New World Datsuns...

Radiator flushed, cleaned, holes fixed, no leaks. Its had coating put in it.
New thermostat
New headgasket

I know shrowds sometime make a difference, but I don't think this is solely the problem.

I can run around my aread all day and the temp needle barely gets above the second mark on the b.

If I cruise to portland where its more hot, or like the other day to bend where it's 85 + out the temp hits three quarters on the gauge. More or less half way on straight stretches, then three quarters up long hills.. If I cruise down hills for distances the gauge goes back down to a quarter or less on the gauge..

Now I understand how cooling system works, or at least I get the idea of it. Start car, it warms up along with the coolant, it reaches a certain temp and the thermostat opens causing water to flow to the radiator, wind gets sucked thru or pushed thru and cools it, sends it back thru the motor to help keep everything else cool.

Looking for knowledge here. Anyone pretty positive what it is? I am ready to throw money at it if need be.

I will say also, I put my hand on the fan and gave it a spin, it spun pretty freely. I'd think even though its a clutch fan it should have some resistance when the motor is off. I hear they disengage around 2k or 2500k rpms then the air flow from driving does the work.

There should be a bit of resistance with a fan clutch. The tell tail sign that that your fan is failing is if your temp goes way up when at a stoplight and it's fine when you are driving down the road.

The fan is not engaged by rpms. It's by temperature. If you are noticing temperature fluctuations, I would actually look at your thermostat because it should be regulating the temp. If it's all over the place it's possible it's not opening enough when needed. If it was stuck open, you would run cold all the time.

I should also mention I don't know exactly what the B clutch looks like, but in general.. that's how they work.

well i had a pro do my rad... Hoping its not that..

Ill drop in a napa premium thermostat, be 11 bucks out the door with new gasket... Cheap, only problem is I can't tell if it does any good till I get in a hot area...

I am hoping to take a week off and disappear, rather not be getting hot a thousand miles from home.

you didn't mention this so I'm just going to throw this up. Did you test your antifreeze with a ethylene glycol tester. If you don't have enough anti-freeze in the cooling system, it will cause your temps to raise. It might look green enough but it's not good to assume.
Testers are cheap, like a Datsun owner/s.

I was under the impression it was the other way around, actually. the antifreeze is there to keep it from freezing, and boiling. its the water that does the cooling. Too much coolant and not enough water will make it run hot...

Ive ran straight water in a few cars and never had issues. At one point, and I don't know if it was close, before, or what for this because I had the radiator done, then I replaced the thermostat, then I dumped the water out (what would come out) and dumped straight anti-freeze in... Thinking I would dump in a whole jug of antifreeze and a whole jug of water.. It took the whole thing of antifreeze and was full.. It got hot quick and I didn't have any heater... Then I dumped some out and added more water, the temp gauge came back down around town.... Recently I dumped what would come out, and put 50/50 in there then hit the road. Around town its a touch lower than before. but still climbed up to 3/4 over in Bend.

When I bought the car, it was fine. It ran about 1/4 of the way up the gauge maybe half way running hard up hills, but was fine.

I would assume the fluctuation you are talking about wouldn't be caused by the the coolant mixture. It would be consistently hot.. You could always take your thermostat out and toss it in a pan and boil it and see what happens. Cost: Free.

yeah it seems like when its hot out, or up hills and the motor is working hard.. I assume some of thats the coolant, since i had to much antifreeze in at one point, slowed down a bit when I mixed it better.

Then on long down hills she cools back off. Ill toss a new lower hose on since there is one in the hatch area, a thermostat is ten bux might as well just replace it and see.

There are two types of clutch fans. Torque coupling and temp coupling.

Torque coupling type use a silicone oil that cannot turn the fan above 2,000 rpm without slipping. The engine revs higher but the fan remains the same speed.

Temp coupling are used for air conditioning models and have a temperature regulation as well as built in slip. When extra cooling is needed more silicon oil is allowed, to increase the torque and speed up the fan to about 2,150 rpm. When not needed oil is removed and the fan slips and reduces speed to 1,650 rpm.

A shroud increases fan efficiency at low speeds like idle and around town.

At highway speeds there should be way more than enough air pushed through the rad just from vehicle speed so a shroud doesn't really help here.

Water holds more heat than anti freeze, or water and anti freeze. However antifreeze does raise the boiling point of water, so worth the slight loss of heat carrying ability. I would make sure you have the antifreeze tested and run what's recommended for your motor. You may still have 85% antifreeze?

Definitely change the thermostat. And don't run a 160. You should be able to run a 185 and drive through the desert all day if your system is working properly. The cooling system should be able to get rid of all the extra heat generated from hard driving in hot weather.

If everything checks out, next time it 'over heats' turn the heater and fan on high. If it goes down then your rad isn't doing it's job. What is this 'coating' you mention? Could it be acting like an insulation? and not letting the heat through to the metal rad?

datsunmike wrote:There are two types of clutch fans. Torque coupling and temp coupling.

Torque coupling type use a silicone oil that cannot turn the fan above 2,000 rpm without slipping. The engine revs higher but the fan remains the same speed.

Temp coupling are used for air conditioning models and have a temperature regulation as well as built in slip. When extra cooling is needed more silicon oil is allowed, to increase the torque and speed up the fan to about 2,150 rpm. When not needed oil is removed and the fan slips and reduces speed to 1,650 rpm.

A shroud increases fan efficiency at low speeds like idle and around town.

At highway speeds there should be way more than enough air pushed through the rad just from vehicle speed so a shroud doesn't really help here.

Water holds more heat than anti freeze, or water and anti freeze. However antifreeze does raise the boiling point of water, so worth the slight loss of heat carrying ability. I would make sure you have the antifreeze tested and run what's recommended for your motor. You may still have 85% antifreeze?

Definitely change the thermostat. And don't run a 160. You should be able to run a 185 and drive through the desert all day if your system is working properly. The cooling system should be able to get rid of all the extra heat generated from hard driving in hot weather.

If everything checks out, next time it 'over heats' turn the heater and fan on high. If it goes down then your rad isn't doing it's job. What is this 'coating' you mention? Could it be acting like an insulation? and not letting the heat through to the metal rad?

This was an AC car at one point.

IDK about the water/coolant... My case is stated above, had to much and it got hot. pure antifreeze is syrup like. added more water ratio had better results.
I can't recall what thermostat I put in there. When I had the radiator done and put to much AF in there i replaced the thermostat. IDK which temp I got it was a year ago. I think 185 or 195, those are the ones it lists for this car at napa.

the coating... Since the radiator had some rust and corrosion in it, they flushed it out and cleaned it up best they could and put a light coating in there, it keeps it from doing that again.

Alright.

Just got off the phone with the rad shop guy... AF does raise the boiling point, to keep the water from boiling and evaporating.. However, the water IS what (mostly) dissipates the heat. It does a lot better job at cooling the system then antifreeze. so if its in err of mixture heavy on the AF side, then it won't cool as much, but if its just a little on the heavy side it should still cool fine.

He is guessing the radiator is OK but will take a peak down inside it tomorrow for me. He also said it may just be an air pocket in the system so he will drill out a little hole in the new thermostat to eliminate the chance of air pocket or at least reduce the chance.

I'm hoping for an effective definite answer, which I know is asking for a lot. I just don't want to replace three parts and have it be something else, and then already be in it 50 bucks worth of money and then drop another 100 on a radiator...

What's he talking about? The thermostat is mounted vertically so as soon as it opens from the heat it will let any trapped air out. Think about it....

Mike dropping knowledge like bad trannies.

Good stuff and yeah, probably not air.. at least at that point.

I'd say have a friend rev it to 2,000rpm and check all hoses for collapse.

How's the radiator cap? And thermostat is new?
Maybe find a higher pressure cap.


For all of my cars I have a special Water Wetter/coolant/water mixture I use.
I love Water Wetter.


Has the coolant mixture been checked at all?

Just a few thoughts. GL.

Im going by his shop tomorrow. I didn't think there would be an air bubble, honestly.. lol... But worth a shot while replacing the thermostat. it was replaced a year ago but everyone says you can get bad ones out of the box maybe it was?

I'll see if he can dip a test strip in there to see aboots the mixture its running.

An air pocket would've bled itself out by now.
You have a fault somewhere.

If the thermostat opens but then sticks part way it would explain the faster you go the hotter it gets. I always have a spare thermostat around.

I love the new avatar, Mike.

datsunmike wrote:If the thermostat opens but then sticks part way it would explain the faster you go the hotter it gets. I always have a spare thermostat around.

Could be. does fine at 60mph in my area... Just hot areas like portland, or bend etc.. flat land or up hills there. Seems alright in my hood, even up hills... maybe a slight increase...

A definite solution would be tits Soon as this is taken care of, I'm putting in a time off request

could also be a blockage in one of the hoses. if they're not collapsing, pull em off and pour some water through em. if it just dribbles out the other end, theres your problem.