Having had abit of time spare on sunday I managed to have a look at my exhaust and have confirmed my exhaust manifold is blowing.

You can hear a tapping noise coming from that area.

I am looking to remove the exhaust manifold on saturday to rethread a couple of known knackered stud threads. Looking to get a tap and die set on saturday to sort this problem.

I was thinking what is the recommended to use for refitting the studs loctite or something similar also I am looking to change the gasket if it knackered what sort of sealant is recommended as I have some proper exhaust sealant but not sure its ok to use on the manifold to head join.

I assume that if any of the current studs have snapped its going to be a bugger to drill them out.

This job has been needing to be done for a while and so looking to get it sorted.

Any tips for removal or refitting would be much appreciated.

I'f i'm correct the best locktite can survive up to 160degrees which is notheing compared to the 600+ that the manifolds go through. The gasket needs changing anyway so no need for seelant on it. clean the surfaces well. skim the manifold(at a machineshop) and you sould be fine.
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Marks DTM Calib

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Re: Exhaust Manifold Blowing
« Reply #2 on: 14 November 2006, 10:17:01 »
You dont need sealent, use a genuine (multi layer metal) gasket and flatten the manifold face as already said, you can actualy do this using a flat surface and some coarse emery as it does not need to be to accurate.......also check it for cracks.

New studs and nuts would be recommended but, I wouldn't locktite them in.....

You might find it easier to remove/slacken the nuts/studs with the engine hot (mind your fingers!) and prey you dont have any broken ones.
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nixoro

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Re: Exhaust Manifold Blowing
« Reply #3 on: 14 November 2006, 11:01:21 »
Thankyou for both the responses

I am liking the Idea of the Emery paper on the manifold tip.

I am also thinking if I am going to be using a tap and die kit chances are I will need thicker studs do Vx do thicker studs or could I get away with using ordinary thicker bolts.

Another thing is the gasket I actually replaced it a while back when I did my clutch hence knowing about the missing studs left it too long really :-[ anyway would it be possible to reuse it or do they become unusable once removed, and so new one needed for refit.

Fingers crossed that none have snapped.
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Ken T

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Re: Exhaust Manifold Blowing
« Reply #4 on: 14 November 2006, 20:13:42 »
Hi there,
an idea I read somewhere recently, was if a stud snaps off flush, why not try welding onto the end of it. This may give you enough to grip with a wrench and loosen. You should of course disconnect battery, alternator, (and the ECU?) to prevent the welding current damaging things.
 As they say in Scotland, "don't force it, use a bigger hammer"  ;D
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mar892ree

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Re: Exhaust Manifold Blowing
« Reply #5 on: 14 November 2006, 20:49:20 »
Absolute doddle if you use freeze spray, such as ambersil or loctite rust freeze/crack , or what ever its called !

As far as welding on to the end of  broken stud, well FORGET IT unless you have a TIG plant / welding set !
You are far more likely to do more damage to the surrounding area using arc or MIG !

Gas tourch might be OK, but a naked flame on an engine urmmmmmmmmmm !!

You will also find that the VERY elevated heat put in to the broken stud and surrounding area will 99% of the time release the broken stud due to expansion of the metals etc ,and also the cracking of the oxides ( rust etc )
Also remember EVERY metal rusts or oxides, doesnt have to be red rust !!! Also there's galvanic reaction to contend with ( reaction between two disimilar metals, with moisture /water acting as the electrolite ! )
Galvanic reaction is a right barstewart, and far worse to contend with than rust alone !
I have known galvanic reaction to absolutly seize metals together and needing literally hundreds of tons  of pressure to part them !

Hence the reason to always put a VERY slight smear of copper grease on bolts and studs especially when screwing them in to a disimilar metal such as steel studs in to an ally head or cast block !
The copper grease will slow down the galvanic reaction A LOT !

mARK

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Eliteman Steve

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Re: Exhaust Manifold Blowing
« Reply #6 on: 14 November 2006, 21:30:03 »
So freeze spray is the stuff to use eh!! Same principle as heat I suppose but no chance of fire :y Is this the same stuff you can get for plumbing applications?
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mar892ree

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Re: Exhaust Manifold Blowing
« Reply #7 on: 14 November 2006, 21:37:52 »
Unfortuneatly NOT !

Both the Loctite and Ambersil products obviously freeze, but lubricate too ! ( high quality penitrating oils )
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mar892ree

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Re: Exhaust Manifold Blowing
« Reply #8 on: 14 November 2006, 21:40:34 »
Here's a link that explains how Ambersil Rust Flash works

http://www.manufacturingtalk.com/news/crn/crn101.html

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The Barge Captain

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Re: Exhaust Manifold Blowing
« Reply #9 on: 14 November 2006, 22:08:38 »
Looks interesting. Anybody know where it can be bought?
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mijfife

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Re: Exhaust Manifold Blowing
« Reply #10 on: 14 November 2006, 22:08:42 »
Hi Nixoro, I had a broken manifold stud on the gls but was fortunate enough to have it out of the car when I replaced it ;)  The manifold on the 2ltr isn't too bad to remove, undo flange to front pipe, remove heat shield on the manifold to access the bolts and undo the metal breather pipe that snakes around the rear breather pipe. The nuts are reasonably accessible and hopefully you'll have enough room to drill out any broken studs too. I'd recommend renewing the manifold gasket as it will probably have been damaged where it is leaking. The holes in the manifold allow for a bigger stud or bolt to be fitted, should you need to drill and re tap up a size.

Cheers Jim
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nixoro

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Re: Exhaust Manifold Blowing
« Reply #11 on: 15 November 2006, 09:46:53 »
Quote
Hi Nixoro, I had a broken manifold stud on the gls but was fortunate enough to have it out of the car when I replaced it ;)  The manifold on the 2ltr isn't too bad to remove, undo flange to front pipe, remove heat shield on the manifold to access the bolts and undo the metal breather pipe that snakes around the rear breather pipe. The nuts are reasonably accessible and hopefully you'll have enough room to drill out any broken studs too. I'd recommend renewing the manifold gasket as it will probably have been damaged where it is leaking. The holes in the manifold allow for a bigger stud or bolt to be fitted, should you need to drill and re tap up a size.

Cheers Jim

Cheers Jim for the advice its much appreciated.

I have removed the cat and the manifold before back when I did my clutch so I have a fair idea of whats going on, my main concern was whether I could get away with using the current gasket or should I buy new. I am just hoping that there are no nasty surprises other than the already known when I come to remove it on saturday.

Sad thing is I have left it so long now and now want to get it sorted, would you believe that back when I got the car I actually had the exhaust manifold replaced but as the work is out of warranty now the garage wont touch it. So now its for me to sort out. And since then its never been back as I know for a fact they messed one of the stud threads up only when i did the clutch I had a look only to find one of the studs floating about on the manifold god only knows how it has stayed on there for all that time.

*edit* forgot to mention when I refitted the manifold when I did my clutch I obviously knew of one missing stud but the rest were torqued into place and so there didnt appear to be any leak, granted I knew it was a weakness though that could return at anytime.

Still bring on saturday, hopefully it will go ok.
« Last Edit: 15 November 2006, 10:05:35 by nixoro »
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nixoro

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Re: Exhaust Manifold Blowing
« Reply #12 on: 15 November 2006, 09:49:37 »
Quote
Here's a link that explains how Ambersil Rust Flash works

http://www.manufacturingtalk.com/news/crn/crn101.html


Cheers for the recommendation if I get any problems I may have to seek out some of this I assume this cant be bought at halfords can anyone suggest where it could be bought from.
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mike9570

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Re: Exhaust Manifold Blowing
« Reply #13 on: 15 November 2006, 18:23:24 »
wot size studs are on the 2.0l block m8 or m10 studs..
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mar892ree

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Re: Exhaust Manifold Blowing
« Reply #14 on: 15 November 2006, 18:50:07 »
M8 x 25 studs mate
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