Manifold sealing

[billg]

Drove 40 miles on 1104 DZ , on it's first real shakedown drive on country roads and straights on the old A1 from Dunbar to Haddington . Dropped in to see Nick Morgan who also has a USA TR3A but his is still LHD.

 

I think I have getting some leaks at the exhaust manifold at higher revs, but with 2" system and a tubular manifold and not having such a gutsy car I maybe imagining it. When I assembled most of the engine ancillaries I did not use any sealants in case I had to disassembled any components.

 

Is it normal practice to use exhaust paste on stainless exhausts and on the exhaust manifold to block surfaces . Once done I presume the gasket is single use only.

 

The tubular manifold was another eBay bargain so it's possible it's not an exact fit.

 

The car goes like a bat out of he'll though even before any tuning at all. No overheating either, misfires or backfires. I have two silencers one a cherry bomb at the rear which is making most of the ASBO rated noises, but It may just be the thin ness of the tubular manifold that's making the most racket. A sort of 4 cyl RR Merlin !!!!

 

Only a few oil leaks to tackle though that may be mission impossible ?

 

Bill G@ NB

[Rodbr]

Hi Bill,

In the past I used plumbers tape to put exhaust joints together, make sure you have the full contact surface covered in tape and breaking the joints is a doddle. PTFE tape nothing more complicated.

Makes steel exhausts and dream to split, but stainless benefit as well.

 

IMHO don't use joint compound as it is hells own delight to break at a later stage.

Rgds

Rod

[mikespain835]

Hi Bill

Exhaust joint paste/sealant is not designed to seal between manifold and head the gasket should be sufficient if the face of the manifold is flat.If it is slightly bowed a machine shop could probably regrind the face flat.It does puzzle me a bit tha t you say it happens at higher revs,when i would have thought any blow should be able to be heard even at tick over or revving it a touch,-a stethascope is useful to detect the area of a blow,also a leak from the manifold causes popping from the exhaust especially on overrun-BE CAREFUL NOT TO BURN YOURSELF!It could be that you're getting revurberation through the exhaust at certain revs?

just my tuppeny worth

Mike

[ians]

Never considered using PTFE tape for this but on checking the melting point is 327 dgrees C and I doubt that the block / manifold interface ever gets to this.

Edited July 20, 2012 by ians

[billg]

I'm surprised thatPTFE is appropriate but people do use it in ovens at least 250 C plus it's soft enough to squash and fill gaps. I may have some sheets of it or any kitchen shop will sell it.

 

It may be that the combination of tubular exhaust plus straight through 2" silencers gives a real racing car throaty roar when the throttle is opened wide as the breathing certainly seems to be very free. Need to meet up with other 3a's to compare.

 

Will do more checks at the weekend.

 

Regards

 

Bill G @ NB

[Fireman049]

Hi everybody ~

 

PTFE tape is a new one on me! Please pardon my ignorance but am I right in assuming that the thin white PTFE used for making watertight joints is OK for exhaust systems?

 

Tom.

[LGFromage]

Masking tape is pretty good too.

 

Tim

[Rodbr]

Hi Tom,

Yup correct plumbers tape. I have used it for years on Golf GTI's, actually come to think of it on any exhaust where a section wore out quicker. We lived in the country then and cow Sh1t eats steel exhausts for fun.

The point is to make a permanent barrier between the mating surfaces and they slide on easy and can be broken with out resorting to a lump hammer.

 

rgds

Rod

[Fireman049]

Hi Rod ~

Thanks for that. Am I correct in thinking that I wrap the tape around the pipe that slides into the other pipe?

Best regards ~

Tom.

[Rodbr]

To clarify a bit after reading all posts on this. I used it for pipe to pipe joints and wound it round from the tip of the male part to the extent of the expected joint. If the "dry joint"is slack on stainless pipe then the number of wraps may be more. Try if possible to wind it on the same way as you wiggle the pipe on that way you don't rip the barrier tape.

 

I have no idea about any other form of PTFE material, as I only used plumbers tape.

 

rgds

Rod

[ians]

You can get different thicknesses. I have three, coloured white, pink and blue.

[billg]

By the way PTFE is extremely poisonous if it burns as it contains Fluorine I once work in factory where I used PTFE components that were turned on lathes in the machine shop and the guys were banned from smoking, especially roll-ups as any PTFE swarf that got into the baccy would have killed them, not sure about its use in very hot manifolds where it could generate fumes??

 

Bill G @ NB

[Rodbr]

Hi bill,

The white stuff is what I used comes in a roll from plumbers merchant. I imagine that plumbers may have to solder joints close to compression joints so you might expect that there would be an Elf and safety notice that this stuff kills you in big writing.

 

I would not advocate the use of any other stuff, only what I know and I can not see a way you could use it at the manifold in any case. I think you have the same manifold as I do and it is a pig to get to seal at the head.

I certainly never saw it burn or even melt or I might think again. Just made getting the joint apart dead easy. taught to me by an exhaust technician.

rgds

Rod

[Alec Pringle]

PTFE tape becomes dangerous around 400F, thereafter it releases fumes . . . . not easily visible, doesn't smell much either, but the effects are definitely not pleasant.

 

'Polymer fume fever' is I think the name of the result, bit like the mother and father of all flu bugs. Ask me how I know - once was enough, thank you ! Low level fuming supposedly gives rise to cumulative effects over time . . . .

 

Like Rod, I've used it in the past for exhaust sealing, works damn well, but having once been hit by the fumes, never again.

 

Cheers,

 

Alec

[Rodbr]

I did a google and can not find references to plumbers dieing like flies. Unless you suck the exhaust or lick the tape probably wont do much harm.

[Alec Pringle]

Plumbers are not generally daft enough to heat PTFE tape with a blow torch . . . . .

 

If you use PTFE tape on an exhaust manifold joint, or adjacent to a catalytic converter, you'll soon enough discover the problem. Further downstream in the exhaust system it probably won't get hot enough to emit fluorocarbon gases.

 

Cheers,

 

Alec

[Nigel C]

I asked the same question to Jeremy brooster ( who runs an excellent vintage and veteran garage down the road from me) about the manifold on poppops Old car. He said black automotive gasket sealant/ mastic. I didn't believe him at first but looking at his Resto's etc we decided to try it. Couldnt believe it would take the heat but it does. Mine now runs on it too, excellent stuff. Only problem it always seems to come in it's own pressurised mastic tube but if you tape the end up well it seems to have a shelf life.