my mother has a dodge spirit, mid 90's... and i think her thermostat is stuck closed... she's been driving around and the engine will overheat fairly quickly. she told me the one day she popped off the radiator cap to which i replied "and you didn't get steam blasted?", she said the cap was cold and so was the upper radiator hose.

1) am i correct in the assumption that the thermostat is stuck closed?
2) if i popped it out, is it really bad to run without one? it's winter here and the ambient temperature this week is around -10c - -15c... i told her she should definitely get it replaced before spring.
3) is there a way to fix the current thermostat? or is it easier to just replace it?
4) if i replace it, will i need any sealers or gaskets that would require time to cure before driving? my mother's mechanic friend said the replacement would take a couple days for all the various goos to seal.

thanks

pull it out boil some water and on the thermostat it should have a number make sure u get it above that number if it dosent open either replace it or run it without it.

im running my daily driver without one after i blew the head gasket cause it wouldnt open :P

PS still running the car with a blown head gasket


also try flush the radiator through the top hose out the bottem through the engine without the thermostat if it wont go through it could have a block

lol you should only need 1 gasket and maybe 2 hours get a pic of the top radiator hose where it enters he engine

Quote :

still running the car without a head gasket

LOL wow... doesn't coolant leak into the cylinders or oil pan?

sorry fixed it :P and yer the oil is milky and the radiator has split cause of it so has the welsh plug :P but its all good 20$ fix ftw

Yup, sounds like a stuck 'stat. Probably no hope in fixing it, as the wax cylinder will have split of seized, so order a new one. Fitting should be quite easy, although you might need to order a thermostat housing gasket too.

If you opt to remove the stat, which I don't recommend (if there was a good reason on a road car the manufacturers wouldn't fit them), then make sure you fit something in it's place to duplicate the open restriction. Without anything it'll flow too much water and you'll never get the engine warm = likely to die very quickly.

Quote from tristancliffe :

If you opt to remove the stat, which I don't recommend (if there was a good reason on a road car the manufacturers wouldn't fit them), then make sure you fit something in it's place to duplicate the open restriction. Without anything it'll flow too much water and you'll never get the engine warm = likely to die very quickly.

i was reading somewhere the only downfall of not having a thermostat would be decreased gas mileage because the engine would never reach optimum temperature... what about if i took the busted thermostat, forced it open and then reinstalled it? would that be any better than running without one altogether?

arent thermostats supposed to be failsave in that the engine runs too cold if it breaks instead of too hot?

Quote from Shotglass :

arent thermostats supposed to be failsave in that the engine runs too cold if it breaks instead of too hot?

not that i know of, by default it stays in the closed position... it takes engine heat to compress the spring or something to open the valve.

(bear in mind i'm not a real mechanic hehe)

Thermostats are there to provide a quicker warmup - the engine heats the water that is in it and gets nice and warm before the cooler water gradually mixes with the hot water and equalises the system.

Running with a closed stat = too hot
Running with an open stat = correct temperature, but takes a lot longer to get there
Running with a stat with the middle bit removed = slightly too cold, and takes a while to get there
Running without a stat at all = far too cold

Considering a stat is a cheap item, and replacing it isn't difficult for most home mechanics then I'd say there is little excuse not to replace it with a working item. But if don't want to, then forcing the stat open (preferrably without increasing the maximum flow of a normal open stat, so don't cut away much) will keep your engine running correctly, but you'll have to be much more careful to warm it up before you use much throttle and load.

Quote from bunder9999 :

i was reading somewhere the only downfall of not having a thermostat would be decreased gas mileage because the engine would never reach optimum temperature... what about if i took the busted thermostat, forced it open and then reinstalled it? would that be any better than running without one altogether?

This is true. Running without the thermostat causes the engine to take longer to reach its optimum temperature, but it will get there eventually. It has a detremental effect on fuel economy because the engine management system sensors notice that the engine is running cooler, and will add more fuel to compensate for the lower temperature, kind of the same as driving an old car with a manual choke, but forgetting to push the choke in again. An engine that is running rich can also poision a catylitic converter in some extreme cases as well, which isnt good, although it would take something a lot more serious than a thermostat problem to cause cat poisioning.

All the thermostat does is restrict the flow of water around the engine, allowing it to reach the optimum temperature quicker, and when the thermostat gets to the designated temperature, it slowly opens, allowing the rest of the cooler water to mix and circulate around the whole of the engine.

In effect, running without a thermostat is not much different to running with a broken thermostat that is stuck fully open, as it has the same end result.

It's also a pain in the butt running without a thermostat in the winter, it takes ages for the heater to warm up.

Quote from danthebangerboy :

It's also a pain in the butt running without a thermostat in the winter, it takes ages for the heater to warm up.

good point.

i was reading somewhere else if she ran the car with the closed thermostat, but turned on the heater and opened the windows that the hot coolant would flow into the heater coil and cool the engine that way... could that be another alternative?

the car is a rust bucket, just had the camshaft replaced or repaired or something, it's a problematic car...

it first started off with timing issues, we drove to toronto, let it sit for a couple hours and drove back... two blocks from my house we're at a stop light and tried accelerating, ended up rolling down the hill and got stuck under a bridge. mechanic said he replaced the timing chain or the gear or something... anywho...

so they fixed that, and the idle has been rough ever since, especially when the tranny is engaged. (ie: stop lights)

and then one day supposedly the cam popped out (??)...

so they fixed that, and now this... i'm sure the part is cheap, but i don't think she plans on driving it much past the spring.

thanks again guys, at least i know if i try working on it she won't be "out of commission" for a couple days.

Hmm, If it is idling as rough as that it could be a number of things, shitty plugs, worn plug leads, worn camshaft etc.. But as you mention the timing was worked on before the problem, i wouldn't mind guessing that the timing could be out by one tooth, maybe even 2. I did that with one of my cars, the top pully moved when i replaced the belt. It ran like a bag of crap!

As for the heater thing, that is more of a get you home kinda trick, using the heater simply removes the heat from the water system via the heater vents. Ok for small runs if she doesnt drive that far but i wouldnt want to travel more that a few miles like it.

Usually, if the thermostat is jammed shut then the top part of the engine would heat up, so the top radiator hose would be red hot, and the bottom one would be cold. If the top hose is cold then and the bottom one is hot, then shouldn't think the heater trick would work, as most car heater systems work off the top water circuit, as the top of an engine heats up first, so you get nice and warm quicker.

it may even just be an airlock if you are lucky.

Quote from danthebangerboy :

As for the heater thing, that is more of a get you home kinda trick, using the heater simply removes the heat from the water system via the heater vents. Ok for small runs if she doesnt drive that far but i wouldnt want to travel more that a few miles like it.

Im always using my capri heater as a temp control in anything warmer then 15 degrees C Thats why most people dont go out driving with me in the summer

Quote from bunder9999 :

i was reading somewhere else if she ran the car with the closed thermostat, but turned on the heater and opened the windows that the hot coolant would flow into the heater coil and cool the engine that way... could that be another alternative?

Coolant is always flowing through the heater core. But unless your car has a really large heater core, and it doesn't produce alot of heat, it will not really have any affect. Look at how big the radiator is compared to the heater core. On some engines, like the one in my car, if it's less then about 25F outside, I can get my car to cool down a little if I turn the heater on with the fan at maximum speed. But anything above maybe 35F, and that doesn't work at all.

Just replace the thermostat. It shouldn't be that difficult. It took me a few hours to replace mine, but it shouldn't take you as long. It was my first time doing something like that, and on my car the thermostat housing is right below the A/C compressor, and the oxygen sensor is in the way of a wrench that's over about 6in long. And, there's no room to use an extension to clear the oxygen sensor.I couldn't come up from below because of the plastic shield that I couldn't figure out how to remove.

On some engines, the thermostat housing is on the top of the engine. On my car, it's on the side of the block, and I had to drain the coolant before replacing the thermostat. I also flushed plain water through the system, and drained it about three times.

Quote :

on my car the thermostat housing is right below the A/C compressor, and the oxygen sensor is in the way of a wrench that's over about 6in long.

sounds like fun.

sometimes i wonder who designs these things...

Quote from robt :

Im always using my capri heater as a temp control in anything warmer then 15 degrees C Thats why most people dont go out driving with me in the summer

Your'e lucky. By looking at your avatar it looks like you have got a very clean mk3, not many left, and none anywhere near what i can afford, the same with al the older fords now i find. I want a mk5 cortina or a mk2 escort myself. One day.

as long as where u live isn't too cold, u can make a "restrictor plate" type deal, just gut the old thermostat, cut the middle out so all you're left with is essentially a "ring" Make sure when u trim the middle out u deburr the part where the water will be flowing thru as much as possible, so there isn't too much turbulence. I used to have this arrangement year round, only when the temperature was around 7c or lower did it create any major issues.

Quote from bunder9999 :

good point.

i was reading somewhere else if she ran the car with the closed thermostat, but turned on the heater and opened the windows that the hot coolant would flow into the heater coil and cool the engine that way... could that be another alternative?

We do that all the time with the work utes, it isn't foolproof, and you still need to watch your temp gauge, but yes, switching the heater on does seem to cool the engine down a bit (sometimes a LOT) on most cars i've dealt with (mainly Toyota's, Isuzu's etc)
It's damn uncomfortable in summer, but it beats walking.

The other thing u might want to try is hosing the radiator fins out (ie flushing the outside of the radiator) with a garden hose. Sometimes, especially in muddy/dusty conditions, you will get a buildup that over time will inhibit the radiators ability to exchange heat. Get your hose, and, being careful not to bend any fins, either with contact or high pressure, give it a good hose out, i've been taught to do it from the back of the radiator to the front, and then give the front a squirt too *shrug* If you're game u can even rip the radiator out and give that a flush too, but it means dumping your coolant.

Quote from senn :

as long as where u live isn't too cold, u can make a "restrictor plate" type deal, just gut the old thermostat,

Can't he just replace the thermostat? Why go through all that trouble for a $20 part?

The reason i did that to mine, is i got sick of changing it out every 3 months, i tried many different brands, manufacturer and aftermarket. Got sick of it, i don't know if it was because i drove the ass off it most of the time or what, but yeah, just got sick of spending $20 for something that in our climate, u don't generally need

lol the thermostat isent just their so the car can warm up its allso their to keep the car from overheating
a thermostat can be lets say for arugments sake 74 deg c

once the temp near the thermo is 74 deg it will open untill cool water has passed it again and it close's thus heats up the radiator while the water in the engine is warming up to said 74deg the water in the radiator is allready below that and keeps repeating the cycle.

older cars with alot of corusion have a tendntcy to make the thermo stat falty my 86 vl has never had one issue with heating problems because i flush the radiator every 1000k with deminrialzed water:P but my 91 daily driver thermostat failed blew the head gasket and welsh plug and split the radiator core a few times and still over heats cause of the head gasket.

but the heater trick works wonders


lol ill tell ya now having to remove the dizzy to remove the thermostat sux

Quote from danthebangerboy :

Your'e lucky. By looking at your avatar it looks like you have got a very clean mk3, not many left, and none anywhere near what i can afford, the same with al the older fords now i find. I want a mk5 cortina or a mk2 escort myself. One day.

got it for £750 2 years ago. 60,000miles, garaged doing nothing for 10 years
I know of a few capris under 1K for sale. or your budget even less? and a mk5 corty shouldnt be too hard to get

Quote from MAD3.0LT :

lol the thermostat isent just their so the car can warm up its allso their to keep the car from overheating
a thermostat can be lets say for arugments sake 74 deg c

once the temp near the thermo is 74 deg it will open untill cool water has passed it again and it close's thus heats up the radiator while the water in the engine is warming up to said 74deg the water in the radiator is allready below that and keeps repeating the cycle.

older cars with alot of corusion have a tendntcy to make the thermo stat falty my 86 vl has never had one issue with heating problems because i flush the radiator every 1000k with deminrialzed water:P but my 91 daily driver thermostat failed blew the head gasket and welsh plug and split the radiator core a few times and still over heats cause of the head gasket.

but the heater trick works wonders


lol ill tell ya now having to remove the dizzy to remove the thermostat sux

I was running the standard temp sender (electronic) in the head, and an old school direct one just after the thermo housing. (so i could see, when i had a thermostat fitted, if it had jammed) the overall temperature of the coolant was far far lower than it was with the thermostat, altho i have heard (unconfirmed) talk of if the water moves too fast thru the motor, it doesn't exchange the heat out, but no mechanic i spoke too could tell me if this was the case

Quote from MAD3.0LT :

lol the thermostat isent just their so the car can warm up its allso their to keep the car from overheating

No, that's the radiators job. The thermostat is merely an automatic adjusting flow restrictor. It does nothing to the temperature. Once it's fully opened (i.e. after the car has warmed up and the whole water system is in a steady[ish] state) then it does nothing but restrict the flow. You can change the temperature at which it opens so that the engine warms up quicker (a higher temperature 'stat) or slower (a cooler temperature 'stat).

If you use a 'stat that is too hot then it'll open (when the water gets hot), close (when the radiator cools the water as designed), open (when the water gets hot)... it'll never settle. This is not good for the engine or the 'stat.

Engines are designed to work at quite specific internal temperatures. The radiator and 'stat size might alter between climates, but the man on the street is unlikely to make things better by using a different rating.

Quote from tristancliffe :

No, that's the radiators job.

[ snip ]

I beg to differ. That would actually be the job of the fan



Regards,

Ian

Quote from Ian.H :

I beg to differ. That would actually be the job of the fan



Regards,

Ian

That is true, but i find the fan is usually like a last resort, in conditions where the radiator/thermostat cooling isn't enough, like when stuck in massive traffic in the middle of summer for example.

I have just noticed that the OP said its between minus 10 and minus 15 degrees where he is, there isn't a chance that the water has frozen is there??