MGTF: Why does only one exhaust work?
 

The TF has a dual exhaust system, but on my car only one exhaust
works. Does the second exhaust switch on automaticaly when the car is
warm? If so how warm. I have never seen it work.

In article >,
(Dom) wrote:

>The TF has a dual exhaust system, but on my car only one exhaust
>works. Does the second exhaust switch on automaticaly when the car is
>warm? If so how warm. I have never seen it work.

Many? cars have what's known as a manifold Heat Control Valve, aka "heat riser".
It basical blocks off one side and forces hot exhaust gas across the
intake manifold below the carb to help promote fuel atomization when the
engine is cold. The exhaust then goes out the other exhaust pipe.
As it warms up, the valve opens. On a warm engine, you should have exhaust
coming out of both pipes. If you don't, the valve is probably stuck
closed.
Older cars used a thermostatic spring to control it, while newer ones
often used a vacuum diaphragm to activate it.

Dom wrote:

> The TF has a dual exhaust system, but on my car only one exhaust
> works. Does the second exhaust switch on automaticaly when the car is
> warm? If so how warm. I have never seen it work.

I thought a TF was a four cylinder?

In any case, a situation where only one exhaust pipe works is usually a
sign of a stuck heat riser valve. Do you also have problems with vapor
lock?

nate

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replace "fly" with "com" to reply.
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Is not the t model an MG from the fifties or late forties ?? Never seen
a heat riser on an MG from modern days so I doubt if yours has one. Are
there 2 pipes the whole way from the engine or one pipe & a dual outlet
muffler??

pater wrote:
> Is not the t model an MG from the fifties or late forties ?? Never seen
> a heat riser on an MG from modern days so I doubt if yours has one. Are
> there 2 pipes the whole way from the engine or one pipe & a dual outlet
> muffler??
>
This may sound stupid, but I wonder if this guy has one of those cheesey
MG kits cars with a VW engine.

Larry

Not so stupid, on here, always a possibility, but doubt that a standard
bug muffler could do what he says it's doing.