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All,
I've just recently replaced my internally leaking original to the car heater control valve.
I installed the new one, made by MTC I think, and well I'm not impressed, especially for what I paid for it.
I tested it before putting it in and it did completely shut off, however once in the car, and still completely shut off, I'm still getting warm air coming out of the vents. Not a fan of this especially since I have zero a/c currently in the car.
What I want to know is how much do I have to adjust the adjusting screw for the feedback loop to shut the flow of water completely off, and if anyone knows or understands how this whole thing really works, I'd really like to know.
Thanks in advance,
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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So I called up the company that I bought the heater control valve from and am getting a free replacement sent to me.
During the conversation, the individual did let it slip that they have been having issues with this valve, so he didn't seem surprised by the fact that this had happened.
If the second one fails as well, then I'll be getting my money back and purchasing something else that I've used in the past. I should have done that from the start, but apparently I didn't listen to that little voice inside my head telling me what I knew to be correct. Stupid me!
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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So I received my second MTC heater control valve.
I removed the first one and what I saw was that the plunger was not centered properly in the tube, thus the reason for the hot coolant continuing to flow through the heater core.
Upon inspection of the part I was able to play around with it and get it to align back up and had it operating properly once again. However, when I started pushing at the components that hold the valve in place, in particular the pivot point, I was once again able to make the valve fail. Ugh!
With this knowledge now in had, I attempted to install the new valve back in the car in the closed position, and being careful not to touch anything around the pivot point. Even though I was careful, I did however slightly brush against it, but thought it wasn't bad, so I filled the car up and tried it out. It too failed and was letting coolant flow through the valve.
Last night I pulled the new valve out and as suspected, the valve was once again off center, and thus allowed hot coolant to flow through the heater core. Both valves are going back and I'm now purchasing a new valve that I've used before and it works very well. Not OEM, but it does work. I should have done it in the first place, but I thought I would try something that was supposed to work like the OEM one. Never again!
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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This is the MTC copy of the original style Ranco valve?
Just wondering because I posed the quality question about that product in an earlier post. I guess this is the answer.
Well, what did you expect from MTC?
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'80 DL 2 door, '89 DL Wagon, '15 XC70 T6 AWD
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Bulletproof,
Not what I expected, but I did not get the quality that was Ranco, that I know!
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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Nothing stupid about what you've done. Posting your experience will be valuable to many readers, as well as yourself.
Curious, will your supplier want the suspected-defective part returned you think?
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Art Benstein near Baltimore
Experience is something you don't get until just after you need it.
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Art,
Yes, my supplier wants its back at no cost to me.
I'll take a really good look at it, and some pictures to boot so I can compare it to the one that is on its way to me.
Regards,
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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If someone is willing to pay for the return, I think that increases the likelihood there's interest in analyzing the reason for customer dissatisfaction and provide feedback to the manufacturer. I wonder, too, how much the MTC valve differs from the Ranco.
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Art Benstein near Baltimore
If you think nobody cares if you're alive, try missing a couple of car payments.
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Is the cable adjusted properly so that when you move the temp control lever to cold that it’s actually moving the valve to the completely closed position?
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Chris,
That was the first thing I checked.
I even removed the cable and moved the valve by hand and still no change.
I'm going to do the clamp off this afternoon and diagnosis from there.
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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Hi Matt,
Without any experience whatsoever with the MTC replica part all I can tell you about that adjustment on the original Ranco valve is the screw operates a small cam which is driven by the expanding wax motor in response to heat sensed in the capillary tube you installed into the airflow. The screw positions the cam so you can adjust lower the amount of coolant flow (think heat for humans - coolant for engines) in response to the air temperature sensed by the cap tube coil.
The cam's lobe helps the feedback to close the valve, not open it. You could check to see it isn't set to minimum, but I would just clamp the hose shut to prove to yourself the valve is actually opening and allowing coolant to flow.
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Art Benstein near Baltimore
It seems like a lot of suppliers are only interested in plugging the hole with a part, rather than making sure the part is of high quality. -Benski
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Hi Art!
Which hose would you like me to clamp shut, the one coming into the control valve or existing the valve?
Then once clamped shut, where would I check to see that I no longer have coolant flow?
Thanks in advance,
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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"heavy sigh"...
I checked the dang valve before installing, and now I need to pinch it off to verify what I most likely already know to be the case, that the valve is NOT shutting off like I thought!
Ugh!
The good news, the part is still under warranty and I can have a new to me part sent out at no cost.
The bad news is that I now need to replace the valve in a very cramped condition as opposed to when I had the heater core out and could freely and easily access things.
Tell me again, why I keep fixing my car????
Thanks Art for the moral support.
I'll check this out tonight after work while doing the other million things that need to get done.
I'll post back what I find out, but I think we already know the answer.
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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Regarding the moral support, I was thinking your test of the valve before you installed it was a good move, and that your test was true. Maybe not. Coolant at 200F might perform differently than your test method.
So, I was hoping you'd clamp the hose and find no difference, which would lay the blame on perception, rather than a faulty part. It has been awfully hot in the recent past. The circulated air has opportunity to be heated without the aid of a heater core with engine coolant flowing through it.
Take it easy and one step at a time. With all those other things you have to do, you might wind up checking it again in the cool weather, and coming to a different conclusion. I can tell you from experience, having a fleet to maintain can get in the way of science experiments diving deep into diagnosis.
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Art Benstein near Baltimore
You can easily judge the character of a man by how he treats those who can do nothing for him. ~Malcolm S. Forbes
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All,
I didn't get to it yesterday after work, just too much stuff going on.
So today I had time to run the experiment.
I got in the car and opened the windows.
Shoved a thermometer into the center duct work and turned on the fan to 3.
The temperature rose from 83 F to 105 F and then cooled down to around 92 F.
While it was doing all this I cut off the water going into the control valve using the type of hose clamp that Art pictured.
Once the temperature refused to go any lower I started the car and let it idle for about 10 minutes. The temperature during that time climbed to about 94 F. At the 15 minute mark I noted the temperature at 94 F, and then released the hose clamp.
The temperature climbed slowly over a few minutes to 120F, at which point, just the fun of it, I opened the valve and the temperature immediately shot up to 132F within seconds. At this point I shut the car off.
I believe the new to me heater control valve is indeed faulty and is not shutting off as prescribed.
What do all of you folks say?
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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Just some last minute thoughts before you get a replacement valve.
Are you sure it's plumbed in the right way? I don't know how hard that would be to do, it's been a long time since I had to work in that area. I see an old post on another 240 forum where someone managed to plumb it in the wrong way and it would "leak". The MTC design appears to be a cross shutter slide type valve. The shutter might not seal as tight to one side of the chamber as the other depending on the direction of flow. I've heard of similar things with backwards flowing heater valves in other cars where the valve plate (flap) is on an off-centered axle or seats at an angle. Those designs easily permit reverse flow, in fact sometimes it's an intentional design to allow coolant pressure to balance on both sides of the valve due to fluid expansion/contraction in various parts of the system.
My other thought was a large chunk of scale or whatever getting into the valve and preventing full closure. The MTC shutter design could easily be prone to something just sitting in the bottom of the chamber and keeping the shutter from full travel to close. When you remove the valve, do give it a good flush in both directions to make sure there isn't something caught inside. You haven't ever put Barr's in it have you? That stuff can cause all kinds of such issues.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now
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Dave,
Valve is in correct and plumbed correctly.
The possibility of debris in the hose is a possibility, but I won't know till I take it apart yet again.
As for Barrt's, NO! I would never put that in any of my cars. I always fix things that correct way.
Thanks for your thoughts.
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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Art,
So my test method was to simply prove through visual inspection that the new valve did in fact close, which it did. The one that was removed showed via visual inspection how bad it was and that it was not closing in any way shape or form.
My plan this afternoon/tonight is too clamp off the hose, and shove a thermometer into the duct work with the fan off and see what I get as a base line. then start the car, turn on the fan on 2 and let it warm up and note what type, if any, change I detect. Once that is done, I can release the clamp and take another reading and see what I see. My prediction is that it will be higher.
On Sunday I was reading a 15 degree higher temperature than ambient while driving the car around town for about 15 minutes. I do not believe I should have seen that type of increase, even with the temperatures as high as they were outside on Sunday.
As far as a fleet, that is true, however, this one is not a daily driver and I have the time to play with it and get it right, which is what I plan to do.
Matt
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1989 - 245, 1990 - 245, 1991 - 245, and 1993 - 245
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The valve itself is opened and closed by the control cable. Adjust so the valve is shut when it should be. The screw adjuster just tunes the +/- small changes that are read by the ether filled copper coil. This is in the air flow so that if it gets a blast of hot or cold ambient air it will open or close the valve to compensate. That's the theory anyway but it's quite crude and you'll mostly not notice any changes. The screw is set by the maker after testing and should have a blob of paint on it to show it's original and not tampered with.
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