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No heat at highway speeds //M6

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six shooter

No heat at highway speeds //M6

Post by six shooter » Wed Nov 05, 2014 11:36 pm

Hey Guys,
Got the M6 out today. Kinda chilly for Texas.
Turned the heater on while warming up. Out came toasty air!

Got on the highway and the toasty went to Luke warm :(

I just replaced the heater valve 2 weeks ago because it did the
same thing last year. Thought FOR SURE the heater valve was inop.

The M6 doesn't have the standard bleed screw. I understand it's self bleeding.
I had the nose way up while filling the coolant back in.
The symptoms act like a inoperative heater valve. I can feel the solenoid
clicking with rotation of the heat rotary knob. Albeit it's not very pronounced
or loud.

Not sure what is going on here

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sansouci
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Post by sansouci » Thu Nov 06, 2014 12:13 pm

What does your temp gauge show? The t-stat may be sticking open letting all that toasty coolant cool down at high way speeds.
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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Post by Pod » Thu Nov 06, 2014 12:58 pm

The easiest way to check the heater valve is to remove it, then blow into the top port whilst passing 12v across the terminals. As you apply then remove the power you will soon feel if it is working OK. In my experience, a slight amount of air leakage is normal.

six shooter

Post by six shooter » Thu Nov 06, 2014 2:40 pm

Engine temp is in the middle.
Drifts slightly left on highway.
Works exactly as every other 6 series I
have owned.

I might have restacked the washers incorrectly.
I assembled them as they came out.

If anyone has a spare plastic heat valve to sell, let me know.

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sansouci
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Post by sansouci » Thu Nov 06, 2014 9:51 pm

From Ralph in SoCal from another post:
Inconsistent functioning during speed - I had the same exact issue with a 633 a few years back. I found that at speed, the heater would not work very well. On a long trip back from Vegas I tried a couple of experiments on the fly. I found out that the heater would return to normal function when engine speed was reduced. Basically by letting the car idle while doing 70 mph on a long downhill. Came to the conclusion that at higher engine speeds the valve would close from the force of the coolant flow. I took the valve apart and found a ruptured diaphragm as well but also found that the plunger was weak. Replaced the plunger and diaphragm and all was well.

I also have several spare units requiring rebuild for when Tom runs out of stock.


Ralph
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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Ralph in Socal
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Post by Ralph in Socal » Thu Nov 06, 2014 11:56 pm

Thanks Ken. I addressed it on the other post as Jose was also experiencing the same issue. And I also didn't want it to seem I was undermining the offer from Tom.


Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)

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Da_Hose
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Post by Da_Hose » Fri Nov 07, 2014 5:55 am

You know what, I had a chance to think about this today. The stock valve is nothing more than an on/off unit. It's normally closed, but put 12V to it and it opens.

So then, how do the valves fail? They fail because the upper diaphragm ruptures. Normally, the diaphragm gets pushed up by the increased water pressure of high revs and helps the electric solenoid. When the diaphragm ruptures, the rising water pressure can't assist the solenoid. So the flowing water overcomes pull force of the solenoid and closes the plunger. Lower the revs, the flow reduces and the solenoid can once again pull the plunger.

Now then, why does the upper diaphragm rupture? Because the currently available replacement heater valve cores are shit. The big problem is that we can't seem to find any more of the good quality, long lasting Bosch cores.

Ok, then. What is the alternative to constantly replacing a KNOWN TO BE SHIT part with a new KNOWN TO BE SHIT part? A very simple solution would be to simply gut the stock heater valve so it is always open, find an alternate valve you can put in-line to control flow and wire that in to the environmental control system instead.

Oh ...... Look at that. A 12V, NC, solenoid operated water valve. I also found valves in a 90 degree configuration so you could actually replace your stocker altogether.

http://www.ebay.com/itm/12V-DC-Hose-Bar ... 916wt_1232

Does anyone have a stock heater valve handy and could you measure the OD of the input port? Is a 12mm valve big enough to supply proper flow? If not, I saw some 1/2" and 5/8" units for the same $12. I do have a small concern. Do we think the water pump delivers more than the minimum 3 psi. required for the valve to flow? Since our common experience is that the heater shuts down when higher revs. create too much pressure in a damaged valve, I am thinking there wouldn't be a problem.

Jose
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1987 M6 - My dream car

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Post by jacko » Fri Nov 07, 2014 4:41 pm

I like your thinking.
Jack
Arlington, Texas. USA

1989 635csi
Automatic

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Da_Hose
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Post by Da_Hose » Sat Nov 08, 2014 6:17 am

So....... can someone with a spare valve handy let us all know the ID and OD of the valve outlets?

Jose
1987 M6 - My dream car

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Ralph in Socal
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Post by Ralph in Socal » Sat Nov 08, 2014 10:16 am

Been moving so as soon as I find the stash of valves.


Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)

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Post by tschultz » Sat Nov 08, 2014 8:52 pm

I will bring one of the used Bosch units to my work and measure it with digital calipers and report back.

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Da_Hose
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Post by Da_Hose » Sat Nov 08, 2014 9:08 pm

Right on!

If we can create a reliable, low cost fix for this issue it would be a nice win for all of us.

Jose
1987 M6 - My dream car

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Ralph in Socal
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Post by Ralph in Socal » Sat Nov 08, 2014 10:07 pm

Both ports measured at 0.78 inch (the tube outside D - not the flare).


Ralph
There is a very fine line between "Hobby" and Mental Illness.

85 635csi Zinno Auto
84 528i Euro
83 635 Euro Arktik
81 528i Kastanien 5-speed
88 528e Bronzit (Granpa Car)
86 535i Auto (For Sale)
81 633 csi (retired)

jacko
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Post by jacko » Sun Nov 09, 2014 4:53 am

Not being a stickler for originality where upgrades are available..... I'd be in to try one.
Jack
Arlington, Texas. USA

1989 635csi
Automatic

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Post by Da_Hose » Sun Nov 09, 2014 5:47 pm

Hmmmmm ..... so then, looks like I need to order a 3/4" valve and a new hose.

Jose
1987 M6 - My dream car

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Post by sansouci » Mon Nov 10, 2014 2:34 pm

All,
Somehow that second post was erroneously attributed to me. Likely to be Ralph's or Da Hoses'.
But anyway, great detective work from all of you.

So you are saying the Bosch rebuild kit that is at BAV 64 11 8 390 132 for $144.95 is crap?
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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sansouci
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Post by sansouci » Mon Nov 10, 2014 2:36 pm

I have totally lost it. Yes I did quote Ralph. Sorry if I created any confusion. I should have used the "quote" button.....
--Ken
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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Post by Da_Hose » Mon Nov 10, 2014 7:01 pm

No, the real Bosch rebuild kits are higher quality. They are also known to die eventually, but you will get much more life out of the repair than if you use the el-cheapo brand valve cores being sold right now.

I have an added interest in trying out an alternative valve because I am running waterless coolant. The newly installed valve core blew out immediately when I converted. I think that perhaps because the coolant is just a little thicker than regular coolant, it might be harder on the valve cores. If I were running totally stock coolant, I might just keep hunting for a Bosch core kit. Since I am looking to sort out a possible issue, hunting down a more durable and easily sourced/changed valve would be a good idea. The valve design is rather old and the newer poppet type valves are extremely durable. It's almost never the physical valve that wears out. It's usually the solenoid.

I have been doing more reading and realized that what we would need is a direct acting valve that can take the higher operating temperature and won't rely on any flow pressure to operate. That means a valve more like this one.

http://www.ebay.com/itm/K1BO-AC110V-3-4 ... 3cd592ee16

You can buy 3/4" barb fittings from Home Depot and it will plug right into the heater hoses. I will get one ordered tonight.

Jose
1987 M6 - My dream car

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sansouci
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Post by sansouci » Mon Nov 10, 2014 7:37 pm

Those look like the inlet valves on clothes washing machines (there are separate hot and cold) or the low voltage sprinkler valves.
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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Da_Hose
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Post by Da_Hose » Mon Nov 10, 2014 9:26 pm

Yup, those solenoids are used for all sorts of stuff. The 0 pressure function is what is most appealing to me. The one I linked before was 110V, but they can be had in 12V.

http://www.ebay.com/itm/QZO-3-4-Brass-E ... 233e5ec9bd

I used the coil from a 1/2" version of the valve above to repair my dead water heater valve in my RV. So I have held them in my hand and can report that they are built solid. I just ordered one and should have it in the next couple of weeks.

Jose
1987 M6 - My dream car

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sansouci
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Post by sansouci » Tue Nov 11, 2014 3:03 am

Real brass body and an interchangeable solenoid. Should be bulletproof. Zip tie it to the firewall and you're good to go!
Sansouci
84 E24 633Csi Auto, Bronzit/PearlBeige 6997510
93 E32 740il M60 Auto, Alpenweis/Ultramarine
60 528i M30 5-speed Green/Beige (crushed)
71 240Z 4-speed White/Blue (rusty & sold)
65 396 Chevelle 4-speed, Marina Blue/Black (stolen)

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Da_Hose
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Post by Da_Hose » Tue Nov 11, 2014 8:42 am

That's what I'm hoping, Sansouci. That kind of valve seems like it should be very durable. I have been able to find brass hose end fittings in a straight and 90 degree configuration that would allow for just swapping out the OEM valve.

Jose
1987 M6 - My dream car

six shooter

MTC Valves

Post by six shooter » Wed Nov 12, 2014 9:01 pm

I know these MTC mono valves are crap.
I tried an experiment today. I unplugged the connector.
Drove the car and it did the same thing. Cool air=higher RPM,Speed.
Idle power gives off good heat. If the valve was unplugged it should remain
fully open and give max heat at all times. Correct?

Since the valve is less than a week old, I don't suspect a failed diaphragm.
Why is the valve NOT staying open at higher rpm?
Especially when it's unpowered.

Inquiring minds want to know.

JAWS

Post by JAWS » Wed Nov 12, 2014 9:45 pm

i just did this repair on mine , i bought the entire new valve part from bavauto for $249.00 (i know kinda pricey) but i bought the entire piece new , and installed it , and bled the system , and it will burn you out of the car , works really well at all speeds highway or idle. I was getting cool air at speeds on highway and above 50 or so. I would recommend replacing the entire unit , if you have the $$$

six shooter

so simple yet so aggravating.

Post by six shooter » Wed Nov 12, 2014 11:19 pm

This system is so simple , yet its kicking my A$$!


is there anyway to stack the washers wrong on the assembly?
If the solenoid was weak than would that effect the plunger
operation?

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