Is using the Palm via my Rtek 2.1 to monitor coolant temp the best way? Dont want to rely on stock S4 gauge, with S5 sensor. My car runs hot, 203 to 208F sometimes up to 216F below 5K rpm. Last weekend took it on a short freeway run ( below 5K), slight up hill it hit 232F oops. Air temps 75 to 85F let it cool down at the off ramp. Then took it real slow back to the house. Just idling it will cool back down to 185 in about 7 minutes. Air temps 75 to 85F, been watching while I drive and logging temp. Every thing I do to fix it has no effect on bringing temps down. stating to wonder if the values on Palm are correct.

Items changed; New OEM size Brass/Copper radiator. Installed Thermostat out out my old NA keg, that brought idle temp to 180-185F. Removed FMIC ( installed a test pipe, not trying to boost it right now.) Under tray install, however, tried one drive with out it and made no difference. tried filling/ ducting space around air path. seem to make it worst. When the car was NA, temp gauge never went above 1/8.

Engine is running strong and is up to 200 miles on rebuild, Fuel map under vacuum is a touch rich. cruising around AFR are 13.1 to 13.6 in most cells. Using MAP base timing, Arghx 9.4 Map. Vacuum at 750rpm idle is 14.5 inHG

 

What fan setup and what do you know about the condition of the waterpump?

 

as simple as it sounds, and so often overlooked is fan direction of rotation and the polarity

it must be pulling if fitted behind the rad,,
and that means not just with the motor polarity turn direction.. but also having the blades in the correct orientation
( many brands allow you to flip the fan assembly over.. those except spal )

asided that.. and if it runs hot with FMIC temporarily removed , then would look hard at the timing
.. and being sure the thermostat bypass is closing correctly

if you now have a s5 water pump and assembly,, and have fitted the s4 thermostat,, then that is the problem right there

s5 waterpump uses the FD thermostat and rubber ring

 

I'm using the stock fan and shroud. At idle, it stays between 180-185F. The front cover, pump housing, water pump are S4. It has a cast impeller. If I remember there was some pitting on the impeller. It was bought used with some other parts from a member. I have an new OEM thermostat on its way from Atkins. I was thinking timing as well. I used S4 pullys and timing marks line up.
Sidenote, with the test pipe in place I can hear the turbo spooling SWEET sound.

 

viscous fan?

if air pump delete then first would make sure you have a yahoo belt ( 10a 550 ) to eliminate the water pump ( and fan ) slipping

then would look closer at viscous fan coupling as it may be shot

 

Yes, airpump deleted. I'm using the S4 stock clutch fan, and a double pully on altenator with two belts. Could still be slipping? I'll look into the yahoo belt system, as I'm not familiar with it.

 

Easy test for the fan thermoclutch:

Car OFF and cold- spin fan by hand, note resistance (effort required)
Car HOT (20 minute test drive) but OFF- spin fan by hand, note resistance...which should be more.

The clutch is supposed to "lock up" (it never does, really) as it get hotter, spinning the fan more and drawing more CFM. There are two failure modes, it either locks up entirely (which is noisy and draws more parasitic power but should cool OK) or it won't tighten up at all, so fan still spins but won't increase the air draw.

 

Thanks , I'll take it for a drive tonight after work.
Does the oil cooloer thermostat ever stick closed? would that make the water heat up? I'll do the touch test on the cooler, should be as hot as the radiator right?

 

It'll be hotter.
The oil tends to run 10-15° hotter and react about 20% slower than the water circuit.

 

Say your out on a Mile High drive or Down Under, on the freeway and outside air temp is 85F or 29C, what is your car's water temp?

 

You talkin' to me?
(channels Travis Bickle...)
If so, on the freeway I'd expect to see 180-190°F, depending on speed.

 

The most likely suspect is the fan clutch. At those kind of temperatures you should HEAR the fan clutch locking and it will sound like a small hurricane under the hood.

A lot of people overlook it because there is a myth that the clutched fan does not pull in cooling air while the car is in motion. This is entirely false and has lead to many hours of frustration and blown up RX-7s.

If I were you I would start by buying a cheap infared thermometer and measure:

Engine temperature @ block
Coolant temperature @ radiator inlet
Coolant temperature @ radiator outlet
Oil temperature @ cooler inlet
Oil temperature @ cooler outlet

Measure both at idle and after the car gets hot on an uphill drive.

We can use those numbers to give you a better idea of where it's failing. It is important to measure the oil temperatures because rotaries unlike other cars shed a very large percentage of heat through the oil cooler.

 

great info. I'll be working on testing and collecting data. I can barrow a good infared gun from work.
I to believed the myth. will be checking the clutch fan very closely.
reporting back soon.
Thanks

 

Took the car for a short drive to this evening. With air temp of 60, I was only able to get the coolant temp on my Rtek to read 189.5F The clutch fan had less resistance after than when I started the engine cold. I could easily stop the fan with my finger while the engine was running. I'll be installing the spare one I have and see if any better.

Fall temps are apon us here in Oregon, may have to wait for the next hot day or a long
uphill section of road to collect some good data.

 

That is dangerous as hell, but a good indicator that it is not functioning correctly.

 

Stumpy the Mechanic agrees.

 

At least use a stick, not your finger. Or thick gloves.

 

I don't fully understand this statement. If you are talking low speeds say 30mph or so then yes I can see where this makes sense. At that speed and below the clutch fan will pull in cooling air. At highway speeds though you don't need a fan of any kind at all. That's why you put e-fans on a thermo switch, so they don't run at speed when they are not needed and actually block airflow if they are running.

Since his original problem was on the highway I would think it is elsewhere besides the fan.

 

Agree with first paragraph, but disagree that he does not have a problem with the fan.

First off, just in case anyone gets a bright idea from this thread...

DO NOT STICK YOUR FINGERS IN THE FAN WITH THE ENGINE RUNNING!

He obviously has an issue with the fan clutch since he stopped it with his bare hand with the engine running. I do believe he has more than one problem with the cooling system because at highway speeds, he doesn't need the fan. I believe the issue with high temps at highway speeds allowed him to also find that he is about to have issues at low speed due to the fan clutch.

 

But sometimes you can stop a good fan with your hand( not recommended stick would be better). Like when you first start it and everything is cold. If you've came in from the highway maybe due to the airflow over the clutch as I thought it should freewheel at highway speeds when not needed to reduce its load on the engine. I don't know. Ditched mine a long time ago so I can't test it. In his first post though he said "Just idling it will cool back down to 185 in about 7 minutes." I took this to be from 216F to 232F. If the fan were bad I would think it wouldn't cool down while sitting and idling as that's when you need the fan most. All this clutch fan talk/confusion on here lately makes me glad I don't have one.

 

From my experience, our engines will not get to operating temperature while idling, and by that i mean true operating temperature. That's why when trying to adjust the TPS correctly, the advice is always "go out and drive the car, idling is not good enough".

Of course the engine will cool down some while idling, because it isn't under load. His clutch fan still works, but we aren't talking about an on off switch. It can fail in 2 ways...

1. starts leaking and the silicone fluid leaks out, slowly diminishing cooling capacity and ability for the thermostat to regulate the fan.

2. Thermostat on the front of the fan fails and it runs at full operational capacity at all times.

I replaced my fan clutch 4 years ago with a brand new one and ouch ouch ouch to the wallet. The reason I went that route is because you can't beat the shear reliability of it. My 7 is a daily driver and it needs to work all the time, so I didnt go with an e-fan setup, even though I'd prefer one in most cases.

My point anyway is, I know from my own personal experience with a brand new factory fan clutch, there is no way in hell you are going to be able to poke your little finger out and stop it without losing said finger or really screwing your hand up.

He obviously has a fan clutch with diminished capacity which he found due to the symptoms of another problem. He still has the factory radiator and its probably clogged and the end tanks with microscopic cracks allowing air in. He is replacing that radiator with a koyo and I bet that fixes his issue, but with the fan clutch getting weak, he is going to have another problem in the imminent future.

 

A few things about the thermoclutch:

A brand new OEM FSM spec clutch never fully locks or unlocks. IIRC, the spec is something like 30-80% and of course, they want you to uncork your spring loaded "fish scale" (which nobody ever has) and measure pull at various temps...which has never been done outside of the manual's photoshoot session.

Yeah it would be nice if it freewheeled on the highway.
Shame it has no way of knowing where it is or what it's doing...the only variable it responds to is the temp of the bimetallic coil on its front and that is crude, third hand information.

The stock system works through brute force.
It's a big, deep fan blade design pulling through a pretty nice shroud...it's not smart but it moves a lot of air.

 

That is correct clocker.

More information of how this works via the department of defense, before the torque converter was invented...


And remember, holding the shaft helps with the fluid coupling process.

 

They will get to operating temp without the clutch fan. If mine sits long enough idling my autometer gauge will eventually get to where it normally runs. Since I have an E-fan there is no airflow over the radiator until it kicks on unlike the clutch fan where you may always get alittle as clokker mentioned.
If done right an E fan is just as reliable. I've had mine 14 years and it has been daily driven most of that. But that is an argument for a different thread.

I guess I worded that wrong. I understand it never truly freewheels but it would have less resistance and be more easily stopped.

I won't argue anymore about the clutch fan. I still beleive that since he is overheating on the highway it is another issue( on the highway). You are right it could be on its way out and was found while trouble shooting another problem.
Also I think you've got this thread confused wit Rotary Bobby's thread where he has a similar problem and mentioned a Koyo. This guy as an OEM style brass/copper radiator, which I had for a few years and thought was barely adequate at cooling my n/a.

 

Think I'll swap the clutch (because I have a spare 160K one) Saturday morning and take it up a long uphill. With all ten fingers. Reporting back Saturday evening.