Bad thermostat housing = lack of heat...

[twlunn]

Ok found this guys site, looking for a solution to why the temperature of the 1.9l never gets into the "NORMAL" position on my gauge.

Some decent info on it.
http://www.theyeagergroup.com/escort_wagon.htm

He writes:
"Cold weather has come to North Texas. However, the cold weather decreased the fuel economy by 2 to 4 MPG. Not sure if this extends from the cooling system overcooling, adjustments made from various temperature sensor input, or a possible problem with the onboard computer. To solve the winter overcooling I approached the problem in the same manner as over the road truckers do with their diesel trucks. Blocking air flow to the radiator. The bra has a custom piece that fits over the upper grill for temperatures below 75 and for very cold outdoor temperatures I place a baffle between the radiator and the AC condenser. The target is an engine temperature of 180 to 190 as the car typically ran during the summer months. Keeping the water and head temperature up resulted in fuel mileage still in the zone of 29 to 33 MPG just tending toward the lower figures which points toward the intake air temperature making a difference as well. Overcooling is an interesting problem but far easier to manage than the much more typical overheating issues 2nd generation Escorts tend toward."

Success! The "vapor by-pass" in the thermostat housing had failed (as indicated by a rattle in the thermostat housing detected while the housing was removed to change out the thermostat) and was letting a lot of coolant past the thermostat. Cold weather fuel mileage jumped about 4 to 6 MPG (depending on whether it is highway or combined fuel mileage) after replacing the housing with one from a '91 Escort. The first tank full after housing replacement was just over 34 MPG with the outdoor temperature in the 30s and 40s, the cool air intake intact, and no baffles in front of the radiator. Once warmed up the stock temperature gauge was rock solid in the middle of "normal". Seems that ECU is very sensitive to not only the coolant temperature but any coolant temperature fluctuations as well.


Looking to see if anyone on the board has replaced the housing and "improved" their heat into the cabin.

I put in a new heater core & t-stat last January and it didnt do much to improve cabin heat or gas milage.....

It was a COLD ride to work this morning (11*)!!!

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EDIT:
Ok, found some older posts by willye disscussing the housing.

My ? is still if anybody HAS installed a new housing AND if it has helped,

TIA,Tom

[AzTumbleweed]

A bad thermostat is the only thing that would cause this. If the temp gage showed normal then it would be a different matter. But if temp gage reads real low then it has to be the thermostat. Never heard of a "vapor-bypass". Only thing coming out of my thermostat is the heater hose.

[twlunn]

Originally Posted by AzTumbleweed

A bad thermostat is the only thing that would cause this. If the temp gage showed normal then it would be a different matter. But if temp gage reads real low then it has to be the thermostat. Never heard of a "vapor-bypass". Only thing coming out of my thermostat is the heater hose.

Check this thread out: He plugged some passages i guess in the housing.
T-Stat housing bypass

Now i know you've mentioned the T-Stat in another one of my threads, and I totally agree.

Today I'm going to Murrays to order a housing, $68, and a new stat.

Once I get the old housing off I'll check it out with the new. Then go from there if if this housing does indeed have a "bypass".

Going to test the old & new stat also.... thanks, Tom

[AzTumbleweed]

You can test a thermostat before you install it. Put it in a pot of boiling water. Should pop open. Then run cold water on it and it should close.

My T-stat housing only has one outlet other than the radiator hose. That's the heater hose. This hose also has the coolant temp sensors in it. I made the mistake of plugging off this hose once. Then what happens is the sensor thinks the engine is cool and makes it run rich. Worse yet the cooling fan won't come on when the engine is hot because the sensor is telling the computer that the coolant as not hot.

Anyway, since you have a new heater core then the only thing that can happen is you have a bad T-stat or one with the wrong rating.

If you installed the heater core yourself then congratulations! You have more patience than I do. What a job that is....
The metal tube with sensors in the photo is the one coming from t-stat housing.....

[dougand3]

I put in a used tstat housing I bought off ebay - still below normal temps driving. Only moves to "O-R" in NORMAL after 20 minutes of idle. Now, the one I bought rattles just like the original I removed - I read that may mean bad. My cabin heat is very low temp. Willye tried plugging the bypass holes in the twin towers without much luck. I guess next I'll try bypassing the heater core by coupling the 5/8" hoses at the firewall and see how my temp behaves.

Now, Where is this Murrays? I'd try a new tstat housing for $68. Most I've seen are $140.

Below are some pics of this atypical housing.

[RatLabGuy]

Hm, my stat housing looks like that...
I'm havin ga similar problem. I have to drive for a good 10 min, and 5+ miles, before the needle will even move. After awehile it will indeed get warm, but never reads HOT etc and talkes awhile. I've replaced teh stat 2 times, the 2nd time I even tested the old one (boiling water), it worked fien but I changed it anyway (for $5, WTF?). Liked the look on wife's face when she came home to me bioling a car part on her stove ;-)
but I'm perplaxed too, maybe I will look into this. I guess what I don't get is, why is that thing there in the 1st place, seems like this is just asking for trouble??
I had been considering just removing teh stat altogether to see if it even could be worse using that a diagnostic for whether that region could even be involved or not...

[KimMG]

If you remove the t-stat, there will be nothing to keep the cold water in the radiator from circulating. This means the car may never get up to operating temp (especially in the winter). What temp thermstat are you using. When you put it on the stove, at what temperature did it open?

[dougand3]

RatLabGuy voices a question I've had - WHY are the bypass towers there? In the 5 housings I've dealt with - never seen anything like it. The 91 -96 1.8L escort housing is much simpler.

I speculate....

1. An emergency circuit if too much pressure builds?
2. Allow extra passage of hot coolant right near the tstat so it will open? This one seems less likely as the heater hose outlet is just right there - seems like flow would be fine w/o the extra draw toward the tstat.

On the "1995 Escort Overcooling Problem" thread, willye tried plugging the bypass holes but got no decent temp rise - that makes me wonder how changing the housing to a new one with a ?closed? bypass circuit (towers) would make a difference.

There is the issue of power flushing the heater core at a rad shop.

[dougand3]

Well, I tried bypassing the heater core by coupling the 5/8" heater hoses with a pipe thread. It behaves the same - it will get up to "O" after 25 minutes idle. But upon driving, it goes back down to 2mm above the "C" (dead cold). Frankly, didn't have much faith that this would work.

Next, I'll try a new tstat housing. Found one at rockauto.com for $48.

[dougand3]

Got a new housing and new 195*F tstat from rockauto. It rattles like the other 2 old ones I have. Also, it has a pinpoint leak in the main tower - AAAARRGGGHH. I tried prestone radiator stop leak - no help. Tried some 2 part epoxy for steel (like JB cold weld) tonite - will see if it works tomorrow. Anyway, temp does behave better.

Temp Gauge.....C--[--NORMAL--]--H

Before - would only get to dash beside C. Heater had Cool Air.
Now - gets to N. Heater has Very Warm Air.

At least now, engine temp is high enough for oil to lube well. I'd like to see O or R but it may not possible.

[AzTumbleweed]

I'm curious now. Trying to figure out exactly what that extra channel in the T-stat housing does and what the rattle thingy is?

I wonder if coolant was flowing through that little hole instead of to the heater core and thus by the temp sensor? Hmmm......

[twlunn]

• Well...the new housing out of the box had a "rattle" just as the old housing had, so much for that.
• Put the old T-stat and the new in a pot of H²O. Old one would barely open to ~1/16th, new one gets to around 3/16ths open. Both opened right at ~190-195°
• Gauge goes to "N" in NORMAL after 25 minutes of idle. Heat output is warmer than before, but not HOT. Immediately drops to between the "C" and "N" when out on the hiway. Output is cooler. Not very comfortable in 20° weather for a 1 hour commute.

I guess I'll try flushing/back flushing the rad/heater core next. I cant believe the new core is fouled that bad after only year though..

I havent looked at the manual, but do these things have a "blend door", it mixes the cold outside air with the warm and thus warm heat-not hot.
Maybe it's not closing all the way.



Well, thanks for the replies, Tom

[dougand3]

Twlunn says "Old one would barely open to ~1/16th, new one gets to around 3/16ths open."

The physics of this baffle me - if the old one opens just 1/16", there is LESS flow to rad, therefore engine coolant jacket SHOULD get hotter.

I'm starting to think the bypass towers may have demonic properties.

My next step - Try plugging both bypass holes and having the tstat as the ONLY channel to the rad.

[AzTumbleweed]

You may be on to something. It does have a blend door (somewhere). The coolant must always be going through the heater core since the coolant goes by the temp sensor on the way. I don't believe there is any way you need to flush your cooling system unless you've been putting mud in it.

Maybe block off part of the radiator with a piece of cardboard. Should work for now. Glad I'm not in 20 degrees. Brrr. I actually saw a hummingbird this morning. Supposed to be 78 today

[twlunn]

AZ, Right now I have 75% on the rad blocked by cardboard. Did that a few days before I did the housing/stat swap.

Dougand3, Willye did this: "The housing has 2 thermostat by pass orifices which I plugged with a custom made bolt cut to fit and more RTV sealant. These are plugged tight! I bolted it all back up and it still runs a steady 170 degrees with a 192 thermostat in it."

AZ, Willye in another post said he had a rad shop "power flush" his system,
then he said the temps were some what better.

If the "power flush" dont work I'm buying that new snowmoblie suit, cuz runn'in the CTD back and forth to work is getting spendy at $2.35 a gal.
But I am really toasty...