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HE351VE with functional VGT on 1997 6.5L

Sounds like your coolant/transmission overheating issues seem to be more cooling stack issues than IAT/EGT issues. I assume you're running the balanced flow water pump with the spin on clutch and D-Max fan for starters? A LARGE Secondary transmission cooler? Stack cleaned and free-flowing? Upgraded radiator?
 
Husker6.5 said:
Sounds like your coolant/transmission overheating issues seem to be more cooling stack issues than IAT/EGT issues. I assume you're running the balanced flow water pump with the spin on clutch and D-Max fan for starters? A LARGE Secondary transmission cooler? Stack cleaned and free-flowing? Upgraded radiator?
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I agree with a cooling stack problem. I don't think air is getting to the radiator through the oil cooler, trans cooler, and intercooler very well, or the radiator is junk. Water pump is the stock 1997 bolt on clutch type but I have upgraded the fan clutch and fan. The radiator was used and I attempted cleaning the fins while it was out, but didn't check or clean the inside. That may be the biggest mistake. I had to add hose barbs to the radiator for the coolant reservoir and heater core return and cut off mounting bracketry to fit in the Chevy core support, so a new unit would need to be modified as well. An aluminum one may work better also.
 
Twisted Steel Performance said:
And don't be fooled with the unproven "balanced flow " thing, it's never been proven, the spin on clutch was a quicker assembly line thing, faster than 4 bolts....

This is all you need for a water pump... https://www.flowkoolerwaterpumps.co...996-1999-chevy-gmc-62l-6-5l-diesel-water-pump
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Ill be changing out the pump sooner rather than later now that this is happening. I remember you recommending Flowkooler pumps in the past and plan to use one.
 
Well, it was probably going to happen sooner or later...

I didn't think anything was hurt after my last towing experience, but this morning while driving the truck to work it was spewing coolant out of the cummins radiator over flow. When I noticed it, I checked the upper hose and it was rock solid. Head gaskets are toast, heads are cracked, or probably both. Timing is awful, as we were supposed to leave for another trip tomorrow morning. I guess its a blessing that it happened while we were home and not on the road. I could only imagine it doing its best Old Faithful impersonation while climbing The Sisters on I-80 east of Evanston.

Now I'm at an impasse. Try to replace the gaskets and most likely heads with the engine in the truck, or pull the engine and do it outside of the truck. The wife likes Option C, sell it and buy a *gulp* Ford. It will get studs, and I'm considering Cometic gaskets. May as well do front and rear main seals while its out, and the Flowkooler water pump. Are Optimizer heads worth the money, or stay with Promaxx heads?
 
Hate that for you for sure.. Promax, I have a thread here about my findings with them, very poor china heads.. I know you don't want to hear this but the P400 heads are by far the best, that's why I keep a set in stock..
 
Chewy1576 said:
I agree with a cooling stack problem. I don't think air is getting to the radiator through the oil cooler, trans cooler, and intercooler very well, or the radiator is junk. Water pump is the stock 1997 bolt on clutch type but I have upgraded the fan clutch and fan. The radiator was used and I attempted cleaning the fins while it was out, but didn't check or clean the inside. That may be the biggest mistake. I had to add hose barbs to the radiator for the coolant reservoir and heater core return and cut off mounting bracketry to fit in the Chevy core support, so a new unit would need to be modified as well. An aluminum one may work better also.
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Sounds like used radiator was not up to the task to begin with and just a guess "you using a shroud?" Oil, trans coolers & CAC have little or no effect on air flowing trough stack unless clogged with dirt and bugs but that appears notto be the case because of your earlier good results.

I have posted information in another post I can't seem to find about sealing the GMT400 series cooling stack around all the gaps of the rad support radiator condenser and other coolers to include the top between hood and rad support.

I see moved the batteries to another location however; with little mods like I had mentioned in earlier post they fit their stock locations using the Ram radiator..

Get a 12 valve w/P7100 IP and make real power or just a stoke setup if that is what you are seeking......
 
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@3bals and I are familiar with the Three Sisters east of Evanston, WY on I-80. We brought back his 6.5 powered motorhome with his Aveo on a toter in tow behind it from Reno in February of 2009 that route. More fun was the long stretch of hard-pack and ice west of Laramie with a 35mph northerly crosswind, but that long 6.5% grade east of Laramie on the way to Cheyenne was fun! Iirc, an old lady on a bicycle passed us going up that grade!
 
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FellowTraveler said:
Sounds like used radiator was not up to the task to begin with and just a guess "you using a shroud?" Oil, trans coolers & CAC have little or no effect on air flowing trough stack unless clogged with dirt and bugs but that appears notto be the case because of your earlier good results.

I have posted information in another post I can't seem to find about sealing the GMT400 series cooling stack around all the gaps of the rad support radiator condenser and other coolers to include the top between hood and rad support.

I see moved the batteries to another location however; with little mods like I had mentioned in earlier post they fit their stock locations using the Ram radiator..

Get a 12 valve w/P7100 IP and make real power or just a stoke setup if that is what you are seeking......
Click to expand...

I guess there was a reason it was replace in the first place right? I took a vacuum to it before installing to get as much of the gunk out of the fins as I could, but maybe I should have used water and a cleaner as well. I hated the idea of hacking up and modifying a brand new one, but now that I know what I need to cut and add to make it fit and work the the 6.5L maybe a new one isn't a bad idea. The stock shroud is still in place, and I was surprised how well it fit with the Cummins radiator but there are still gaps around the edges that could be filled in to improve air pulled through by the fan.
 
Of critical importance is venting steam on a 6.5td you will notice two small inlets by the filler port on the GM radiator the top one is the steam port there is little or no information on this however; GM thought venting the steam generated within the engines so important the incorporated it into the LS series gasser's.

In order for the steam to escape on your setup you can use a "y" connector and a accumulator "not a recovery tank."
 
FellowTraveler said:
Of critical importance is venting steam on a 6.5td you will notice two small inlets by the filler port on the GM radiator the top one is the steam port there is little or no information on this however; GM thought venting the steam generated within the engines so important the incorporated it into the LS series gasser's.

In order for the steam to escape on your setup you can use a "y" connector and a accumulator "not a recovery tank."
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I added ports to the Cummins radiator for a steam vent and the heater core return, to be as close as possible to the original GM cooling system. The steam vent seeps a little coolant but some high temp RTV sealed it.
 
Twisted Steel Performance said:
Any updates?
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Sorry guys, borrowed my father in law's 97 F250 to make the camping trip so I've been out of cell range for a few days.

I'm going to be tearing it down to see what is going on. I want to do Cometic MLS head gaskets, but the required surface finish for a good seal has me worried. Optimizer heads and studs when it's ready to go back together, I'll PM you @Twisted Steel Performance about pricing. I'm going to try to do it with the engine in the truck, I don't have the time nor tools to get the engine out. Plus I don't want to get digging too deep and find other issues, so as far as I'm concerned the bottom end is perfect 😁. While the coolant is drained I'll get the radiator checked and cleaned and change the water pump. I considered a Cummins swap but don't want to go to that extent. I still believe the 6.5 can do what I want it to.
 
Chewy1576 said:
I want to do Cometic MLS head gaskets, but the required surface finish for a good seal has me worried.
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I wouldn't attempt MLS gaskets if you aren't going to have the deck machined specifically for them. When I built my LS, even though it had MLS gaskets when I tore it down, the machine shop was very persinickety about the deck and decked it just to be safe.
 
n8in8or said:
I wouldn't attempt MLS gaskets if you aren't going to have the deck machined specifically for them. When I built my LS, even though it had MLS gaskets when I tore it down, the machine shop was very persinickety about the deck and decked it just to be safe.
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I'll steer clear of them then. I just want something that will hold together under unrestricted boost.
 
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