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Discussion Starter #1
Okay so is their a way to check the Radiator “fuse” if its getting power whatever what it is because its this black box looking thing doesnt look like a regular fuse. But i want to test it to make sure its not bad, because i was having problems with overheating on the highway and checked my coolant this morning and it actually was low. But as i was filling up the system and allowing it to burp the air bubbles for about 20 min with the heater on Max. But only my Ac fan came on and not the big radiator fan next to it. Would this cause overheating on the highway tho? Because going 70mph i would think the car is getting lots of air to cool it down at those speeds even without the fan. So how can i check this black box “fuse” for the radiator if its good or not?
 

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You really should keep everything in one thread...

What is this "black box" thing? I am guessing the relays, and if so, that is a possibility - just test them. If you are unsure how, then swap with good, known ones. It can also be the fan itself or your CTS (sensor) which the ECU references on 2G's.

-sent from my Galaxy Note 9
 

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It's not a fuse, it's a relay.
Here's the way I understand how that fan works:
1) There is a temperature sensor (two actually, at least one is sort of a bi-metal strip switch) at the bottom of the radiator.
2) The ECU monitors the sensor, and when it trips, it turns on that relay, which in turn, turns on the fan.

You can see if the fan works by taking the top off that relay (pull it out and then you kinda have to wiggle the top of the relay off).
Once you get the top off, put it back in its original place.
If you press in on the "switch" in the relay, the fan should come on. If it does not, then the fan motor may be bad.
If it does the relay may be bad.

If you had a datalogging device, some of them allow testing of the fans (not sure which ones do and which ones don't...
 

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Alan, is any of what I am posting untrue, if so, please clarify...

Bob. :)
 

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hehe I would say 99% correct. OP did not mention it here (had to search other thread), but he has a '95 R/T which should not have the two thermoswitches at the bottom of the radiator like 1G's. Were you thinking of the resistor instead with the "metal strip"? Great job explaining the manual "test" of the relays though! lol I was not sure if I wanted to mention it since it is often confusing without a visual aid. I usually use a small blade to help cut that top off and force the switch inside.
 

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Discussion Starter #6
It's not a fuse, it's a relay.
Here's the way I understand how that fan works:
1) There is a temperature sensor (two actually, at least one is sort of a bi-metal strip switch) at the bottom of the radiator.
2) The ECU monitors the sensor, and when it trips, it turns on that relay, which in turn, turns on the fan.

You can see if the fan works by taking the top off that relay (pull it out and then you kinda have to wiggle the top of the relay off).
Once you get the top off, put it back in its original place.
If you press in on the "switch" in the relay, the fan should come on. If it does not, then the fan motor may be bad.
If it does the relay may be bad.

If you had a datalogging device, some of them allow testing of the fans (not sure which ones do and which ones don't...
To test it like you said do i have to have the car running or can i just test it while the keys in the on position?
 

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It's been a while, but I "think" you can do it with no key
 

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Discussion Starter #8
It's been a while, but I "think" you can do it with no key
and my car has 2 for the radiator fan. One for Low and one for High. Which one of these should i test and how the hell do you pull them out lol? It looks like they are clipped in but i cant seem to push the clip down so it can let loose the relay.
 

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I know mine just pull right out. It takes a bit of effort, but they do.
I would test both relays while your at it (even though you said the A/C fan works)
 

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Discussion Starter #10
I know mine just pull right out. It takes a bit of effort, but they do.
I would test both relays while your at it (even though you said the A/C fan works)
FINALLY GOT THEM OUT!!!! Man they were stuck lol And i looked up online how to test them with a Voltameter i had which was actually super easy. And they were both good. But something weird happened 🤔 the good thing is my car didnt seem to overheat anymore on the freeway but then my radiator fan actually kicked on this time. It legit had not kicked on at all for the past 2 days even in the morning as i was burping the system for 20-25 min i was waiting for the fan to kick on but nothing...... Could maybe me pulling the relays out and putting them back have done something lol? I also unplugged and plugged in my radiator fan connector for the heck of it 😂. Or could this be a sign that my fan is starting to fail 🤔
 

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Discussion Starter #11
hehe I would say 99% correct. OP did not mention it here (had to search other thread), but he has a '95 R/T which should not have the two thermoswitches at the bottom of the radiator like 1G's. Were you thinking of the resistor instead with the "metal strip"? Great job explaining the manual "test" of the relays though! lol I was not sure if I wanted to mention it since it is often confusing without a visual aid. I usually use a small blade to help cut that top off and force the switch inside.
And sorry /: i thought since this was something with the radiator fan i had to make a new thread. Im still kind of new to using this site lol. But yeah those “Black box things” i was talking about were actually called Relays 🧐 i didnt know that 😧 im still learning lol but tested the relays with my Voltameter and a youtube video lol and they were good and popped them back in my fans kicked on again for some reason lol after test driving to see if the car was overheating which it wasn’t so that was good. But they havnt turned on for the past 2 days..... so thats why im thinking that could be a sign that my radiator fan is starting to give out??
 

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Wait, both fans are working now, and it's not overheating...

What year is your car?
I have been experiencing random issues with my relays in my 92TT for the past few years.
Electronics get old and eventually (sometimes intermittently) fail.

Update?

Bob.
 

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Discussion Starter #13
Wait, both fans are working now, and it's not overheating...

What year is your car?
I have been experiencing random issues with my relays in my 92TT for the past few years.
Electronics get old and eventually (sometimes intermittently) fail.

Update?

Bob.
Mine is a 1995 Dodge Stealth r/t and yeah it didnt seem to overheat anymore after driving it on the freeway. I think “burping” the system and filling it up to the coolant neck actually fixed the overheating well it seems like it did. I was actually low on coolant and it was barely visible looking down at the coolant fill neck. But i have no leaks anywhere of coolant so im hoping its not my headgasket and its burning coolant :( the car has 170,000 miles but never see any white smoke driving around. And Yes miraculously the Radiator fan started to work again after i popped the relays back in after testing them.... which was weird lol. i disconnected and reconnected my Radiator fan connector as well but i doubt that was what fixed it lol. Im almost guessing that its a sign that my Fan is starting to give out idk if you have experienced something like this
 

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Discussion Starter #14
Okay i seem to be having small amounts of coolant being pushed out my Overflow container. And after driving it back from work, i see that the overflow container is alll the way full to the top. I just put new coolant yesterday and bleed the system of air. But what would cause coolant to be pushed out my overflow and make it fill all the way to the top?
 

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Probably a bad cap. It can cause you to push coolant even when you arent overheating. Get a new cap, make sure its a good one with at least stock PSI rating (14?), and clean up the inside where the rubber seats before installing the new one. Exact same thing happened to me.
 

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Discussion Starter #16
Probably a bad cap. It can cause you to push coolant even when you arent overheating. Get a new cap, make sure its a good one with at least stock PSI rating (14?), and clean up the inside where the rubber seats before installing the new one. Exact same thing happened to me.
Is their a specific way to install the new radiator cap or can i just take the old cap off with the car Cold and just pop the new one on?
 

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Discussion Starter #17
Is their a specific way to install the new radiator cap or can i just take the old cap off with the car Cold and just pop the new one on?
Sooo does anybody know the proper way to install a new Radiator cap? Or can i just pop off the old one with a Cold car and just pop the new one on? Im bout to pick it up and see if it will fix my issue with coolant being pushed out my overflow even when i am not overheating.
 

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Discussion Starter #18
Sooo does anybody know the proper way to install a new Radiator cap? Or can i just pop off the old one with a Cold car and just pop the new one on? Im bout to pick it up and see if it will fix my issue with coolant being pushed out my overflow even when i am not overheating.
And ima be picking one up from Autozone that says online holds the same pressure as stock about 13-14 psi. Or has anyone had bad experiences with using their Duralast Radiator caps?
 

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And ima be picking one up from Autozone that says online holds the same pressure as stock about 13-14 psi. Or has anyone had bad experiences with using their Duralast Radiator caps?
You're overthinking this. Remove old cap --> clean surface inside where rubber seals --> install new cap making sure to lock fully.

I am running a duralast cap and it has been fine for at least a few years.
 

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Discussion Starter #20
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Dont know if you guys can see the picture that well but theres a little chunk of rubber that is missing from the rubber on the Radiator cap. Would this cause it to lose Pressure and maybe be why my car kept pushing coolant to the overflow even when not overheating Causing me to lose some coolant
 
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