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Discussion Starter · #1 ·
Well, I think I have just searched the entire 3si archive and I've narrowed my weird heat problem down to either my thermostat is sticking (<---likely) or my waterpump is going (unlikely since it was replaced 2 years ago).

How do I replace the thermostat? Pictures would help a lot! I know I can get the part from AutoZone or NAPA, but I don't know if I need the housing and the thermostat or just the thermostat. and the gasket. Thanks in advance.
 

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Thermostat and O-ring rubber gasket.

You can see my FAQ for how to do it (the section about changing rad fluid), or you can just yank off the housing, pull the old one out, and slap in the new one. The main use of the FAQ for you will be little tips on how to not make it so messy.

I used a NAPA thermostat and gasket and, unlike at least one other person here, have had no problems with it in over two years.
 

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Discussion Starter · #3 ·
Yeah, I saw your faq, but I got a little confused. Where exactly is the thermostat?? On the radiator or at the other end of the lower rad. hose?? Should I plan on a lot of fluid draining out??

Edit: What are the benefits of a 180 degree over a 170 degree thermostat? Which should I get?
 

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you know where you add coolant? (at the engine, not the overflow tank) If you go down from there, you'll see where the lower radiator hose connects to the engine... it's a little metal half-ball shaped looking plate.. (best description I can think of).. it is held on by three bolts.. the thermostat is in there. You may be able to change it without draining the radiator, but whenever I've changed mine I've drained the radiator first.. it's not very hard to do, esp if you have an n/a.. you just have to remove the intake hose and it's right in front of you.. on a TT though, it's a little trickier than that..
 

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Discussion Starter · #5 ·
Ok, so let me make sure I have this right......


Drain about 1 gallon of fluid from the radiator via "petcock" on the driver's side bottom of the radiator. Then follow the filler neck down to where it meets the radiator hose and at that junction is the thermstat. Remove a few bolts, bolt on the new. Refill coolant and that's it?? That sounds bit too easy. Especially if this fixes my problem.

I'm having the same problems you had before silverbullet with my heat and the temp gauge. I'm going to hope it is the thermostat. I would much rather change a $20 part than pay $400 for a new water pump installed.

Last question remaining is whether to get a 180 or 170 degree thermostat.
 

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We have here a multitude of descriptions, just enough that the truly unwary could unbolt the wrong thing.

My method is to locate the hose coming out the bottom of the radiator, and follow it all the way up to the other end. *That* end is connected to the half-ball shape thing as described above, and the thermostat is inside the half-ball thing.

170 degrees is the factory rating. 180 degrees means it will let the engine get even hotter before it opens. I don't know what effect this would have, since at operating temperature the coolant is 195 degrees anyway, but if some clever Japanese engineer with a degree said to use 170, you may as well stick with 170.

Draining a bit of rad fluid is a good idea if you want to avoid a mess. When you unbolt the half-ball thing from the engine, the hose connected to the half-ball will be full of rad fluid, so some of that is likely to spill out. Your thermostat will probably be stuck to the engine side rather than the half-ball side, and when you pry *it* out, you'll get a few more ounces of rad fluid dribbling out as well. All in all, you may want to park your car somewhere where it won't matter if rad fluid spills down to the ground - like maybe on your neighbour's lawn.

If you haven't changed your rad fluid in the last year or so, then why not buy a jug of Prestone and a jug of distilled water, and follow my FAQ instructions. This way, all the dribbling out problems are taken care of.

And the NAPA one is 12 bucks, not 20, so it's even cheaper than you thought :).
 

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Discussion Starter · #7 ·
Andrew Caple said:

And the NAPA one is 12 bucks, not 20, so it's even cheaper than you thought :).
lol....I just got off the phone with them. $10 for the thermostat and gasket with AAA discount. :D Then I guess $10 in coolant, maybe less. Woo hoo!!
 

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thermostat

iceccool2 said:
Ok, so let me make sure I have this right......


Drain about 1 gallon of fluid from the radiator via "petcock" on the driver's side bottom of the radiator. Then follow the filler neck down to where it meets the radiator hose and at that junction is the thermstat. Remove a few bolts, bolt on the new. Refill coolant and that's it?? That sounds bit too easy. Especially if this fixes my problem.

I'm having the same problems you had before silverbullet with my heat and the temp gauge. I'm going to hope it is the thermostat. I would much rather change a $20 part than pay $400 for a new water pump installed.

Last question remaining is whether to get a 180 or 170 degree thermostat.
Just order a stock mitsubishi one...thats what I did. You have the removal and installation process correct. you should definitely drain the coolant and put new coolant in when you are done. the only thing you have to realize is that you might need to take a couple of intake or intercooler hoses off that get in your way. but otherwise go ahead...its a simple job. just be sure that when you rip the thermostat out you have rags so you dont get everything green

chris
 

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Discussion Starter · #9 ·
thanks 93v......yeah I'm going to just do a flush and fill of the fluid esp. since the weather just got sub-freezing here. Don't need any issues with the coolant. I'm going to hope this doesn't take me too long since I'll be out in the freakin' cold! I'm betting on about 2 hours for my first attempt. Mistu part is not in stock at the local dealer and is $36. I'll go with my $12 NAPA one with the warranty.
 

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Discussion Starter · #10 ·
Ok, so the install went fine. I ended up running out of patience for the car to cool down and I just went ahead and did it while it was still a bit warm. Took me about 20 minutes from start to finish with about 5 minutes in there figuring out why my gasket didn't fit....they gave me the wrong one ::doh:: Well my overheating on the temp gauge seems to have gone away, but my heat still doesn't work right.

I'm having some weird voltage issues, I think I'm going to have my battery tested tomorrow.

Edit: Almost forgot, when I removed the thermostat housing, it stunk like rotten eggs. Any clue what that was??
 

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>when I removed the thermostat housing, it stunk like rotten eggs. Any clue what that was??

Yeah, that was Not Normal.

Rotten egg smell is hydrogen sulphide (or something like that - it's been 25 years since I took chemistry, but it's sulphur in one form or another), and is definitely not how your coolant should smell.

OTOH, how old was the old coolant? Maybe it was crap to start with, and it's been there a million years, and maybe there was sulphur in it and that's why it smells.

*IF* you know that the old coolant was real coolant and was not old, *then* you have a problem, and I don't know what it is.

*IF* you have no clue how old, or even what, the old coolant is, then I'd give the new coolant a few weeks, and check again for the smell. If it's back, then you have a problem.

There is a reason for the rotten egg smell coming out of exhaust, but I've never had it so I've never paid attention to the cause. Do a search, and see if anybody else has discussed it.
 

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he didnt mean exhaust...he meant the thermostat and cooling system. (if it was exhaust, it would be your cat rotting) and yes hes right. that smell should be there, but im pretty sure i know the smell you are talking about. thats just the smell of really old/bad coolant. if it looks brownish, its old and nasty. not 100% sure, but thats where my head is taking me.

chris
 

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Discussion Starter · #14 ·
I always thought the rotten egg smell from the exhaust was a bad O2 sensor. I dunno....well I didn't change much fluid yesterday, but I guess I'll try that out and see if that helps. We're getting 4-6 inches of snow tonight so I want to get my freakin' heat working! :D Thanks guys for the help....I'm also looking into this being a battery problem. Anything to avoid a waterpump replacement.
 
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