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6.5 stat by pass
- Thread starter J-ME
- Start date
Twisted Steel Performance
Anything worth doing is worth overdoing.
No it's not..
The single is said to flow better than the duel but I can't confirm one way or another, my single system has never run hot so no need to change what's working..
The single is said to flow better than the duel but I can't confirm one way or another, my single system has never run hot so no need to change what's working..
Jaryd
Extremely Deplorable
Since you have a 96 yours could have either tstat crossover, single or dual
some say that putting a restricter in the bypass helps on a duel stat system
some say that putting a restricter in the bypass helps on a duel stat system
NVW
Well-Known Member
The restriction helps the dual system on warm up, the single doesn't need it as the "T" stat has the foot that closes the bypass.
- Staff
- #6
To clarify, if you have a single stat, do not add a restrictor, if you have a dual stat then yes, add a restrictor in the bypass line. The restrictor forces more coolant through the radiator since the dual stat system does not have a bypass blocker like the single stat has.
Will L.
Well-Known Member
On the waterpump and fan:
Afaik, no one here has yet used a flowkooler pump.
I have never heard of the Drama fan.
There is a nightmare history of the 6.5 waterpump every since the v belt went to the serpentine belt. The V belt pumps were good, no real issues. The serpentine reverses the direction, and so the inpeller was reversed. Major issue began. Many waterpump revisions later, it was discovered the volume of water going through the left side of the engine got most of the water, near 70%, so right side heads, blocks suffered.
This was solved by the waterpump with the spin on style fan clutch redesign (nicknamed the balanced flow) so all the 4 bolt style serpentine belt pumps even though partially corrected in some redesigns are generally converted to the spin on style.
The pumps cannot be tested of an engine, as part of the redesign involved eliminating one of the heater hose taps in the waterpump. Also the original spin on pump had a restrictive fitting in it, and through weird coarse of events the manufacturer making that fitting went under, sompart of the correction ceased, so a diy fitting became the only option.
Because there was massive lawsuits between the maker of military hmmwvs using the engine and GM, neither company shares all the information with the public. It has only been through a few different employees as they retired from the 2 companies that all the information came out.
That is as short as I can make the story, but I ramble on- haha
So - is the “FlowKooler” going to give equal flow out the 2 heads with the entire system in place? That is the big question no one here has tested yet.
Simply removing the crossover and building two fittings and pumping water into 2 barrels for measurement doesn’t work because you have to take into account the smaller hoses flow as well. So a junkyard crossover for destructive modifyication becomes the easiest route, and is subjective in how you do it.
The most successful combo used here has been the spinon gm waterpump- others here know part number, I can never remember that one.
Then either the metal fan # 15992650 no longer available new- junkyard only, or the new available duramax 2001-2005 plastic fan. You sometimes have to trim either the fan shroud or the fan as it is larger. Leroy can trim the fan on request, as hummers/ hmmvs can not trim the fanshroud as a fix, he started doing it for customers.
Then the fanclutch. The sooner the fanclutch engauges, and at the higher the lockup percentage the better. Kennedy Diesel sells one he has made that has the fastest lockup and the highest percentage lock up of any viscous clutch available.
More on next post...
(See told you I ramble)
Afaik, no one here has yet used a flowkooler pump.
I have never heard of the Drama fan.
There is a nightmare history of the 6.5 waterpump every since the v belt went to the serpentine belt. The V belt pumps were good, no real issues. The serpentine reverses the direction, and so the inpeller was reversed. Major issue began. Many waterpump revisions later, it was discovered the volume of water going through the left side of the engine got most of the water, near 70%, so right side heads, blocks suffered.
This was solved by the waterpump with the spin on style fan clutch redesign (nicknamed the balanced flow) so all the 4 bolt style serpentine belt pumps even though partially corrected in some redesigns are generally converted to the spin on style.
The pumps cannot be tested of an engine, as part of the redesign involved eliminating one of the heater hose taps in the waterpump. Also the original spin on pump had a restrictive fitting in it, and through weird coarse of events the manufacturer making that fitting went under, sompart of the correction ceased, so a diy fitting became the only option.
Because there was massive lawsuits between the maker of military hmmwvs using the engine and GM, neither company shares all the information with the public. It has only been through a few different employees as they retired from the 2 companies that all the information came out.
That is as short as I can make the story, but I ramble on- haha
So - is the “FlowKooler” going to give equal flow out the 2 heads with the entire system in place? That is the big question no one here has tested yet.
Simply removing the crossover and building two fittings and pumping water into 2 barrels for measurement doesn’t work because you have to take into account the smaller hoses flow as well. So a junkyard crossover for destructive modifyication becomes the easiest route, and is subjective in how you do it.
The most successful combo used here has been the spinon gm waterpump- others here know part number, I can never remember that one.
Then either the metal fan # 15992650 no longer available new- junkyard only, or the new available duramax 2001-2005 plastic fan. You sometimes have to trim either the fan shroud or the fan as it is larger. Leroy can trim the fan on request, as hummers/ hmmvs can not trim the fanshroud as a fix, he started doing it for customers.
Then the fanclutch. The sooner the fanclutch engauges, and at the higher the lockup percentage the better. Kennedy Diesel sells one he has made that has the fastest lockup and the highest percentage lock up of any viscous clutch available.
More on next post...
(See told you I ramble)
Will L.
Well-Known Member
Mermber @ak diesel driver (your thread link please?) here did a great write up on a differnent fanclutch and fan option using an electro viscous fanclutch so you can set your own desired engaugement temps to deal with your environment and uses better.
You can even wire in a simple on/ off switch that could e employed to enguage early on specific hills you want early fan cooling, or then off if crossing deep water as to not destroy the fan under water. I am not dure if he ever did, but you could also add a trinary switch in the a/c system and engage the fan for better condensor cooling as needed for a/c system.
Outside of his idea,
There has been a gluttony of others tried. I worked at a company that did in field testing for gm on the 6.5 back in the 90’s. The overheating was part of what we did. Our company didn’t solve it, but I think we helped them discover major parts of it. Working with a couple of their engineers, we discussed over a dozen variations of using the rear head cooling ports which GM kept blocked off. GM experiments with every conceivable application you can image using them. Don’t bother with the hose kits connecting them together and back to the heater hose circuit. Gm found devistating effects - basically moving the problem to another area. The only successful use of them involved 2 seperate waterpumps that were electronically controlled and exterior radiator packs via elaborate fittings with flow tubes in place of the block offs.
When they described it, we built one in house to see effects, and back in the 90’s material costs alone was over $1000. It’s results were not a complete fix, so...yeah.
Another option is the hmmwv fanclutch. It is an instant, 100% lockup clutch. It defaults to on. It is released by pressure from the power steering circuit via electric solenoid. Member here @Twisted Steel Performance (@ link not working? Auto name fill wont happen) had one installed on his truck using the 4 bolt style Water pump with good success.
If I was to ever use the 4 bolt waterpump- one of any kind- I would absolutely use the hmmwv set up.
Viscous and electro viscous all have roughly a 5 year lifespan. The hmmwv is a rebuildable unit. Used ones can be had on ebay, as well as rebuild kits.
I have one that I am trying to build an adapter to make function on the spinon waterpump for the best of both worlds, but haven’t been able to spend any time on it in nearly 8 months now. A good friend in charge of a large hmmwv fleet had delays in getting the hmmwv fanclutches, and tried using viscous fan clutch system on several hmmwvs with devistating results. The advantage of the immediate 100% clutch was instantly proved.
You can even wire in a simple on/ off switch that could e employed to enguage early on specific hills you want early fan cooling, or then off if crossing deep water as to not destroy the fan under water. I am not dure if he ever did, but you could also add a trinary switch in the a/c system and engage the fan for better condensor cooling as needed for a/c system.
Outside of his idea,
There has been a gluttony of others tried. I worked at a company that did in field testing for gm on the 6.5 back in the 90’s. The overheating was part of what we did. Our company didn’t solve it, but I think we helped them discover major parts of it. Working with a couple of their engineers, we discussed over a dozen variations of using the rear head cooling ports which GM kept blocked off. GM experiments with every conceivable application you can image using them. Don’t bother with the hose kits connecting them together and back to the heater hose circuit. Gm found devistating effects - basically moving the problem to another area. The only successful use of them involved 2 seperate waterpumps that were electronically controlled and exterior radiator packs via elaborate fittings with flow tubes in place of the block offs.
When they described it, we built one in house to see effects, and back in the 90’s material costs alone was over $1000. It’s results were not a complete fix, so...yeah.
Another option is the hmmwv fanclutch. It is an instant, 100% lockup clutch. It defaults to on. It is released by pressure from the power steering circuit via electric solenoid. Member here @Twisted Steel Performance (@ link not working? Auto name fill wont happen) had one installed on his truck using the 4 bolt style Water pump with good success.
If I was to ever use the 4 bolt waterpump- one of any kind- I would absolutely use the hmmwv set up.
Viscous and electro viscous all have roughly a 5 year lifespan. The hmmwv is a rebuildable unit. Used ones can be had on ebay, as well as rebuild kits.
I have one that I am trying to build an adapter to make function on the spinon waterpump for the best of both worlds, but haven’t been able to spend any time on it in nearly 8 months now. A good friend in charge of a large hmmwv fleet had delays in getting the hmmwv fanclutches, and tried using viscous fan clutch system on several hmmwvs with devistating results. The advantage of the immediate 100% clutch was instantly proved.
Last edited:
Will L.
Well-Known Member
Please do share whatever your final choices are and the results.
What else are you doing in your engine build? Have you rebuilt these engines before?
What else are you doing in your engine build? Have you rebuilt these engines before?
ak diesel driver
6.5 driver
Electric Fan clutch
So for those who want accurate fan clutch engagement this could be for you. I know on my 96 the fan clutch has never engaged the entire time I've owned it. Living in cooler climates does have it's advantages. I even tried modding the spring to no avail. This clutch will only work with the spin...
www.thetruckstop.us
Pretty long, part numbers are at the end. And no I didn't end up using the ford one
Thanks for that info, Much appreciated. No i haven't rebuilt a 6.5 before but have rebuilt a number of other engines being a automotive mechanic. Thanks guys