Termostat problem

[s14unimog]

I replaced my thermostat today and turned my car on to see how everything went... well the car started to over heat pulling out of the driveway, so I popped the hood and felt the lower radiator line. Cold, no biggy maybe a defective thermostat. took out the termostat, tested it, worked, reinstalled, overheated. So again I felt the lower line, COLD!!!! :confused: WTF, I am racking my brain to figure out wtf I'm doing wrong. Does anyone know what I'm missing? i know its a pressurized system so I filled the block with water, waited for it to bleed through the top of the termostate and put the lower hose on really quick, and its still fu*king over heating. Anyone?

[s14unimog]

hopefully we have some late nighters up that want to help me out because its 11:30 here and I have work in the morning.

[zero.counter]

When you replaced the thermostat, did you remove all of the gasket material so that the thermo was making a good seal?

[s14unimog]

yeah i scraped both the block and the thermostat housing clean before reaplying more RTV

[zero.counter]

Bleed any air out of the system and even though you tested the thermo, see about replacing it once again as a precaution...

[projectRDM]

Jack the front end up as high as possible. You'll never bleed the air unless it's pushed past the thermostat and into the radiator.

[s14unimog]

Russ, connect the lower line onto the thermostat housing and to the radiator and jack the car up? I'm thinking its going to have to get pretty high to flow all the air all the way into the radiator. I'm also assuming us a hose while the car is in the air and blow water through the top line to blow all the air out? Why does it have to be this fu*king hard to change a damn thermostat?

[Rezlo]

Doesnt your thermostat have a bleed hole? if it does you shouldnt have air pocket problems. (remember to put the interiour fan onto hot to help pull air out the coolant system)

What messed me up real bad a few times with my blown mitsu V6 was the temp sensor failing, it was like the engine would heat up REAL fast according to the gauge yet i had no presure or heat in the hoses, turns out AutoZone and Napa sensors suck and fail fast :)

How long does your car run before the needel says its overheating? and does your interiour fan run cold or hot in the hot position when u do this.

If that fails maybe start looking at your waterpump.

[projectRDM]

Yes. Leave all hoses connected, remove the radiator cap, and jack the front end up. Start filling from the top with the bleeder cracked and continue until water is pushing past the bleeder. Rev it numerous times while filling to keep the water flowing fast enough to pressurize the block. It may take up to 20 minutes.

If you ever open the cooling system again, keeping it up sitting uphill or jacked up will usually eliminate any serious air pockets and eleviate the added steps needed to bleed it fully.

[s14unimog]

my car warms up to perfect operating temp (according to the stock guage) in about 30 sec. to a minute and will stay there until i move the car around.. I'm assuming it stays there b/c its 40 degrees outside and when I turn on my heater its warm but far from hot

Russ,

When you say leave the bleeder cracked, you mean bleeder at the bottom of the radiator.....?

[Rezlo]

Temp sensor garanteed

[420sx]

yea your temp sensor is fucked. its not overheating, its the sensor. i can bet money on this one.

[projectRDM]

No, the bleeder bolt on the intake manifold.

And guys, if the lower radiator hose is cold (like mentioned) then the thermostat isn't opening, that's got nothing to do with the temp sender or gauge. You can bet all the money you want on it but you'd be wrong.

[Rezlo]

And guys, if the lower radiator hose is cold (like mentioned) then the thermostat isn't opening, that's got nothing to do with the temp sender or gauge. You can bet all the money you want on it but you'd be wrong.

Ill bet you $10 on paypal,

It is IMPOSIBLE that his car gets to opperating temprature from cold in 30 seconds.

Which leaves the coolant sensor to blame

[projectRDM]

Ill bet you $10 on paypal,

It is IMPOSIBLE that his car gets to opperating temprature from cold in 30 seconds.

Which leaves the coolant sensor to blame

You're talking about two different things. Are you betting that the car doesn't reach operating temperature in 30 seconds, or that the overheating problem is the temp sender? That's the original byline of the post and that's what we're all talking about. You're right that 30 seconds isn't even close to warm up time and the sender or gauge is bad, but that has nothing to do with the lower hose staying cold and the car overheating, which is the topic at hand. You could plug the sender hole with a tampon and still overheat if the thermostat isn't opening.

And I wouldn't bet a dime using paypal unless I wanted to pay an extra 20% back in fees and have my inbox flooded with spam mail for a month.

[Rezlo]

From the engine standing cold the gauge saying its at OT in 30 seconds from start up is imposible (on the engine side of things) It takes FAR longer to heat up even if the the thermostat was completely blocked off.

I have had the Identical thing happen, his lower hose isnt warm yet because IT ISNT WARM CAR HAS ONLY BEEN RUNNING FOR 30 SECONDS, THE GAUGE IS INCORECT "IE THE SENDER IS TOAST"

Man, is 420sx and I the only ones that can read or trouble shoot?

FYI the heat from the combustion chambers will only start to heat coolant up in about 60-90 seconds of the car running, most cars thermostats wont open till about 5 minutes of running, that is why 95% of thermostats have bleed holes so the pump doesnt cavitate and the hot coolant can run from around the sleeves and head towards the thermostat so it can open. The lower radiator hose should only warm up after about 2 minutes or more of the car running, not 30 seconds.

Thats kinda basic, the car isnt overheating, the gauge is incorect.

[s14unimog]

thanks for all the help guys, I replaced the temp sensor and the car didn't overheat. I should have not relied on the stock gauge for a reading...the guage said "H" so I shut her off and the lower line was still cold b/c the car never had a chance to warm up. thanks for the help again..Zilvia is a great trouble shooting tool!