Manifold Heater Pipe

[Joe]

Hello,
Newbie with first post, am trying to replace manifold heater pipe(rusted out) on my 77 2500TC bought new one from CW and on his web says to drill old one out. So is it doable with basic drill? and is new one just slipped in, or should it be welded in place. Any tips helpful.
Thanks
Joe

[Alec]

Hello Joe,

I don't understand the reference to drilling operation. The rear of the pipe has a bracket to the rear manifold stud and the front fits into a compression fitting at the back of the water pump. You may find that trying to unscrew the compression nut that the base of the fitting unscrews from the water pump instead.
If you can cut or break off the ninety bend at the rear of the pipe it should then come out quite easily. (That may not actually be necessary so try and unscrew it as it is. Does the new pipe come with an olive as that will be required to fit your new pipe. (The fitting is a typical plumbing compression fitting.)

Alec

[Clifford Pope]

I think Joe is talking about the manifold heater pipe, not the car heater pipe.

I've just been out to look at mine. I hadn't taken any notice of this before, but I see there is a steel pipe running right through both branches of the inlet manifold. It does look the sort of set up I can imagine being a devil to replace - a mixture of crumbling from rust but rusted solid inside the aluminium. I've never had to do this job so can't advise, but it must depend on whether the steel pipe runs inside solid aluminium, in which case the seal would not be too critical, or actually through the air passages?

[johnnydog]

Assuming the pipe you refer to is the straight steel section running through the inlet manifold that 'CP' suggests then it can be replaced but ideally needs the inlet manifold removing from the car. One of our local Register members replaced it with a section of 15mm or 1/2" copper pipe many years ago - perhaps not particularly the best from an appearance point of view but did the trick. I recollect that he cut very thin discreet slots in the aluminium either to aid the release of the old pipe or to accommodate the new copper pipe (it was one of the two). This didn't affect the operation of the inlet manifold as the water pipe doesn't have any load on it and is just for the passage of water.
It is one piece and from memory only a tolerance fit. I have never replaced one myself but as aluminium and steel have differing expansion rates, would a spell in the oven (preferably when you're on your own in the house!! ) help to loosen the the pipe from the manifold? With possibly with a suitable sized drift then to aid removal if the remaining exposed ends are reduced to a length that they are workable? A local machine shop would probably be able to remove it and fit the new piece for a relatively nominal cost if you struggle to do it yourself.
I also wouldn't have thought that a good used one would be difficult to source as another alternative.

[Joe]

Clifford is right that is the pipe I'm referring to, I only thought of drilling because Chris Witor suggests it on his web page when you order a new stainless replacement, which is what I did. But possibly taking it to a machine shop may be more expedient.
Thanks

[Joe]

Forgot to mention manifold is already off as I had to remove to replace the pipe Aiex refered to, which then revealed that the other pipe had a hole in it as well!

[johnnydog]

At least the pipe running behind the exhaust manifold from the water pump housing is easy to replace!
Worth bearing mind that one I replaced on a Triumph with stainless (I think it was my S) had to be trimmed slightly at the water pump end for a 'comfortable' fit relative to the pipework at the bulkhead end. Others I have replaced on my Mk1 and early Mk2 fitted comfortably as supplied.
One thing that is sometimes overlooked, not all Mk2 2000s are the same - very early Mk2's had the same pipe as the later Mk1's. I made that mistake ordering a Mk2 stainless pipe for my J reg 2000, and then on dismantling found that it actually required a Mk1 pipe. Its the angle of the pipe at the bulkhead end that is different.
However, the year of your car shouldn't be a problem.

[tony]

I replaced the one on the one on my Mk2 a few years ago with copper. Unless you have access to a drill press and something solid to bolt it to I'd take it to an engineering shop.A small job for someone with the right gear.Its liable to pick up on the narrow bore and throw you across the room if you try it with a portable drill. The original pipe is cast in the aluminium manifold. I just araldited the new one in place.
Tony.

[Clifford Pope]

Does the pipe run through solid aluminimum, not through manifold air space?
If so, then the tightness or quality of the seal would not matter.
But its purpose is presumably to supply heat to the air intake as soon as possible after start-up. In which case it would surely work better with a good heat contact, suggesting that it ought to be a press fit rather than say being loose with just some araldite to hold it?

I'm a bit sceptical about these water-heated inlet manifolds. It seems to me they can't supply any useful heat right at the start, requiring the engine to have already been up and running before the water heats up. They then produce most heat when the cooling water is hottest, exactly when you don't want heat.
An exhaust heat exchange with a thermostatic flap diverter would give almost instant heat and then turn off when the job was done.

[Joe]

Thanks for all the replies, I found the same for the one under the manifold and had to trim it a bit to line up with retaining stud. Will take it to machine shop I know, and get them to install with a tight fit, to be honest not sure myself if it will help with stuttering on warm up problems, but have been told it should? Worst case scenario will have two shiny new pipes under the bonnet and gave the body work under carbs a good polish.