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  #1  
Old March 29th, 2015, 07:37 AM
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Thermostat question

I was told if you do not use the heater as I drive mostly in during the warmer months, I could just run my truck without a thermostat. Is this true?
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  #2  
Old March 29th, 2015, 08:29 AM
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Originally Posted by usadventureracing View Post
I was told if you do not use the heater as I drive mostly in during the warmer months, I could just run my truck without a thermostat. Is this true?
No that's not true.

The thermostat keeps the engine warm. If you don't have one the engine will run too cold, be constantly over fueling to try and warm up and the oil will be thick putting extra stress on components.

Hopefully the giver of the advice isn't someone you are paying to work on your truck as that would be very bad!
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Old March 29th, 2015, 09:27 AM
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No I am working on my truck. I boiled over yesterday and now I think I may need anew radiator. When I felt the radiator the top half was hot but the lower half was not warm at all.
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Old March 29th, 2015, 09:36 AM
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Quote:
Originally Posted by usadventureracing View Post
No I am working on my truck. I boiled over yesterday and now I think I may need anew radiator. When I felt the radiator the top half was hot but the lower half was not warm at all.
water pump maybe
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Old March 29th, 2015, 09:45 AM
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I just replaced the waterpump with a new one.
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Old March 29th, 2015, 11:02 AM
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Originally Posted by usadventureracing View Post
No I am working on my truck. I boiled over yesterday and now I think I may need anew radiator. When I felt the radiator the top half was hot but the lower half was not warm at all.
back flush it or have it rodded out at a rad shop. If thy doesn't work have them rebuild it.
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Soapy water / KY jelly, etc. is is basically a must. Yes, good idea to remove trim panels - only takes 5 more minutes to do so.
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Old March 29th, 2015, 11:05 AM
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The radiator shop wants 400-600 to record it and I can get a new one for much less, so I am thinking a new new one.

------ Follow up post added March 29th, 2015 10:06 AM ------

If I boiled over did I ruin the engine (3.5)?

------ Follow up post added March 29th, 2015 10:07 AM ------

Also started to consider replacing the engine with a 3.9, any good ones out there for sale?
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Old March 29th, 2015, 11:12 AM
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Quote:
Originally Posted by usadventureracing View Post
The radiator shop wants 400-600 to record it and I can get a new one for much less, so I am thinking a new new one. ------ Follow up post added March 29th, 2015 10:06 AM ------ If I boiled over did I ruin the engine (3.5)? ------ Follow up post added March 29th, 2015 10:07 AM ------ Also started to consider replacing the engine with a 3.9, any good ones out there for sale?
Maybe maybe not Only way to tell is to try it. Change your oil before running it again though as it will be messed up.
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Soapy water / KY jelly, etc. is is basically a must. Yes, good idea to remove trim panels - only takes 5 more minutes to do so.
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Old March 29th, 2015, 01:17 PM
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Just another opinion, but many folk run without thermostats in the summer and replace in winter.
I did it last year, and was never too cold.
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Old March 29th, 2015, 01:37 PM
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Quote:
Originally Posted by usadventureracing View Post
The radiator shop wants 400-600 to record it and I can get a new one for much less, so I am thinking a new new one.

------ Follow up post added March 29th, 2015 10:06 AM ------

If I boiled over did I ruin the engine (3.5)?

------ Follow up post added March 29th, 2015 10:07 AM ------

Also started to consider replacing the engine with a 3.9, any good ones out there for sale?
I just picked up a new radiator from SafariHP for my tdi and got it at a very good price. I would definitely call Stephen.
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Old March 29th, 2015, 02:25 PM
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Just another opinion, but many folk run without thermostats in the summer and replace in winter. I did it last year, and was never too cold.
That's terrible advice. Just because you can doesn't mean you should.

Why would you run an engine with basically zero control over its operating temperature??

The purpose of the thermostat is to keep the engine at an optimum temperature and then be able to open to use additional cooling if the engine is working hard. I think most people fail to grasp how a thermostat works in a car engine.
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Soapy water / KY jelly, etc. is is basically a must. Yes, good idea to remove trim panels - only takes 5 more minutes to do so.
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Old March 29th, 2015, 02:55 PM
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My neighbor told me this and he said it was an old hot rod trick. That is why I brought it up.
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  #13  
Old March 29th, 2015, 02:56 PM
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Jason

I hear you, and I was equally concerned when it was suggested as a temporary remedy to my overheating issue last summer (by my uncle- mechanic). I read up on everything re: thermostats (and engine cooling systems) and was totally skeptical, but he reassured me.
I'm not an advocate of it, but having had real world experience in running it and watching my temp gauge like a hawk, I can say the engine works fine.
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Old March 29th, 2015, 03:04 PM
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My overheating started after I replaced the waterpump and had the expansion tank fixed. I ran it the other day and all was fine, but I went out for a test drive yesterday and pulling in the driveway is when I boiled over. So I did not run it long after that as I just pulled it in the garage. I figure I will change out the thermostat, expansion tank cap and radiator. I have no idea how old the radiator is so I figure I would purchase with a new one. When I replace the three items my cooling system will be brand new so if that is not it I am going to call uncle and look for new engine as I want to stop pouring money into the 3.5. I also replaced the valley pan last spring and ran all last year with no issues.
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Old March 29th, 2015, 03:52 PM
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Are you sure it overheated or did it just puke coolant from the expansion tank? You may be lucky and just have an air pocket in the cooling system. I know the 3.5 EFI can be a pain to get all the air out.

I agree with Jason… don't run without a stat but for a short term fix I think it's ok.
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Old March 29th, 2015, 04:04 PM
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I think it overheated. I removed the radiator and thermostat so I am just going to purchase new. The radiator was hot on the top end and very cool on the lower end. Radiator is ready for replacement anyway. I figure I will start new and see how it goes. If I replace engine with 3.9 I should still be able to use the new radiator.
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Old March 29th, 2015, 06:45 PM
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Quote:
Originally Posted by drdread View Post
Jason I hear you, and I was equally concerned when it was suggested as a temporary remedy to my overheating issue last summer (by my uncle- mechanic). I read up on everything re: thermostats (and engine cooling systems) and was totally skeptical, but he reassured me. I'm not an advocate of it, but having had real world experience in running it and watching my temp gauge like a hawk, I can say the engine works fine.
Basically running without a thermostat you are using all the cooling ability of your radiator etc all the time to keep at normal running temp. That suggests a major issue as your engine should have been hugely over cooled. I've been in the same situation where my thermostat failed open. I had to block the radiator from completely with cardboard to achieve operating temp ranges. If you ran at normal temp you have some gremlins to iron out. I hear that it worked for you ( more like your engine survived the experience ) but we shouldn't suggest someone else does it apart from an emergency fix.
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Soapy water / KY jelly, etc. is is basically a must. Yes, good idea to remove trim panels - only takes 5 more minutes to do so.
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  #18  
Old March 29th, 2015, 09:53 PM
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Originally Posted by leastonce View Post
That's terrible advice. Just because you can doesn't mean you should.

Why would you run an engine with basically zero control over its operating temperature??

The purpose of the thermostat is to keep the engine at an optimum temperature and then be able to open to use additional cooling if the engine is working hard. I think most people fail to grasp how a thermostat works in a car engine.
I've had my D90 only a few days but I have noticed that the temperature gauge only goes up about 1/4 of the way up the gauge. I would expect it to run at about the 1/2 way point.

What is the "normal" operating temperature of these engines (NAS '95 3.9L V8)? I suspect my thermostat is bad and is stuck wide open but just wanted to see where these engines should be on the temperature scale.

thanks
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Old March 29th, 2015, 09:54 PM
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~195F is the number most used
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Old March 29th, 2015, 10:41 PM
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Originally Posted by drdread View Post
~195F is the number most used
What gauge position does ~195F correspond to?
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