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morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

My car has a bit of an issue...possibly because of the FMIC or maby because of my big ass front spoiler...or maby its not really a problem....in any case i'm interested in improving the cooling system because what i'm after is engine longevity.

the issue is that on hot summer days if i cruise at higher speeds(above 130Km/h) the water gauge needle will climb over the midle of the scale. the faster i go the higher the wather climbs. i havent tested going to the limit...i did 200+ for a couple of kms but never more...and the gauge needle climbed over the midle and almost reached the next division line (the one before the RED area)

I'm thinking to install a dual fan system on the water radiator.
-What are your expiriences with these things? are they worth the hastle?
-Is there a bolt on system that one can buy?
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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

What do you mean dual fan? Does yours only have one fan? If so, I'd most definitely upgrade to the dual fan shroud, just need to find an A/C equipped donor car. Bolting in should be no trouble, the biggest challenge will be proper wiring.

Alternatively, if you're going to go to the trouble, why not just get a high capacity aftermarket fan like a Spal or a Davies Craig?
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morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

mine has only one fan..in UK this was and probably still is not a problem..but here the climate is way hotter.

would a dual fan system from a 944 bolt on?

i have no problem going aftermarket with the fans, wiring will not be a problem as it will be handled by a shop.

i'm going to look for those aftermarket fans you mentioned...thanks
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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

No, the 944 dual fan shroud is not direct bolt on, but the profile is the same, so you should be able to adapt it with some creative fabrication. Frankly, I wouldn't bother with that approach...I'd either get a stock dual 924 setup for complete bolt on, or go with a completely custom aftermarket setup.

But, speaking of 944s, the other thing that might be worth considering would be to swap in the larger 951 rad + dual cooling fan. It's not direct bolt in, but it shouldn't be too hard to adapt. Take a look at endwrench's guide to Installing a 951 radiator.
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wombat · Posted: Mon Aug 03, 2009 10:16 pm Post subject:

I would say a dual fan should help alot. Two things lead me to believe this 1: My 924 has a dual fan and it appears to be the standard. 2: The hated work truck that keeps breaking down used to do a very similar thing but only at between 80-100km/h it would climb to the edge of the red zone at 200*F so I changed out the fan for a bigger dual unit and it now sits at between 150*-175*F. I think that it has something to do with air folw at a higher speed because in 5th it is doing the same RPM at these speeds as it is in 4th at 70 and it keeps cool at 70 OK???
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RC · Joined: 25 Mar 2007 Posts: 2637 Location: Australia

Stock dual fans or aftermarket multiblade dual or large single fans may make an improvement in situations where airflow through the rad is limited, such as stuck in slow traffic or running stationary in the garage. There is no way they will move more air than driving at 100Ks+. In fact, at even much lower speeds they will be an obstruction to flow, running or not.

Your gauge reading does not appear to be unusually high, even with a FMIC. Both prior to and with a FMIC installed my gauge reads cooler the faster I go. Highest was the 3/4 line (one below red) reached while traveling slowly in low gears, stuck behind a semi, on a long and very steep mountain range on a hot Aussie day. Admit I was anxiously eying the gauge creep up but quickly dropped after I eventually passed the truck and gave it some. Actually at 200+ for at least 1/2 hour stretches it never gets past 1/4, the first line.

Possibly you have partially blocked rad cores or block, circulation or coolant issue, retarded ignition timing, incorrect mixture, or another cause of hot running at speed. A larger rad won`t hurt at all even if it doesn`t help much. What value thermostat and fan switch are you using?

It`s been recommended that the IC & rad should be sealed with a gap of an inch or so between them. Works well in my experience.

Smoothie brings up a good point that I just read in another thread:

Scorpio · Posted: Tue Aug 04, 2009 3:51 am Post subject:

+1....I think you may have another problem...at 200km/hour ide be guessing you have more than enough airflow...
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gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

I don't think you have a problem (my 81 924 came with ac and dual cooling fans, and ran normally at over the half mark (close to 3/4) on the termperature gauge before I changed parts).

This is way hotter than my 77. I switched the 77 924 to the 180F thermofan switch and thermostat after I replaced the headgasket, and never had another problem with overheating (normall ran at 1/4 mark on the temperature gauge after changes.

Now, I'm running an aftermarket heavy duty radiator marketed by Performance Products under the Autotechnic label (dropped the coolant temperature by one hash mark), along with a 180F thermofan and a 180F thermostat, and Redline Waterwetter.

The temperature gauge now sits at just over 1/4 mark with the ac off, and close to 1/2 mark with the ac on.

The stock thermostat and thermo fan switch are 195F or 200F here in the U.S. 180F and 160F alternative parts are available, and I tried the 160F parts, but found that they are too cool in the winter. Sitting on Interstate 5 in a traffic stoppage during snow conditions, there wasn't enough heat to defrost the windows, or heat the cabin at all. So I had to remove them.

I would say try the first thing to do is add the stock dual cooling fans from a later 924 or 931. Wire the 2nd fan in parallel to the main fan of it will run anytime, the main fan runs. Then add the 180F thermofan switch and thermostat. Then, if you want to run a little cooler, swap to the 160F thermostat. Don't add the 160F thermofan switch unless the car is running real hot with the 180F thermofan switch.

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

in the city or driving slow it has absolutely no problem whatsoever..gauge never goes past the half even in a hot summer day behind a truck or at the stoplights.

dont know about the thermoswitch or thermostat as i never looked...i've bought a new 82°C thermostat anyway..maby i'm going to swap that in.

IC is way more further away than 1 inch from the rad..

having trouble finding a way to aproach this issue...i dont want to drive the car that fast more than i do now..but i want to know that if i want to or if i have to it can handle it without problems.

what i'm thinking...

-thermostat jammed halfway open
-crappy water pump(installed it 2 years ago) as a barely used part from my NA engine..normaly this should be no problem..but i'm just thinking outloud.
-stuck radiator

going to start by installing a new thermostat, thermoswitch works perfectly...install a dual fan shroud..
then if still hot...a new water pump
and in the end..if nothing fixes it i'm going to take out the radiator and sent it to a shop for cleaning and pressure the cooling ports inside the block.
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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

gohim · Joined: 02 Nov 2002 Posts: 4459 Location: Rialto, CA

There usually isn't any problem with 924 and 931 radiators clogging up because they are 100% brass, unlike the aluminum and plastic radiators of many other cars.

Unless you were running conventional coolant (containing phosphates and silcones), which could have caused deterioration of the cooling systems alloy components, I would do the dual cooling fans, the thermofan switch and the thermostat first.

Rocco R16V · Joined: 03 May 2009 Posts: 497 Location: PNW

morghen · Joined: 21 Jan 2005 Posts: 9095 Location: Romania

thanks for the help guys,

today i'll swap in the new thermostat and see what thermoswitch i have.

but ideola has a good point there...the trouble is i dont have one of those gauges....i'll try to have one shipped from somewhere.

the add for the dual fan shroud is posted...
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ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

pocketscience · Posted: Tue Aug 04, 2009 9:27 pm Post subject:

Dan, Dan, Dan - you obviously didn't read all of Corky's book did you?? He talks about turbulators at length

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