Engine/Transmission (1994 - 1998) no thermostat.....bad?

[NBowlin]

will running with out a thermostat until the new one gets here hurt anything?

mine worked fine until i had the head redone and swapped headgaskets. now it doesnt work. i took it out and put it in a pot and boilded the sucker to see if it did anything and it didnt. so i ordered a new one but who knows how long it will take to get here.

 

[dodge cummins]

i was always told that diesels without a thermostat will overheat,not a good idea

 

[BushWakr - RIP]

Your temperatures will cycle over a wider range... the thermostat's real job is to maintain a relative constant and correct engine temperature while driving.

You "can" go without but I would not want to do it for long.

If you keep an eye on the water temps and don't let it overheat you should be ok for the short term but you will have temp swings that will result in smoke, "carboning" of the injectors and so forth... .



pb... .

 

[moparguy]

Keep in mind this is just one man's opinion, and we all got one. I'd think the main problem would be running to cold since our cooling systems are sized with an eye on engines working hard in hot weather, the block wouldn't get up to temp and you'd see cold wear issues, things like moisture buildup in the block, incomplete combustion of fuel contributing to cylinder wash, cold feet ect.



If it were me, I'd pull the fan, and totally block the radiator in order to build a little heat. And of course watch the temp in case I'm full of it.



Good luck, RJR

 

[NBowlin]

I havent driven it since i pulled it. thought i would ask. I cant catch a break with this bast*** of a truck and the mail. It has sat and waited for parts longer than it hasnt. fun stuff huh..... oh well.



Thanks guys I appreciate it. It will sit where it is.

 

[biggy238]

Mine has had the thermostat stuck open for 3 months now and I replaced mine yesterday.



I noticed an increase in mileage, ofcourse temps, and low end power was increased enough to feel it.



On the other hand running without it wasn't a problem except for the cold feet.



Someone else had posted a pic of the thermostat with a piece of rubber ring that had torn apart and lodged in the t-housing. Mine was identical.

You will definately be alright until you are ready to replace it.

 

[Jschafer]

Even though the T-stat was stuck open it still created a resistance in the system, if the T-stat is removed the coolant flows through the engine to fast and does not cool eficiantly.

At least that is the case with a gasser.

 

[Kirwin]

Theromostat removed

Gentlemen, With the thermostat removed the truck will overheat!!! Oo. with the engine below normal temperature, the thermostat causes the waterpump to recirc the water in the block until it opens. When it opens, it blocks the recirc path and routes the water to the radiator! Check your service manual it explains it quite well. I'm not sure if all years have the same set up but I believe they do. Ken Irwin

 

[41jay]

Gentlemen, With the thermostat removed the truck will overheat!!! Oo. with the engine below normal temperature, the thermostat causes the waterpump to recirc the water in the block until it opens. When it opens, it blocks the recirc path and routes the water to the radiator! Check your service manual it explains it quite well. I'm not sure if all years have the same set up but I believe they do. Ken Irwin

I had a t-stat problem once, mine was stuck open and the truck would not get warm and in the winter time too. I stuck cardboard in front of the radiator or even blocked the radiator off completely with card board did not hurt my truck but i was frezzing.

all because i was avoiding changing it. don't do it long but it did not hurt my truck and that was 152,000 miles ago.

 

[mechanic]

I agree with kirwin. IF the system has a bypass system that is closed (by the thermostat) in proportion to the opening of the main thermostat valve. Any engine that has this type of cooling system will overheat if you remove the thermostat because the coolant is not going to the radiator, but is recirculating through the block and head.

If it dose NOT have this type of system, it will run cold if the thermostat is removed. I don't remember which way the 12 valve systems are designed.



I have heard stories for the last 50 years about situations in which the engine

over heated when operated without a thermostat, but in 43 years of working on cars I have never encountered one myself, except for the systems that are designed as described above. I am not saying that it cannot happen, but I have not seen one. All my experience has been in the area Oklahoma City, where our temperatures are not as cold as the northern states or as hot as the desert states, our temps range from a minimum of -5 degrees in winter (which is rare) to 110 above in summer (also rare). Our normal range is 10 to 105 winter to summer lows and highs.



It is not good to run an engine of any type in a cold condition. As stated by one of the other respondents, it causes a host of problems that boil down to a very short engine life. In actual tests by Continental Engines, the life of the engine was shortened to 10% of the normal life, when operated at 40 degrees F. Cylinder wear was . 001" per 1000 miles.



In short, it would be best not to operate the engine unless you must. Hope all these inputs help.

 

[DPinkston]

In actual tests by Continental Engines, the life of the engine was shortened to 10% of the normal life, when operated at 40 degrees F. Cylinder wear was . 001" per 1000 miles.

Was this a gas or diesel engine? By operating at 40* do you mean the water temp was never allowed to exceed that?



Danny

 

[mechanic]

Was this a gas or diesel engine? By operating at 40* do you mean the water temp was never allowed to exceed that?



Danny

As I remember the report, the water temp was held at 40*. It was a gas engine, however I think that the effect would be as at least a severe with a diesel fired engine. I have worked on small diesels for 23 years. (Mostly VWs) and what I have seen with them is that a diesel likes cold operation even less then a gas sniffin engine. I have seen rings stuck in carbon/soot, oil thickning, and unbeliveable cylinder wear when they are used for short runs during which they do not get fully warmed up. These engines will not cool without a thermostat because they have a system as outlined in the posts above. So I have not seen one (VW) that operated cold because the thermostat was removed.



Any engine that runs on liquid fuel will be adversly effected if the operating temp is reduced because the fuel tends to condense in the cylinders and the condensed liquid dosn't burn it then "washes down" the cylinder walls. The hotter the engine gets within the thermal limits of the materials in the engine, the better the fuel vaporizes and the more complete it burns, therefor leaving less unburned fuel to wash the cylinders and dilute the oil.



I will try to look at the study again and correct any memory errors that I may have accumilated since I read it.



I hope this adds a little to the information pool.