Has my gauge gone haywire?
 

We all know how inaccurate the water temp gauge is, but mine started acting really funny as of today. Mind you, air temperature was low 70s and radiator is full of fluid. I happen to notice my gauge passing by the 7th dot, it continues to climb almost to the beginning of the H, maybe the 12-13th dot and then it steadily drops back to 6 then 7. My entire drive to work which is roughly 40 minutes my oil temp stays right at 215, but the water temp dances back and forth the entire way.

Return trip home, air temperature is now 50 degrees. Oil temp stays at 200 degrees. Again, the water temp gauge dances back and forth the whole way home. Any thoughts?

If not a failing sensor, thermostat sticking maybe?

How many miles?

If the water temp is changing quickly and/or jumping 2 or more dots at a time, I suspect the sensor or wiring. If the swings are slow and steady, then Jordo! may be on the right track with the thermostat. Or it could be a faulty readout.

Try monitoring water temp directly from the ECM with an ODB/CAN monitor.

83,000 miles. The swings are pretty fast, immediately moving several dots. Will try to monitor through scanner.

Have you checked fluid level?
When I had a leak and my fluid dropped down to very little I would get a swing temp, jumps up and then back down. Inspected the car and found the leak.

yup you may has some air in the motor not good, your heads might not have coolant in them and that is how head gaskets get blown.

^^^^^This

I would check for an air pocket and if you have one, look for the leak.

and if you can't find a leak, well, I know where your leak is and it isn't pretty.

My fluid levels appear to be fine, right at the max line on the over flow reservoir.

let the car cool off and pull the cap on the coolant neck.

Check the radiator cap, and even then you could have a fluid pocket in the block or by the sensor. I know S14s were notorious for this.

Was not at home all day, pulled the radiator cap for a while and no effect still. Beginning to think I may have a problem for sure though. I have the CSF aluminum radiator, but it's had a small leak from the start (got it used). I recently tried some Radiator Stop Leak for aluminum radiators and my fluid level has stayed perfect sense. However, from what you guys have been saying I may have a bigger problem now. :shakes head:

Nah, sounds like a sensor to me. My fuel gage dots did the same thing. I took it to the dealer and they replaced both sensors and no more dot issues

was the neck full to the lip of coolant when you pulled the cap? Did it come bubbling out when you pulled it.

It was still sitting in the same spot I left it, right at the Max line on the reservoir. Nothing came bubbling out.

No the metal cap on the coolant neck engine must be cold

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I was thinking head gasket too, but I figured it would just climb up and stay up without, say, the heater on full blast. Could temps swing like that with a failing gasket?

OP, I'd also check your oil to see if there's any evidence of coolant in it (e.g., looks milky and/or separated).

Or find someone on local forums/facebook who has a compression tester. They're like $30 from Harbor Freight.

Checked cap on coolant, it was not at the lip or bubbling out, checked oil as well and it does not appear milky at all.

how far down was it, it should be at the inside lip, you may have an air pocket if it was low.

I've definitely got an air pocket then because it is extremely low. My overflow tank is full though. Maybe that bars stop leak wasn't the best option?

Looking at 1slow370's fees you're racking up quite the tab! :D

^yes he is

Also time to bleed, go get one of these from a pepboys or something http://www.summitracing.com/parts/li...FYdffgod4UQAqQ

Attach it where the metal cap goes and fill er up to the top of the taper part. Then crack the bleed plug on the top of your csf radiator and hope it doesn't break/strip and close it once coolant starts coming out. Then start the car and turn the heater on and keep it full to the top of the taper part. let it come up to temp so the thermostat opens and then shut it off and let it cool down. Repeat this process 2 more times then shove the stick in the funnel, remove and dump it into the coolant jug and put the factory cap on. Check it again in a few days to see if it is still going down. If you chose to put in more stop leak while doing this add it first before filling the system. If the level continues to go down and no leaks can be located you need to get the head gaskets changed.

The vast majority of additives are, at best, the equivalent of duct tape ... cheap duct tape ... maybe more like Scotch tape. More often than not, they end up making the situation worse. When they do any good at all, they merely mask the primary problem, which often leads to bigger problems down the road. If it's a DD, use only what's recommended in the Owner's Manual.

They work great if you put them in right before you sell it and some sucker buys it without checking the tank for sediment and the fluid for proper color! Ask how I know :shakes head:

HAHA I remember back when cadillac and some GM models had problems with radiators sealing and FWIW there is a GM part number for a tube of BARS leaks pellets.

Edit: but if you can find the leak fix it, a radiator shop should be able to weld a leak on your csf radiator if it isn't in the midlle of the thing.

Use a couple of eggs. Problem fixed on leaks.

I greatly appreciate the amount of help from you guys, especially 1slow370. As if admiring your build was not enough, now I expect a bill from your services. Better get the paypal ready. :rofl2:

Get it bleed and figure out if the gasket is bad first, then you can pay me if there is anything left of your life savings after changing it lol