engine and drivetrain heater valve fix?

[boldtu]

My heater is not working and I heard from another member that it may be the heater valve that is on the engine side of the fire wall. is there any way to fix this if it is the problem? can I rebuild it?

chet

[Mike87]

Check the FAQ...

http://www.bmw2002faq.com/content/view/73/32/

Section '3j' is a bit on the heater valve.

[JLENHAM]

The most common failure is the cable that actuates the valve fails. If this is the case, you can get heat by reaching in and manually moving the valve.

There is an old style all brass valve that probably can be rebuilt, and a newer one that is larger but has a plastic valve that probably can not. Before Mike Self jumps in here, I will remind you to take a picture or make careful notes as to the location of the arm before disassembly, it can be reinstalled in the wrong position and then you get heat when your lever is on cold.

Check the link, there should be an illustration that will point you in the right direction, passenger side, under the hood, see hoses going through firewall near centrally located fan by windshield base, see brass valve.

Have fun, I have successfully put this repair off all winter long- I have perma-heat, getting warm now so I plan to bipass the heater box for the summer and repair the valve.

[JerryC]

Have fun, I have successfully put this repair off all winter long- I have perma-heat, getting warm now so I plan to bipass the heater box for the summer and repair the valve.

My tii is on the same "winter heat program". I open the windows if it gets too warm.

That's one of the beauties of these old cars. Most "failures" are not urgent and debilitating. You just temporarily tolerate a reduction in functionality but can still get around.

[JohnS]

Definitely check out the FAQ write-up on this. I just pulled and rebuilt the heater box on my 1974 and couldn't have done it without the instructions from the FAQ. My (newer style) heater valve started to leak, so I decided to bite the bullet and pull the entire box for rebuild. Glad I did because the seal around the top of the heater box was toast and water was leaking into the car next to the firewall and seeping down under the carpets. While I was at it, I had the heater core pressure checked and rodded out. One of the most worthwhile rehab projects I've done on my car in a long time. Good luck,

--John

PS, it wasn't all that hard to do.

[JohnS]

Here's a picture of the heater valve in the Open (Heat ON) position.

[Chris_B]

Here are a few thoughts on basic toubleshooting to determine the cause of your problem. As another poster has said, likely your coolant valve to the heater core is not opening. Sorry for the long discussion, but troubleshooting heater problems can be a bit complex.

The first thing to do is check the operation of the valve by observing its operation through the opening in the middle of the air plenum behind the firewall where the center latch for the hood resides- from the driver's side. Have an assistant move the "cold-warm" lever back and forth. If you can't see the lever moving, then the problem is with the adjustment cable or the connection at the valve.

If the lever seems to be moving, the lever arm could be stripped at the valve. If you see that the lever arm is spinning on the shaft of the valve, you will need to remove the valve from the box for refurb or replacement. This generally is possible without removing the box from the chassis.

If the valve seems to be operating correctly, there could be blockage in the coolant flow through the heater core (most likely, in the core itself or caused by an air bubble blocking the coolant flow between the block and the core). The easy test for this is to feel the input/output hoses to the box. The input is on the right (passenger side) and the output is on the left (driver's) side. Warm on the right and cold on the left indicates that coolant is not flowing through the core. Lastly, the problem could be caused by low coolant temp in the motor, likely the result of a stuck (open) thermostat, or really low coolant level preventing flow of coolant to the heater core.

If the motor seems to be operating at temp (you should check this with a thermometer, because your in dash temp gauge may not be reliable), and you determine there is warm water at the valve but not flowing through the core, you can pull the valve and inspect. With the valve out, you can disconnect the other side of the box at the block and push water through from an external source; observe the flow and determine whether there is blockage in the core (in which case you will need to pull the box to refurbish or replace the core).

In the unlikely event that you have warm coolant on both sides of the box but not in the cabin, it could be that the footwell and defrost flaps are closed. In this case, you should be able to feel heat if you put your hand near the box inside the cabin. Presuming you have set the flaps in the open position, this likely is being caused by a defect in the cables that open the flaps. Time to pull the box for a refurb.

[boldtu]

thank you very much, I looked at the valve and it seems to be operating, but it may be stripped like you said so I will check out the valve out of the car, if it is stripped is there a fix for this. The heater valves I have found are $150 plus and I would like to avoid replacement. thanks again

chet

[Chris_B]

You could epoxy the lever arm to the shaft- JB Weld.

[jgerock]

Be careful when working on the heater valve linkage. While re-attaching the control cable to the valve arm, the tiny "pin" bolt broke in half. More parts required now to complete my install.

BTW - I left the linkage arm attached to the heater valve when I took apart my old heater box. I was fearful of messing up the $$ valve, but I broke the mounting tab on the box instead.

[Durandal]

on the topic of heaters does anyone know how much air is pushed by the blower motor? like the CFM rating? my heater has never worked, from the outside of the car I can see the blades are rusted and the motor looks bad, I have a spare heater box that Im not using but the motors the same....

I want to replace it with one (new) that doesn't cost me a metric ass-ton and is at least as strong... any body know? forum search didn't find any answers

[Chris_B]

WAG = ~100 CFM? The problem would be mounting a non-factory fan in the top of the box. I guess you could fabricate a new top.

[jerry]

Be careful when working on the heater valve linkage. While re-attaching the control cable to the valve arm, the tiny "pin" bolt broke in half. More parts required now to complete my install.

BTW - I left the linkage arm attached to the heater valve when I took apart my old heater box. I was fearful of messing up the $$ valve, but I broke the mounting tab on the box instead.

anyone know if this special bolt available? i've broken one myself.....

[JohnS]

My special bolt (BMW calls it a pin) also broke when I removed the cable from the valve. I ordered a new one from Max. Part #64114674219

[jgerock]

I just ordered a new pin (bolt), washers and nut from Maximillian. The parts aren't readily available and are getting more expensive.

I was going to search the "drawers" at Lowe's, but don't think I'll find that special shoulder bolt/pin. Wonder if anyone has a spare or knows of an alternative?