Heater Control Valve (HCV) Elimination

[DPDISXR4Ti]

I always strive to simplify my engine bay, so eliminating the HCV and associated plumbing is on the hit list when I do a coolant system overhaul this spring. Obviously this has been much discussed on the XR platform, but I can't recall seeing anyone do it on a Scorpio. Will I be the first?

P.S. Ed, we all already know you think this is a horrible idea.

[DPDISXR4Ti]

The only thing I might consider as an alternative is a simple flow-valve like this, but I'd need to study the coolant routing to see if blocking (rather than bypassing) the flow on that line would be a problem. I suspect it would be.

[brokencase]

I'm always happy to see a modern and less expensive substitute, or even a self engineered solution.
But I'm not sure about the simplification you speak of. I'll have to dig around the XR4ti area to see what you are talking about.

Back in 2015 I recall Rock Auto blowing out Scorpio heater control valves for around $24. I should have bought a spare at that time.
Now they go for big bucks.

If mine goes I will probably reverse engineer it and machine/tig a new one out of stainless steel.

[john keefe]

Uh Oh... another critical NLA part to worry about. Brad, I'm not familiar with the XR discussions about this. Curious why you want to eliminate it altogether? I understand making room in the bay for a hi-po setup, but that means no cabin heating or defrosting, right? Relegating it to garage storage for Winter, or is there something I'm missing? (e.g., bypassing/replacing the valve with a better cabin-heat transfer mechanism?).

Sorry guys if this is long, old debate not worth bringing back up again.

[DPDISXR4Ti]

but that means no cabin heating or defrosting, right?

Not at all. You still have the heater core plumbed, sans the bypass option otherwise provided by the HCV. Yes, this means a little more heat in the cabin in the summer months, but it's negligible; there are cars built this way from the factory.

[john keefe]

there are cars built this way from the factory.

Good cars, or econo-boxes?

[brokencase]

OK - I think I get it (although I still would like to look at the manual or follow the hoses in the car)

I think what you are saying is that the stock valve diverts both ends of the heater core. So in one state, the water circulates through the core. In the other state the water loops through the valve.

You are proposing with your alternative valve that only one side of the heater core needs to be blocked off to stop flow through the core.
This has the desirable side effect of hose simplification. Another side effect is a transition to a more affordable, readily available and modern replacement valve. What is the substitute valve from BTW?

If above is what you mean then I have a few questions.

Why didn't the factory do it this way from the get go? Will the EATC still be happy after the mod?

When the stock valve is in the state of bypassing the heater core, where does the coolant return to? Is it possible this circulating loop is necessary for some reason? Like maybe better cylinder head cooling? Faster warm-up?

[brokencase]

There are other 4 port heater control valves out there that would probably work on the Scorpio.
For example, this unit for a 97 Aerostar... $8 from rockauto

https://www.rockauto.com/en/moreinfo.ph ... 09&jsn=626

You need to be careful. Some are "normally open" or "normally closed" so you need to verify that.
I find this page to be informative in this regard .
https://www.uacparts.com/legacy/UACProducts_HCV.html

Of course the plumbing/mounting may have to be suitably modified...and you have to figure out which port goes where.
But it's better than paying $100 for the original Scorpio part.

[DPDISXR4Ti]

there are cars built this way from the factory.

Good cars, or econo-boxes?

My '91 Alfa 164 was configured this way from the factory. It was a $25K car in 1991. I've never noticed it being too warm in the cabin in the summer, and the A/C hasn't worked in the car in years.

[DPDISXR4Ti]

I think what you are saying is that the stock valve diverts both ends of the heater core. So in one state, the water circulates through the core. In the other state the water loops through the valve.

Yes, that is precisely how it works. XR & Scorpio are the same part.

You are proposing with your alternative valve that only one side of the heater core needs to be blocked off to stop flow through the core.
This has the desirable side effect of hose simplification. Another side effect is a transition to a more affordable, readily available and modern replacement valve. What is the substitute valve from BTW?

If above is what you mean then I have a few questions.

Why didn't the factory do it this way from the get go? Will the EATC still be happy after the mod?

When the stock valve is in the state of bypassing the heater core, where does the coolant return to? Is it possible this circulating loop is necessary for some reason? Like maybe better cylinder head cooling? Faster warm-up?

You are correct with regard to the alternative valve. I found it on a junked Volvo 240 - it was definitely a replacement part, so not sure if it was plumbed as original, or someone had done a similar simplification.

At this point I have the same question as you with regard to the effects of removing the bypass function. I need to study the flow path to determine if it's something that can be done without issue. If not, I would ditch the idea of using ANY valve and just plumb in the heater core as part of the continuous loop. There are plenty of us who have done this on the XR without significant effect.

I'm not even aware of there being a supply issue with the factory HCV, although I have heard of alternatives being discussed before - the Aerostar valve sounds familiar. The motivation for me was simplifying the engine bay and reducing points of critical failure. In the spring I'm planning on a coolant system overhaul, so "everything coolant based" is on the table. Weirdly enough, the Nissan alternator gets included in that project.

[dimswits]

I always strive to simplify my engine bay, so eliminating the HCV and associated plumbing is on the hit list when I do a coolant system overhaul this spring. Obviously this has been much discussed on the XR platform, but I can't recall seeing anyone do it on a Scorpio. Will I be the first?

P.S. Ed, we all already know you think this is a horrible idea.

Certainly won't be the first, as I've removed it from every Scorpio I've ever owned. The configuration is identical to that of the XR, save for the vacuum to the valve being electronically controlled rather than mechanically by a temp select slider.

BTW regardless of any misgivings anyone may have, that valve is a stupid piece of over-engineering that is completely unnecessary given the age of the cars. It is a binary valve that is open at all times unless full cold is demanded from the climate control, which is when it is commanded closed in order to coax an extra few degrees of cooling out of the air conditioning. I would even posit without any hard data that it contributes to the clogging of the heater cores that is common to both cars.

[DPDISXR4Ti]

Certainly won't be the first, as I've removed it from every Scorpio I've ever owned. The configuration is identical to that of the XR, save for the vacuum to the valve being electronically controlled rather than mechanically by a temp select slider.

I thought if anyone had deleted the HCV from a Scorpio it would be you, so glad you chimed in. The idea of using the simple inline flow-valve was more an after-thought on my part; the basic thought was to just eliminate the valve.

Funny enough, I'll also be having a mechanical slider in the Scorpio once I get around to installing the Euro manual controls. I've now got everything I need for that - just need to do it.

[dimswits]

Funny enough, I'll also be having a mechanical slider in the Scorpio once I get around to installing the Euro manual controls. I've now got everything I need for that - just need to do it.

Hey, I know a guy who had that exact same plan and even amassed all the parts too . He never started the project and hasn't driven his Scorpios much at all in the last few years.

Will you have AC in that car?

[john keefe]

So, if you're eliminating the valve, do you then just plumb the in/out hoses together (sleeve-insert + clamps)? Or, running a single, new hose all the way to the core?

[brokencase]

Simplification would be as follows...

Currently you have a heater valve with 4 ports. Two of the ports go to the heater core. The other two are "incoming" water and "outgoing" water.

With the new valve you have two ports. The "incoming" water goes to one port of the valve. The other port of the valve goes to one port of the heater core. The other port of the heater core goes to wherever the "outgoing" water went to.

I believe two hoses are eliminated and replaced with some longer hoses.