Heater valve bypass to fix "heated dashboard vents"?

[MadScience]

Originally Posted by arctictraveller

Leaks aside, I haven't re-read the entire thread, but did you simply block the coolant flow or install a bypass? I'm still interested in knowing if there are any issues with blocking the return flow by using a simple on / off valve.

I used the Ford valve to bypass. It seemed easier than trying to think through the implications of blocking. I felt like I'd need to pull some of the manifolds off to be sure that there isn't any tricky non-obvious routing.

It's probably just paranoia, but I'm trying to get out of the business of hoping something is fine with this beast.

Edit: Draining two not entirely full gallon jugs worth of coolant from the bottom of the radiator eliminates all but a couple of drops of spillage.

[JWA]

Over this past summer I worked quite a bit with a scheme to block coolant flow from the front heater coil to achieve this "cold air vents" modification. While that didn't work out quite as expected (my fault 100%, over-designed an unnecessarily elaborate system) I did discover completely blocking coolant flow from the engine had no ill effects on any operating parameters.

As already pointed out the port from where hottest coolant flows in only a small portion of total flow so it not being "in the loop" presents no problems.

Not sure if anyone else has noticed but the 5.4 gasoline engine coolant quantity is a whopping 4 gallons. This being my first time messing with coolant I assumed the normal amount of 2 gallons would fill it up.

Its this reason Ford's have such great heaters. Even my new-to-me '05 with rear A/C & heat produces 109* F exiting air temp when the engine and all coolant have reached an operating temperature of about 175* F.

[jblaze5779]

So just to update. I put the 12v actuated ball valve on in July and haven't had one problem since. I brought a switch to the dashboard and can open it and close it on the fly. Also, I have a thermometer in my ac vent and cannot tell a measurable difference in air temp with the ball open or closed. Total project cost was about 50 bucks so I'm not really worried about it.

One plus is that when it's cold I can take the heater core out of the system to warm up. It doesn't really help that much but my 7.3 needs all the help it can get to warm itself when cold.

[MadScience]

Interesting. The difference in AC vent temperature was dramatic for me. Like 20-30 degrees less. I'm dealing with the v10 FWIW.

I wonder if your heater core might need a flush?

JWA: How do you know that there were no ill effects? It seems like fallout from a hot spot in one of the heads could take a while to result in notable damage, but once it does it might be a bigger deal.

[JWA]

Originally Posted by MadScience

JWA: How do you know that there were no ill effects? It seems like fallout from a hot spot in one of the heads could take a while to result in notable damage, but once it does it might be a bigger deal.

In what way would blocking that passage affect the heads?

While going through my experimentation I watched the dash temperature gauge as well as an OBD-II scanner programmed to report coolant temperature. Probes on the coolant lines were attached to a multi-channel electronic thermometer which obtains its readings via K-type thermocouples.

Issues regarding coolant flow problems as reported by the typical on-board sensors Ford builds into its vehicles.

[MadScience]

I'm not sure that monitoring the primary coolant flow would necessarily catch any pockets where the coolant is suddenly not moving as much as it should anymore. Such a pocket, wherever it might be, would result in an area being under-cooled.

Understanding how it's supposed to flow by looking at all the passages on the physical parts would answer that for sure. As would perhaps a better diagram than the one I've been able to find. If you have this information, folks here would appreciate it.

I feel like enough folks have been doing this mod on the 7.3 PSD that someone must have looked at this carefully by now and would have raised a point. However I'm not so sure about the gasoline engines.

FWIW, on the Ranger, which is a totally different engine, but has this valve as a stock part, Ford choose to go with the more complex to install bypass, for some reason.

[jblaze5779]

Originally Posted by MadScience

Interesting. The difference in AC vent temperature was dramatic for me. Like 20-30 degrees less. I'm dealing with the v10 FWIW.

I wonder if your heater core might need a flush?

JWA: How do you know that there were no ill effects? It seems like fallout from a hot spot in one of the heads could take a while to result in notable damage, but once it does it might be a bigger deal.

I know that's not the case since I replaced the heater core in July also. It had a nice leak going.

[arctictraveller]

Installing a shut off valve has proven to improve A/C performance for lots of us. In a fit of desperation, (it was about 105deg's in the shade and I was suffering badly) I simply clamped the hose shut and the difference in cooling was quite noticeable. As you may know, this issue is caused by the heater core being right behind the blend door, next to the plenum where the evaporator supplys cold air. If the blend door leaks even a little, hot air from the heater core mixes with cold air, raising the outlet temp. Even if the blend door doesn't leak air, eventually that plenum will heat up the whole box, again raising the outlet temp, although not as much. It might also depend on how well your A/C is working. If it's a little low on refrigerant, or the condenser or evaporator is partly blocked, cutting off heated coolant will make a bigger difference. As for a bypass valve verses a shut off valve, I have to believe Ford used a bypass valve for some reason. I had no problemsfor the short time I had it clamped off , but I can see how a reduced or eliminated coolant flow could cause a hot spot in the head somewhere. It might not become obvous for some time though, and a small area of excessive heat would probably not be picked up by any sensors unless they were quite close to the spot. Then again, perhaps it doesn't matter, but why did Ford use a bypass valve rather than a less expensive shutoff valve?

[JWA]

Anyone having any doubts or concerns that redirecting or eliminating coolant flow to the heater core on a Modular Motor as installed in the E-Series beginning model year 1997 forward should avoid the steps offered here.

[MadScience]

After replacing the hoses, I no longer have a leak on the connections to the valve, but I now I have a leak at the clamps to the replacement quick connects right by the heater core. Sigh.

I've ordered a pack of Oeticker clamps with a matched plier. I'll see if that finally does it.

I also moved the constant pressure clamps I had on those two connections just a little further away from the end of the hose, but that seems almost random at this point.

I did, somewhere in debugging all of this, flush out the heater core, and really just got a little bit of rust out. I was honestly surprised by how little came out of there. The flow seemed unrestricted, at least with a 20psi pressure regulator on the hose. Yes, I did a final flush with distilled water.

JWA: What concerns exist with redirecting? Well, other than not wanting to live through the leaks I'm dealing with?

Also, considering what I do for a living, which involves building highly reliable systems of a very different nature, I do appreciate the work that goes into a properly engineered product. However, we get away with so many little changes, that I really did not see this one as being as problematic as it's turned out to be.

All that said, I have regular screw type hose clamps holding together other parts of this very same coolant system without any issue. Sure, they are not the most perfect solution, but I do feel like the root cause lies somewhere other than the clamps. I'll take another shot at flushing the heater core the next time I have things apart, but really, it seemed to flow just fine.