strange temp gauge activity
 

I'll be driving and my temp gauge will go down to zero, then back up to the regular operating temp, then drop about 3 lines, then go up again, then down, and it keeps doing this. It will happen every now and then, but mostly when i accelerate from a stop. I am also loosing coolant and its not a BHG. Could the thermostat be causing my coolant loss?

There is probably a small leak in a hose somewhere. The temp gauge going up and down is probably a loose connection on the temp housing. Did you check the hoses behind the head? Those are a common trouble area as far as coolant hoses go.

I checked all the hoses. Dye'd the coolant so it would show under a black light and saw nothing leaking at all. It never leaves coolant on the ground when parked. Could the loose temp housing cause me to loose coolant?

A loost temp housing definitely would. It would be leaking down the front of the motor. And it would burn off all the coolant while driving so while it would leak after you drive it, no coolant would be visible

Well in this case all of the coolant is showing on the front of the radiator. (thanks to the dye) but I think that it is just because it is coming out of the overflow tank and spitting onto the front of the rad. if there is a rad leak wouldn't it be on both the front and back of the rad? at least just a LItTLE bit?

Tell-a-gram for mr. d_train
 

Dearest D_Train,

Go get a block test done immediately ! (stop)

Your symptoms are sounding like a BHG ! (stop)

Temp gauge needle acts as you described when coolant level in engine gets too low. It goes down when air is touching the sender, then goes up when hot coolant touches sender.

Coolant over-flowing from overflow bottle indicates OVER-HEATING engine.

NOTE: A friend's '92 turbo over heating was a dirty radiator.

Good Luck, your pal skippy.

I have had both done. Both Negative.

Mr. nickleye is right. Thats why the needle goes down 3 notches and then back up, thats when it hits an air pocket.

Your symptoms scream BHG. If you are clearly losing coolant and gaining air in your cooling system, and its not leaking on the ground then the only thing it can be is the head, block or the head gasket. You should be praying its only the head gasket. I've seen cracked blocks on multiple cylinders before.

Did you remove the overflow hose from the nipple on the radiator and plug the nipple when you did your block test? If not, then you sucked outside fresh air into the tester giving you a false negative reading.

The shop did the block test. I don't know. How Fucked Am I? There seems to be no overheating, and the shop tested and tested and tested for a BHG. He had it there for 3 days testing on and off.

Also, i'm not burning any coolant. I get the low coolant light about every 150 miles, and theres no white smoke but also i never leave coolant on the ground except out of the overflow tube.

There does exist the possibility that the sender is bad or there's a short in the wiring.

EDIT: Nevermind... just saw that you're loosing coolant.

OK...I'll spill the beans. Mine did the same EXACT thing.
Block test showed no problems.

Finally (a month later) put the smog machine tailpipe tester probe at the open radiator cap while engine was idling.
BINGO.......a few hundred HCs. = BHG

All better now, 2.3 years.

PS: coolant goes into overflow bottle from engine, which leaves air is in the passages.

Over night the coolant should get sucked back into engine as it cools down.

Thats what it does. I'd just hate to pay a shop all the fucking money and then have it not be it. i'm gonna try the thermostat first.

i took my car to toyota and they told me i didn't have a blown head gasket .
they were wrong ,wrong, wrong

<insert Queen song here>

Repeat..
NOTE: A friend's '92 turbo over heating was a dirty radiator.

I just talked to him, and after 2 weeks of driving, it never gets hot any more.

If block test, AND emission snffer test are OK, then try radaitor cleanout or replacement.

mines does the same as your only when i hit turns at speeds of 20mph making left or right ..buh it goes back to normal...ill let you know when i find my issue

True. After I swapped my turbo engine in, I used my OLD radiator from my red car and it over heated on a long highway drive. Turned out to be a dirty radiator. So I bought a new radiator and a new fan shroud.

hmmmm... radiators aren't that hard to replace and pretty cheap right? Maybe i'll try that. or should I just try flushing the radiator first? is there anything that "cleans" it

I work in a Pennzoil and there is a lot of 2 step products to clean it or you can always do a Rad flush !

read this thread
 

Fixed!!
 

Radiator Cap. I'm out $9.99 + $100 for testing at two different shops. No BHG though! :-D

Radiator cap was causing the coolant system to depressurize. Fun.

Whenever I sell a job that has anything to do with the cooling system, a new cap goes on it.

So I just assumed the radiator cap was new or had been tested by the shop you took the car to.

I say...everyone that does not know their cap is good, go buy one today !

And your original complaint was that the temp gauge was fluctuating, so that will be caused by low coolant in the engine. Keep an eye on it.

Thanks for the heads up. I'm going to flush the coolant system soon. Its prob. hitting bubbles and dropping i'm guessing.