Heater bypass mod

Stevehose

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Due to member interest from another thread, I am posting the mod that 61Porsche suggested I do to my car since we are both in tropical climates and infrequent users of the heater.

This mod bypasses the heater core which will result in cooler vent air, a/c air, and cabin temps because it eliminates heat soak from the hot coolant. It has made a big difference in my a/c temp and overall cabin comfort. So if you rarely use the heater, consider this mod, it takes only a couple of minutes to do or undo for winter.

Stuff a towel under the firewall heater core connections to collect coolant spill and remove the hoses. 61Porsche uses a 1/2" by 3" copper pipe, I used a 1" brass 90 degree elbow. Disconnect the hoses at the firewall and install the piece and secure with the same clamps. Make sure there are no kinks in the hoses. I blew out the remaining coolant from the core with air then capped them off. Simple, quick, effective and 100% reversible. Thanks Jerry!

IMG-20110330-00189.jpg
 

lip277

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You can also do this if your heater core has developed a <cough... cough...> leak.

:cry:

I found a single hose at NAPA that bridged the two connections together (block and head) without any additional adapters. I should have made note of the P/N but.... I think it is printed on the hose. I'll look if anyone wants me to.


I also capped the heater core spuds with large 'vacuum hose' caps that give it a more finished look than just leaving them open.
 

Sven

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Kevin,

What about driving on those cool spring, summer, and fall mornings? And the occasional beautiful winter days we have here? Time to rip out the center console and replace that core unit. I have a spare one you can have (pressure tested & cleaned) I was going to reinstall, but decided to put in a new unit for additional insurance/piece of mind.
 

NewSixCoupe

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I have a valve in place of the elbow in your car, Steve. I just turn it off/on in summer/winter...
 

lip277

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Kevin,

What about driving on those cool spring, summer, and fall mornings? And the occasional beautiful winter days we have here? Time to rip out the center console and replace that core unit. I have a spare one you can have (pressure tested & cleaned) I was going to reinstall, but decided to put in a new unit for additional insurance/piece of mind.

I know - I have a good spare as well... Just too many things going on to get it installed.
 

deQuincey

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Not that I'm aware of. My BMW guru mechanic installed it when I first got the car.

you have to show us that, though

if it is a 3way system it will be ok, so the valve will not close, but change from position 1 (through the radiator heater) to position 2 (heater by-pass), and that will be ok

take care of a "close-blocking coolant" position, i have been told about refrigeration problems in the rear cylinders if you do so

well anyway a photo will be highly appreciated

regards

i will explain myself a bit:
esquemarefrigconvalcula.jpg


consider three posibilities, first original condition as it is in the car, the rear side of the cylhead brings hot water into the heater, and out from the heater to the rear admission collector, ok

first modification, a simple valve system, you will get the by-pass from the heater, but the rear side of the engine will not have a nice coolant circulation, what is certainly dangerous

second modification, a 3 way valve (drawn in red) plus some other "T" pipe will allow by-pass (in green as summer condition) or heater pass (in orange as in winter condition)

agree ?
 
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deQuincey

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As installed:

thanks lens

i can not tell from the pictures, if it is a simple valve or a more complex thing (seems the simple one)

what do you think of my explanation ? have you ever experimented any coolant heat problems ?

regards
 

sfdon

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Keep in mind that the m30b35 engine in the e24, e34, e32 have no hot water hose at the back of the head whatsoever and that the e23, e28, e24 early models all have valves that just close and do not divert water at all.
 

NewSixCoupe

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thanks lens

i can not tell from the pictures, if it is a simple valve or a more complex thing (seems the simple one)

what do you think of my explanation ? have you ever experimented any coolant heat problems ?

regards

I remember my mechanic telling me that "this is the way BMW should have done it". No overheating problems whatsoever in five years of ownership...
 

alanmcg

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if that is what it looks like, you certainly WOULD have overheating probs if you turned that valve! if all your mechanic did was bypass the heater, then dont see why there is any need for the valve.
 

EJ333

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Does anyone have the NAPA part # for bypass hose ?

I have a valve in place of the elbow in your car, Steve. I just turn it off/on in summer/winter...

Anyone know the NAPA part # for the bypass without needing a adapter ?

You can also do this if your heater core has developed a <cough... cough...> leak.

:cry:

I found a single hose at NAPA that bridged the two connections together (block and head) without any additional adapters. I should have made note of the P/N but.... I think it is printed on the hose. I'll look if anyone wants me to.


I also capped the heater core spuds with large 'vacuum hose' caps that give it a more finished look than just leaving them open.
 
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