PLENUM TROUBLES

[GRIFFONMARK]

Removed lid off plenum. Aaarggghhh! Four of the trumpets are loose and have rattled about so much they have started to wear through the lid. Are they supposed to be loose? I don't think so. No. 4 has wedged at a daft angle and must have been jammed against the lid. No. 3 has worn the hole it sits in oval. Is there any rule for the heights of these things? Any ideas how to seal them back in?

Regards

Mark

[pwd95]

Register on here;

http://www.v8forum.co.uk/forum/index.php

& use this link. It's a link to a chap who's selling a neat & clean looking trumpet base for £10 on the classifieds.

http://www.v8forum.co.uk/forum/viewtopic.php?t=414...

[rev-erend]

Either buy a replacement or stick them back in .. perhaps JB weld as they do not move or some kind of glue - although I have no idea what to use..

Epoxy ?

[leorest]

RTV Silicone?

[Roger McLittriss]

Trumpets were originally fixed with a sealant that usually appears dark brown after the passage of years.
They often work loose due, I guess, to the different thermal expansion rates of steel trumpets and alloy base. It's not generally a problem as long as they don't become displaced and when they do you can normally hear them tinkling at idle. I've never heard of them chewing through the plenum top before! However it is a thick casting so I wouldn't worry too much.
A high temperature epoxy would probably be as good an adhesive as any though you may well find ordinary Araldite will work fine to fill any gaps.
Spare inlet manifolds/ plenums etc. come up quite regularly on Ebay although I suspect a good few have been weighed in this year due to the price of scrap!
The trumpets are all the same length, it's the ports in the base that are machined differently making the central four sit higher.

[GRIFFONMARK]

Thanks for that Roger, I'll go the glue route for now.

[GreenV8S]

Roger McLittriss said:

I've never heard of them chewing through the plenum top before! However it is a thick casting so I wouldn't worry too much.

If they've managed to remove any significant amount of material, I think I'd be more concerned about where that went to.

[Roger McLittriss]

GreenV8S said:

Roger McLittriss said:

I've never heard of them chewing through the plenum top before! However it is a thick casting so I wouldn't worry too much.

If they've managed to remove any significant amount of material, I think I'd be more concerned about where that went to.

Good point! Probably a bit late by now though

[900T-R]

Roger McLittriss said:

GreenV8S said:

Roger McLittriss said:

I've never heard of them chewing through the plenum top before! However it is a thick casting so I wouldn't worry too much.

If they've managed to remove any significant amount of material, I think I'd be more concerned about where that went to.

Good point! Probably a bit late by now though

Might want to change oil & filter, then.

[GRIFFONMARK]

Don't know where all the fine aluminium particles went, don't see how they got into the oil via tha inlet, probably gave my exhaust an alloy lining. Dodging down to dodgsons, my local motor factors to see what glue they've got. This seems to be a common problem so I don't think getting another 2nd hand one would be a long term solution. Interestingly, it was the longer ones that came loose ( ie the ones not stuffed in as far) so maybe the tight fit wasn't as tight as Rover anticipated.

Regards, Mark

[honestjohntoo]

In 1996 I cleaned and serviced my (Twin) Plenum, even took the trumpets out of their recesses.

Upon refitting, all the trumpets were loosish, not tight, so I put a bead of silicon gasket sealant (same stuff used to seal the plenum to trumpet housing joint) around the trumpet close to the bottom and pushed each one into place. The bead spread out in the upper regions of each recess as the trumpet went home and any excess was wiped off, in case it broke away in use.

The following day the sealant had cured and there has been no tinkling noises since - 12 years.

Edited by honestjohntoo on Tuesday 25th November 01:01

[GRIFFONMARK]

Thanks honestjohn, that's exactly what I'll do.

Regards

Mark

[GRIFFONMARK]

Got some superb high temp epoxy from local factors, sets in 5 mins and a nice matching grey colour, shame its hidden in the plenum. Everyhting glued neatly in place.