240Z--Is This (4 cooling fans) An Over Kill? - Nissan : Datsun ZCar forum :Nissan Z Forum: 240Z to 370Z
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post #1 of 13 (permalink) Old 06-09-2014, 05:49 PM Thread Starter
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240Z--Is This (4 cooling fans) An Over Kill?

It is 102 degrees in Vegas. I just took my 240 out for a run, with new AC on, to see if it still runs hot. It does, according to a thermocap that I have on it reads 200 idling after the run and 220 with engine turned off. It would not start after turning it off. The see-thru fuel filter is empty. I have not tested it yet with the AC off. Does the empty see-thru fuel filter indicate vapor lock? Are vapor lock and heat soak the same? I replaced the thermostat with a 160 degrees. I will replace the thermocap with the regular nissan rad. cap and see what happens. The thermocap and a 1/4" mesh wire front grille are the only things that I have done to it since my test drive two weeks ago on an 80-dereee day with almost perfect temperature-gauge reading...in the traffic on the Vegas Strip. A rebuilt harmonic damper, new distributor, and a new turbo oil pump have been installed. My Z us virtually stock...no headers. I did not attempt the Strip on the last run. Thanks, Ernest
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post #2 of 13 (permalink) Old 06-10-2014, 12:46 PM
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Internet just ate the definitive answer to your question...

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post #3 of 13 (permalink) Old 06-10-2014, 05:00 PM
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Originally Posted by Goldie240 View Post
Does the empty see-thru fuel filter indicate vapor lock?
Maybe... I don't have much experience with vapor lock.. But I don't think so. I think the fuel coming in to the engine bay WAY over by the fender should never get hot enough to evaporate.I think vapor lock happens in the carbs mostly due to their placement over the exhaust manifold.

I think you've got a clog somewhere. Or a fuel gauge that's not telling you you're empty. Don't laugh. It's happened to me.

I just went through **** trying to diagnose a fuel delivery issue that I thought I solved when I changed the filter between tank and electric pump. It would run, then run rough, then stall when I really drove it. Then start again etc.. I kept blowing out lines, cleaning carbs, changing other filters (engine bay) etc.. The filter between tank and pump was in backwards.. :\

An ill timed or incorrectly timed engine will run hot. And have starting problems.
An engine that is too lean will run hot and have starting issues as well.

Start from the very bottom with your diagnostics.


If the carbs are slightly clogged or the needles are a little sticky it can run then not start again too. It will start and run sipping fuel, but suck the bowl almost dry. Then you go to start it and it's no good. Make sure your fuel delivery is 100% on point before you go nuts with cooling fans.

1971 240z HLS3014364

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post #4 of 13 (permalink) Old 06-10-2014, 09:49 PM Thread Starter
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Thanks joeytekno; I will look into the possibilities that you mentioned.
Tony D. when you get a chance, "shoot" it back to me again. Thanks to both of you!
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post #5 of 13 (permalink) Old 06-11-2014, 09:42 AM
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My basic gist was "that's not so hot"

It ended with do you have the stock fan, shrouds and clutch on the car? As I've gone through Vegas when it's a lot hotter than that with only a three core radiator and all the rest bone stock save for the 160 thermostat and water wetter and was rarely over 185-190.

The water is not spitting overboard and you're going to the middle of the "M" in "TEMP" which will not be an issue if you have:

Water Wetter.
Proper Anti-Boil (60/40?)
16 or 24# Radiator Cap
The aforementioned fan/shroud/clutch assembly in 3-Core (or better) radiator,

The fuel? That you gotta live with, put a pusher pump in back to prime the mech pump

Now girlfriend calling me for massage, so voted out again, sorry Dude!

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post #6 of 13 (permalink) Old 06-11-2014, 01:48 PM Thread Starter
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Thanks Tony D. I do not have the stock fan, clutch or electric fuel pump. I have the thin shroud/housing that came with the dual electric radiator fans. I have only the 2-core aluminum radiator, 13 psi radiator cap and 50/50 coolant with no water wetter. Maybe, I should do all that you mentioned, bite the bullet and buy a 3 or 4 core radiator and reverse the fans polarity and move them to pusher position for clearance (although mine has only about 200 miles on it). If it would accommodate the 4-core, that would be my preference to maximize the volume for once and all, since I am in the desert. I want to enjoy driving the car. At some point, after your nightly massage, let me know if we are on the same page. I am lucky to get a good back scratch, so enjoy .
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post #7 of 13 (permalink) Old 06-11-2014, 05:51 PM
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50/50 is for cars in winter that will see temps approach freezing.

Here's the thing with coolant mixes. Nothing cools better than water. Except MAYBE water with water wetter added to it. I'm not sure and I'm using things I havent studied in a long time here. But When they measure the specific heat of materials and fluids water is the scale they use to measure it against.

So 50/50 robs some of the cooling ability from your system. BUT the properties of the coolant will change the Boiling temperature of the fluid.
Straight water boils at 100 degrees C or 212 F.
A 50/50 mix will be up around 230 degrees F.
So it is helpful to have coolant in the water IF you plan on letting your water get over 212F to begin with. So there's a Thermodynamic problem here. If you use all water can you keep the temps (give a 10% safety factor) below 190 degrees F?

If you do add coolant you lose some of the ability to cool the engine, but raise the BP.. Hmmm... Tough one. I don't remember my Thermo equations or formulas at all except
PV=nRT from Chem which I tutor sometimes..

What that basically says is Press.*Volume=n(constant)R(constant)*Temp.
So if your temp goes up either your pressure will go up or the volume will go up.

Once water or a coolant mix is changed to a gas (the only way the volume can go up) the specific heat changes. Now you're in trouble.

So you've got to be able to contain ad maintain your system at a higher temp to avoid boiling. So can you do that with all water?
Can you do it with Water Wetter and Water? Experiment and let us know.

Also maybe temp gauge and thermo cap arent accurate. Use a meat thermometer and or laser thermometer.

My temp gauge is WAY off. I'm on the P in temp when I'm at 200 degrees. I know this is fine, yet it's still unsettling.

Almost my whole post is basically reiterating what Tony D said. I really only banged out all that stuff above to see if I could still explain it properly and I'm not sure so googling "antifreeze mixes and boiling points"
got me this site which I haven't vetted but looks ok at first glance.

http://hellafunctional.com/?p=629

P.S. A lot of what water wetter does is removing the cohesive properties from water. Water is a trip. It's natures best coolant, and is both cohesive and adhesive. Adding soap to water removes the cohesive properties as well. This is really useful if you've got stagnant water with nothing living in it but Mosquitoes. If you add enough soap they can't land on the water and lay their eggs.

1971 240z HLS3014364

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post #8 of 13 (permalink) Old 06-12-2014, 01:32 AM
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So you've got to be able to contain ad maintain your system at a higher temp to avoid boiling.
got me this site which I haven't vetted but looks ok at first glance.
http://hellafunctional.com/?p=629
Not a bad treatise on the subject. To your cranial tech library you might want to add the boiling points of the mixes.
http://www.heat-transfer-fluid.com/p...ling-point.pdf
On some engines that are, say, running very lean you could get hot spots in the heads/block that might boil pure water locally but which would collapse as the bubbles moved/cooled to a cooler location. In effect, the radiator/temp sensor wouldn't see it but the collapsing/sucking bubbles (cavitating) could do long term damage by removing material in the coolant path. [An unlikely, long term possibility]

There, I've typed out my own cranial tech just so I could.

If you're running hot anyhow, the cavitation could reach the radiator before they collapse as the liquid cools. The radiator is thin and may not like the pitting over time.

zippityzda

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post #9 of 13 (permalink) Old 06-13-2014, 07:59 AM
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The guys running water/water wetter use 24# caps.
Add to this the added pressure in the block from the pump, and you're running water pressures in the block and head closer to 60psi at high speeds.

Then you slow down to idle. Water flow stops, and your pressure--which formerly was 60psi...quickly drops to static cap pressure plus whatever you get from the pump (so maybe 30psi if that, at idle.)

So, what do you think happens to the boiling point of your water?

Remember what happened in class when you put room temperature water in the bell jar and pulled a vacuum. That was roughly a change of 15psi. The water went from boiling at 100C to boiling at 21C.

Then, you stuck that frog in there and started pumping...

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post #10 of 13 (permalink) Old 06-13-2014, 08:04 AM
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Please consult the Grape Ape Racing articles on coolant and what happens. It's pretty much a definitive explanation on the subject, and the formation of nucleate boiling spots (and the suppression thereof) are major concerns in the L-Engine.

If the engine goes 'runaway' meaning holding 190 driving, but overheats and then can't cool back down without shutdown...you have runaway - llikely caused by nucleate boiling in the back two cylinders of the head.

If not, then you simply are running hot. And those temperatures are not 'hot' IMO. Especially with the proper anti-boil mix. The best thing you can do at this point is raise your static pressure to supress the microboils that may happen... if you can do that, you shouldn't have a problem with the engine at any time.

Then you just work on your fuel problems. I chose to run a 160F thermostat because everything under the hood stays cooler, and it helps keep the fuel from boiling at inopportune times.

What has been will be again, what has been done will be done again; there is nothing new under the sun -- that means
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