D.Rock

I recently started getting a coolent overtemp annunciator after about 20 min. of normal driving. I stopped driving the car (like the manual suggests) and checked under the hood. The coolant level is fine and all of the hoses appear to be intact and connected. Could this be a waterpump related problem and if so what kind of corrective action should be taken? Thanks...Doug

ChuckH

...thermostat.

Open the reservoir, start the car, and let it sit and idle. Watch the reservoir. There should be no movement of the coolant at first and then you should start seeing coolant flow back into the tank at an increasing rate. Check your guage regularly while doing this too! If the engine gets hot and you never see coolant flowing back into the tank or it only trickles in when hot, then there is no circulation. That either means there is blockage somewhere, the thermostat isn't opening, or the pump isn't working (not likely or you'd have more problems!). Another thing you can do is compress a hose and hold it. You will be able to feel if there is flow through there.

I would definatly start with the thermo. They don't tend to last that long,a nd they only cost about $10.

You didn't say what year your car is. If it's an older one with a 5 cylinder engine, the thermostat is pretty easy to replace. It is positioned on the driver's side front of the engine block. There is a main radiator hose that goes into the block and attaches to a metal piece that is attached to the block.

I was able to leave my undertray on and put a foil pan under the car. If you test first, you'll know where the coolant will flow out from the undertray. Then, slowly loosen the bolts and let the coolant drain out slowly to the undertray and then into the pan. Obviously, if you have something that will fit down in the engine compartment, it will be easier to drain directly to that. Once this is done, remove the bolts the rest of the way and make sure the hose is fully drained. The thermo is right there and you can pry it out. Mine was fused, via corrosion, to the block, so I had to work it pretty good, but it eventually came out. It was toast anyway, so prying on it wasn't a concern. My thermo was literally broken and stuck somewhere in between closed and open.

Anyway, once it's out just pop the new one in and put everything back together. Then, add coolant to the reservoir and start the car with the top off the reservoir. Let the car idle and with any luck your coolant will start flowing. Let it go for awhile until any air bubbles are worked out of the system. Then, turn off the car, top off the coolant, and put the cap back on.

Easy! :-)<p>Charles
2000 Nissan Xterra SE V6 4x4
'98 A4 2.8 Q-Tip (employer owned)

Tom Serrago

they contribute to an overheating situation. Are any of these symptoms noticed?
As Chuck suggests, definitely replace the thermostat first.
Is the temp gauge also displaying a high temp reading when the coolant temp annunciator (coolant temp light in auto check system?) starts to flash/sound? If not, it may be the auto check temp sender going bad.
HTH

Tom Serrago

85 5KS Avant
99.5 A4 tqms

D.Rock

Thanks for the insight...the car is a 92 100S (V6) with 138K miles and it runs perfectly in every other regard. I haven't noticed any leaking or stange noises so that leads me to believe that the problem is not the W/P. The temp gauge does rise as I drive the car and the auto check sys. light comes on and flashes/chimes when the gauge reaches a certain point. Since it happens after about 15 minutes (the gauge rises evenly until the light comes on). The more I look at it the more I think it's a blockage.

DKG

D.Rock I have a 93 100s v6. I just replaced my H2O pump , Idler pully, Thermostat,crankshaft seal,Timing belt .I have 141k mi. The thermostat is real easy to change . It was stuck. Shokan had good prices.The manuals are good to have too.

QCRAZY

In the V6's the impellors on the waterpumps have been known to spin off the shaft! Just something to think about if the thermostat doesn't fix it!!

Good Luck...hope it's just a thermostat!
---
Andrew
90 80Q
91 90
95 90Q

Ray Calvo

From '90 Coupe Quattro experience, agree. Fixed overheating problem there (nt)

koke

There are a few things that come to mind. First, the thermostat, as has been suggested. Check to see if the radiator tanks are betting hot as the car heats up, indicating that the thermostat is opening. If it is, the problem could be the fan switch in the radiator, or the wiring harnass. To check the fan switch, disconnect it from the bottom of the radiator (passenger's side). With the key in the "run" position, jump the middle pin to either of the outer pins. The radiator fans should spin at one of two speeds, depending on which pin you connect.<p>--Jim 95 90SQ