Thermostat

[Rick Biarritz]

Pulled the thermo from my 83 Eldo.  I THINK it's stuck in the open position.  How can I tell?  I'm obviously a novice so keep that in mind when answering.  Thanks.

[grinch]

There's a center disc that slides on a center shaft and an outer ring that holds the shaft.  The disc will slide on the shaft (open) when heated to allow the coolant to flow.  If it's open while it's in your hand, it's bad.  It opens at around probably 195 degrees, which would be quite uncomfortable if you were holding it.  The ultimate way to test it would be to put it in a pot of water with a thermometer that reaches above boiling point, heat the water, and see what temp the thermostat opens.  That's the old school way.  The best way of knowing is to replace it with a new one.  I have in the past, in emergency cases, taken the thermostat out completely.  I wouldn't recommend that for any prolonged period of time, but it will get you home or allow you to diagnose other issues. 

[Rick Biarritz]

Yep, the disc is pushed all the way down on the shaft, and I can slide it up and down on the shaft.  I guess it's bad.  Thanks.

[Otto Skorzeny]

Who cares if it's stuck or not. Put in a new one.

[grinch]

What was the original problem with the car?  A stuck thermostat will make the car take a long time to warm up and the computer will stay in closed loop, causing poor driveability and very poor fuel mileage.  Worst case scenario, it stops up or burns up your catalytic converter. 

[Rick Biarritz]

It's all very strange.  See if you can follow this, because I can't.  The heat will not come on.  Crank up the heat and it blows nice cold AC.  The first thing that was discovered was the heater valve (don't know if that's the real name) was squeezed shut with a plastic tie.  This would prevent any water from going to the heater box, correct?  Took the tie off and now, as predicted by my car savvy neighbor, the AC is not blowing cold.  Peering into the open radiator the water does not appear to be circulating.  Why?  Additionally, my neighbor took the vacuum hose off that heater valve, and it doesn't appear to be pulling vacuum.  Turn the heat on, no vacuum, turn the heat off, no vacuum.  He blew down the tube and felt no resistance.  What I fear is that there was some sort of problem, and the guy who sold it to me pulled one of those junior mechanic, jerry-rigged self fix-it things.  For example, somebody tried to steal the car once, so this guy installed his own kill switch under the dash.  Seems to work fine, but I don't trust this kind of thing one little bit.  Any advice would be greatly appreciated.  Thanks. 

[grinch]

I'm really guessing without having the car in front of me. 

First off, you probably have vacuum issues.  Either the control head is defective or there is a vacuum line disconnected somewhere.  That needs to be traced.  The reason for the tie on the heater valve would be because of this problem.  I don't know what line he was blowing into, but if it was the vacuum line it may be the culprit.  If it's not hooked up on the other end (no resistance), it would not be able to transfer vacuum.  Also, to throw another tidbit into the fire, your heater valve may be defective.  I don't know whether it is supposed to be closed with or without vacuum applied.  I would guess that it would be closed when it is without vacuum, but again I'm guessing.  I've never tested one. 

I know on mine that the climate control determines when and where the vacuum is applied.  I purchased the shop manual which was an immense help in tracing such problems.  One thing I did notice is that the engine needs to be fully warmed up before the climate control begins acting like you think it should.  Maybe the thermostat isn't letting the engine reach operating temperature?  Which leads me to the next item on the list, the lack of circulation in the radiator.  Without the engine being at the temperature where the thermostat opens (usually 195 degrees), the water won't circulate.

The last thing about the kill switch?  I would probably try to return it to original, or as close as I could.  Maybe bypass the switch?  You don't want it to fail someday when you really need it NOT to.

[Otto Skorzeny]

Don't despair! Anything mechanical can be repaired and set right.

Kill switch? I have them in my vehicles ever since my '77 F100 was stolen 4 years ago. Not a bad thing to have.

With the help of your neighbor, start by addressing the cooling system as it is vital to the continued survival of any engine, particularly the HT4100. Drain and flush the entire system. Replace any hose or component that shows wear or is of undetermined quality. If a new heater valve is warranted, buy one.

Next on the agenda would be your vacuum system. Bad vacuum lines can be hard to detect sometimes. It would be a good idea to replace each with a new one. Do one at a time so you don't get confused. Make sure you use proper diameter hose and that they are routed correctly according to the manual. Check all the little "T" connections to make sure they aren't cracked, etc.

If your system has any of those little one way valves in them (they usually look like little sewing machine bobbins) be sure to re-install them facing in the right direction.

[Rick Biarritz]

Thanks for the help.  You too, Grinch.  Going to bed now, but will read over these again in the morning.  Needless to say, all belts, hoses, thermostats, etc. will be replaced no matter what.  Car has almost 90k miles, after all.  Big question, though -- this vacuum line thing, that IS a nightmare, right?  I have to trace the line through the firewall to the back of the climate controls on the dash, yes?  Remove entire dash?  Or just part of the dash?  Still, a nightmare, or am I wrong about that?  Thanks again. 

[grinch]

Don't look at it as a problem, look at it as a challenge.  Diagnosing is time.  Buy a good service manual, take your time. 

If that doesn't work, set the thing on fire and claim vandalism.

In all seriousness, I have found this site to be very helpful and informative.  Most of the time someone has had the same problem and can help you out. 

[The Tassie Devil(le)]

As far as the Heater problem, was the hose tied up so as to not let water through the heater core because it was leaking?

Once you got the water flowing, is the carpet under the heater core wet?

Bruce.

[TJ Hopland]

I dont have one of these cars or a manual at the moment so I am going from memory so I could be wrong but didnt these cars have a bent driven vacuum pump on them?  Seems like my 83 Fleetwood did.  I never had any issues with it so I dont know what it operated.  Things like HVAC and power brakes would have been logical.  Perhaps past 'experts' that had worked on this car thought that pump (mounted top right side?) was a 'smog' pump and removed it to unleash all that extra power?   Just a thought from deep in the memory banks.   I would also be looking for check valves and and vacuum canisters to make sure they are alll working and connected.   

Sadly the most common reason for non circulating coolant in the engine is air bubbles being pushed into the cooling system from a bad head gasket.   When the bubbles get to the water pump the flow stops because the pump cant pump air.  Hopefully thats not your issue.   If things have been removed like the vacuum pump and smog pump (if it even had one) I would be looking to confirm that the water pump is still turning in the correct direction.   A pump turning the wrong way will still move some coolant but not nearly what it should.  I dont remember if its even possible to arrange the belts to turn the wrong way but at this age anything is possible.

[grinch]

Rick-

I think this is going to be one for the textbooks, definitely keep us updated on the fix(es).

[Rick Biarritz]

Okay, here goes...  Last night, I think I said I had discovered that the old thermos was bad.  This is incorrect.  I was looking at the wrong part.  Today I purchased a new thermo.  Put the old and new side by side in boiling water.  Knowing now where to look, I could clearly see both thermo's open wide.  I removed them from the water and they both slowly closed.  So, here are my conclusions thus far (keep in mind I am a total novice):  The engine is being serviced just fine.  Though, I'm a bit confused by the fact that I saw no water circulating in the radiator yesterday afternoon.  I think I had the engine running long enough to get the water flowing.  Maybe not.  Driving from NY to DC, I was unable to get the heat blowing because of the aforementioned twist tie on the heater valve.  The twist tie is now off, and the AC does not blow cold.  My problem therefore lies somewhere in that valve and/or vacuum hose that runs off of it.  Sound good so far?  In a few hours, I will take my very first drive since purchasing the car.  I will report back.

[76eldo]

Make sure that the radiator is full of coolant.  Also, check the hoses coming in and out of the heater core.  Are they both equally hot?  I have seen heater hoses looped together to bypass the heater core due to leaks, and I have also heard of used car cheats putting short chunks of dowel material inside of the hoses, then clamping them back to the core so that there is no flow, but it looks like there should be.

Does the air flow change from top(defrost) to middle (AC) to Lower (Heat)?  If not that's a vacuum problem as well.

Don't overlook taking the car to a cooling system specialist, or at least call one in your area to ask a couple of questions.

The kill switch is probably cut into the distributor feed, and could easily be eliminated.

Good Luck,

Brian

[Glen]

I’m going in a different direction on this.  I see your main complaint is with the A/C and heater. 

Keep in mind on these cars the heater and A/C run at the same time.  The air coming in is cooled to the max to get the most water out of it.  Then some of the air is routed through the heater core and some is routed around the heater.  A temperature door controls the mix of reheated air and the air that bypasses the heater to get the correct temperature. 

With that in mind I am thinking your problem is a stuck temperature door.  It is stuck in the max heat position.  With the heater valve held shut by the plastic tie only cooled air was available as there was no reheated air.  Now with the heater core working as it should there is no cool air because it all goes through the heater core. 

You don’t say anything about the temp gauge reading high or any symptoms of an overheating engine, so I conclude there is no problem with the radiator, water pump or thermostat. 

Does this make sense to you?

Glen

[grinch]

Glen-

Good point, a/c and heat does run at the same time.  The problems has to lie in the vents.  Would you happen to know when the heater valve shuts the coolant flow off to the heater core?  Darn it, now you've gone and made me think. 

[Rick Biarritz]

I think you are onto something here.  The guy who sold it to me said quite clearly that the problem was in the "door."  I've not reported his words earlier because I think he's full of crap and trying to hide a thing or two.  He was adamant, however, that there was no heater core leak, and the did say the problem was the door.  And, yes, there are no engine overheating problems that I can detect.  I did drive the car from NY to DC with no problems.  Now, I just know you can tell me where this door is and you will then tell me it's easy to fix, right?   

Also, I did the check recommended above -- when I crank up the temp, the air comes out the bottom vents, defrost hits the windshield, and AC comes out the dash.

Oh, does the "door" diagnosis jive with the fact that the vacuum line mentioned earlier seems to be pulling no vacuum?

Thanks, all.

[STDog]

Getting to the mix door is not going to be easy.

You may be able to reach he vacuum motor for it to test with a vacuum pump.
Might even be able to change the vacuum motor (I don't know the 80s cars).

Could be that the vacuum source for the mix door and water valve is bad/leaking causing both to be inoperable.
Sounds probably give that you have floor, defrost and panel vents all on at the same time, which is not a normal configuration.

Looking like you need to check all the vacuum motors and lines in the climate system.

[Rick Biarritz]

No, no.  Perhaps I misspoke.  The floor, vent, and dash blowers are NOT all on at the same time.  I tested all 3 and they blow only when they are supposed to.