Throttle body heating...is it needed?

[Billwill]

My M40 318i has two water pipes running to the throttle body...as I am sure most E30s do.
This obviously runs engine coolant into and out of the front section of the throttle body...I presume this is to prevent icing up in cold envirements.
The M40 has a plastic section of piping feeding water from the engine block to the heater core and it also runs up to the throttle body. The plastic section has broken where the feed pipe is taken off...really bad design from BMW to use plastic where metal would have been a more logical option.
I will be making enquiries about the cost of a new plastic piece but I think I am going to be extremely shocked at the price from the dealers.
So I am thinking of blocking off the broken section so that hot water no longer flows to the throttle body. Where I live the overnight temperature in mid winter never goes below 8 degrees Centigrade so icing up of the throttle body should not be an issue or am I missing something here?
Do I need this heating effect for normal driving and will there be some performance or economy issue with the water pipes blocked off?

[scjimbo]

There is something you are missing. The throttle body will freeze up in humid conditions. It really has nothing to do with outside temperature. Rather more to do with the percentage of water in the air. A throttle body be its nature aerosolises the fuel which will drop the temperature of the castings to below 0 if not heated. My guess is if the good people at the motorworks put it on there its probably needed.

I would say get the pipe from the breakers. If not if you email me with a fag packet drawing. I can probably make you a metal one if its not to complex.

[kam-325i]

A throttle body be its nature aerosolises the fuel

Thats the job of the injectors, Not the Throttle body.

Lots have done the throttle body heater pipes removal on the M20 engines without any adverse effects....

Not heard of any problems with doing the same on the M40...

[zaust]

Should have been the first mod you done. The throttle body will not freeze in our climate. It gets nowhere near cold enough. If anything it will allow for a better bang when the motor is up to temp.

[kam-325i]

The inlet manifold is a huge heatsoak anyway.........

[Brianmoooore]

It's carbs. that freeze themselves up - latent heat of vaporisation. No such thing with injectors, which just atomise the fuel, not vaporise it.
You might be pleasantly surprised if you price up that pipe from BMW.

[Billwill]

Thanks for the answers Guys...today is a holiday in SA so first thing tomorrow I will phone the dealers and ask for a price.

E30 spares here are very expensive and we do not have decent "Pirate" suppliers who could help with a better price. If the price is reasonable I will replace the broken pipe..if not then I will bypass the heating function of the throttle body.

[Billwill]

OK according to my online "realoem" and "BMW fans-info" pages there does not appear to be a part number for this broken piece of mine.

Looking at realoem E30 318i Cooling system water hoses there are hoses item 16 pn: 11531717590, item 4 pn:11531709052 and item 20 pn: 64211381192.
All of these hose attach to the part I am looking for with no part number.

I will have to go to the dealers tomorrow but it looks like I am going to have to go for plan B and bypass the system....not many breaker yards around and any old E30 will have the same plastic part about to disintergrate.

[Billwill]

OK as I figured...local dealership does not have the part listed at all.

I managed to repair this plastic plenum.
The section of plastic pipe that had snapped off I filed down level, drilled out to 12mm and fitted a self-tapping threaded insert into the plastic. The insert is 8mm inside diameter and 12mm outer.
I then trimmed a small section off the existing hose to get a smaller internal diameter and hose clamped the hose onto the metal insert.

The two other plastic male protusions were also a bit worse for wear as the very end bits had snapped off but I managed to get the hoses on OK. If this does not work I shall have to repeat the job of inserting hollow threaded inserts into the plastic housing.

[Speedtouch]

Not a BMW I know, but I run a 1970 Morris Minor Traveller and have run it for years without the hot water flow to the alloy inlet manifold with a large 1 3/4" HIF SU carb and no issues with carb icing, and that's here in the UK on the South East Coast which gets pretty cold at times due to the North Sea wind whistling about the place.

Interesting point from scjimbo about the humidity though...