so what the hell is all this stuff for?

[irish44j]

swapping in an M42 into my M10 car. The engine I've rebuilt didn't have the coolant/HVAC hoses, but the 2nd engine I got for parts did (photo below).

Now as I see it there should be a hose coming off the back of the head that is the "IN" hose for the heater. Then there is an "OUT" hose from the heater that runs to the plastic "pipe" on the block. I would think it should be simple.

But on my spare M42 it has what looks to be some kind of valve with a couple other hoses and a T-connector. The hoses are not cut clean at the end, so it kind of looks like some kind of hack-job by a previous owner.

So what's the deal with this? Is this some kind of pressure relief/bypass valve for the heater? I can't seem to find the valve in realoeam diagrams...it just shows hoses going to and from the heater and nothing else.

Thoughts?

(on a side note, yes, I've already done the other MUTI alterations ;) )

[TobyB]

Are you talking about the aftermarket 'flushing' stuff on there,
or the BMW retrofitted 'don't cook the heater core' t- stat arrangement?

'Cause the lower right of your pic is the t- stat to protect the heater core,
and the upper left looks like one of those 'flush it yourself and save' rigs you could get
at Schucks, back when it was still called Schucks...

t

[irish44j]

sorry, not a very good pic....I'm talking about the mess of hoses in the foreground.

I'm talking about the stuff on the lower right dealing with the heater.

upper left is the vac line for the brake booster with the one-way valve in it. That should be original, since the one on my M10 looks exactly the same.

So is this "heater mod" necessary - or do people remove it? Just asking because if I need to keep it that's a lot of extra hoses to most likely replace.....

[Dj Buttchug]

those hoses are OEM. what you are dealing with is a heater valve. Remove the valve and call it good. Theres no need for it, and youre heater will still work. Everything attached to the metal heater valve can go. Basically the heater valve acts like a thermostat to regulate coolant flow to the heater core. Both of my cars no longer have this.

[Simon S]

^^ yep.

Some discussion on the recall/heater pressure bypass valve can be found in this thread.

Having it or not is a judgement call. In your case with a hard-running rally car - I might be inclined to keep it..