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210 hot or NOT?

Yeah, I hate it but Ford made the better work diesel earlier. GM made the first diesel pickup though by a long shot I believe. It was not really designed for a heavy work truck. It was designed as a easy start in any climate more gas like driving fuel mizer. GM was just slow to pinpoint the heat issues and got beat up pretty bad in the early to mid 90's with the other trucks. It does take a total systematic mod scheme to bring the 6.5 up to speed. But hey they are still cranking out the latest and greatest versions of the 6.5 in pretty good quantities can Ford say that about the 7.3?

The high compression kills the 6.5 when loaded and working hard. 210 ECT in and of itself is not that hot for the avg engine. But add 21 22:1 compression and you get superheated combustion temps that IMO cause early peak cylinder pressure. This snowballs in overheating the cooling system. And it causes a lot of stress to the bottom end that probably accelerated cracking in a lot of blocks.

Isn't the Ford lower compression with 0.8 more liters to boot alot more quarts of oil and a bigger cooling system. Yeah, its probably a better stock work truck but I imagine it has some problems too. Your truck looks a lot sharper than a Ford though IMO. Drive what you want every make has its better years and worse.
 
GM does a s#it job with their cooling systems. Further they can't find cooling system issues very quickly, see LLY overheating. Something about being in a snowbank in MI and ignoring their proving grounds in AZ. Their customers complaining about fan noise had them delay fan lockup till higher temps rather than design a quieter fan. Trailblazers also suffer AC performance when over 100 degrees out due to cutting corners on cooling.

In any case a fan clutch is junk after 5 years due to fluid breakdown and leakage. (They loose 200 RPM per year.) The 6 blade fan is junk. I sent one 6 blade fan to the metal scrap yard with the overheated and blown engine still bolted to it! The old clutch will try and lock up but can't hold. They, 6 blade clutches, did not hold very long factory before the fluid overheated and started to slip. New body style with airflow issues, reverse rotation, and GM kept the same 6 blade fan and raised the turn on temp. Balance flow issues on the water pump and lack of cooling air took ~10 years for GM attempt to fix via production changes!

The cooling improvements that allow you to tow foot on the floor are HO water pump, new HD fan clutch, and 20" steel or 21" Duramax fan. I used a 180 T-Stat and a low temp Kennedy clutch. I also had a new condenser and radiator. EGT's you can get with a DS4 vs. my DB2 can push this to the limit though. You do not need dual t-stats. I pull a 10% grade with the 1993 equipped with the Kennedy clutch HO pump and 180 T-Stats - Duramax or 20" steel did not make a difference with the 24" cargo trailer. The Duramax fan is better at idle for AC however. 210 was the peak temp I would get with the pickup as the hill slowed me down to 43 MPH.

$300 if you do a standard clutch, better fan, and HO water pump. More if you go with extreme, low temp special order, components.

If you back off the throttle as things start to heat up and give the system time to kick on you can skip the low temp stuff although I would still run the 180 t-stat towing. The low temp stuff kicks on early to limit the peak temp as it is a race against time at WOT.

This is how you fix the GM weakness for the cooling system. Other brands do a better job factory, but, aftermarket has stepped in as well as newer GM design to fix the problem.
 
DB2 trucks don't run anywhere near the egts as DS4. I am seeing that already with my 93. I also to add to that still wholeheartedly believe the radiators are worthless junk and nowhere near big enough. I intend to prove that theory in the weeks to come.
 
GM Guy said:
I think something is to be said for the late 99/2000 cooling system. my clutch never seemed to kick in, but I was loaded to 15K total and made it across Wyoming without issue, and then switched trailers, loaded to 20K combo we went to central california, pulled donner at 40 degrees, so that helped, but it still would hold below 210 on the flat.

havent pulled the radiator yet for cleaning, but it needs it if I am going to pull in summer, rather than spring. got as high as 85 on the spring trip.
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Something to be said for lighter heat load with a handshaker vs. an Automatic.

Acesneights1 said:
DB2 trucks don't run anywhere near the egts as DS4. I am seeing that already with my 93. I also to add to that still wholeheartedly believe the radiators are worthless junk and nowhere near big enough. I intend to prove that theory in the weeks to come.
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Call Ron Davis out of AZ. He will tell you about GM's experiment with a thicker radiator. It failed as the problem is lack of radiator airflow due to the body style' aerodynamics. As it doesn't work Ron Davis will not build a thicker radiator. He will build a thicker one for the Trailblazer SS as that does some good.
 
I could be wrong, but even with better airflow trhough the rad. I believe that you will still have cooling issues as I have tried all sorts of things to fix/figure out what would be the best solution.

When I get on the warm side and bring egts down to 900/1000 sustained the coolant temp comes back in line pretty quick, indicating lack of pulling heat out of the combustion chamber efficiently.

I think that coolant flow is a major factor, even with the 99ho W/P which has helped, it still will hit 210/215 at 1,100 egt sustained after 5min. with a load behind me.

It might be that coolant isn't pulling the heat out of the cylinder [heat saturation] fast enough to keep up with temps being generated at high loads and long periods of time.

I'm not to worried about it now that I have the optimizer, it doesn't seem to mind running up to 215/220 for short periods, although I don't give it a steady diet of those temps.

I believe combustion temp control is the key to keeping the 6.5 alive. I will try multiple stage water inj. to test this theory and will be towing a heavier camper this spring adding another 5,000 lbs to what I tow now.
Along with a ATT or equivelant I think I will be fine. If not I will swap out to 411 gears for the hills that give me a challenge. I only say a challenge as I like to run it at 70/75 up 8% grade for the ten miles or so and thats when I see 215/220 ects. It seems to me that lower comp. ratio or W/M might be the only thing left to do other than port and polish the heads for faster flow and evacuation of the exh. gases of which the gm 8 is also choking back evacuation of gases at high boost/rpm. I run 18/20 lbs. at 2,500 rpm, about 75 mph., while towing which is the reason my temps get so high [only uphill BTW]. Other than that it never goes above 195/200 ect.

I believe that the heads are the major impediment to the 6.5 cooling and performance issues.

I hope kenny posts his results with the brass rad. that I think he is going to experiment with.
 
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Yep. Gonna try to get that one back from the junky tommorow and have it recored to 4 although it looks like it could accomodate 5 cores. I have to talk to the rad guy. He can build anything.
 
So all u cooling folks what can I do to my 6.2 N/A to help with cooling????? Can I switch to a different fan???? My radiator is new just installed. Radiator guy said my fan clutch looked and acted good but can I do the mod thing with the bimetal ribbon???? any info is appreciated.
 
Not to mention the 7.3 is an International motor!, the 6.5 is a Detroit diesel what do you see more of on the road???? that is why getting a military hummer take out motor or an optimizer is the way to go that is also an International motor!
 
Crankme69 said:
Thanks the exhaust is 4" DE already. The radiator is spick & span clean with a new AC 190 delco stat & K47 air box & it's got a multi chip tow economy & performance tune with brand new injectors.

The water pump & clutch I have not touched...& I might stop throwing money into a burning pit.

I might sell this SOB & look for a clean 7.3. Why do we fight this? I love my truck but all this work & money for what a stock 7.3 can deliver out of the gate? It just ain't adding up to me...:nonod:

Great truck if all I use it for is to go to get groceries...:eek:
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I have done alot of mods too and still can spike temps up in a heart beat with this engine! It does get frustrating! Thought many times to just sell it!
 
The optimizer so far has been the great equalizer for me. It takes the abuse so far and doesn't complain. It will run to 220 ect a little slower than the detroit 6.5 that was in it stock. The only issue I have now is that I tried an old hot rod trick [using a restrictor instead of a t-stat and the the pump flows so much gph that it sets off my low coolant light under sustained WOT while towing. After lifting my foot it takes a min. or two for the light to go out. I always change back to the gm t-stat when not towing, otherwise it won't warm up past 150*.

I will be making a ram air cold air box to bring down the IAT and custom intake and use a 2 or 4 inch cowl hood plumbed with said custom air box to see if that will help with the heat issues. No intercooler yet. If all else fails acummins will go in when the optimizer blows up.
 
Can I switch to a different fan????
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can I do the mod thing with the bimetal ribbon????
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Yes and yes. But I haven't heard to many guys needing to do that. How did he check your F/C. It sounds like that might be the first thing to replace or mod to see if it helps.

If you mod it and it starts to work think about buying another one as the original is probably on its way out. Or you can look up all the other cooling mods in the stickys to help point you in the right direction.
 
robzombie4551 said:
I could be wrong, but even with better airflow trhough the rad. I believe that you will still have cooling issues as I have tried all sorts of things to fix/figure out what would be the best solution.

When I get on the warm side and bring egts down to 900/1000 sustained the coolant temp comes back in line pretty quick, indicating lack of pulling heat out of the combuction chamber efficiently.

I think that coolant flow is a major factor, even with the 99ho W/P which has helped, it still will hit 210/215 at 1,100 egt sustained after 5min. with a load behind me.

It might be that coolant isn't pulling the heat out of the cylinder [heat saturation] fast enough to keep up with temps being generated at high loads and long periods of time.
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Having done some testing on heat balance and cooling scheme testing on stationary Diesel engines it does seem to be a long story with many angles and I don't know all of it by a long shot.

Heat of the burning fuel and compression heat has to be removed in 3 major ways with a 4th small contributor.

1. EGT alot of heat is wasted out of the exhaust. IAT has to be inline and compression stroke heating can't add too much heat or it puts even more stress on the 2nd heat rejection mode [the engine is basically an air pump powered by the fuel and converts the fuel energy to mechanical]. EGT is cooled by mass of air, IAT, controlling air pump losses, timing of combustion and pressure spikes of compression and power stroke and ease of exit.

2. ECT the radiator has to shed the majority of the heat of the metal of the head (where the combustion and compression heat is concentrated).

3. The oil has to cool the piston (which sheds heat with oil and IAT and air mass) plus lubricate things.

4. There is a bit of air cooling if you are lucky. Mostly of the thin areas like the valve covers, oil filter, and oil pan which helps shed some heat.

GM was marginal on all fronts for a truck and undersized for a tow vehicle.
It has high compression ratio, small air flow, poor radiator and small coolant system with unbalanced flow, small oil cooling, and poor air circulation through stack and cramped engine bay.

From what I saw radiator design was complicated too. Thickness vs "density", fins (straight vs fluted or curved) vs tubes and "rows or passes" vs coolant flowrate vs air flow rate and tank design. There are improvements to be made I am sure. I know GM probably paid as much or more attention to economics than performance. Plus if you have altered the system with better pump or fan then the whole design has been modified but only partly if I can say it that way. Thicker is not always better but there are many other areas to trade off and change to improve things.

I think by about 99 they had most of the cooling improved well enough but by then the IDI 6.5 was out of class with other designs and power requirements.
 
orrum said:
So all u cooling folks what can I do to my 6.2 N/A to help with cooling????? Can I switch to a different fan???? My radiator is new just installed. Radiator guy said my fan clutch looked and acted good but can I do the mod thing with the bimetal ribbon???? any info is appreciated.
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I don't think I ever had a cooling problem with a 6.2. Is your rad Copper/brass or plastic/Aluminum ?
 
Was copper/brass but the new one is aluminum/plastic. Dont know what the thermastat is, PO put one in trying to fix the overheating problem but it was a leaky radiator, it was very slowly leaking under the bottom and being blown out the drivers side fender bumper area and u couldnt see it till I pulled the horse trailer n blew it out real good! LOL Happy to see that leak, I figured it was cracked heads till then. It ran about 200 and after the new radiator it runs about 170. Thats good news about a 6.2 not overheating, did u tow with one much?
 
On my Tahoe motor I connected the two rear coolant block off plates ,with a tee and ran that to the heater,which will return into the radiator. I don't know how well it will work,but I've seen lots of v8 gas motors with RR heater outlets. It seems to be the hottest spot
 
Crankme69 said:
READ the POST closely I love the truck, here let me list out what I have done so FAR! Instant gratification you got to be kidding me!
Injectors
Chip
DE exhaust
K 47
new AC compressor
New brakes & lines
Alternator
Vac pump & Vac lines
Cleaned radiator new AC stat
New surp belt
New GP's
New Batteries & cables
New rotors drums
Swap intake manifold to delete EGR

Yea I prolly missed few things & yes you pissed me off with that statement.
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Crank, ever since you've been on this board you've bitched about your 6.5. Like I said, I've been there and done all the mods with a great outcome. I see that you have not upgraded your cooling system, but you chipped it. Hmmmm. Like I said, buy a 7.3 Ford. They're great. My friends love them.
 
Hello, 6.2 Diesel I totally did not understand anything u said. Can I do what u said and will it help my 6.2 N/A stay cool cause she gonna have to pull my horse trailer n the Appalachian Mountains! I really dont want to blow her up.
 
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