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Water pump advice
- Thread starter Rachet
- Start date
denata
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4 bolt for mounting fan?
Last edited:
denata
Well-Known Member
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What part number water pump Delco ?
Yes, GEP offers both 4 bolt and screw mount fan pumps.
Will L.
Well-Known Member
I don’t have the number handy. Does anyone else to help him?
MrMarty51
Well-Known Member
It seems that someone not too long ago got a new Delco coolant pump but I dont remember if it was the center mount fan clutch or if it was the bolt on unit.
denata
Well-Known Member
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Looks like this is the right pump.
Opinions needed - Performed Optical Bump
Well everything has arrived. Just got my pump, controller, and gaskets in today. I took a vacation day tomorrow so let the fun begin!! And the inspector is at it again!! I think she approves 🙃
www.thetruckstop.us
Here is the part number list I have and should be up to date for ACDelco numbers....
88926231 - 252-717 - ACDELCO HO water pump new - cast iron imp, dual thermo, bolt on fan
88926230 - 252-716 - ACDELCO std water pump new
88894044 - 251-589 - ACDELCO 6.5 water pump new - stamped steel impeller-single thermo
88894036 - 251-590 - ACDELCO 6.5 HO water pump new - cast iron impeller-dual thermo-bolt on fan
(19168610)
88894035 - 251-603 - ACDELCO 6.5 water pump-screw on fan, stamped impel.
(19168609, 12456231)
88926231 - 252-717 - ACDELCO HO water pump new - cast iron imp, dual thermo, bolt on fan
88926230 - 252-716 - ACDELCO std water pump new
88894044 - 251-589 - ACDELCO 6.5 water pump new - stamped steel impeller-single thermo
88894036 - 251-590 - ACDELCO 6.5 HO water pump new - cast iron impeller-dual thermo-bolt on fan
(19168610)
88894035 - 251-603 - ACDELCO 6.5 water pump-screw on fan, stamped impel.
(19168609, 12456231)
Big T
Well-Known Member
Last time I looked for water pumps on RA, the AC Delco spin-on-fan pump was $210. Something is going on there.
Big T
Well-Known Member
DON'T TRUST R/A TO LIST THE CORRECT PARTS !!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Will L.
Well-Known Member
@denata
The one Twisted Steel Performance (Chris) shows at the bottom of the list is the correct one.
88894035 - 251-603 - ACDELCO 6.5 water pump-screw on fan, stamped impel.
(19168609, 12456231)
Send him a pm for how to order it and be done without worries.
@n8in8or Can you describe how you made your restriction fitting for the water pump please. I remember your method seemd much easier than how I did them.
Denata- All your hummer is missing for the complete balanced flow system is that restriction fitting. Provided you use the AC Delco spin on pump like it had originally.
But I seriously suggest adding a high quality after market engine temperature gauge and install the probe in the passenger head to the rear easily accessed once the engine cover is off. The factory hummer gauges used for temperature from 1996 and newer were total crap for accuracy.
The one Twisted Steel Performance (Chris) shows at the bottom of the list is the correct one.
88894035 - 251-603 - ACDELCO 6.5 water pump-screw on fan, stamped impel.
(19168609, 12456231)
Send him a pm for how to order it and be done without worries.
@n8in8or Can you describe how you made your restriction fitting for the water pump please. I remember your method seemd much easier than how I did them.
Denata- All your hummer is missing for the complete balanced flow system is that restriction fitting. Provided you use the AC Delco spin on pump like it had originally.
But I seriously suggest adding a high quality after market engine temperature gauge and install the probe in the passenger head to the rear easily accessed once the engine cover is off. The factory hummer gauges used for temperature from 1996 and newer were total crap for accuracy.
Last edited:
Will L.
Well-Known Member
You need to spend a lot more time reading some older threads to keep that hummer engine alive bud! Or it is going to cost you many thousands more $$ long term.
The restrictor fitting: where the 1” hose connects from the thermostat crossover to the water pump. LeroyDiesel.com sells one that is nicely made and if you don’t mind spending the money- just buy it from him. But many of us here are trying to save money with parts, so just made them ourselves. I am guessing the $75 plus shipping to you will be double. So that why I figured maybe you make your own.
When the design change happened they made a different fitting originally that still used same size hose, but had an opening of 3/8” diameter for 1/2” long inside the fitting. This restricted the amount of completely hot water going from before the thermostats back into the waterpump and into the block where it mixed with the coldest water in the system. Only having one return hose into the water pump. Is part of the fix in getting the same amount water to flow through the two sides of the block and heads. Hence the term “balanced flow”. But the change to the dual thermostat crossover meant too much maxed out temperature water not getting cooled off, so a company was hired to make the fitting for AC Delco who makes the water pump for GM. They out a patent on it, owner died, family wouldn’t release production rights to Delco or GM. So they went back to the normal sized one and problems started coming back. GM released what the details were to those of us working in the dealerships and said that IF an owner was to make this on their own that we are to never remove it, and to reuse it if we install a new pump. Then they said the estimated time truck owners would have spent making them. Then magically if a truck owner did not have one in his truck, we could add on that same amount of time to our warranty card for an un listed reason- so you figure out what gm was saying to do. Out here in the southwest where the overheating problem was the worst- they actually had a trainer show guys how to weld one up with a brass plug inside to remove then warming it with a torch in the middle of cool time so it would keep it from hardening then drill it out, or welding in an alternator spacer that had a gm part number from the older trucks, or making that from washers. They kind if tried to make it get to the public to do this on their own.
There was talks about using reducing bushings to 3/8” on both ends, but heat hose is not made in that size so that idea got abandoned. Gm tried at one point an insert that went into the heater hose and was held in place with a hose clamp- but that hose is already a tight spot.
Not everyone believes balance flow is an issue. However they all do a bunch of cooling modifications to try solving it not realizing this is the biggest issue.
Because of the crazy angle and reduced airflow our hummers have, amplified if you drive over 60mph because of the aerodynamics of our hood and windshield- this is a bigger problem. Where you are at, I doubt that becomes an issue. But if you do find your temperature creeping up- DO NOT get rid of your original radiator. DO NOT get the aluminum ones- there is plenty of hummer owners that all saw higher temps with the Davis, Griffin, and ebay radiators. Have it rebuilt into a 4 core preferably using dimpled cores. Those who have done the balanced flow and the radiator rebuilt that way never get over 210° no matter what they do.
Eric said has something like 50,000 miles on his custom radiator in his hmmwv and doesn’t have the restriction fitting and has only hit those temps a couple times.
The restrictor fitting: where the 1” hose connects from the thermostat crossover to the water pump. LeroyDiesel.com sells one that is nicely made and if you don’t mind spending the money- just buy it from him. But many of us here are trying to save money with parts, so just made them ourselves. I am guessing the $75 plus shipping to you will be double. So that why I figured maybe you make your own.
When the design change happened they made a different fitting originally that still used same size hose, but had an opening of 3/8” diameter for 1/2” long inside the fitting. This restricted the amount of completely hot water going from before the thermostats back into the waterpump and into the block where it mixed with the coldest water in the system. Only having one return hose into the water pump. Is part of the fix in getting the same amount water to flow through the two sides of the block and heads. Hence the term “balanced flow”. But the change to the dual thermostat crossover meant too much maxed out temperature water not getting cooled off, so a company was hired to make the fitting for AC Delco who makes the water pump for GM. They out a patent on it, owner died, family wouldn’t release production rights to Delco or GM. So they went back to the normal sized one and problems started coming back. GM released what the details were to those of us working in the dealerships and said that IF an owner was to make this on their own that we are to never remove it, and to reuse it if we install a new pump. Then they said the estimated time truck owners would have spent making them. Then magically if a truck owner did not have one in his truck, we could add on that same amount of time to our warranty card for an un listed reason- so you figure out what gm was saying to do. Out here in the southwest where the overheating problem was the worst- they actually had a trainer show guys how to weld one up with a brass plug inside to remove then warming it with a torch in the middle of cool time so it would keep it from hardening then drill it out, or welding in an alternator spacer that had a gm part number from the older trucks, or making that from washers. They kind if tried to make it get to the public to do this on their own.
There was talks about using reducing bushings to 3/8” on both ends, but heat hose is not made in that size so that idea got abandoned. Gm tried at one point an insert that went into the heater hose and was held in place with a hose clamp- but that hose is already a tight spot.
Not everyone believes balance flow is an issue. However they all do a bunch of cooling modifications to try solving it not realizing this is the biggest issue.
Because of the crazy angle and reduced airflow our hummers have, amplified if you drive over 60mph because of the aerodynamics of our hood and windshield- this is a bigger problem. Where you are at, I doubt that becomes an issue. But if you do find your temperature creeping up- DO NOT get rid of your original radiator. DO NOT get the aluminum ones- there is plenty of hummer owners that all saw higher temps with the Davis, Griffin, and ebay radiators. Have it rebuilt into a 4 core preferably using dimpled cores. Those who have done the balanced flow and the radiator rebuilt that way never get over 210° no matter what they do.
Eric said has something like 50,000 miles on his custom radiator in his hmmwv and doesn’t have the restriction fitting and has only hit those temps a couple times.
denata
Well-Known Member
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Very interesting. I thought it was a backup small circle. When the thermostats are closed and the radiator duct of the stove is also closed. on a hummer, the stove valve does not just close, it shunts a small circle. and the liquid moves anyway.
In the fight against overheating. I jammed this channel. the rubber buffer on which the headlight is mounted perfectly fit there.
By the way, the link is forbidden for me.
In the fight against overheating. I jammed this channel. the rubber buffer on which the headlight is mounted perfectly fit there.
By the way, the link is forbidden for me.
dbrannon79
I'm getting there!
I recently replmy 4 bolt hub pump with the Delco spin on pump. I'll look and see which one it was but I know I used the truck application for a 2000 3500.