Can You Help Me Stop Overheating?!! Options

[JohnnyWadd]

Hey, guys. I'm about to embark on a project to help a friend figure out why her car is overheating. It's a 1992 Talon 2.0L Non-Turbo. She knows I'm a DSMer (though she doesn't call it that), so she enlisted my help. I took five minutes to look at it, but I didn't get very far into it, yet. I figured I'd post what I know so far and see if someone can give me a little insight as to what to look at. Maybe that'll make it a bit easier on me once I do dive in.

Anyway, the girl called me and told me that someone had told her that the water pump was out. I asked her how sure they were, and she said they were positive. So, I asked her if it was leaking any coolant from anywhere. She said "no". In my experience, a bad water pump leaks because the seal usually goes bad. Could it still be the water pump, even though it's not leaking? I've never seen a water pump just stop circulating. Hell, even when they leak, they usually still circulate, don't they? And the bearing can't be seized up. Since it's run by the timing belt, I'm sure it would've shot that bitch out of there, then I'd be in major trouble.

So, I went to the car and started her up. I only let her idle for five minutes in the driveway. I never took her out on the road. As she sat idling, sure enough, she started to get hot. As the temperature rose, though, I noticed that the cooling fan never kicked on, even though the guage approached the red line. I decided to try and jump that temp switch to see if I could kick that fan on. I know there are a couple of temp sensors on that car. The only one I messed with is the one on the thermostat housing. Is that the right one? Is that the switch that's responsible for cycling that cooling fan off and on? If not, where is it? On the radiator?

Anyway, I disconnected the plug and tried to jump across it to kick the fan on. Nothing happened. I them messed with the circuit breaker for the fan on the fuse block. Took it out, then put it back in. Still nothing. I plugged the temp switch back in and kind of played with the wires a bit, but still was getting no love from it.

Then, as I was going around to the driver's side to make sure I wasn't running it too hot, the fan kicked on all by itself. Seemed a little late to me. I felt like it should've been running much sooner. It had been running for quite a while and hovering near the red before it decided to comply. Not sure if it started because of what I'd done or not. Anyway, I watched the guage, and it dropped to a more reasonable level, but then it decided to start rising again. I decided to kill it before I got it too hot. Then we be really screwed.

So, what do you guys think? I think that there's something wrong with that fan or the switch or the relay. I don't think the pump is bad. If that water wasn't circulating, I don't think the temp would've dropped at all when the fan kicked on. That is, unless the temp sensor for the guage is near that fan, and it was reading the temperature of the coolant near where the fan was cooling it down. But, then if it wasn't circulating, the coolant in the radiator wouldn't be hot at all, right?

I'm a little confused. I'm guessing if it was strictly the fan, it would run much cooler at highway speeds, right? You know, with air passing through the radiator. Let me know what you guys think. As soon as I get a chance, I'm going to dig deeper. I'll post what I figure out.

Thanks for reading this, and I thank you in advance for any advice you might be able to give.

Jon

[black92_tsi_awd]

Take the cap off the water housing tstat hereon the engine and watch the flow. That will tell you if the pump is moving water. Watch the flow as the engine heats up, the flow will increase as the thermostat opens, if it opens late change the thermostat.

If I remember right, there's 4 temp sensors. 2 in the tstat housing, for the A/C and one for the ECM to read. There is another sensor lower for the dash gauge.
Then there's the thermo switch for the fans that's below the left hand side fan (looking from the front)-check that one.

[natedogg]

Skim through this thread. It has a lot of overheating advice packed into it.

http://www.dsmcentral.com/invision/index.p...wtopic=3564&hl=

[black92_tsi_awd]

How'd I forget that thread!!

[The Iron Goat]

Skim through this thread. It has a lot of overheating advice packed into it.

http://www.dsmcentral.com/invision/index.p...wtopic=3564&hl=

Yes, yes. Learn and laugh at Brett and his painfull battle with his car.

[ICGerms]

...And the bearing can't be seized up. Since it's run by the timing belt...

No, it's not. BUT, maybe the alternator/water pump belt is loose enough (and/or the bearing IS seized) that it's not turning the water pump. Kinda far-fetched, but possible, I suppose.

[The Iron Goat]

My guess would be the thermostat. If no hot coolant is entering the radiator, the fan will not kick on, right? On the other hand, the guage sensor is on the engine itself, which is rapidly overheating. The temps went down when the fan kicked on because the t-stat finally opened up a little. I'm betting you'll fix your woes with a new t-stat.

Or it could be the canooten valve.

[turbohcar]

Put a 160* thermostat in it atleast to try. It's only about $6 from Advance Auto Parts. Mine was running funny like that for awhile and the cooler thermostat is finally what kept it below normal operating temp. It stays right at 172* at cruising speeds.

[JohnnyWadd]

Hey, Germs, the water pump is run by the timing belt. If that bearing was seized up or loose, it would've quit running real quick. I'm sure most of us have gone through the blown timing belt / bent valves fiasco.

My buddy is a mechanic. He said it's rare for a pump to be bad without leaking. He said what usually happens is that corrosion will eat the fins off and the circulation will gradually slow down as the fins get smaller, then stop circulating altogether. The other thing he's seen is for the propeller to just spin off the shaft all together. Then everything's spinning fine, just nothing to push the coolant around.

It's snowing here, so it'll be a few days before I dive in. I'll give her a go probably on Sunday. Got two concerts on Friday and Saturday, so I doubt I'll turn many wrenches on those days. Keep your suggestions coming. I'll let you guys know as soon as I know more.

Jon

[natedogg]

The water pump is NOT run off the timing belt on a 2.0 4g63 engine. It is run off an accessory v-belt that is also wrapped around the alternator pulley and the crank pulley.

[JohnnyWadd]

Well, then this car must not have that engine. There is only one belt on the alternator and crank pulley. I wish that this one weren't run by the timing belt.

Actually, I've never seen a 1g 2-liter where the water pump is run by anything other than the timing belt. Not to argue, or anything. Just never seen it.

Jon

[Taxiwardance]

On a 4G63 the timing belt does not drive the water pump.
Not very familiar with the 1.8, or the logistics of its setup. But that may be what your speaking of?

[90GSX]

1.8 water pumps run off an accessory belt just like the 2.0

The belts run as follows:

Crank pully-alternator-water pump pully
crank pully-ac compresser
water pump pully-power steering

Timing belt runs the crank, cams, oil pump and a couple idler pullys

[The Iron Goat]

Actually, I've never seen a 1g 2-liter where the water pump is run by anything other than the timing belt. Not to argue, or anything. Just never seen it.

That can't be true. If it's a 1g and 2.0L it is a 4G63. Period. And as shown in the picture above, the 4G63 doesn't run the pump off the timing belt. There isn't a difference in the accessory section between turbo and non.

And even if the pump had seized, you would be able to tell by the horrible squeal from under the hood and decreased alternator output.

[natedogg]

Actually, I've never seen a 1g 2-liter where the water pump is run by anything other than the timing belt. Not to argue, or anything. Just never seen it.

Then apparently you've never seen a 1g 2.0 before. A 1G 2.0 is a 4g63, period. And a 4g63 does NOT run the water pump from the timing belt, period. The pic that Taxi posted illustrates this pretty clearly.

If you said a 2G non-turbo, I'd be more inclined to believe you because that would be Chryslers 420A and I don't know much about that engine.

[BudmannG]

I just got off the phone with Mitsubishi. And Jake said the 420a is ran off the timing belt. So Jon you are diving into a 420a.

[natedogg]

If its in a 1G, its not a 420A, unless someone did some serious engine/transmission mount fabbing.

[BudmannG]

That's what I told him and he said that 2G has the 420a. And that it is a Chrysler motor also. He looked them all up and said, the 420a is the only one that is ran off the timing belt.

[JohnnyWadd]

They way I understand it, the 4g63 is the 2.0L that is made strictly by Mitsubishi and the 420A is the 2.0L made strictly by Chrysler. The 420A is strictly a non-turbo engine from 2g DSMs, though from what I've read, it seems to me that they look the same at first glance. Or, at least I read something about one being a "mirror image" of the other, whatever that means. I'm guessing it means that they're either identical in look and mounting, or that they look the same but one is mounted exactly opposite of the other. Not sure. I'll keep digging.

Apparently, my Talon (the stolen one) is a 4g63. You're right, though, natedogg. I was just remember incorrectly. For that I apologize. I remember that I had to take the belt off the change the pump, but now that I think back, the timing belt doesn't actually run the water pump. It just gets in the way when you have to change it.

As I said before, when I looked at Robyn's car, I didn't dig much. The engine looked the same as mine, so I assume it's also a 4g63. If you check this link, apparently '92 DSMs had both Turbo and Non-Turbo 4g63 engines in them:

http://www.roadraceengineering.com/mitsumo...pplications.htm

Since her engine looks like the same engine as my Talon and I can find nothing about anything other than a 4g63 engine coming out in 1g models, I'm going to assume that her engine is a 4g63 also. Thus, I'm also going to assume that the water pump is the same as mine and I'll have to go through the same process to change it.

This is one thing I found off of the web:

--------------------------------------------------------------------------------
What does 4G63 mean?
What does 420A mean?

These are engine model designators. 4G63 is the Mitsubishi model number for the DSM turbo engine, which was built entirely by Mitsubishi. The 4G63 model number was used for 1G turbo, 1G non-turbo and 2G turbo engines; although the engines are somewhat different from each other, they retain the same basic design.

Please note that there are different 4G63 engines, although posters on the Talon Digest almost invariably mean the turbo 2.0L version. Generally speaking, components from one 4G63 can be fitted to another 4G63, because the basic components (head, block, etc) are the same.

420A is the model of the Chrysler-made 2G 2.0L non-turbo engine. Fundamentally different from the Mitsu 4G63 engines, the 420A represents a distinct shift in DSM evolution, as Chrysler took over engine duties on the non-turbo cars. Generally, components from 420A engines cannot be fitted to the 4G63 engines, or vice versa.
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I'm still learning this stuff, so forgive me if what I wrote above is incorrect.

Jon

[JohnnyWadd]

I just read this stuff again... man, I feel like an idiot!!!

And, you guys jumped me for it. Good job!! I'm proud of you.

I actually laughed while reading it.

Anyway, let me say again: I was wrong in my recollection!! You guys are right, and I did know that the timing belt doesn't actually run the water pump. It's just that you have to remove the timing belt to get at the pump. I've done the job twice on my own car, it's just that it's been so damned long since I'd done any major mechanical work on a 1g DSM, my memory escaped me.

Sorry guys. I feel like I wasted your time.

I'll try to do better in the future.

Jon