[mk3_ftw]

so ive been doing alot of searching and came up with nothing to help me. here is my problem. i have a 88 turbo. only mods are 3" exhaust, cruise delete, and characoal canister delete. my problem is whenever it is idling the temp guage reads fine but if you get on the gas a little bit the temp guage goes down and if you really lay into the gas it goes all the way down like it is coldbut once u let off it goes back up right away. the car runs, drives, and boosts fine. sorry if something like this has been posted already. thanks in advance

 

[hornet7288]

have you changed your thermostat lately?

 

[mk3_ftw]

have you changed your thermostat lately?

no i have not changed the thermostat yet. it is on my to do list when i replace the radiator hoses

 

[mk3_ftw]

anyone have any ideas what could be going on?

 

[hornet7288]

My guess is that maybe the thermostat may not be working properly. I am no expert or anything, but I would start there since they are not terribly expensive.

 

[mk2racer]

Is this the stock gauge or an aftermarket one?

Assuming the gauge is working properly, it is most likely a thermostat stuck open. There are really only two reasons it would "overcool": a) tstat open or b) bad gauge or sensor


I only wish I had your problem, mine is fine at idle, but overheats when you hit the gas.

 

[mk3_ftw]

i will replace when the thermostat when i replace the radiator, and hoses. when i was changing the valve cover gaskets and replacing all vaccum lines i noticed one of the vaccum lines was disconnected from the sensor on top of the thermostat housing i doubt this was the cause but a good start for now. thanks for the help everyone

 

[LHargrove]

Is this the stock gauge or an aftermarket one?

Assuming the gauge is working properly, it is most likely a thermostat stuck open. There are really only two reasons it would "overcool": a) tstat open or b) bad gauge or sensor


I only wish I had your problem, mine is fine at idle, but overheats when you hit the gas.

And this is how the universe maintains it's balance.

 

[Eli]

well it depends how fast are we talking its dropping here? because temp sensors are like oil sensors, they're an electric resistor so if your needle is moving quickly (like two second quickly) my moneys on the fact that the temp sensor isnt wired up quite right. or is getting crossed with something thats leeching its signal.
i mean but this coming from a noob so take it with a grain of salt.

 

[ToySup88]

How quickly does the temp gauge change? If it changes slowly (many seconds), then the problem is a cooling one (thermostat, radiator, etc). The temperature of the antifreese changes slowly. If it changes quicly (1-2 seconds), then the problem is electrical (sensor, wiring, gauge).

I have a problem where my gauge changes quickly and haven't spent the time to isolate it yet.

 

[Gnome]

This should be similiar for the MKIII...
The MKIV's temp sensor is a thermoresistor that ranges from high ohms (cold) to low ohms (hot). My thi=ought is that the plug is loose or broken and wiggles under accel.

 

[mk3_ftw]

This should be similiar for the MKIII...
The MKIV's temp sensor is a thermoresistor that ranges from high ohms (cold) to low ohms (hot). My thi=ought is that the plug is loose or broken and wiggles under accel.

this is kinda what i was thinking. it drops way to fast for it to be the thermostat. where is the thermoresistor at?

 

[mk2racer]

In the thermostat housing, the one with a yellow wire.

 

[mk2racer]

I would laugh if it weren't true. Seems like I always end up doing the "balancing" lol, but my luck may have finally changed tonight!!

And this is how the universe maintains it's balance.

 

[mk3_ftw]

just changed the thermostat with all the hoses last nite. so as soon as my flex-a-lite fans arrive ill get it on the road and see if it helped if not ill start looking at wiring