Tempertaure Gauge On the Move

[Bell]

One again I ask for assistance. For the last few months since I got my NA the temperature gauge has stayed steadfast in one place. About and 1/8th past the midpoint toward H. Well in the last week it has taken off. It's goes all the way to hot just to drop back to the midpoint and all the way in between. I can actually see it moving. Coolant overflow reservoir has not changed. Would anyone like to start taking guesses at what it could be?

Possibly unrelated there's a smell of coolant every once and a while when driving. Also I've got some sort of irregular tick in the engine. Suppose the water pump could be having trouble. I replaced that a month ago and the first three weeks of it seemed just fine.

Any thoughts would be greatly appreciated.

[fwMiata]

heater core leaking? and it has been said that driving sparingly in a miata causes the thermostat to open very slowely causing mild overheating. i dont have htis problem cause i drive it hardish.

[tailchaser]

Step 1. Buy a new pressure cap. Don't do anything else until you've completed step 1.

[channelmaniac]

If the temp gauge moves up & down then you can troubleshoot it like this:

1. Coolant level - low coolant or air in system can cause fluctuations in temp
2. Replace cap
3. Check to make sure fans turn on
...a. Check fuse
...b. Bypass the switch on the thermostat cover to see if it's bad
...c. Check for 12v at fan
4. Replace Thermostat
5. Flush & fill (maybe things are clogged up!)

If you smell coolant:

1. Check for leaky cap
2. Check for leaky hoses
...a. ESPECIALLY the ones under the CAS unit going in to the heater core!
3. Check for leaky water pump (unlikely since you recently replaced it)
4. Check for separation between core and the top/bottom on the radiator

Did you replace that little itty bitty o-ring on the back of the water pump? I hope so - cuz if it's leaking you will curse & curse as you have to disassemble everything to replace it.

If you have the Miata with the hoses that sit under the CAS (the ones going to the heater core) then check them for oil! If oil gets on them then they will deteriorate and leak. Common problem. Replace the O-ring and the hoses.

I'm sure if I forgot anything that someone else will chime in.

Raymond

[altiain]

If you smell coolant:

1. Check for leaky cap
2. Check for leaky hoses
...a. ESPECIALLY the ones under the CAS unit going in to the heater core!
3. Check for leaky water pump (unlikely since you recently replaced it)
4. Check for separation between core and the top/bottom on the radiator

One other thing to check - look for coolant residue on the frame where the overflow resevoir outlet is. When my car was having overheating problems I would occasionally smell coolant, but I didn't have any leaks. However, if I parked the car after watching the needle move and left it for a few minnutes, I would come back to hear a bubbling noise under the hood. What I had was coolant boiling off in the overflow resevoir, and condensing in the little downpipe and dripping onto the frame rail.

I didn't discover this for a while because so little coolant is actually boiled out of the system during the process that the level always looked "just about" where it had the last time.

In my case, a new radiator cap, a new t-stat, and a good flushing seems to have cured the problem. I intend to make this an annual pre-summer ritual from now on, as the Miata t-stats and rad caps seem to fail pretty regularly.

[POS Racing]

Step 1. Buy a new pressure cap. Don't do anything else until you've completed step 1.

This is great advice! BTW. what year is your car Bell??

[Treibenschnell]

Step 1. Buy a new pressure cap. Don't do anything else until you've completed step 1.

This is great advice! BTW. what year is your car Bell??

Sage advice!

I would listen to these experts... otherwise you might end up like I did and be a headline on our own front page.

Pressure cap is the first step!

[Kestrel]

"One other thing to check..."

Ditto. Exact same symptoms in my car. All I've done is replaced the cap ($2.95 at Autozone) and the problem was completely solved!

[EvilSpeeder]

Step 1A: Check to make sure the connection to the temp sender is SECURELY plugged in. I had one with a bad connection that did similar things.

[Treibenschnell]

My downfall ended up being the hose to the heater box.... gave way and spewed coolant all over the place.


Thanks again, Kags, I still owe you many beers!

[Kags1969]

mmmmmm....beer.......

[Treibenschnell]

mmmmmm....beer.......

[Screamin'Screw]

Another "Freebie" thing is to pressure wash the readiator and make sure they radiator and condenser is clean.