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HO Water Pump with single thermostat crossover?

P

proth1975

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With my recent starter issues out of the way, I found another issue to tackle... A leak. I'm losing a pint every couple of days or so. I'm going to start with the cheaper (and easier) parts first.

So, what I'd like to do is eventually (with funds permitting), move to the upgraded system. I'm thinking of going with the water pump and lower radiator hose first, then the upper hose and dual themostat crossover later.

Will this work? Can the HO pump work with the single crossover housing?

Also.... Are there any place on the back passenger side of the engine that are good leak spots?

-P
 
gnel said:
I put a H/O water pump on my single thermostat truck and it works fine.
Click to expand...

:thumbsup::thumbsup: Same here. Had a dual stat system on the shelf. Decided to keep the single stat and add the HO pump, HD fan clutch and plastic DMax fan. No regrets.
 
Whew... I was worried about it being on the side of the head (the side) facing the firewall... that would have been a job.

-P
 
The side/end of the head. Not on the valley side. On a newer LSx engine, they keep the grounds there, where the alternator would bolt to on the front of the head.

-P
 
great white said:
Pretty sure I recall 99.5 and up the most desirable pump to have.....
Click to expand...

ak diesel driver said:
Which also uses a screw on fan clutch
Click to expand...

The 99.5+ water pump with the screw on fan clutch is the better pump that has balanced flow to each side(the 97-99 was roughly an 80/20 split for flow whereas the 99.5+ was about a 60/40 difference between sides. Also HEATHS latest cooling kit uses the 99.5+ pump, a screw on fan clutch, DURAMAX fan blade, and a single stat system as the single stat housing provides bettwer flow to the radiator when the stats open. The dual housing doesn't have the bypass block off like the single stat housings have that blocks off the t-stat bypass hose when the stat opens. Alos only use an AC DELCO t-stat as the aftermarket ones have too tight of a spring on the bypass flap which can prevent the t-stat from going full open and cause overhating.
 
You need to find and fix your leak before you add pressure to the system. The only downside I have ever read about with the HO pump and single t-stat was higher block pressure and soft plug failure concerns. The thought was that the single t-stat would not flow enough so GM used 2 vs. a really big single t-stat. Hence the slight increase in block pressure from the restricted water pump. Vs the 16 PSI rating of the radiator cap, well, I just don't see the weak water pump output pressure making a difference that is going to matter. Neither does Heath apparently with their product line.

That said the HO pump with a 4 bolt low temp clutch, 180 summer t-stat, and 9 blade fan will keep you cool with a clean radiator stack no matter what you throw at it. (Towing 10% grades in AZ with the fuel and boost turned way up...)

If you have the money to spend then go for the proven better for the balance flow with the latest thread on pump... Shop it as there are deals to be found. I have not found it to be required but, I am also running a DB2...

Having used both fans I say the Dmax fan does better at idle speed with more airflow, but, the 20" 9 wing steel fan is better at rated full speed with less clutch slip. You can't go wrong with either fan. Only concern is shroud trimming with a 21" fan in some, not all, cases.
 
THEFERMANATOR said:
The 99.5+ water pump with the screw on fan clutch is the better pump that has balanced flow to each side(the 97-99 was roughly an 80/20 split for flow whereas the 99.5+ was about a 60/40 difference between sides. Also HEATHS latest cooling kit uses the 99.5+ pump, a screw on fan clutch, DURAMAX fan blade, and a single stat system as the single stat housing provides bettwer flow to the radiator when the stats open. The dual housing doesn't have the bypass block off like the single stat housings have that blocks off the t-stat bypass hose when the stat opens. Alos only use an AC DELCO t-stat as the aftermarket ones have too tight of a spring on the bypass flap which can prevent the t-stat from going full open and cause overhating.
Click to expand...


Doesn't Heath include some sort of orifice tube to rectify this dual stat problem?
 
From the MaxxTorque article Bill wrote a while back.
"At the conclusion of an exhaustive evaluation, we had determined a clear and decisive winner in the factory service replacement water pump: part number 88894035. This GM pump proved to be vastly superior to all others in terms of bias with a much improved and nearly equal coolant flow, side-to-side at 2,500 RPM. This represents a tremendous improvement in flow to the passenger side under heavy operating conditions. Where the flow rate on the passenger-side had been a paltry 22 GPM with the ’97 high volume flange type pump, the 88894035 pump provided 48 GPM!
"During this work, we performed evaluations of both single and dual thermostat systems with the good pump. We realized the best cooling system performance when we combined this improved pump with the older style, pressure-balanced, single thermostat type system. This combination creates desirable pump-pressure in the coolant passages of the cylinder block and heads that helps to prevent steam pockets. Another very important characteristic of this type thermostat is that it simultaneously blocks the water pump bypass port when fully open in order to route all coolant to the radiator under high load conditions. This is our favourite combo."
 
Found the leak... turned out the the thermostat cross over bolt was loose from a battery cable replacement. It was then leaking from front, and running along the intake, before finally running down the back of the block. Still going to do the upgrade to the HO pump though!

-P
 
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