Engine Runs Cold No Cabin Heat

Maintenance/Repairs
,
21

I always had to check the box to see if it had the seal with the thermostat or not and buy the seal separately. I usually bought a couple of them at a time to have on hand for thermostat changes.

One thing that bothered me is why the engine over-heated? It was assumed a bad thermostat again? Not likely. Tester’s method for releasing trapped air started me thinking is it possible there is a head gasket leak causing the air bubble? Some cars just have excessive cooling capacity so they will never get up to operating temperature in the winter without closing off the radiator. But why the overheating?

Something not making a lot of sense.

22

Tester,

The air trapped somewhere has been discussed here as well. However the fact that it has a reservoir with a small hose off the top of radiator would indicate that any air that may be in the system would bleed up to the reservoir. I went a different procedure with your suggestion.
I just got back from a job site and I backed down my driveway which is on an incline of about 8-9 degrees. I checked the hose and radiator top temp and it was about 155F. The ambient temp locally is 50F. So the temp would be higher than I had recorded in the past.

I squeezed the hose and there was some pressure but not what I would expect. I then opened the reservoir and released all pressure. I could then easily squeeze the hose and as I did I could see coolant squirting into the reservoir. Can’t say there was any air bubbles since the reservoir is a foggy yellow plastic. After about 10 minutes of this I closed every thing up and took a run around the block, about 1 mile. Checked again, hose was slightly pressurized as before and temp was the same.

_I then used my left handed monkey wrench and banged three times on the muffler bearings. _
Nothing changed… all remains the same.

23

Bing,

I agree with the not making a lot of sense. The head gasket leak was discussed as well. Shop put a hand pump with pressure gauge on the reservoir and pumped it up to 15+ psi. It held the pressure steady for 5 minutes. No leak.

As for the over heating, that is totally out there. And since the next day it started up with out a problem and ran just fine just adds to the mystery.

Thanks,

Les

24

No.

The heater core is the highest point in the cooling system.

So any air trapped in the cooling system is going to go into the heater core. That’s why there’s no heat.

Believe me. I’ve serviced many E150 cooling systems. And purging the air out can be a real pain.

Unless you have a RADKITPLUS, the method I described is the next best way to purge air from the cooling system.

Tester

25

Apparently I am too much of a newbie. Had to wait 4 hours to post a reply since I have certain limits. Did not know all the rules so I got blocked. :relaxed:

Tester,

I can agree that if there is air in the heater core it would explain why there is no heat in the discharge air to the cabin.

But would you not have the same end result if the engine coolant temp is low for some unknown reason??

Not trying to argue with you but placing the van on an incline should have the same effect by getting the air (if any) to the highest point in the system. Yes??

Thanks,

Les

26

Tester is usually not wrong. Need to provide some outlet for the air in my view.

27

Bing,

I will give it a shot tomorrow. Will report back the results.

Thanks,

Les

28

Tester & Bing,

So I put the van on the slopped driveway again except this time I placed it on my ramps. The van is now sitting at about a 10 degree angle. Ambient temp is about 54F. The top of the radiator is now the highest point in the loop along with the vent line to the reservoir.

Ran the engine for about 15 minutes at idle and the top hose started to heat up. Left it get about as hot as it is going to get, about 153F with my infrared temp probe on the radiator top at the hose and then started to remove the clamp. Coolant started to come out immediately so I released the clamp.

I then released the pressure by opening the reservoir cap. Released the clamp again and used a screwdriver to open the top of the hose. Only coolant came out, no air bubbles that I could see escaped. Re-clamped the hose and ran the engine another 10 minutes this way and then re-tightened the cap.

Ran for another 30 minutes, and during this time I used my Coroplast sheets to block the radiator air flow. I increased the temp at the radiator top to as high as 218F. The hose was very hot to the touch that I did not want to leave my hand there for very long. The hose had pressure but did not seem more that previous. It was easily squeezable, but could not crush it. During this time I checked the vent air temp inside and it was about 105F. Which is more that before. However, the ambient is up and the engine temp is up. Once I removed the Coroplast sheets blocking the radiator all went back to the previous lower temps.

Note 1)
It seems to me that since under pressure I had coolant at the top hose when the clamp was loosened then there would not be any air in the system.

Note 2)
It seem to me that if engine coolant temps where higher then all would be good as for cabin inlet air temp at colder ambient temps.

Note 3)
As suggested by Rod that the Stat is not sealed properly and coolant is constantly passing through the system and not allowing the engine to get up to a good normal running temp.
If that is true then checking and verifying needs to be done. Agreed.

Note 4)
If Note 3 is true then the question comes into play what started this whole thing was that the system was running cold. (And still is). Just flushing the core did not help which is why the first and original Stat was replaced.

I totally agree that this is not rocket science but something originally changed that started this whole adventure. Is it not also possible that there are more than one cause going on that are causing the domino’s to fall badly.

What would be nice would be having a second E-150 w/ 4.2L sitting beside mine and run all the same. That would be the best way to evaluate this problem. I did go to the point of checking for van’s for sale on line in the area. The closest I could find was 235 miles from me. :cry:

We won’t have a cold day until next Saturday, 37F. So this is rapidly becoming a non-issue.

Again any thoughts or suggestions will be greatly appreciated.

Thanks and have a good rest of your weekend.

Les

29

The U tube videos I have seen on replacing this thermostat all show a thick black o-ring that goes in before the thermostat, then the thermostat, then the gasket. A couple of good mechanics have tried to tell you this,but you haven’t seemed to want to hear it.

30

Oldtimer,

I have heard, but I do not have a good way to confirm myself. I will discuss with the my shop guys tomorrow and get a confirmation of how the Stats were installed.

You may have misunderstood my typing in that I was asking that if the Stat is not the problem what are the alternative that may be going on. Since I have not received any comments in that direction I have to assume there may not be another reason.

More later.

Have a good evening.

Les

31

Well, since you have such a large difference in temp between heater hoses you heater core could be partially plugged but you say the flow is good and it has been flushed, you seem to have adequately addressed the air in heater core idea so if there are other possible causes, I can’t think of them.

32

blocking airflow seems to get your temps up where you want them, any chance the cooling fan is stuck on? This van likely has a mechanical fan clutch, can you spin it by hand with the engine off?

2 Likes
33

After a while, the options become, take it to a “good” shop, live with the problem, or trade.

1 Like
34

Except live with the problem may cause a catalytic converter failure, an expensive fix and fix again if the problem is not resolved.

35

Sound very frustrating OP. If I had this problem I think I’d probably idle the engine until it should have warmed up to normal operating temp, say10 minutes of idling from a cold start, then I’d remove the “hot” supply hose to the heater core at the firewall, let a cup or so of coolant run out, then let another cup flow into a foam container, then I’d stop the engine & measure the temperature of the coolant in the foam container. It should measure in the 180 - 200 degree range. Which btw means you need to be careful when you do this, so as to not burn yourself. Then at least you’d have some evidence what the coolant temp is… If it is in the correct range, then you can eliminate thermostat issues as the cause of your no-heat in the passenger compartment problem. That what you need to do first imo, decide if the problem is the coolant temp is incorrect, or the coolant temp is correct, but there’s still no heat from the heater.

At this time you could also put the “hot” hose back on, and remove the return hose. Run the engine again and see if the flow rate coming out the return hose is nearly the same as what came out the “hot” hose. Be careful when doing these experiment you don’t run the coolant level too low though. You’ll have to top up the radiator several times probably.

Re: thermostats. I have a hard time believing an experienced shop would make a mistake installing a thermostat. But such a thing is possible I suppose. They can be installed both backwards and upside down. Usually that type of mis-install causes overheating, not under-heating. Whenever I buy automotive thermostats, I have to also buy the correct gasket , separate from the thermostat. The gasket doesn’t come with the thermostat in other words. This is b/c the same thermostat is used in a variety of cars, and as long as your vehicle is among that group, it is only the gasket that is make/model/year specific. Of course you need to be sure the thermostat part number you are buying is the correct one for the vehicle, there’s bypass and non-bypass thermostat designs for example, and those can’t be interchanged. If you surf over to rockauto.com you can figure out what part number is correct fairly easily, might be worth it to double-check the shop’s work on that. Any time I purchase a thermostat, before installing it, I put in in a pot of water on the stove and use a thermometer to make sure it opens at the correct temperature and the correct opening dimension.

I’m guessing there’s nothing wrong with your thermostat, and you don’t have an air bubble problem either. And the problem is either the heater core isn’t flowing rapidly eough b/c of a clog, or the heater core is flowing fine, and getting plenty hot enough, but the hot isn’t reaching the passenger compartment b/c a vent door or heater fan problem. Best of luck.

36

Hello all,
I deliberately held off responding since I wanted to move forward with my plan and do some evaluation and testing so that I had all my ducks in order.

The following is what has taken place over the past 24-36 hours or so.
Monday:
I talked to my shop guys and discussed the issue of sealant or gasket around the Stat. Was told that they only installed the gasket with no additional sealant around the Stat. It was said that there is no room for a gasket due to the receiver or counter bore size in the top hose flange. The thinking that there was no additional space. I expressed the opinions heard here and that coolant was bypassing the thermostat causing the low temp problem. It was agreed that we needed to open it up and take a look and work out a solution at that time. Also requested that I assist in the breakdown and assembly. Appointment set for Tuesday morning.

I then went to a local Auto Zone and requested to see what they had in stock for my van in the respect to Thermostat w/ gasket and independent gaskets. What was shown to me was a Duralast 15119 Thermostat w/ Seal. Everything on the screen indicated that it was a direct fit. Also a Fel-Pro 35390T Gasket that was a hard plastic with a sealant on both sides.

Tuesday:
Arrived at the shop. Van pulled into a bay and we started the tear down. After disassemble parts were laid out and measured. The thickness of the old .050” vs. new .047” Stat (without the gasket) was a difference of about .003”. The gasket was .150” thick with an overall OD of 2.275”.

The outside diameter if the old 2.125” vs. new 2.120” was .005” difference. The receiver or counter bore depth in the hose flange was .042” x 2.200” Inside Diameter.

When the Fel-Pro gasket was installed over the Stat on the hose flange the Stat would flop loose with maybe what seemed to be about a .015:-.025” gap. Given the dimensions of the counter bore being .042” and the Stat thickness being .050” this seemed a bit odd. However, it may have been due to a surface not being totally flat or square to the other.

The original gasket was, I assume, a felt paper type and it would seem that it would somewhat swell when wet and fill the gap and seal it. However, that may not have been the case. After looking at all the parts and how they assemble and fit the decision was to use the original Motorcraft stat, apply a bead of Permatex “Right Stuff” Gasket Maker to the outer surface of the Stat and fit into the hose flange. Then used the Fel-pro Gasket and buttoned it up. Since we had all torn down, I decided just for laughs and giggles to have the heater core flushed again. It was clear with good flow.

Once coolant was refilled the engine was started and left run for 15 minutes. Now here is the part of the dissertation that all reading this far just this want me to get to the punch line…………………… :slight_smile:

This is a quick evaluation but it seems that Rod had nailed it. The upper hose is now running at about 165ºF to175ºF which is considerably more than what I had previous. The internal air discharge temp is at 115ºF which given the higher ambient temp of 60ºF it still an improvement with a 55ºF Delta-T which is about 25ºF more than before.
So all totaled this is all “more better”. :tada: :confetti_ball:

This has be quite educational event for me as well as the guys in the shop. I find it interesting that with just a gap of maybe .025” could make such a huge difference. Not saying it should be ignored or discarded, I just find it interesting.

The other interesting (unusual) thing that may deserve some thinking is that the temp gauge is still holding at the point on the dial. I would have suspected it would go up a ??little?? Unless the resolution is radically coarse when it is at mid-range. The gauge needle still reaches the same run point as before in about 4 minutes or so. At this point I am not at all concerned, just find it another odd issue.

I would like to thank Rod and others that have contributed to this discussion and solution.

Problem solved and fixed. Case CLOSED!! :+1: :+1:

As always my home is when I post these typing’s is that others will become educated as well as a result of reading.

As for the guys at my shop, they have learned something new. No one individual or shop would ever be expected to know everything. What is important is that they did not just blow me off as a kook and turn their back on me. We have worked on this together and I thanked them for that.

Thanks,

Les

3 Likes
37

Glad everything worked out for you, and thanks for posting the end result! And I’m glad to see that the shop did so well by you.

38

Good post Les, thanks for the follow-up. I have to say, I don’t recall ever seeing any reports of such a problematic thermostat installation here before. In most instances where there was a problem, it was that the new thermostat was bad out of the box, or it was installed with the wrong orientation.

39

It’s been nearly thirty years since I first ran across this problem @GeorgeSanJose. And I didn’t recognize the cause until I had replaced the thermostat twice.

1 Like
40

Rod, This is just a curiosity question. Is this issue unique to the E-150, 4.2L engine or Ford?? Are there others that have the same problem. I have to assume that it is NOT industry wide.

I can safely say that should I ever have an issue in the future with another Stat replacement I will insist that the a sealant be applied before assemble no matter what the objections.

Thanks,

Les