• Welcome to The Truck Stop! We see you haven't REGISTERED yet.

    Your truck knowledge is missing!
    • Registration is FREE , all we need is your birthday and email. (We don't share ANY data with ANYONE)
    • We have tons of knowledge here for your diesel truck!
    • Post your own topics and reply to existing threads to help others out!
    • NO ADS! The site is fully functional and ad free!
    CLICK HERE TO REGISTER!

    Problems registering? Click here to contact us!

    Already registered, but need a PASSWORD RESET? CLICK HERE TO RESET YOUR PASSWORD!

What t-stat cooling upgrade is the best?

GM Guy

GM Guy

Manual Trans. 2WD Enthusiast
Messages
4,838
Reaction score
846
Location
NW Kansas and SC Idaho
I am leaning towards either a Kennedy kit or a SS diesel kit.

I have been told that the crossover housing, hardware, and the neck the hose mounts to is GM, the hoses are gates, undisclosed brand of Pump on the Kennedy kit. Anyone know what the water pump is? Also, do gaskets come with this?

I have no clue what brand the SS diesel kit is comprised of. clarification would be greatly appreciated.

As great as they are, i will not put heath in this discussion, as i personally disagree with their kits design (aka sticking w/ the single stat)

any input greatly appreciated, thanks!
 
also, is therea any advantages to 180s instead of 195s? I would think that the only thing is that there is a temperature reserve w/ the 180s. would 195s give better fuel economy?
 
Go with the Heath Cooling upgrade. Stay away from SS Diesels. As far as Kennedy there was alot of controversy at the old site wether the dual therms actually benifits or not. I chose the Heath. Kennedy's kit IIRC uses the 4 bolt fan. Heaths upgrades to the big nut. What's more important is cleaning your radiator and coolers. Everyone says "oh they are clean or Oh I cleaned them" Unless you pulled the grill and pulled all the coolers including A/C cond and cleaned them on the ground, you did not clean them. Sometimes that is enough for some but you are running a 95 whch has the small water pump. I would say go with Heaths setup. It did not completley solve my towing issues but it did help. I think I need to buld an intercooler because Heaths setup actually did just about solve mine until i put the turbo master on and brought the boost to a more respectable level.

As far as the dual vs single thermostat it was a poor attempt by GM to correct a problem the cheap and easy way. The bottom line is these truck should have been intercooled. GM threw a turbo on and choked the exaust system and the engine can't breathe. Allowing the water to move faster with two therms isn't always the soluton. If it was why not just take the term out right ?? Because the water needs time to absorb the heat. If you get it moving to fast it won't absorb any. My 2000 has the dual setup like kennedy sells and it overheats just as bad as my 95 if not worse. Bottom line, if you are gong to push the truck hard or increase HP you need to intercool it somehow IMHO. I have had many discussions on this and the old forum and I have both setups, pre 97 and post and it doensn't make a sh#t of difference if you ask me. I also firmly believe the A/C condensor doesn't allow enough air to the rad. I know a guy with s 6.5 dump trucks. No A/C in any of them and he has no issues towing skidsteers, mini exc etc. He is also running stick shifts.
 
Acesneights1 said:
I also firmly believe the A/C condensor doesn't allow enough air to the rad. I know a guy with s 6.5 dump trucks. No A/C in any of them and he has no issues towing skidsteers, mini exc etc. He is also running stick shifts.
Click to expand...


my truck's got no A/C and i've had it loaded down to the axle a few times with junk in the bed and the temp gauge never even moved off normal. its got the dual t-stat setup on it(stock) and the HO waterpump that looks original by the paint flaking off it. have yet to tow with it but that may be coming up as i tow my friends Pontiac Le Mans to PA before his wife makes him sell it. :prrr:
 
My Kennedy fan clutch did keep things cool but was slightly more mpg to run it as once engaged it almost never disengaged, the Heath clutch cycles, never ran a SSD but since they copied a lot of Kennedys stuff, I suspect they have same fan clutch as Kennedy
 
On my '96 (dual t-stats stock) I put on the SS Diesel Duramax fan kit and have been very pleased with it. That being said, it rarely has to engage, but when it does it cools it fast and turns right back off.

I also run the 180F t-stats from Kennedy (Robert Shaw / Prestone brand). No real difference that I can tell.

Granted if you keep the front end cleaned out they run much cooler... Somehow mine collects leaves?
 
So the heath upgrade has the hummer water pump?

If i go w/ heath, i will have to get their cooling fan/clutch as well? or will another one work?

I guess the new question is how should i mix and match colling and fan upgrades? all heath, all kennedy, etc?

I take it the all heath setup would be the best?
 
Turbine Doc said:
My Kennedy fan clutch did keep things cool but was slightly more mpg to run it as once engaged it almost never disengaged, the Heath clutch cycles, never ran a SSD but since they copied a lot of Kennedys stuff, I suspect they have same fan clutch as Kennedy
Click to expand...

Immitation is the best flattery? :D ):h
 
Is this what everyone wants me to get?

http://www.heathdiesel.com/P/HDP1600/


I guess mixing/ matching products isn't such a hot idea. probably having two things designed to work as a system is better? What does everyone think?

So with this upgrade, the stock t-stat housing is retained, but the t-stat is replaced with a specialty t-stat? How many parts are GM (or hummer) with this kit?

Is the screw on fan the best route, or the 4-bolt flange style?

Is it best to stay with 195s, or go 180s. Surely 195s get better fuel economy, right?

I noticed that there is an extra-heavy upgrade for the dual stats. Is it still best to stay w/ the single t-stat upgrade? or should i upgrade to the dual t-stat housing?

I basically just want the best cooling for fairly heavy towing, and want to retain fuel economy. (do not want fan kicking in too early)
 
I had a chance to call the good guys from Heath back in April of 2008. They explained that according to their thinking, the bypass-blockoff concept has merit, which is why they like it. I am going to try and paraphrase what I heard, but I do not claim to speak for them. I'm just trying to add to the body of knowledge here.

Here's the thinking, if I understood it properly:

* The block-off thermostat sends coolant to one of two places - either bypassing the radiator and directly into the input of the water pump, or through the radiator.

* By employing a block-off strategy, it ensures that when the thermostat is fully open (i.e. the coolant is up to operating temperature) 100% of the coolant is being forced through the radiator.

* Some of the 1996 side-mounted thermostats were also of the block-off type, and worked the same way as the 94-95 thermostat crossovers.

* The concern they have is that the constant-bypass type of crossover, which is what is used on 97+, does have greater flow capabilities leading to the radiator, but since GM went away from the 'forced bypass' design, the coolant (when up to operating temps) has two places to go - bypass back to the inlet of the water pump AND/OR to the radiator. They claim to have some people who have done the 97 cooling upgrades, and STILL have cooling problems. Their theory (which makes sense to me) is that since there is nothing "forcing" the hot coolant to take the trip through the radiator to have heat removed, that coolant will simply take the path of least resistance, and if the path of least resistance is back to the water pump inlet, this will simply send hot coolant right back through the engine again, without having been cooled, thus exacerbating the cooling problem, not fixing it.

*They say that their fix for '97+ cooling systems that are still overheating has been to put a restriction into the path leading to the water pump inlet, thus making the path to the radiator the 'path of least resistance', thus solving the cooling problem.

* They claim that use of the single bypass-type thermostat crossovers with the HO water pump, coupled with the HD fan clutch and HD fan has provided the most consistent cooling performance, even over the '97 systems.

* They claim to not have seen any evidence of over-pressurized systems nor 'blowing frost plugs' when retrofitting an older 6.5 with the HO water pump.

My personal analysis of it is that this makes a lot of sense, and I will likely put the HO pump on my Tahoe as a result, and NOT change the crossover.

Sincerely,

Rob :)
 
Again before you spend money have you cleaned your rad/coolers ? You are wasting your money if you didn't. That solves most peoples problems.
 
I installed a new radiator a while back after overheating issues. I have replaced the T-stat with an OEM t-stat and I have the single stat housing and factory water pump. I run the A/C in the summer and can load a substantial load grossing about 30,000 lbs. and I only have to turn the A/C off if I'm moving through town where the air flow is low. Once I turn the air off on a hot day like that, the coolant temp quickly recovers and I turn it back on.

I also have Heath's fan clutch.
 
so with the heath kit, all that is changed is the water pump (replaced with factory GM Hummer app.) and the t-stat (aftermarket)/

Does the heath kit basically make the water pmp 99+ style? (thread-on)
 
Did you get a new cooling system? I'm not sure why you should stay away from SSDS, but it would cost you less and you get more.

It is proven fact that the only way to cool water more is to send it through the radiator more times. Assuming you have already cleaned everything and it is working optimally.

So dont listen to an argument that it doesnt spend enough time in the radiator. I'm sure there is a point at which the returns are diminished but your low output pump isnt doing it. I dont know if the dual t-stat helps or not, but at least youre getting something for your money and it makes sense if increasing flow.

Another thing for people that still dont get enough cooling is to cool your OIL which does pull heat from your engine more so than water. Add another oil cooler somewhere other than in front of the radiator and you'll probably see water temps go down too.
 
buddy said:
Did you get a new cooling system? I'm not sure why you should stay away from SSDS, but it would cost you less and you get more.

It is proven fact that the only way to cool water more is to send it through the radiator more times. Assuming you have already cleaned everything and it is working optimally.

So dont listen to an argument that it doesnt spend enough time in the radiator. I'm sure there is a point at which the returns are diminished but your low output pump isnt doing it. I dont know if the dual t-stat helps or not, but at least youre getting something for your money and it makes sense if increasing flow.

Another thing for people that still dont get enough cooling is to cool your OIL which does pull heat from your engine more so than water. Add another oil cooler somewhere other than in front of the radiator and you'll probably see water temps go down too.
Click to expand...


Thermodynamic flow is a balancing act you can have either too much flow or too little flow, which is purpose of stats dual or single to try and regulate for proper flow, flow too fast thru the rad and coolant is not in long enough for proper heat transfer to occur, flow too slow and coolant absorbs too much heat, both conditions lead to overheated engine.

Exacerbating this is rad fan/clutch, dirty rad, dirty condenser, hot trans., improper coolant mix

To properly keep the engine cool one has to do a total system view.

Rad/condenser cleanliness essential, on mine since I HD tow adding an extra trans cooler helps keep temps in check since rad isn't dealing with added trans heat, also added a retuned fan clutch/plastic fan, oil bypass filters which adds 1.5 qt extra oil to be heated, plus filters being away from side of engine allows some indirect cooling via ambient air flowing over the filters, also deep ribbed trans pan with extra 3.75 qt trans fluid.

From what I read on what GM did with the h/o pump & dual stat, they did not go far enough in studying the problem, IMO they forgot these are variable speed operated, and are towing loads bigger than planned for, made no provison to monitor EGT so when things like vac pumps or WG solenoids failed, overheat was result, quick fix get more water thru the block.

The GM-8 is undersized for towing, and has to make up with higher boost to keep engine supplied with required volume of air (cfm), which puts IAT very high corrected with IC, WMI or swapping to better turbo, ATT for instance.
 
Thanks, a good read on the cooling is in MaxxTorque, lots of info on GM diesels, including the 6.2/6.5

I also have a Z28, and it didnt really run too hot but would get to maybe 210 sometimes. I put on an electric high flow pump and lowered the T-stat 10 degrees and it never gets over 180 anymore, probably killing my fuel economy, but thats why I drive my truck all the time I guess :)
 
Turbine Doc said:
Thermodynamic flow is a balancing act you can have either too much flow or too little flow, which is purpose of stats dual or single to try and regulate for proper flow, flow too fast thru the rad and coolant is not in long enough for proper heat transfer to occur, flow too slow and coolant absorbs too much heat, both conditions lead to overheated engine.
Click to expand...

x2 I used to have a 69 Mustang, the thermostat went and I thought I could run it without temporarily. Wrong, It would overheat very quickly. Leo
 
You must log in or register to reply here.
Back
Top