# How can I get my heat back on 733i?



## JustKeepsOnGoin (Oct 13, 2013)

Hello--

New to this forum. I have a 1984 733i that probably has 450K on it....The only thing that has been replaced is the water pump. I had the transmission rebuilt in 1995 because I by the time I changed the fluid, I had waited waaay too long.

Anyway, I have kept the car on full heat setting for years because the last time I had turned the temp setting to cool, it almost didn't make it back to providing heat....and that time it made a clanking sound when the heat was coming back on.

Now, it just blows room temperature, no matter what setting it is on (up/down, auto, etc).

Heater control valve?

Heater diverter valve?

Not sure, but for one of them which is located in the engine compartment, top passenger side on the firewall, I took the hose off and found nothing blocking or closed in there. I flushed that system out with a hose (some darker gunk came out too) and refilled with proper coolant after it was flowing clear water. No luck.

I don't have the bucks right now to fix, the rest of the car runs great. Operating temp is normal, drives fine. No coolant leaks inside the car foot wells or on the ground.

I'm hoping for an easy fix suggestion that will let me keep the heat flowing on the floor at all times. I don't need to adjust anything for cabin temp. Something I can do myself that won't cost me anything. I don't mind bypassing valves if need be.

Thanks!


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## mach8 (Dec 1, 2013)

not sure about your car, I have a '88 735i and the heater control valve in the engine compartment has two solenoid operated vales. When the rubber in the valves goes the heat stays on all the time, if there is no power to the valves they stay open so again you have heat all the time. 

If the switch controlling the valves is faulty and they have 12 volts all the time they will stay closed - no heat.

there is an auxiliary water pump attached to the heater control vale on the intake side.
If you aren't getting any heat your aux water pump may not be working, if you have one, or something may be plugging up the valve I'd guess.

I'd check the Shogun's BMW site as well as Timm's BMW site on meeknet.co.uk


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## John in VA (Feb 21, 2006)

One of the best E23 forums - http://www.bimmerboard.com/forums/e23/
Another great resource - http://e38.org/e23/


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## JustKeepsOnGoin (Oct 13, 2013)

Thanks much to both of you....ironically, it "fixed itself" a couple of days ago....hadn't run the car for a while and the battery barely started it after three tries....I revved it a bit when it did turn over and the heat has been on since....who knew?!


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