replacing thermostat??

[Quakecom]

Hi everybody

I heard a couple of people talk about replacing their thermostats because the engine would warm up and preformance would take a hit. Could someone please explain this whole thing to me...I might be having the same problem but would like to get some more info on this before I take action....
Please help me out...

Thanx guys

Quakecom

 

[<<MONOCHROMOUS>>]

i replaced my thermostat because i HAD to, it overheated after 2 mins.

assuming you dont know how it works, heres a quick lesson:

your car needs coolant in the radiator, but not all the time, when it is warming up it wants all the heat it can get. the thermostat is a valve with a spring that blocks the hose that carries the coolant to the radiator. when the engine is not hot enough, it is closed. when it heats up, the metal of the spring expands, opening the valve and letting the coolant in. there are 2 main types of thermostats, 2 stage and multiple stage. 2 stage ones are either all the way open or closed, multiple stage ones open at different amounts depending on heat detected.

i had to replace mine because it was stuck shut. the 'stat is not ABSOLUTELY necessary, so if i was really in trouble i could just take it out, letting the coolant go full all the way through, which is not that bad unless its cold outside. instead i just replaced mine, $10 at the auto store.

you are supposed to drain the radiator coolant before you change it, since it is right in the middle of a hose full of coolant. i couldnt drain mine since my safari bar is bolted onto the radiator shroud..... so i just opened up the 'stat housing, spraying coolant on the engine (DOH!). i put the new one in and closed it back up, adding a little more coolant to the tank. then took it for a test drive, it seemed just fine.

if you are bored or want to see if the thermostat was the problem, put it in a pot of boiling water and watch it, it should open.

hope this helps some, let me know if you have any more ?s

 

[Quakecom]

more Qs....

thanx for the intro to thermostats...
i do have some more questions though...

How should a normal thermostat function/behave under normal condition ? (I live in Boston, and the weather is rather cold here lately, in case you need to know..)

I heard ppl talking about replacing their stock thermostat with some thermostat that go up to 190 degrees (?).. Whats the reason behind this? any advantages?? disadvantages??

Thanx for any help....

Quakecom

 

[93Blue2door]

Can you tell me exactly where the thermostat is located? Also is there any other steps to removing the old and replacing the new than draining the radiator fluid?

Mine must be stuck open. My engine heats up a lot less than it should. Needle barely makes it into the "normal" range. I have the tow package and extra radiator so I hope that's not adding to the problem.

 

[Perry]

Follow your top radiator hose and when you get to the motor that is were the therm. is at.
There is three bolts you have to take out and then you just pull the cap off.
I had to replace mine for the same reason I think you are having. It would not warm up very fast and once it was warmed there wasn't much heat.
One thing after I did mine the needle still doesn't get much above the "N" in normal but there is a lot more heat.
It's an easy job, but takes awhile since everything is so close. I took off the tube for the air breather to give more room.
Good luck!!!!!!!!!

 

[sink]

It is VERY close in there. Reminds me of the spark plugs. I had trouble getting on the bolt located at about 9 O'clock. I used one of those flexible extensions once I broke it free with an open end. I also took the air tube out to do this. I tied the wiring harness back also. Stock T-stat is rated at 195. I can't remember where the radiator drain is. I also disconnected the hose at the driver side, bottom of the radiator to help draindown and to flush my system, I had never done that before and its a good idea. If you changed coolant in your truck's life, just drain down below the T-stat hieght. If not, drain it all and flush with clean water and refill. 93Blue, if your not getting warm inside, go ahead and change the T-stat. Your big radiator will not be a factor either way. To add to Monochromus' lesson- The t-stat lets coolant circulate from block to heater core while closed. When it opens due to coolant temp reaching a high temp, it puts the radiator into the loop. I learned in my lifetime that if you even suspect you're too cold inside, just change the t-stat and get on with it. It has always solved it for me.

 

[<<MONOCHROMOUS>>]

sink is right, the 'stat is an inexpensive fix that is very important! about the aftermarket stat, if stock is 195, then the only thing i can think of is that the aftermarket one is a multiple stage stat.

 

[93Blue2door]

If the stock is rated at 195 degrees and the aftermarket is a multistage would it be bad if I got one rated at 200, or should I stick with 195? Remember I do have the extra radiator. It's like half the size of the main radiator but there it is. 195 seems a bit high anyhow. My 4 cylinder uses 180 I think.

Wish I had had the sense to get the engine block heater as well. Only $12 for the option I think. Can one be placed on aftermarket?

 

[Gearhead]

DO NOT RUN AN ENGINE WITHOUT A THERMOSTAT

I read in an earlier post that a thermostat is not required and that you can remove it. THIS IS A VERY BAD IDEA AND WILL CAUSE MASSIVE DAMAGE TO YOUR ENGINE! One of the jobs of the thermostat is to restrict coolant flow in the engine. This restriction (even when the stat is fully open) forces the coolant to stay in the engine longer. Without the thermostat the coolant will pass through the engine so quickly that there will be no heat transfer. The end result will be an overheated engine even though the temp gauge was reading in the normal range.

 

[<<MONOCHROMOUS>>]

it was me who said that earlier, i guess i forgot to mention that it WOULD be ok if it was stuck closed and you had to go out and get a new one. it is JUST TEMPORARY however, and like you said, it not that safe for the engine

 

[93Blue2door]

OK Gearhead, guys that didn't address my question. The thing is my engine is not overheating, it's underheating.

 

[<<MONOCHROMOUS>>]

does it underheat all the time? just when you start? the thing with the thermostat is it could be stuck open. give some details as to what you mean by "underheating"

 

[93Blue2door]

It takes a lot longer (about 6 miles) for the temperature needle to just get in the normal zone when it used to take about a 1 1/2 miles of driving. And the needle doesn't go up much more than about two or 3 milimeters to the right of the marker showing the normal zone and that takes a really long time. Also My heat isn't that much warmer than slightly warmer than lukewarm. Coming out of the vent about 70 degrees when normally on most cars it comes out about 100-110 degrees. Doesn't matter anyway I bought a multi stage thermostat for it.

The box says I need a quality sealant on the gasket. What should I use?

 

[<<MONOCHROMOUS>>]

check your old gasket, it might still be ok, i just used my old gasket, otherwise, ask at the car store, they will know just what you need, its their job good luck to you and let me know how that multistage works out

 

[shooter_1000]

This is to late for you to consider. I live in central Canada and it tends to get cool here. What I did 2 days after I bought my Exlplorer in '92 was to change out the factory thermostat 192 or 195 I believe it was for a 205 degree thermostat from John Deere. So there is hotter thermostats available and the increase in temperature is noticeable. In fact, I have driven down the highway when it was minus 35 degrees, with my jacket off in the cab wearing a t-shirt.

Just something to consider for those that live in colder climates. Oh yeah, I leave that thermostat in year round and have had no trouble with overheating on hot summer days.

 

[sink]

Good - you got a new T-stat and thats the bottom line. PERIOD. Your symptoms are classic T-stat replacement-time- no doubt! You'll change it and be happy.
For sealant, I always use permatex silicone blue RTV, oxygen sensor safe- or for hotter stuff, permatex orange RTV. For the stat gasket- blue is OK. Even if someone tells you to skip the sealant, DONT skip it unless you like squeazing your hand in there to fix it. Make sure all parts are dry. Put a light film on both gasket and flange. I do highly suggest taking my previous advice on the flush. IF you do flush it only-, remember that you won't get all of the fresh water back out of the block. Refer to your manual for system capacity and put straight antifreeze back in unitl you have put 1/2 of the total capacity. Then top off with mixed.

 

[b]

I would always suggest changing out your t-stat with a like rated model. Your computer would have to work too hard to correct all the other mod's that are needed to keep the rig running the best.

Go ahead and change out the gasket and coolant entirely also.

The whole procedure takes 1/2 hour if you have a 1/4" hose attached to the drain peep valve under the rad.

With the simple and cheap ($15-maybe) change, you will notice heat faster, improved gas milage (maybe), and better performance in cold weather.

Good luck!