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Temp gauge all over the place on my 2000

Acesneights1

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Northeast CT
Anybody ever have that problem ? I was thinking grounds but all other gauges are fine. I got in the truck and after 5 mins down the road gauge was upto 225 then to 210 then to 225 then finally settled out at 185. Thinking maybe the temp sensor. Don't see how the truck could have gotten that hot that fast. it was jumping all over the place. Heater was blowing hot air and coolant overlflow is full.
 
Uhm, it sounds like the temp sending unit wire is intermittently broken or grounding. Someone OBD2 wanna tell him the wire color please?
 
I'll check it out. The wire looked ok for as much of it as I could see easily but I will investiagte further. Think it could be the therm ? Remember mine has two.
 
In that case [2 T stats]It would be hard to believe BOTH would be failing at same time,unless one gave up the ghost already a while ago.
got to be electric then.Gauge??
 
You always said you had overheating issues on your 2k, but not on your 95, right? Maybe one of your t-stats was junk for a while, and now the other joined suit.

You need to verify via scanner or thermal thermometer which is accurate.

Is it fluctuating FAST meaning, there is no way the engine is warming up / cooling off that quick?

Or is it slow enough that it COULD be actual engine temp?
 
Re-read your OP and it MUST be a guage failure, or more likely the Coolant Temp sender that is on the Drivers side block by the first (closest) injector.
 
On 2nd thought, maybe you never had overheating issues and you were just incorrectly reading temp values, via defective guage or CTS.
 
Great avatar!

Are you sure it's not a head gasket starting to go? Can you read the temp sensor using a scanner? It is read from a different place than the sender for the gauge. It may not spike the temperatures terribly if it's not very bad. The other thing you could do is take the temp. probe from the driver side head and put it into the passenger side head to see if it acts the same.
 
Hey guys. well There was 2 SnapON MT2500s at the swap meet today for 200$ each. Like A dope I hesitated and they were gone so I don't have anything except a code reader. The temps were fluctuating very quickly but i drove the truck today and it was fine. Traced the wire back to the harness, looked fine. rad hose soft while truck is running.
Matt,
Both trucks have overheating issues when towing but most of hte posts i did were on the Tahoe when I had the camper but good memory.
I did have to put a little antifreeze in it about a week ago which has been bothering me but it hasn't gone down since. Basically this is what happended. drove the truck about 15 miles to a diner last night. shut it off and we went in sat down and ate. Truck sould have been relatively cool if not totally cold. I started it and about 2 mins later driving down the road notice the temp gauge way up. Then it came down. Then it went up. Today it was fine but i didn't go that far with it. Just into town. Maybe it's time I bought autoenginuity. That's about the best way to go without a tech 2 right ?
 
Aces, if you don't have any OBD1 vehicles you work on I'd recommend Autoenginuity. It is a whole lot more full featured than the MT2500. Plus I believe 2008 was the last year Snapon was updating the cartridges for it since most users have switched to the Modis scanner.

I bought the MT2500 because of the OBD1 diagnostics (have 3 or 4 OBD1s to work on) and price. I have found myself wishing I'd bit the bullet and bought Autoenginuity with domestic pack, especially since my father just bought a 2006 Ranger and my cart only goes up to 2000.
 
I gotta agree with SnowDrift and say a head gasket failure Ace. Been down that road with a vehicle or two in the past. Good luck, and lets hope it's not.

Agreed with Gerald. My subaru's temp gauge did this. it would swing way up to hot, then into the middle then back up to hot then down to the normal range. Had exhaust gasses being forced into the cooling system from the blown headgasket. Never saw a puff of white smoke form the tailpipe either.
I hope it's not a headgasket Kenny. If it is, let me know I'd be glad to help you with the repairs.
 
Head gaskets if that is the the problem and the fix isn't that bad to do. 17 TTY bolts per head along with new fel-pro gaskets.

Just a fun Saturday is all, but great opportunity to make it a weekend project and clean the piss outta everything inside there.
 
Aces, if you don't have any OBD1 vehicles you work on I'd recommend Autoenginuity. It is a whole lot more full featured than the MT2500. Plus I believe 2008 was the last year Snapon was updating the cartridges for it since most users have switched to the Modis scanner.

I bought the MT2500 because of the OBD1 diagnostics (have 3 or 4 OBD1s to work on) and price. I have found myself wishing I'd bit the bullet and bought Autoenginuity with domestic pack, especially since my father just bought a 2006 Ranger and my cart only goes up to 2000.

My 95 is OBD1 but I have GMTDScan for it already.
 
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