I suggested this on the other site, but it was kinda lost in the thread.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /><o:p></o:p>

There are a couple of guys out there offering a "cooling improvement" that taps into the unused block-off plates in the back of the heads. Their idea is to run tubing/hoses from these plates to the thermostat housing or heater return hose.<o:p></o:p>

I personally feel this is ass-backwards. The last thing the heads need is taking coolant away from them. I am thinking about reversing that idea. I have seen something similar on 400 SBC gas dirt-track motors that chronically overheat, and it helps a lot.<o:p></o:p>

In looking over the front of my motor, it occured to me that it would be easy to tap into the plate that holds the water pump. There is a channel for coolant to flow from the arms of the pump into the block. That is (relatively) cool water, having just gotten back from its vacation in the radiator. <o:p></o:p>

I would drill and tap into the housing and using tubing or hoses, take this cool water back to fittings mounted in the backs of the heads. I feel that this would go a long way to stabilizing head temps overall.<o:p></o:p>

I fully intend on doing this and reporting back success or failure, but if anyone has a damn good reason why this wont work, I am willing to listen. Also, I am still pondering what size to make the hoses/tubing. Suggestions or advice is appreciated.<o:p></o:p>

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Thanks!<o:p></o:p>

Tim<o:p></o:p>

If coolant is removed from the heads it will be replaced with coolant depending on what path the coolant takes it may help.

Sounds plauseable. It seemed to help the guy that had the thermocouple on each cylinder to do the opposite. I know it would cost ~ $150 in probes to demonstrate that each cylinder was at X at each phase but that's the kind of stuff that really puts the questions to bed.

I like the idea. But..

You mentioned that there are others that take coolant out of the back of the heads and inject the coolant back into the engine at the crossover or water suction port on the water pump. I've seen a Hummer page describing this, with small coolant tubes. I recently had a discussion with Bill Heath on his "Balance Cooling" Upgrade, it a similar idea to what I've seen but uses a balance tank in between the two back head ports to Balance the cooling system. I suggest you give him a call and he'll fill you in on the details. From my discussion it sounded very promising. There was quite a lot of testing involved in the system, to actually prove that it did work.

I, like you am NOT satisfied with the cooling system of the 6.5TD! Even with the HO cooling mod, the cooling is problematic, may not show up on the temp gauge, but there is problems. Ever burn a #6 or #8 cylinder? I sure did!!

GM's solution has always been (even on the 6.2) just give the back cylinders a little more piston to cylinder clearance to allow for extreme heat expansion of the pistons, because of a HOT running system. I don't think this is a good solution, I'm ready for a solution, I think Heath has it, but will have to try and see.

Tim

I've considered the cooling mod myself. Remove coolant from the rear of the cyl heads and dump somewhere. Not sure where.

I'm not too sure your idea will work.

Won't you have equalized pressure resulting in a no-flow situation?

I think I might have to go with Billman on this one, dumping pressurized coolant in the back of the head might have an equalization effect which would probably cause no change in the acctual water temp at the crossover, but would make temps skyrocket in the back of the engine. Ever take two garden hoses and point them at each other? The water goes out, but in the engine there is no out so where would the water go?

The system that Bill Heath is pushing is apparently used in high HP racing and such, so there must be some merit to it although I'm not sure it's worth the $$ he is asking...

Check out Bill Heath's new kit, I'm on waiting list myself, "Thanks Spindrift" he got my kit I think for his engine rebuild but he needed it more than me so I'll forgive him, Bill instrumented heads and made a kit that appears to have address the lack of cooling for 6.5, once mine arrives, I'll do a install & operation review on it with pics.

Tim

I've considered the cooling mod myself. Remove coolant from the rear of the cyl heads and dump somewhere. Not sure where.

I'm not too sure your idea will work.

Won't you have equalized pressure resulting in a no-flow situation?
Billman-

Coolant flow through the engine is from front of block to rear of block, to back of heads, and forwards to front of heads where it exits at the thermostat housing and then on to the radiator.

IMHO, taking water out of the system at the back of the heads gets you nothing other than slighly increased flow through the block, which really don't help anything. I feel that it would actually starve the heads of what they need most, cool water. And the kit offered on that Hummer site does just that.

My way, additional water will be added to the system at the back of the heads. This water, and the water from the block will still travel forward and out the thermostat housing. The water pump will still be cramming water into the front of the block, and water will still circulate as normal through the engine and out the thermostat housing.

It won't 'equalize pressure' and stop flow any more than a small stream dumping into the colorado river will stop its flow as well.

Tim

I saw the Hummer site kit and while good in theory I think may still need some work, flow addition is important, but correct volume is even moreso, you can increase flow and still overheat, here is why if flowing too much too fast the cooling medium does not stay in system long enough to permit heat transfer it is a fine balance to add flow and pick up heat at the same time.

2 ways generally to control temp; actively with thermostat controlled devices, or passively through a metered orifice, I would like to see temp data on Hummer site that shows they have the kit sized properly.

The install of Bill Heath's I saw on Spindrifts ride, brings water from back of the block left & right head, into what I'll call a "balance chamber" then into water cross-over header either in front of or just after thermostats, I don't remember which.

anybody got an URL for the hummer site so we can get a look?

anybody got an URL for the hummer site so we can get a look?
http://www.flashoffroad.com/Diesel/RearheadCooling/rearHeadCooling.htm

looks pretty simple and relatively easy to do. does it work though?????

I have talked at length with Bill Heath about his system. He has done alot of research and testing. I think he has a good idea and product. I thought good enough so I bought it. I haven't had any time to install it but will within the next week. I will report what I find as well as pictures. Maybe we could get Bill to chime in and tell everyone about his testing?

loosening the back cylinders is ass backwards, why would you want more clearance between two peices that are closer in temperature than two pieces that are farther apart in temperature. Cold water hits the front two cylinder liners..........that's where they need to be looser.:rolleyes:

"Thanks Spindrift"
TD,
Just because you came late to the dance is no reason to take out all of that hostility on me. :D Good to see you. She's pullin' real good.