[desertboy]

Looks like I won't have the time to repair the Heater Core O-Rings for another few weeks and I like to bypass the Heater core. I'm loosing about 1" coolant from the Expansion tank every 300 miles (running down under the passenger side carpet). I ordered a couple of 1" - 90 Degree Elbow pieces from our local Napa to make a U-Fitting and was wondering if there are any issues running the car with the Heater core bypassed? I understand the extra bit of cooling the heater core routing provided would be lost.
Comments from anyone with experience running their P38 this way would be appreciated.

 

[Guest]

I ran mine for about 6 months with the heater core bypassed with no ill effects.

 

[desertboy]

Thanks Max, What did you use to bypass it? what I would like is a single hose from the top of the cylinder block to the 3-way connector or two hoses that can be connected using a plastic connector. If anyone has any part numbers (year make and model)? My current plan is to use two 90 degree elbows on the existing hose assembly with a single hose connecting the two elbows making a U. Am I correct in thinking that the hoses can be connected with a 1" O.D. connector?

 

[Guest]

I used the hose that comes out of the engine and just rerouted it into the t connector. You can flip around the t to reroute hoses, then put it back when you get the o-rings done.

 

[desertboy]

Thanks for the Tip. With the BMW expansion tank in place I cant see how the hose from the cylinder head can be turned to fit the plastic T-Fitting. Mine may be sitting differently to your tank. I have the expansion tank fitting coming to the middle of the T with the heater core hose at the fire wall side of the T fitting. I can't see how it can be turned without making a kink in one of the hoses. Then again, I could be feeling very dumb today and missing the obvious.

 

[Guest]

Is yours a bosch or gems engine, cause that could be the difference, mine is a gems engine. Now that I think about it, I cut the hose from the engine to the t to get it to fit, as I replaced it and the pipes that go to the heater core once I finally got around to replacing the o-rings. IIRC, the hose that I cut was only about $20 to replace.

 

[desertboy]

Mine is a Gems and cutting the hose makes sense. I was going to repair it tonight without lowering the coolant level (hence the 2X 90 degree joints). What I like about the way you did it is, there are no extra connections that can brake. I guess we are all paranoid about cooking a Rover engine miles from home (I have been there).

 

[Davo_50]

Hello,

This is one of several threads on Bypassing the Heater on a P38. Some say use 1" elbows otheay use a 3/4" elbows. Other simply say obtain a copper U Tube from Plumbing Supplier. What is the correct size of parts to link the Heater inlet and outlet hoses?

I am off on a long trip tomorrow and want to fix this before I go.

Regards

Davo_50

 

[RRToadHall]

depends on GEMS or Bosch. different process depending on model. also depends on if you want to reroute a hose, cut a hose or just join them at the cowl.

 

[Gilbertd]

Just pull the hoses off where they connect to the two pipes that run through the bulkhead and join the hoses together with a U. On a GEMS, the pipes are around 20mm, so you can use either 19mm (3/4") and do the clips up tight, or 21mm if you can get them. 1" (25mm) would be too big and you'd risk splitting the ends of the hoses resulting in an even bigger leak.