Digi7ech

iTrader: (1)

I drive 32 miles each day one way to work. About 28 miles are highway.

The engine is turbo and has a brand new waterpump and a Koyo radiator.

While driving normal in AZ heat(100+) I run around 1/3 to 1/4 on the guage.
I will get on the highway and after 10-15 minutes the temp will rise to 1/2 way and sometimes creep a few millimeters up on the stock S4 gauge.

It will not go down at all while driving on the highway(5th gear doing 80mph/no boost).

I replaced the thermostat last night with another OEM but it didn't work.

As soon as I get off the highway it will drop back down to 1/3

I don't have an airpump and the pump was slipping a bit during normal driving.
I put the yoohoo belt on it and the noise went away.
The yoohoo it loose though and is not adjustable.

I can only assume that my alternator belt is warming up and then slipping on highway constant rpm driving.

I've ordered a dual alt pulley but won't get it till Friday.

Any thoughts on what could cause it?

Possible belt slipping?
Stock fan clutch going bad??
Clogged oil cooler?

I plan on putting my Permacool Efan and Black magic temp switch on friday before a BIG drive down to Tucson so cooling is a #1 thing for me now.

Oh yeah BTW.
Is 45psi oil pressure on highway normal for a rebuild with 10w-40 oil?

Snrub

iTrader: (1)

Are you running an undertray?

I'm pretty sure 45psi is too low on the highway. I'm connected at 19.2kbps so I'm not going to look at the factory manual for you. Why are you running 10W40?

SureShot

First - A slipping belt is less of a factor at highway speed. Ram air will cool the radiator.

Possible causes:
Are the stock deflectors installed around the relays forward of the Radiator Core Support?
Is the Stock Bottom shroud still in place?
Are the Oil Cooler fins clear of debris and clean?
Does the Oil Cooler thermostat function properly?
Are the Radiator Fins clean of debris?
What ratio Coolant to Water are you running?

Digi7ech

iTrader: (1)

Well a slipping belt shoudl cause problems no matter what speed your at. Yes the radiator is getting ran air thus the stock fan is useless but the water pump is not moving the coolant into the radiator efficiently....

-The bottom shroud is currently not on but I can add it on tonight.
-Oil cooler is free of debri other than a small leak on the end which has caused some gunk buildup.
-No idea how to test the oil cooler tstat.
-Radiator is brand new and completely clean and free of any dents.
-Ratio is around 65% water to coolant.

I'm running 10w 40 because oit was all they had in non synthetic for now. The oil will be switched out in around 1500 miles any ways since it's a rebuild.

Should I go 20w/50?

SDrotary-FC

i don't run the under try and have no problems with my set up even in 100+ degree days, trying running a 0/20 spilt water/coolant. I run 10w40 as well and mine is much higher

Syonyk

Try that out. If the bottom shroud is missing, you'll overheat on the highway (or at least run hot) because all the ram air will just bypass the radiator, and the radiator fan will be trying to cool things. Path of least resistance and all that...

Also, I believe the suggested oil for RX-7s in warmer weather is 20W-50 (look at the FSM - the engine uses some insanely heavy oil).

I have a S4, and once it's warmed up with 20W-50, I get 30 PSI or so at idle, and 60 when over 2500 RPM.

-=Russ=-

mort2002

iTrader: (1)

i have similar problems but only on hills in the upper 90 temps. i have no undertray a brand new 180 therostat good water pump stock radiator, a ford taurus electric fan on high, and it gets to the point where i have to pull off of the road and let it idle and cool down. it cools off really fast though. i dont know the problem either.

poor_red_neck

Damn dude, that's some thin oil in there... In 90+ temps... I'd use 20W-50 and no thinner.

Your undertray taken off is also not helping you very much. Its one of those things that mazda just plain old engineered correctly. The front grille is basicly a semi "sealed" unit that flows straight through the radiator... the undertray also helps out more with your oil cooler... as its not such a large area as the radiator.. and isnt getting much air passing by it.

SDrotary-FC

guys i have'nt used mine for years with my koyo, my temps never rise over 1/4 even in 100+ degree heat, your problem lies elsewhere

poor_red_neck

Never said its causing the problem... I simply said its not helping matters much, and I'd use it just to give the oil cooler more air passage.

I know its not hurting much being on, that's all.

Digi7ech

iTrader: (1)

Well I can always do an oil change

I have the fram quick drain system so I just screw in a plug and it starts draining :P

I am debating if I shoud put my Permacool 16 inch fan in. You think it will help or pssibly hurt the situation?

Snrub

iTrader: (1)

The undertray makes a huge difference in cooling, again, I would bet this atleast a substantial contributing factor. A LOT of people who complain of mysterious high temps don't have it on. Look at the way that the rad is angled, it goes way back. The air that is forced into your car is looking for a easy exit. The engine bay is a huge restriction and the pressure is much lower underneath the car. Air will be sucked out even though it doesn't look like a very direct path. (think about how those horizontal mounted ICs work) Having the undertray on also improves your CD .01.

Digi7ech

iTrader: (1)

Well as long as I can find all the botls I'l put it all back on tonight.

I even have the tranny undertay ehhehe w00t to the S4 aero package!

Hollywood56

Check your timing.

WAYNE88N/A

Man, with all the stuff Digi's done to his car lately, if the timing's off he needs to be shot, lol.

On the 100 degree days here in Houston, i can do 75+ down the freeway at about 1/3 on the gauge, but after I gotta kick it in to pass an idiot, or if I have to follow an 18 wheeler for a while, it'll climb to 1/2, then slowly come back down when I get the airflow going into her again. This is with the underbelly pan on, no fan (only turn my e-fan on at stoplights & ATM's), and completely new coolant system. So, moral of the story is, 1/2 gauge is normal on a 100* day, Digi

Hollywood56

Yes it is wayne...lol....my 88 gxl does the same thing.

Smoken'

iTrader: (1)

maybe your running lean at that rpm range...

Digi7ech

iTrader: (1)

Lean at 3krpm? I doubt it.
I'm at zero boost(no boost but almsot out of vacuum)
I have a walbro pump and my fuel rail is doing 45psi at idle.
The timing is dead on.

I put my undertray on tonight and will hope it helps out tomorrow when I drive to work.

SureShot

You might also want to check the fan clutch.
After 100,000 miles the bearing seals inside wear, and the bearing lube starts to weaken the clutch fluid's grip.
Both the S4 & S5 clutch freewheel when cold.
The s4 clutch increases it's bite gradually with temperature rise.
The s5 clutch is more on-off. (It just coasts until is gets warm)
Once they are warm, the fan speed goes up with engine speed to about 4000 RPM.
As the engine revs higher the fan stays at ~4K.
If your warmed up fan only revs up to ~2500 RPM, it's bad.

BDoty311

My car does the same thing, it will run nice and cool around town, but once I drive for awhile on the highway it starts to run hot. Once I go off throttle for about 10-20 seconds, it will drop back down to around 180-185. I'm sure my air hogging FMIC isn't helping anything either.

Ol-Skool

Just a small peice of advice, if you are thinking about running a thermo fan instead of the standard clutch fan, dont.

Nothing will beat the clutch fan for cooling, i cant remember reading above but if you have removed the radiator shroud for any reason, i would recommend putting it back on as it makes a huge difference imo.

Check your tune, have you changed it recently, have you made it run more lean than you used to have it to get more power out of your motor. When a motor runs rich it will help cool the motor down too aswell as help safeguard your motor from detonation etc.

luck!

Digi7ech

iTrader: (1)

I am getting the car on a wideband Saturday for AFR verification.

I am going to shocked if I ever see lean areas. I have cleaned and tested 550's A walbro fuel pump and I have a pressure gauge. I run 45-50psi at idle so I highly doubt I'm lean.

My timing is dead on. I know it. Like Wayne said. If it's off I need to be shot

I understand that the stocker is great. I know from first hand experience.
I will switch later on to Efan t5o clean up the engine bay and get rid of that huge thing.

I have a Permacool 2950cfm fan and a Black Magic temp switch.
I will fiberglass a shroud for the fan once I put it on my car.

I drove to work today with the undertray on and so far it never went over 1/3.
I didn't get a full test though due to jackasses doing the exact speedlimit in the passing lane.

I'll try it out tonight as well.

I have not altered anything for more power out of my car yet.
It is rebuilt and is about to hit the 1000 mile mark. I have hit 5-7psi once by accident but that's it.