Since I've seen temps already rising when driving through some mud in 4l, a cooling upgrade becomes temptive.

This would be upgrading to the '97 setup with dual thermostats and the stronger water pump. But I've seen a kit offered by SSDiesel, including the '97 upgrade and a Duramax fan and another fan clutch. They call it 'Cooling System Package Combo Kit'.

Now I wonder if it's worthwhile to go for the kit including the Duramax fan and clutch. Has anybody installed the kit and some experience with it?

Another thing is that I do never hear the fan running. I would expect to hear it when it fully kicks in on higher temps. Maybe the fan clutch is broken and does not engage. Is there some way to test the clutch?

If your getting too hot in 4L, I would look into an electric fan to keep air moving at low speeds. I think that and the dual Tstat setup would work best for your application.

Hm, I've been thinking of an electrical fan, and I agree that it can be advantageous at low speeds. But I rarely drive through the mud as I did, so that's not the crucial application, and I can stop and let it cool down any time when I do so, though it's no a good idea to get hot in the first place. But it was the first time that I saw getting temps that high in 4l.

More important to me is improving longivety in general and staying out of trouble in towing applications. What's better for that, electrical fan or clutch fan?

Are there suitable electrical fans readyly available? It might turn out to be very difficult to get one of sufficient size and power.

Which one is more reliable? My experience is that I've had once a broken clutch on another car many years ago but never any problem with electrical fans.

Hmm... Yesterday I hauled an empty trailer 75 miles and then loaded 75 miles. I got a chance to see what temps I was pulling at speed and at what ECT and EGT.
At 70-75MPH ~5 psi (10 psi on hills and overpasses) steady around 11 am I was seeing the low reading for my ECT (180*F) and EGT was 550-600*F , Then on the way home loaded with another 3 tons the ambient had risen to 96* F in the shade. I drove the same 70-75 mph , EGt's stayed at 600-650*F but ECT's started rising to 190, then 195. The last part of my journey was hilly with stops and starts but I laid into it to see how hot she'd get and ECT's rose again to 200 but even after a few accelerations at 15 PSI it never passed 200*F. I never heard the fan clutch engage either and I wonder what a better fan/clutch would or wouldn't do. If they don't kick in till 210*f I'd have never seen it come on.

I

If you tow heavy, then the low temp fan clutch should work wonders, and I guess even if your crawling, your engine speed will be enough to drive the fan at low tire speeds.

Lots of options and they all have advantages.

Hm, how high may the coolant temp go without getting dangerous?

As far as I've been reading, there are/can be hot spots in the engine so that I won't see it overheating until it's too late.

My gauge is in degrees C --- the needle can come close to 100 (212F) during normal driving but quickly goes down to more appeasing levels then, apparently once the thermostat opens, then climbs up again. Depending on outside temperature and load (speed), it tends to go up and down a bit.

But sometimes, when towing uphill or driving through the mud, it goes up and gets a bit closer to 100, and that scares me and I turn on the cabin heater to get it down --- it works remarkably well, but is not exactly a good solution.

And I didn't have occassion to tow my camper with a working turbo yet. Temps may be higher or lower with that, I don't know. Also, I've found I had to fill with some more of the red coolant stuff to make sure it won't freeze when I was in Sweden this march. The coolant stuff will somewhat impact heat transfer.

Do I have to worry when it's getting up like that? Or can it still go further without danger? At last, the accuracy of the temp gauge is doubtful --- if it shows a few degrees too low ...

I know, I should get my EGT gauge installed, but I'm still hoping to get a new dowpipe and then install the gauge ...

I bought the 'Cooling System Package Combo Kit' from SSdiesel just keep in mind i only installed it about 3,000 miles ago. Here in south-east Texas yesterday it was about 97 outside with a feel like at 104. With that said i was out driving all day some stop-n-go some just cruising. My temps in stop-n-go would get to about 190 and cruising were about 180 or a little less, going by factory gauge. i run a 50/50 mix of coolant (green stuff and water). Right after i install the kit i did go out of town about 365 one way pulling a 6x10 trailier total wieght being maybe 1500 lbs. I don't really pull anything over 2,000 not that i can't just don't need to. But anyway the temp stayed at 180 on the flats and maybe 185-195 when it would down shift going up hill. Well that's been my experience with it so far, so as of today i'm glad a bought it. Hope that helps.

Thank you very much for the input!

How hard was the upgrade to install?
Does the Dmax fan make a noticeable difference compared to the stock fan?

The install wasn't bad but i was already putting a new IP on so i already had the water pump and fan off. You will have to do some grinding on the alternator bracket, so that the cooling cross-over will fit and set flat on the heads. A small surface grinder (4" grinding wheel) will fit to remove part of the bracket for the cooling cross-over. I found that a end-grinder (Dremel tool) takes a little longer but is easier to hold, use, and see while your gringing. I also had the trim the cowling around the new fan a little (a 1/4 inch or so) all the way around not that it was hitting or rubbing i just want to make sure that it never did hit or rub. I don't know how much difference there is between the two fans as far as cooling. However i know there is a BIG DIFFERENCE in weight the D-max being much lighter.

Hey, that sig sure looks familiar...
And I thought I had the only one ;)

Olee,

FYI,
Here's a link to photos I took when upgrading my 95 cooling system and doing the DSG gear install:

http://community.webshots.com/album/42727688JuUMeK

And here is a breakdown of the major parts I used to do the cooling upgrade - this includes the harmonic balancer as well (good to change while you are at it - bad units can lead to crank failures):

Quantity GM Part # Description Total
1 12553405 Housing - Crossover Manifold $78.93
1 10154688 Engine Crankshaft and Camshaft Balancer (Harmonic Balancer) $67.81
1 15683910 Radiator Hose Lower $31.54
1 12564276 Water Outlet $34.14
1 15977350 Radiator Hose Upper $12.48
1 10243629 Hose $2.39
4 24504922 Thermostat Water Hsg Outlet Bolts $1.88
1 15010202 Engine Fan Blade (from Duramax - fits 97 Fan Clutch) $33.87
1 15022302 Engine Air Cooling Fan Clutch (1997 VIN S 6.5 Diesel) $56.62

Total price delivered to door in Fall 2002: $319.66 - Source www.teamchev.com (http://www.teamchev.com/). I work with Gale. I know prices are higher now, but if you don't need any help from a vendor to do the install - you probably won't find a lower cost source to the door. You can use 97 GM thermostats or depending on where you are at you might try Robertshaws. Murray's autoparts handles Robertshaws where I am at.

I never had to trim anything for my Dmax fan. The OEM fan clutch has never cause me any problems and like the idea of the lighter fan. It seemed to sound a little different to me than the metal fan. Another part of the conversion is the fuel return lines. The metal tubing that connects to the injector pump and injectors which returns flow to the tank needs a little modification. I took the "T" in the line, cut it out and re-used it with rubber fuel line to re-route things so there wasn't interference. I've got 60,000 miles since doing it and the engine temp has been steady ever since.

Thanks for the great info! I'll have to think about it --- doing some other things along with it is a good idea :)

A big problem with such things is that I'm living in Germany and cannot get the parts easily, and shipping costs can get quite high. And I must make shure to get anything I might need before I start --- if I miss some part that costs $2.50 but is important, I might have to wait another two or three weeks to get it. But I need my truck every day.

Sometimes I think I should make a trip to the US just for buying car parts, but there's limits on the luggage you can take on the plane ... They would probably look odd at you, carrying an exhaust system in your handbag and such ;)

Shipping (shipping _only_) for an exhaust is $360, for example.