Skyline R33 Temperature Problem

[bastiaan45]

Hi guys,

I'm from the Netherlands, and read this forum regularly due to all its knowledge here, been very helpful many times!!

I do have a problem here, and cant find a solution. Please excuse me for not introducing before, i will do that gladly if necesary.

I have a R33 GTS T from 1997. Enjoyd it a long time.

Last week i noticed the temp did not reach normal level. Was not a big difference, but the needle did not reach the place where it normally was.

I put in a new thermostat. That is where the weirdness begins. I filled up with coolant again, drove a while, filled again so all air should be out of the system i'd say.

The temp reached the right position quite soon as it should, but heater took long to become warm. After like 15 mins of driving, i also have good hot air from the blowers. But, after like 40 minutes of driving, i noticed the lower radiator hose is still cold! The one that connects the radiator to the thermostat housing. It seems, the thermostat is not opening due to some reason.. The temp meter does not exeed the normal position, so it does not seem to be running warm. On the other hand, i saw the temperature sensor is in the top hose, so it does not measure coolant coming out of the engine, only that going in.

Also, my radiator gets warm, and the upper hose to, but just not the lower one!

Could there still be air in the system (wich i doubt) or is it my waterpump maybe thats gone? Could you please help me, i would not know where to start.. Maybe theres an easyway to test the waterpump? Or, do you know any other problems that cause this symptom?

[MatthewT85]

The temp meter does not exeed the normal position, so it does not seem to be running warm. On the other hand, i saw the temperature sensor is in the top hose, so it does not measure coolant coming out of the engine, only that going in.

ummm cant really help you too much, hopefuly someone can, but the top radiator hose, one where the temp sensors is is where the coolant comes out of the engine and into the radiator. Im pretty sure thats the way it flows...

[PN-Mad]

Last week i noticed the temp did not reach normal level. Was not a big difference, but the needle did not reach the place where it normally was.

I put in a new thermostat. That is where the weirdness begins. I filled up with coolant again, drove a while, filled again so all air should be out of the system i'd say.

The temp reached the right position quite soon as it should, but heater took long to become warm. After like 15 mins of driving, i also have good hot air from the blowers. But, after like 40 minutes of driving, i noticed the lower radiator hose is still cold! The one that connects the radiator to the thermostat housing. It seems, the thermostat is not opening due to some reason.. The temp meter does not exeed the normal position, so it does not seem to be running warm. On the other hand, i saw the temperature sensor is in the top hose, so it does not measure coolant coming out of the engine, only that going in.

Also, my radiator gets warm, and the upper hose to, but just not the lower one!

Could there still be air in the system (wich i doubt) or is it my waterpump maybe thats gone? Could you please help me, i would not know where to start.. Maybe theres an easyway to test the waterpump? Or, do you know any other problems that cause this symptom?

This sounds like air lock to me. Did you bleed your coolant system at all, or just re-fill it? Do you know the thermostat opening temprature, sure you got the right one?

First thing to try is bleeding your cooling system, this must be done with the heat on full hot. Put a bleeder / or some kind of funnel rig into the top of your rad, and let the car warm up. Keep topping up the coolant, and check for bubbles. There is another bleeding screw in the manifold I have heard of, but I'm not good with RB25 motors.

The waterpump is not the issue- because you would not have got 40 mins of driving with a broken pump without overheating.

Other option is simply its too cold out in your winter, and the heatercore is cooling the motor enough not to need the flow of the radiator.

[bastiaan45]

Hi, Yep, i also bled the coolant system. No bubbles anymore, filled up multiple times..

I do not know of any other bleeding screw in the manifold i must say.. I did not use that.

Also, i have a geniune nissan thermostat, 76.5 degrees, exactly the same that came out, and i checked it before in hot water, it works. Thats why after a ride like that, it should have already gone open, 76.5 degrees is not to high of a temperature..

[bastiaan45]

What also might be important, and why i could say its could be the waterpump, even after longer driving, theres no pressure on the radiator. I can just turn the cap of with hot engine, no coolingliquid comes out, no sissling etc, the cap just comes of and the cooling is exactly full.

Bled again today, no bubbles. Im a first mechanic, and have not seen this before, even with quite a bit of skylines.

Before i start changing all kinds of stuff, forums like this can be extremely helpfull i learned. Hope somebody can help, thanks!

[mad082]

how cold is the air temp where you are at the moment? if it is cold then you will always have one hose that is hot and one that is cold, this is because the water has been cooled by the radiator. if both hoses are cold then you need to worry, but from memory the hose from the radiator to the thermostat is the hose carrying the cooled coolant from the radiator. so it should be colder than the top hose

[bastiaan45]

Hi,

Well, it is quite cold here. Only few degrees above zero. Only even under that must be said. Thing is, i noticed a week ago that the temp meter was just like a mm under the normal temp, thats why i guessed the thermostat. I renewed it, but now i noticed the lower hose doesnt get warm, did not check it before.

Is there an easy way to check the waterpump of an R33 if it works? Thing is, that theres no presurre on the system seems weird to me.

Also, i do understand what you say about the lower hose, and that its coolant that runs from the radiator into the engine, where it has been cooled in the radiator, and with cold weather, will not become warm.. Is quite obvious actually. But, on about all other cars, the hoses both should become warm when the stat opens.. i have never seen this.. ALso, its weird the temp did not raise, even not after 30-40 minutes driving,.. So if i could test the waterpump, that would be great..

Also, it is weird that theres no pressure on the system.

[drunkn snail]

pic from google of the bleed valve

http://i73.photobucket.com/albums/i235/Neil_85/Misc/BleederScrew.jpg

try that first and if it still doesnt work properly then rip out the thermostat and take it for a spin, obviously it will run like shit in the tempretures you live in but it should be able to help eliminate some things

[bastiaan45]

Thanks for your tip! Will do that first thing tomorrow morning, and post the result here.

About the waterpump, how can i check this? Is no pressure on the system a pointer to the waterpump?

[mad082]

to check the water pump, take the thermostat out, connect it all back together and then take off the top radiator hose. start the car. if the water pump is working it should start pumping out coolant.

also, on a cold day, because the the temp of the coolant in the radiator is so cold, it will actually affect how much the thermostat opens. so it will take much longer for the radiator temp to come up and the lower hose to warm up. the colder air temp will also have a bit of a cooling effect on the engine just from flowing around the engine bay

[bastiaan45]

Thanks for your help guys.

Bled the system again just a moment ago. This time with the screw on the intake manifold. Bled it till coolant came out, and filled up the radiator.

The lower radiator hose gets little warm not. Still not hot, but i feel there is little warmth, when i left the car running while bleeding.

I think i should just blame it on the cold temperature. I must say, its -3 Celcius here today, so 3 degrees of frost, quite cold.

Temperature gauge stays where it should, i reckon after 15 mins driving and 15 mins idle while bleeding, all is okay, otherwise it should have overheated right? And i did not see anything on the meter, temp stays as it should...

[mad082]

yeah things will always be a bit different when you are talking air temps below freezing.