Weird Coolant Temp Problem.

[SYNFULL]

Hi,
I have been having a ball driving my car for the last 6 weeks. I absolutely have a blast cruising around- I wish there were some nice curves around here to really open it up. I have noticed when the car gets up to temp it stays in the same spot- the third hash mark to the right of 190. Well today it went there for a few min. and then slowly went all the way to redline. This happened on my way to work and home (only 10 min). I noticed when I shhut the car off, the gauge didn't go all the way down, it stayed above 100. Now I'm thinking it's my gauge and it must have gotten thrown ff somehow but I check the coolant and the front tank is empty. A new radiator was just put on and the mech. told me he bought a new tool to **** the air out of the whole system. I don't know if he ever put anything into the overflow tank in the fascia. So, I fill it up with a hand syphoning pump and take if for a spin. The gauge is still wacko. It went to where it usually goes for a few min. and then went all the way to redline. When I turn the car off now it doesn't go all the way down. SO I don't know
1. Is the temp gauge or sender broken?
2. Is the car really running hot and needs to be burped?
3. Both of the above
Thanks
Gary

 

[Ulysses]

The car is most likely running hot. Once you let the tank go dry, air will enter the system. Has to be bled (burped) out.

 

[Tom F&L GoR]

Ask the mechanic if they have a diagnostic reader you can use. There are three temperature sensors - one for the idiot light, one for the gauge, and one for the ECU. If the gauge or gauge sensor is screwed up, the diagnostic reader can look at the ECU sensor and see what temperature the ECU thinkgs it says. If lower, you have a gauge problem, if same, you have a coolant level problem.

Not going all the way down with key off doesn't sound right.

Radiator caps can also contribute to something like this. Did you get a new one? The drop center type, if not working properly, will let hot coolant out but not **** it back in well upon thermal contraction. (Or there's a leak in the hose.) Best insurance is to get a spring center cap (the metal center on the water side of the cap is spring loaded up - check by snagging with your nail.)

 

[V10 ACR]

Check the fan relays and it could also be a toasted fan motor.

 

[SYNFULL]

I will burp the car tomorrow. The thing that throws me is the fact that the temp gauge is not going all the way down. That made me think there is a problem with the gauge- until I found the front tank empty.
My radiator cap is the stock cap, it hasn't been changed. I did put headers on it last week and i don't have any heat shields on them yet. Maybe something is too close to the headers and is burning out.
I will check about the diagnostic reader, I doubt if he has one though.
I will see what happens tomorrow when I purge the system.
Thank for all your help!
Gary

 

[Edward 96GTS]

Tom,
Where can I get the cap you are referring to? Do you have a part # or brand name?
Thanks,
Ed

 

[95Viper]

I'm not sure when the spring type cap started but I know the 2001's have them. My 95 did not, it has the drop type. I replaced with a 2001, perfect.

 

[Eric H]

i had that problem ONE day when it was about 99 degrees, if i drove it above 3k rpms for more than a few minutes in slow traffic, it ran REALLY hot, havent had a problem since....coolant level looks fine, i just dont think it likes running high rpms in hot weather without ample air cooling it down.

 

[SYNFULL]

We I nearly had a meltdown today. I followed the burping procedure and the car seemed fine. When i drove it too work the temp went all the way up to almost redline and then went down to like 225 and stayed there. After work I went to Lowes and on the way home it went into the red zone and stayed there. This time the coolant engine light came on. By the time I got home which was only a few miles, the coolant was boiling over. I think I narrowed it down to the fan. It isn't running. I looked in the service mannual but it say's to see a different diagnostic manual to troubleshoot it. I checked the wire going to the fan. There are three leads. The middle one has 14 volts going to it (I don't know how it's getting 14). The ones on the ends have nothing.
Would the fan not working cause the car to overheat that much, and is there anything else I can test to make sure it is the fan?
Thanks
Gary

 

[Vic]

I don't have anything to offer as far as your current situation, however, there were some water pumps made that had a tendency to slip the impeller on the shaft. When mine went bad, the symptom went like this- At idle, the temp would be normal, because the impeller was spinning fast enough to circulate the water. But when the engine was revving above, say, 3000, the impeller would lag behind, and the temperature would soar. That happened to me on the track. I nursed it home by short shifting, keeping the revs really low, and a new water pump fixed the problem for good.

Wish you luck with your troubleshooting.

 

[SYNFULL]

Vic,
Thanks for your help. I don't think it's the water pump because the service manual said that if the water pump was bad then the heater would not work. The heater seems to be working so I'm pretty sure it is the fan - as it isn't. However I don't know if the fan is shot or something is not telling it to come on. As I sad above, there is 14 volts coming from the middle wire of the plug going to the fan.

 

[Vic]

Damm, wish I knew what to tell 'ya.

Did you try applying 12vdc directly to the fan motor to see if it will turn? Better check the wiring diagrams for the pin break outs.

 

[SYNFULL]

I think that's my next step, when I find the wiring diagram.
Thanks Again!
Gary

 

[V10 ACR]

I had the same problem on my 2000 ACR. Open the cover in front fo the fuse block and you will see three relays. If one is meleted, then it's the fan.

 

[Russ M]

Synfull,

You need to stop what you have been doing, your attempts at diagnosing will or already may have done serious damage to your motor.

Take it to someone that knows, and I do not mean drive it there unless you are hard up to rebuild your motor sooner rather than later.

 

[95Viper]

Stop driving it before your motor goes! Find good Tech in your area!

 

[SYNFULL]

Beleive me guys, I am not driving the car until I get this sorted out. It never hit redline before so I wasn't sure if it was running hot or the gauge was screwy. And where I was driving to (work) is only 1.5 miles from my home so it doesn't really even get a chance to get very hot. Driving home from work it seemed fine so I decided to go to Lowes. On the way home form there is when it got hot, and that was less than 1 mile from home. I do know these aluminum motors can't take heat so I hope nothing happened. The antifreeze didn't start coming out until I got in the garage.
The fan does work when I give it 12 volts so I am going to try changing the relay's.
Thanks
Gary

 

[SYNFULL]

Troubleshooting Results
Fan works when 12 volts is applied
I tested the plug going to the fan- there are 3 wires-
lt green (high speed) - dk green (low speed)- black which is ground
When the motor gets up to temp 14 volts is coming from center wire.
When the motor gets hotter the voltage switches to the light green wire and is 16 volts.
When I plug the fan back in nothing happens?? Does the fan have to be grounded somewhere also? I don't understand why the fan isn't working- any help is appreciated
Thanks
Gary

 

[Ulysses]

What was your setup when you applied 12 volts and where did you apply it to?

Your voltages sound too high, where did you mount your probe ground?

It sounds like you are getting power to where it's suppose to be, but you may have a bad ground. May want to check continuity on ground.

 

[SYNFULL]

The 12 volts was from the body ground and the 12 volt jumper post.
The probe was grounded to the black wire going to the fan, and also to the body.
I was thinking bad ground also but then I wouldn't be getting the voltage reading between the black wire (ground) and the power wires.
Thanks
Gary

 

[Ulysses]

I would double check the high/low relay again and make sure that one is off and the other is on during low speed, and vice versa. If the high/low relay is shot, it could be powering both the high lead and the low lead at the same time. That might mess with the fan.

 

[TampaViper]

the volatages actualy sound within reason (coming not from a viper mechainc but a previous physics major). i agree with others before, however, who suggested having a viper mechanic look at it. using the old wisdom that usually it is the working moving mechanical part that is defective, it is more likely the fan than the signal to the fan that is defective.

 

[SYNFULL]

I think I have solved the problem. When I checked the ground to the fan I used a meter and it seemed to be getting a lot of resistnce. I ran a new ground wire and voila! I don't know where the original ground runs to the fan so I hope it doesn't effect anything else.
Thanks
Gary

 

[Ulysses]

I believe that the only thing on that ground wire is the fan.