• 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!

anyone use the "Rear Head Cooling System Kit"...........

deejaaa

deejaaa

Diesel Beginner
Messages
1,719
Reaction score
621
Location
Texas
cost is $310.00 each from Flash but feel i could make my own for under $10.00. the #8 gets hot and could crack the block as far as i understand. i have many brass fittings, steel pipe i can weld onto the extra block-off plates, would only need heater hose.
RearheadCooling.jpg

looks simple enough.
 
jrsavoie said:
I've always been curious about this and how it ties in
Click to expand...
google "Rear Head Cooling System Kit" and there is a lot of info. flash is what i was looking at.
i would like to know if it's hype or good. sounds logical but i have no experience. 3/8" hose is what is needed for the hose.
 
I think it was close to $500. Heaths has some cylinder thing the hoses go into. My truck was heating up to 3/4 when towing our tow hauler. I called Heath and he said to clean the front of the radiator. So I did. Still did the same thing. So I bought the HD fan clutch. Still did the same thing, So I replaced the radiator. Still did the same thing, so I did the balance flow. Still did the same thing. So I've decided to run it until it blows up. My fan clutch takes forever to engage. As soon as it engages it cools it right down. So I'm just going to run it. Oh I also did New Delco thermostats. I should check it and see if it is actually running that hot or if the gauge is reading hotter than it is. The Balance flow kit I don't know if I could build because I don't know what is inside that cylinder.
 
1999gmc said:
I think it was close to $500. Heaths has some cylinder thing the hoses go into. My truck was heating up to 3/4 when towing our tow hauler. I called Heath and he said to clean the front of the radiator. So I did. Still did the same thing. So I bought the HD fan clutch. Still did the same thing, So I replaced the radiator. Still did the same thing, so I did the balance flow. Still did the same thing. So I've decided to run it until it blows up. My fan clutch takes forever to engage. As soon as it engages it cools it right down. So I'm just going to run it. Oh I also did New Delco thermostats. I should check it and see if it is actually running that hot or if the gauge is reading hotter than it is. The Balance flow kit I don't know if I could build because I don't know what is inside that cylinder.
Click to expand...


This thread should help
http://www.thetruckstop.us/forum/sh...-Clutch-mod&highlight=fan+clutch+modification
 
1999gmc said:
I think it was close to $500. Heaths has some cylinder thing the hoses go into............................. The Balance flow kit I don't know if I could build because I don't know what is inside that cylinder.
Click to expand...
looks like a connection, two hose into one thing, just like a 'tee'. i would guess you spent close to $1000.00 but still have the same symptoms. hmmmmmmm.... i will make some rear head ports. connect them with a couple of 'tee's', 3/8" hose and see if it does anything. maybe do a before and after. i just looked and didn't see that i had any extra block off plates so i will make them myself from plate. now i need to find gaskets for a template..........
 
OK folks.

This kit is basically an answer for a question that was never asked, or at least not one that had not been corrected already.

The concept was to shunt off cooling water thats coming up from the block (it enters the head at the rear) and to reroute the coolant.

The true answer was the HO water pump and dual stat crossover.

FLOW is the answer as increasing it throughout the block, heads and radiator.

The dual stat crossover along with the HO pump increases the flow through the block by 70% and through the radiator by about 10%.

When the stats are closed the water is recirculated through the heads under a much higher flow rate and pressure than the original set up.

When the stats open the coolant return flow to the block is shut down and the entire flow then runs into the radiator.

The HO pump is well worth the $$$ as is the dual stat X over.

The bottom line is this, if less than $20 worth of hose and fittings would have corrected the problem, does anyone really think that the engineers would have gone to the trouble of designing and manufacturing the dual stat crossover and HO pump.

That change was not an insignificant little blip $$$ wise.

Coolant needs to flow through the entire block and the full lenght of the heads at a fairly good velocity in order to scour out any steam pockets and the thoroughly cool the heads and the block.

Slowing up the flow with the hose shunt goodies does nothing other than allow the forward cylinders to heat up more as a direct result of the coolant being routed off prematurely.

Just another BAND AID fix that did little other than make somone some $$$$

As I said, if this was the answer, the big boys would have done it right off and not spent big $$$$ to redesign the system.

Cracked #8 cylinders is due to several factors, the biggest of which is the presence of a severe stress riser right under THE HEAD BOLT thats located at about 8 oclock near the back of the block and around 1 inch below the deck surface.

The AMG blocks have had the decks thickened and the stress riser was removed.

THE STRESS RISER I AM SPEAKING OF IS A BULGE RIGHT UNDER THE BOLT AREA.

THIS CAUSED THE THINNER AREA ADJACENT TO THE BOLT TO CRACK RADIALY AROUND THE CYLINDER WALL.

If your worried about your #8 cylinder cracking, there is little that can be done on the 97-99 blocks. If its gonna crack, its gonna crack, and all the gizmos in the world are not going to stop it.

I hate to be the harbinger of sad news but, thats the way it is with these things.

Some cracked, some did not. I have seen a total of 3 blocks that have done this.

One came from an H1 Hummer 1998 model with less than 100K on the clock.

The others were from pickups.

Save your hard earned $$$ for good parts like a HO pump and crossover kit.

Missy
 
I asked Heath about the his cooling setups. He said if you have the single t-stat you should leave it that way and go with his HO setup. I know he sells both single and dual setups. I agree that the engineers changed it for the reason of low coolant flow. There is a maxxtorque article that shows temps can be held down with a lower t-stat, new fan clutch, and a HO water pump even in a single t-stat setup. I have yet to decide what cooling setup I want to go with. I towed a 5th trailer to California last Aug my ECT ran high depending on how I drive. I kept it at 50Mph for the most part however any kind of grade just pushed the ECT up to where I was uncomfortable so I let off the throttle and just took my time going up. I just drove the engine within it's limits and it made there and back without too much difficulty. The engine has about 140000 miles on it I don't expect it to pull hills at 60Mph. It's interesting when you read so much info about the issue of heat it seems there are many views as to what is correct.
 
thanx missy, answered the question. won't waste my time, esp not my smack. i have the 99 engine w/ ho water pump and single stat. never had a issue, yet.
 
I have balance flow manifold on one and stock setup on other both cool equally well when equipped with latest pump offering the flash offroad setup is too small IMO, also remember radiator stack for H1s is different than the stack of our trucks. At one time Bill was selling BF to H1 crowd who had deep pockets when he could get them made, it was all lazer cut stainless parts, high $$$ silicone hose and specially fabricated coolant crossover, when his procurement/labor cost went thru roof he stopped carrying them. That and running his "Balanced Flow" pump-stat-fan-clutch setup negated need for the BF manifold setup.

AS Robyn point out flow was the issue in 97+ rig GM went too far with the flow, and undersized in previous models flow too little you overheat, flow too much and you overheat combined with dirty rads/bad fans-clutch and it is a compounded problem.
 
Single stat with a HO pump is said to provide too much pressure to the freeze plugs and this is why GM put in two T-stats - one big T-Stat would not flow enough to keep the pressure down. Single T- Stat does not have a bypass issue and the pressure hasn't bothered me. Heath Recommends keeping the single T-Stat if you have it.

Regardless a HO water pump, clean radiators, Low temp fan clutch less than 5 years old (Kennedy Diesel or mod your own). 180 T-stats, and a 20" steel or 21" Duramax fan will keep you cool no matter what you throw at it within the limits of a turned up DB2 IP. (WOT up a 10% grade towing to Payson in 100 degree heat. Only Death Valley is worse - 8000 above to 200 below sea level with 117 degree heat and very little room between the 1000' marks.) In other words these items get you results.
 
WarWagon said:
Single stat with a HO pump is said to provide too much pressure to the freeze plugs and this is why GM put in two T-stats - one big T-Stat would not flow enough to keep the pressure down. Single T- Stat does not have a bypass issue and the pressure hasn't bothered me. Heath Recommends keeping the single T-Stat if you have it.
...........
Click to expand...
are you saying, a single stat will be too much pressure on freeze plugs but Heath recommends it? and you are running the HO pump with single stat and have had no probs?
 
Sorry for the stupid question, but is the H.O. pump the one with H.O. in the casting? Seems obvious but just wanted to check with the experts!
Best Wishes
Mike
 
1999gmc said:
I think it was close to $500. Heaths has some cylinder thing the hoses go into. My truck was heating up to 3/4 when towing our tow hauler. I called Heath and he said to clean the front of the radiator. So I did. Still did the same thing. So I bought the HD fan clutch. Still did the same thing, So I replaced the radiator. Still did the same thing, so I did the balance flow. Still did the same thing. So I've decided to run it until it blows up. My fan clutch takes forever to engage. As soon as it engages it cools it right down. So I'm just going to run it. Oh I also did New Delco thermostats. I should check it and see if it is actually running that hot or if the gauge is reading hotter than it is. The Balance flow kit I don't know if I could build because I don't know what is inside that cylinder.
Click to expand...


HEY I HOPE U GET THIS IN TIME!! this is well well WELL worth it, i had the same problem with a 6.5, it is the beast but its still got the single thermostat n smaller coolant pump but put an electric fan on that thing man, im serious i bet u wont ever have a problem agian! its probably big enough to run dual fans. my buddy bought a complete kit with harness thermostat relays everything except the fan from autozone for around 25 30, i dont remember exactly but it wasnt any more than that, i would really highly recommend getting the adjustable thermostat, it has a solid state board with a pot type knob on it, u could also put it on a switch, either by itself or along with the thermostat. or one fan one way the other the other way, possibilities are endless. i hope this helps man. by the way id also highly recommend u get the fan controller off ebay u wont find a better deal for a good product. even if u get a bad one all u do is let them kno n they send u another one u dont even have to send the old back, just a pic or video showing it doesnt work. yea the stuff usually comes from china but where do u think over 99% of the electonics come from u use everyday? they know what theyre doin with electronics and the quality actually has started to rise. back to my point, they make theyre living off these sites its their stores, just on ebay they dont want unhappy ppl leaving bad reviews because thats the first detail an experienced buyer looks at to make sure the sellers legit. im really sry for the long ass post.. kinda jus happens
 
Welcome to TTS.

Electric fans in a 6.5 have a reputation of doing an Ok job while driving empty, and do not have a good reputation when towing.

Try pulling a 5K#+ closed trailer out 70 to Hagerstown with an electric-only fan setup and see if the 6.5 stays cool. Scuttlebutt is that it will not.

The 6.5 could benefit from an auxiliary pusher fan in front of the stack in addition to the motor driven fan, but not all grills have enough room to allow this.
 
On the thread heading of rear head cooling kit- avoid it like the plague. Missy hit the high points. Some of the testing we did with/for GM involved several versions of this- all were detrimental. Some gave lower gauge readings but created eddy currents and pockets of no flow inside the block- most specifically around cylinders 7&8. Also loss of flow through the front of the heads which increased cracking issues between the valves.

On electric fans: they can only help at low speed like stop lights. Otherwise at high fan engagement or high speed like freeway travel, they impeded air flow. So only add them if all is good at high speed AND high rpm once normal fan is on AND you have a problem with too much heat at stop lights or slow speed. Most commonly needing help for the condenser needing flow.

Balanced flow water pump is the only real solution.
 
Its all covered but I will add clutch, clutch, clutch! I too did all the upgrades, thermostats, balanced flow pump, fresh rad and new Severe duty hayden clutch - still had high temps. It was the fan clutch. Almost refused to engage from new. Returned it for another - same thing.
I got the Kennedy early engagement one and it works spot on like you think it should. I could have almost skipped all the other work and just got the Kennedy clutch and been ok.
Sandy
 
You must log in or register to reply here.
Back
Top