thermostat question

[sambudo]

What thermostat is the correct one does it matter which one you use? I recently replaced mine with a 195 degree. I live in the PNW, and it can get cold in the winter. do theses take a while to get warmed up? I don't know, i have the i-6 250. When i look at my temp gauge it doesn't look like it works. i don't see the pointer in the gauge. should i be able to see it? or do i have to wait until the car warms up? I've never noticed it worked. Only had the truck for 1 mo. slowly going thru and repairing what I can.

[sambudo]

this is what i tool out looks like it was 180degrees.

[WIDESIDE72]

I would stick with the 180 or even a 160. No need to run a 195. Those didnt really come into use til emission engines in the 90's trying to clean up exhaust gases with higher temps.

Sounds like your gauge is broken.

[bigmac73]

I would unhook the gage wire from the sending unit and ground it to the block, and see if the gauge moves, i think it should jump up if it is grounded

[cdowns]

the 195 is fine and makes the cab ALOT more comfortable to be in in a shorter amount of time/// where u live it will raise the driving comfort level considerablly in the winter

[Andy4639]

The thermastat will open at 190 degree's. This in turn will give you better heat. The needle should be up in the gauge so U can see it once the motor has warmed up to correct temperature. Is the temp wire hooked up to the senor on the engine?

[MARKDTN]

Nothing wrong with a 195. Why would you want a 160 if you are trying to make the heater work? Use a good quality t-stat. I only use GM or Robertshaw, I have had bad luck with discount house brands. Sounds like your gauge may be bad. You can replace it or have it rebuilt if it tests bad.

[sambudo]

Originally Posted by Andy4639

The thermastat will open at 190 degree's. This in turn will give you better heat. The needle should be up in the gauge so U can see it once the motor has warmed up to correct temperature. Is the temp wire hooked up to the senor on the engine?

yes it is, how long does it typically take for one of these engines to warm up? When i tested it last night it ran 1/2 hr but still was cold.

[msgdsrf]

Sounds to me like you've now check the gauge but you may still need to check the snding unit. 10-15 min to warm up at most.

[swamp rat]

Originally Posted by msgdsrf

Sounds to me like you've now check the gauge but you may still need to check the snding unit. 10-15 min to warm up at most.

Absolutely something wrong here, i wouldn't go below a 185 degree thermostat for this area, personally i run a 190. A performance guy might squeek a tiny bit more horse power out using a cooler thermostat but its not worth it.

Make sure the thermostat is installed right side up, and also check for proper hose routing. When the thermostat (about 10 minutes run time) opens it sends warm water thru the heater core regardless of if the heater is turned on or not so both the hoses should also be warm, if there not then the core could be blocked or hoses routed improperly, the only way to check is to pull the hoses and put some low pressure air or water thru to check the flow and look at the manual for routing.

Have you checked the cowl for debre built up thru the years? that can block the air from entering the heater, might even need to pull the hood hinge on the passenger side and then pull the electrical heater motor and check for crap build up there as well, that can and has been known to damage the squirrel cage.

[sambudo]

Originally Posted by swamp rat

Absolutely something wrong here, i wouldn't go below a 185 degree thermostat for this area, personally i run a 190. A performance guy might squeek a tiny bit more horse power out using a cooler thermostat but its not worth it.

Make sure the thermostat is installed right side up, and also check for proper hose routing. When the thermostat (about 10 minutes run time) opens it sends warm water thru the heater core regardless of if the heater is turned on or not so both the hoses should also be warm, if there not then the core could be blocked or hoses routed improperly, the only way to check is to pull the hoses and put some low pressure air or water thru to check the flow and look at the manual for routing.

Have you checked the cowl for debre built up thru the years? that can block the air from entering the heater, might even need to pull the hood hinge on the passenger side and then pull the electrical heater motor and check for crap build up there as well, that can and has been known to damage the squirrel cage.

Really good information everyone. I'm starting to think i put the T-stat in wrong, spring side down? I ran it tonight and the hose that goes from the bottom of rad to block came off. The seal was not strong enough as it leaked out the bottom. it seemed to start getting hot then the water shot out. Can i run straight water through it until i can get the hose secured to the radiator?, i noticed. I'm going to look not the heater, doesn't seem to be working.

[Andy4639]

Thermastat spring goes down into housing. It also has a front and back though I have never had any problems with it in any I have installed. U need to make sure U get all the air out of the system as well. This will cause all kinds of heating and cooling problems if air is traped in the system.

[TBONE1964]

First of all, I would like to ask what was the condition before you changed the t-stat? Did you have the same problem as you do know?

Either way you have what sounds like two separate problems.

As others have mentioned, check for heat at the heater hoses after the truck has ran for at least ten minutes. They should both be warm. Sounds like you might have figured it out already.

If you need a cluster repair, send me a PM. I also can sell you a good known original style working temp gauge for your cluster. Use caution when grounding the wire to the sending unit as it will damage the gauge if you are not careful. Another thing to consider with your gauge issue,, is your temperature sending unit.

Keep us posted.
Tom

[PanelDeland]

Is the heater blowing warm? You may have a plugged heater core,either the tubes or the heater box may be plugged with leaves,a rats nest or other debris.Try feeling of the hoses and see how warm they are.Check the radiator hoses to see if they're getting hot,if they are check both hoses going to the heater,one should be pretty hot and the other warm.If either or both are cold then the core isn't getting hot water.Is the temp cable hooked up to the valve(non-AC)?

[motorcritter]

I wouldn't run straight water any longer than it takes to sort out the problem, not just freezing damage, but internal corrosion, too. I recommend checking the wire from the sensor to the gauge, age, heat, vibration and handling may have damaged it- no continuity=no gauge reading.

[sambudo]

Well I didn't have much working time on the problem. I did take off the hose that goes into the water outlet. I did what I didn't think I did, and thats put the T-stat in the wrong way. I did! So I will reinstall it tomorrow. Stay tuned. Thanks for the help!

[swamp rat]

That should help it open sooner!

[sambudo]

Well now that I have the theromstat installed correctly and heats up in 10 minutes, and leak issues. I still do not have the temp gauge working. I will work on this and make sure that it is connected properly. Then check the heat sending unit. Do i need to pull this out to check if working properly?

The heater does not work, i need to replace the heat hose under the dash, and the bottom lever is missing from my heat control. looks like all hooked up in the back, just no lever.

Also after the car heated up the radiator hoses were warm and the heater hoses were very hot, is this normal? Thanks again for everyones input.

[Andy4639]

The heater does not work, i need to replace the heat hose under the dash, and the bottom lever is missing from my heat control. looks like all hooked up in the back, just no lever.

Also after the car heated up the radiator hoses were warm and the heater hoses were very hot, is this normal? Thanks again for everyones input.

Can U explain this a little better.
What heater hose under the dash are U speaking of?
The lever missing is it the fan switch? I'm not real sure for a non AC truck.

[sambudo]

Originally Posted by Andy4639

Can U explain this a little better.
What heater hose under the dash are U speaking of?
The lever missing is it the fan switch? I'm not real sure for a non AC truck.

The temp switch is missing. Whichever hose is under the dash.

[swamp rat]

Originally Posted by sambudo

Well now that I have the theromstat installed correctly and heats up in 10 minutes, and leak issues. I still do not have the temp gauge working. I will work on this and make sure that it is connected properly. Then check the heat sending unit. Do i need to pull this out to check if working properly?

The heater does not work, i need to replace the heat hose under the dash, and the bottom lever is missing from my heat control. looks like all hooked up in the back, just no lever.

Also after the car heated up the radiator hoses were warm and the heater hoses were very hot, is this normal? Thanks again for everyones input.

The 5/8 and 3/4 heater hoses will be as hot as your water temp, if a 190 thermostat then at least that hot probably even a bit hotter because the water that flows to the heater just went thru the engine. The Heater core will always have hot water flowing thru it.

The bottom lever controls a flap door inside the heater body, the door is what allows the air to flow across the heater core. If i remember correctly the air flows from the blower, then to a door which allows ether, none, all or part of the air to flow across the heater core, if it allows none then the air goes around a bypass and comes out ether the heat or defrost outlets depending on the position of that control. The door is moved depending how far you push the lever to the hot or cold side, and by varying the air across the heater core is what controls the temperature.

The temp gauge is very possibly the sending unit which is usually screwed into the head but not sure on your engine. The sending unit is not suppose to have Teflon tape on the pipe threads as the threads are the ground. Auto parts stores sell sensor safe thread sealer made for this application.

[sambudo]

Originally Posted by swamp rat

The 5/8 and 3/4 heater hoses will be as hot as your water temp, if a 190 thermostat then at least that hot probably even a bit hotter because the water that flows to the heater just went thru the engine. The Heater core will always have hot water flowing thru it.

The bottom lever controls a flap door inside the heater body, the door is what allows the air to flow across the heater core. If i remember correctly the air flows from the blower, then to a door which allows ether, none, all or part of the air to flow across the heater core, if it allows none then the air goes around a bypass and comes out ether the heat or defrost outlets depending on the position of that control. The door is moved depending how far you push the lever to the hot or cold side, and by varying the air across the heater core is what controls the temperature.

The temp gauge is very possibly the sending unit which is usually screwed into the head but not sure on your engine. The sending unit is not suppose to have Teflon tape on the pipe threads as the threads are the ground. Auto parts stores sell sensor safe thread sealer made for this application.

the lever that open and closes the flap is missing, also the hoses under the dash that would transfer the heat are also torn up, need replacing. Not sure if i have a heater switch, not sure how the heat turns on. regarding the sending unit, can i just replace this? Will water leak out if i remove this?

[swamp rat]

I think the hose under the dash your referring to is just a duct hose that runs from the heater box up to the defrost vents, About maybe 2 1/2" in diameter. they usually rot out and need replacing, the good news is they only cost about $13 and some change, call Wes at Classic Heartbeat, he's a board vender here on the forum and he lives in Washington state. http://www.classicheartbeat.com/

Per the picture above, the top lever is the one that moves a flap door that directs heated air to ether the floor heat port or the defrost ports.

The middle one is hooked to a 4 position switch that controls airflow ie the electric switch, (Off, Low, Med, Hi).

The bottom lever that is missing per your post is the Temp, the one i was talking about earlier that directs the air ether over the heater core or around it.. The opposite end of the cable should be hooked up to that flap door lever sticking out of the heater box, i just cant remember off hand if its on the top of the box or where.

Brand new replacements for the heater control unit (picture above) are i think over $200 but you could score a used one in the parts part of this forum for much less.


It is common on these old trucks to have never had these cables or controls lubed so sometimes the control lever(s) may bind up break and then need replaced. Look under the dash and follow the cables to where they connect to the heater box, move the lever and look at the other ends to see if the actuators are moving.

The sending unit is a temperature sensor and is threaded into a hole that is in the water jacket so yes if you pull it out the water will come out. so its best to drain the radiator..Remember my post above and the special thread sealant? You haven't added antifreeze yet have you? if you did just catch it all in a bucket, I hook a length of rubber hose to the drain valve to direct it to a bucket..

I cant see your truck so i cant look it over and see if i think any of the wiring is messed up, but i'd probably do that before i went and ordered a new temp sensor, Do all the other gauges and lights work on the gauges?

[sambudo]

Originally Posted by swamp rat

I think the hose under the dash your referring to is just a duct hose that runs from the heater box up to the defrost vents, About maybe 2 1/2" in diameter. they usually rot out and need replacing, the good news is they only cost about $13 and some change, call Wes at Classic Heartbeat, he's a board vender here on the forum and he lives in Washington state. http://www.classicheartbeat.com/

Per the picture above, the top lever is the one that moves a flap door that directs heated air to ether the floor heat port or the defrost ports.

The middle one is hooked to a 4 position switch that controls airflow ie the electric switch, (Off, Low, Med, Hi).

The bottom lever that is missing per your post is the Temp, the one i was talking about earlier that directs the air ether over the heater core or around it.. The opposite end of the cable should be hooked up to that flap door lever sticking out of the heater box, i just cant remember off hand if its on the top of the box or where.

Brand new replacements for the heater control unit (picture above) are i think over $200 but you could score a used one in the parts part of this forum for much less.


It is common on these old trucks to have never had these cables or controls lubed so sometimes the control lever(s) may bind up break and then need replaced. Look under the dash and follow the cables to where they connect to the heater box, move the lever and look at the other ends to see if the actuators are moving.

The sending unit is a temperature sensor and is threaded into a hole that is in the water jacket so yes if you pull it out the water will come out. so its best to drain the radiator..Remember my post above and the special thread sealant? You haven't added antifreeze yet have you? if you did just catch it all in a bucket, I hook a length of rubber hose to the drain valve to direct it to a bucket..

I cant see your truck so i cant look it over and see if i think any of the wiring is messed up, but i'd probably do that before i went and ordered a new temp sensor, Do all the other gauges and lights work on the gauges?

Well good news and bad news! First the good, I checked the heater blower and it worked direct link from the battery to the motor. The fuse to the heater looked good, but I replaced it anyway with a 20a. I checked all the cables, and all are still hooked up and seem to operate correctly, except the one with the missing lever.

The middle one that is hooked to the 4 position switch seems to only work in the off, and high position! I don't think I have a low or medium air flow option. The cab warmed up pretty good.

The hose I have been referring to directs the air flow to the defrost, this will need to be replaced. Rick at Chevy Metal in Vancouver,Wa. gave me a small section that I think might work. Thanks,Rick!

I still need to trouble shoot my temp sensor sending unit. Yes I put Antifreeze back in, as the other day it wasn't leaking. Seemed to be holding water and pressure fine. So I put it back in. Well tonight after running it for awhile I noticed it was leaking from the same spot, bottom rad hose. I can't get it to seal correctly. any suggestions? The hose only fits at an angle, I've tried putting it on several ways? I'll have to drain and try again tomorrow night.

Regarding my temp gauge, Rick said it might be possible that the needle pointer fell off. So some weekend, I'll pull off the gauge cluster and check this out. If it's bad possible repair it or replace it. Thanks swamp rat and others that have been guiding me thru this little project. Much appreciate all of you!

[swamp rat]

Originally Posted by sambudo

Well good news and bad news! First the good, I checked the heater blower and it worked direct link from the battery to the motor. The fuse to the heater looked good, but I replaced it anyway with a 20a. I checked all the cables, and all are still hooked up and seem to operate correctly, except the one with the missing lever.

The middle one that is hooked to the 4 position switch seems to only work in the off, and high position! I don't think I have a low or medium air flow option. The cab warmed up pretty good.

The hose I have been referring to directs the air flow to the defrost, this will need to be replaced. Rick at Chevy Metal in Vancouver,Wa. gave me a small section that I think might work. Thanks,Rick!

I still need to trouble shoot my temp sensor sending unit. Yes I put Antifreeze back in, as the other day it wasn't leaking. Seemed to be holding water and pressure fine. So I put it back in. Well tonight after running it for awhile I noticed it was leaking from the same spot, bottom rad hose. I can't get it to seal correctly. any suggestions? The hose only fits at an angle, I've tried putting it on several ways? I'll have to drain and try again tomorrow night.

Regarding my temp gauge, Rick said it might be possible that the needle pointer fell off. So some weekend, I'll pull off the gauge cluster and check this out. If it's bad possible repair it or replace it. Thanks swamp rat and others that have been guiding me thru this little project. Much appreciate all of you!

Could it be the wrong hose??

If your gonna drain the coolant go ahead and swap out that sending unit, its not that expensive, be sure to get some sensor safe thread sealant in the sealer section of the auto parts store.. If the lower hose is old just replace it too, if its new or close to now then clean the hose and radiator inlet of any water scale build up and wipe it nice and dry, the hose should not be hardened from heat or deformed from the hose clamp compressing on it.

I had one time i was dealing with the same lower hose leak but couldn't get a hose right away and still needed to drive the truck, so i cleaned up the hose and radiator then smeared a bit of red high temp silicone in the radiator inlet slid on the hose and clamped it down then let it sit over night before filling it. it got me home and then some.