Classic cars forum & vehicle restoration.
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ukdave2002
Joined: 23 Nov 2007 Posts: 4109 Location: South Cheshire
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Posted: Tue May 03, 2022 11:18 am Post subject: Exhaust manifold gasket...or lack of one |
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The Bedford CA is lacking power, a quick check with a vacuum gauge indicates an air leak , spraying brake cleaner around the inlet manifold confirms this. I wanted to make sure that I had carb and manifold gaskets before dismantling, thought I was ok as I have a NOS head gasket kit, alas it appeared to be missing any exhaust manifold gaskets (it has 4 individual gaskets for the inlet manifold) . Checking the contents on the box, there is no mention of an exhaust manifold gasket, there is a single crushable exhaust pipe gasket but not a manifold gasket. Checking another set and its exactly the same.
The Bedford workshop manual makes no mention of an exhaust gasket, or adding any sealant
Am I missing something? Or were Vauxhall/ Bedford so confident in the accuracy of their manifold/ head machining that it was determined a gasket is not required?
I haven't dismantled anything yet.
Dave |
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Kenham
Joined: 12 Mar 2012 Posts: 209 Location: Kent
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Posted: Tue May 03, 2022 12:53 pm Post subject: |
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I seem to remember early land rover having no exhaust manifold gasket |
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MikeEdwards
Joined: 25 May 2011 Posts: 2476 Location: South Cheshire
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Posted: Tue May 03, 2022 6:35 pm Post subject: |
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The book I'm looking at (Service Training Manual for Engine and Clutch Bedford CA Mark 2) says for the petrol engine:
"The intake and exhaust manifolds are attached together at the centre by studs and nuts, and a gasket seals the joint. Circular collars to which gaskets are fitted, locate the intake manifold ports with those of the cylinder head. The exhaust manifold makes direct contact with the head."
That seems to contradict itself, to me. (ETA makes a bit more sense now I've found the photo).
Later in, in the disassembly section, it says "Remove the nuts securing the intake and exhaust manifolds together, separate the manifolds and detach the gasket."
Is this picture any help?
_________________ 1976 Vauxhall HP Firenza, 1976 Vauxhall Sportshatch (x2), 1986 Audi coupe quattro, 2000 Audi TT |
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Ray White
Joined: 02 Dec 2014 Posts: 6330 Location: Derby
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Posted: Tue May 03, 2022 7:07 pm Post subject: |
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I would be inclined to cut some gaskets from heat resistant material regardless of what the literature says. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4109 Location: South Cheshire
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Posted: Wed May 04, 2022 1:45 pm Post subject: |
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Mike, many thanks for the "no" exhaust /manifold gasket conformation.
Ray, the problem I'll have introducing a gasket is that it will shift the inlet manifold away from the head, I'll just have to make sure that all the mating surfaces are clean and flat, an apply a smear of high temperature sealant.
Thanks again
Dave |
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consul 57
Joined: 09 Nov 2017 Posts: 488 Location: somerset
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Posted: Thu May 05, 2022 1:28 pm Post subject: |
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the consul has no exhaust gasket, and if you have a heavy handed owner who tightens up the manifold bolts too tight it deforms the manifold and it never seals.
i bought a brand new stainless one and that was bent and would not seal, got it straightened and it is much better now. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4109 Location: South Cheshire
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Posted: Fri May 06, 2022 7:51 am Post subject: |
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consul 57 wrote: | the consul has no exhaust gasket, and if you have a heavy handed owner who tightens up the manifold bolts too tight it deforms the manifold and it never seals.
i bought a brand new stainless one and that was bent and would not seal, got it straightened and it is much better now. |
Good point, I shall check the manifold for any deformation, given the lack of a gasket I'd imagine there can only be a few thou difference anywhere across the manifold.
Dave |
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consul 57
Joined: 09 Nov 2017 Posts: 488 Location: somerset
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Posted: Fri May 06, 2022 12:01 pm Post subject: |
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i put my one on the kitchen worktop and shone a light from behind, it was bent by about 3mm, from new!
got a chap to straighten it, he welded across the back and the heat pulled it back straighter. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4109 Location: South Cheshire
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Posted: Sat May 21, 2022 6:21 pm Post subject: |
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I found that I had a couple of other manifolds, they were not required as the original pair are straight, however the way they had been bolted together (suspect the exhaust to inlet was torqued up before fitting to the head) meant that the inlet manifold was about 20" thou away from the head so the existing gaskets were not compressed properly.
So I slackened the inlet /exhaust joint bolts, applied some Wellseal to all faces, torqued up the head manifold joints, an then the inlet/exhaust.
Vacuum measurements now look good and its running better, however the dwell is all over the place, so suspect a worn distributor shaft, will investigate more tomorrow.
Dave |
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consul 57
Joined: 09 Nov 2017 Posts: 488 Location: somerset
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Posted: Sun May 22, 2022 10:13 am Post subject: |
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if your dizzy is worn, mine was at only 40,000 miles, dizzy doctor in somerset rebuilt mine, ran much better then. |
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ukdave2002
Joined: 23 Nov 2007 Posts: 4109 Location: South Cheshire
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Posted: Sun May 22, 2022 5:32 pm Post subject: |
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consul 57 wrote: | if your dizzy is worn, mine was at only 40,000 miles, dizzy doctor in somerset rebuilt mine, ran much better then. |
Yes that might be the way forward, I measured 14" thou play, so that will be throwing the timing and dwell well out Its an AC Delco dizzy, I know the DD does a lot with Lucas as we buy from him, these AC Delco distributers don't have separate bushes, so it would require a new mainshaft and cam, a bushing fitted to the housing and new advance springs, or the mainshaft cut under size and a suitable bushing fitted in the main housing.
Dave |
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