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Discussion Starter #1
Do any of you fellow forum members have any opinions, thoughts, ideas, or advice on what is the best replacement water pump to get for my 96 Impala ?
I’m leaning towards the ACDelco Genuine Original OEM pump 251-255. $290 with thermostat housing and bleed screw.
Would anyone recommend an electric ?
I don’t trust my engine to bad electrical connections, shorts, failures and electric motors that slowly wear out and reduce flow.
Should I go standard flow or high flow ?
Any and all advice is appreciated !!!
Thank You...
 

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Few if any who converted to electric,ever converted back. It's almost a freebie since one saves the money for a new mechanical pump right off the rip. Electrics have so many advantages starting with not leaking coolant all over the opti ever. One can be swapped out in 5-10 minutes if you needed to (which I never have)....
 

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Would anyone recommend an electric?
I don’t trust my engine to bad electrical connections, shorts, failures and electric motors that slowly wear out and reduce flow.
Should I go standard flow or high flow?
Unless the type of [racing] you'd do is specifically aided by an electrical H2Opump, can't think of why to switch from a PROPERLY FUNCTIONING OEM-type mechanical H2Opump to an electrical one.
For more info about Meziere's WP118HD (the only one I recommend, all others should be considered inferior copies), read this

Electrical vs Mechanical Water Pumps
 

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Obviously many (including myself) don't share that opinion. I don't regret one minute converting to electric probably 15+ years ago. Far better,and more consistent cooling while in traffic. Able to run pump w/fans upon motor shutdown. Though the Meziere HD is a popular choice... I don't require their 55gpm coolant flow,or their amperage draw that goes along with it...
 

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To be clear: I'm NOT saying they're a bad idea.

I previously owned a wagon [which I will always miss].
After months of marginally acceptable & worsening coolant temps, it became clear that the nipple that came directly from my cam (the one that drives the splined key, which in turn drives the pump) had somehow worn smooth.

It would've cost $900 to remove & replace the H2Opump, Opti, front cover, & all that stuff that comprises the things behind the front cover that drive the H2Opump.
OR
It cost $250 to go from mech H2Opump to electric H2Opump (I did none of the mech labors).

I never looked back. I put over 120,000 HARD miles on a MeziereHD, with no complaints.
The rest of car, much as I still miss it, was no longer worth fixing after 248,000 miles of my inconsiderately aggressive driving behavior.
Personally, in NYC summers, I would not want a lesser H2Opump - but I suppose it's possible the MP118SD would've been sufficient? I can't say.

Pretty sure only Meziere rebuild their H2Opumps - at a pretty reasonable price - when they eventually fail.

So long as you use one of Innovative Wiring's electric H2Opump harnesses, I don't recommend against it at all.

Roughly when my present mech H2Opump starts behaving like it wants to be replaced, I'll reconsider converting to a Meziere, maybe even Meziere's standard duty version.

But I'm at least 10x more to buy a Meziere, compared to just about any other brand, just from the remnants recollected from when I 1st made this decision.
 

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The following warning is out of a sense of duty to you all …

If you choose an electric H2Opump:

1. Please use high quality wiring, such as one of Innovative Wiring's kits for this purpose.
Had some issues with lesser kits (Meziere's is inferior to Innovative Wiring's, obviously).
Also, make sure it has its own separate dedicated circuit. Don't be like me, overdo it right the 1st time.

2. One of the things that will be tougher to find (hopefully not impossible) is Spartus' warning kit. No clue why Innovative Wiring doesn't have it as well on their website …

3. Seriously consider enabling the High Coolant Temp EnRichment bit.
Since electric H2Opumps normally keep coolant temps lower than mech H2Opumps, & electric H2Opumps fail suddenly & totally, enabling the High Coolant Temp EnRichment bit after 105°C / 221°F is probably pointless.

4. At the very least, seriously consider keeping a spare in the glove compartment, with a spare O-ring.
 

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OP

Sadly "AC Delco" is nothing like it was. Even when it was, for me, my new under warranty 96 went through 8 of them and took out as many Optis.

20 years ago when my car went out of warranty I went Meziere 118 HD. 90+k miles later it still works. I have had a spare in the trunk for the last 15 years as at the time I bought it I assumed EWP's were short lived on street cars. Needless to say the Meziere has long outlasted any AC Delco I ever had and has lasted as long as any mechanical typically does...with exception to the LT1 AC Delcos and their clones.

My $.02 if buying mechanical get at NAPA. I have had good luck using their WP's vs other "brands on my other cars. YMMV

Some feel warning lights, buzzers, etc are necessary with EWP's....frankly I find my temp gauge works fine and I monitor it, like my oil pressure, as habbit

and as noted if you do have a EWP and need to swap it, you can do it in 5 min wearing a tuxedo and not get dirty
 

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Some feel warning lights, buzzers, etc are necessary with EWP's....frankly I find my temp gauge works fine and I monitor it, like my oil pressure, as habbit
If someone ignores the gauges the "Check Gauge" light comes on. I worry about drivers that could ignore gauges and warning lights. If the mechanical or electric pump fails it shows up the same on the gauge.


"Check Gauge" light comes on for: low oil pressure, low or high voltage, 255degF coolant, or low fuel. The RM has a "Hot" light beside the gauge. Is the 96 Impala different?


Easy to read gauges are one of the good features of this car line.
 

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If you do go ACdelco, make sure to go with the OEM as you have listed. Their other option has a heater line (I think?) bent incorrectly which puts it in contact with a belt (I think again?). I can go look if you really need the details. I ordered the cheaper option, bent the line for clearance, ended up with a coolant leak where that line presses into the pump body, and then ordered the OEM and did the whole job again.
I had always been against the electric pumps due to info I had read long ago. But they have been popular on this forum for a very long time. If I were to do the job again, I'm pretty sure I would go electric.
 

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If someone ignores the gauges the "Check Gauge" light comes on. I worry about drivers that could ignore gauges and warning lights.
If the mechanical or electric pump fails it shows up the same on the gauge.

"Check Gauge" light comes on for: low oil pressure, low or high voltage, 255°F coolant, or low fuel.
The RM has a "Hot" light beside the gauge. Is the 96 Impala different?

Easy to read gauges are one of the good features of this car line.
255°F / 123.9°C is so way much too hot for liquid coolant, nevermind that it's much more likely that the coolant has either stopped flowing, or has leaked out before it reached 239°F / 115°C.

Reality is, if the dash temp gauge is touching that white line before the gap before the red, even though the 'Check Gauge' light has not come on yet, it should have.
In other words, GM's 'Check Gauge' light & the accompanying bong both come on far too late.

On the other hand it's much tougher not to notice the difference between 14.7:1 & 11.2:1, so long as you're the driver …
 

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255°F / 123.9°C is so way much too hot for liquid coolant,
Hotter than I would like to run a motor.


nevermind that it's much more likely that the coolant has either stopped flowing, or has leaked out before it reached 239°F / 115°C.
I do not understand this statement.


Water boils at [email protected]
50/50 boils at [email protected]
60/40 boils at [email protected]


Unless you run just about pure water the system will not boil until after 255degF and should stay in the system.



By my memory on my car 225degF(scantool) was dash temp gauge needle touching that white line before the gap before the red.
 

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H2O boils @ 249°F @ 15psi
50/50 boils @ 265°F @ 15psi
60/40 boils @ 270°F @ 15psi

Unless you run just about pure water the system will not boil until after 255°F and should stay in the system.

By my memory on my car 225°F (scantool) was dash temp gauge needle touching that white line before the gap before the red.
It was cruel of GM to:
set the fan-on thresholds as high as 229°F & 234°F
set the Check Gauge light & alarm to go off as high as 255°F; it's just too late if there is any coolant loss or any flow irregularity
fail to activate the High Coolant Temp EnRichment bit

IFF there were no leaks, and the proper volume of coolant was otherwise flowing normally, 248°F would be the ceiling of acceptable.
However:
* if there's a leak ANYwhere, the pressure ceiling is now less than 15psi.
* if ANY of the coolant is not circulating properly in the engine due to a restriction or blockage, or H2Opump wear, there are hot spots
* if the coolant is chemically contaminated, even if it is not boiling, its heat transfer properties are adversely affected

Two other things that most overlook:
The dash temp gauge gets its reading from between cylinders #6 & #8, but the cylinder most likely to be damaged by overheating is #7 [then #5].
Transmission fluid that reaches 230°F [by being in contact with coolant over 230°F] has had its service life shortened considerably. In other words, GM is proximately responsible for our 4L60E's subpar reliability.

The above are the main reasons why pcm reprogrammers lower the fan-on settings so low, and why the High Coolant Temp EnRichment bit should be activated.

To sum up, 255°F @ the dash temp gauge is far too late.
 

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To answer the OPs question:
Gates makes a great factory style mechanical waterpump for LT1s
and you can get one inexpensively at RockAuto.

I also firmly believe that electric water pumps should
only be used on race cars. They are unreliable on daily
driven cars and anyone that tells you otherwise doesn't
drive their car daily.

Nab
 

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I bought a Gates from RA, be sure to inspect the heater hose tubes closely.
Mine had a loose one and I didn't notice until after I installed it.
Had to remove/ship back/reinstall replacement (that one was ok).
So far so good no leaks/noise etc. and been a few years now.

 

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Discussion Starter #16
Would anyone recommend an electric?
I don’t trust my engine to bad electrical connections, shorts, failures and electric motors that slowly wear out and reduce flow.
Should I go standard flow or high flow?
Unless the type of [racing] you'd do is specifically aided by an electrical H2Opump, can't think of why to switch from a PROPERLY FUNCTIONING OEM-type mechanical H2Opump to an electrical one.
For more info about Meziere's WP118HD (the only one I recommend, all others should be considered inferior copies), read this

Electrical vs Mechanical Water Pumps
Mine isn’t functioning properly, it’s weeping out the bottom vent hole onto my opti...
It needs to be replaced, but if most the mechanicals new or remanufactured seem to be questionable in quality and durability, I may choose to go electric.
Cheaper, quicker to change, and won’t ruin my opti even if it does fail sounds like some pretty good reasons.
Thank you everyone for your input. I listen to all of it and consider it all...
 

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To answer the OPs question:
Gates makes a great factory style mechanical waterpump for LT1s
and you can get one inexpensively at RockAuto.

I also firmly believe that electric water pumps should
only be used on race cars. They are unreliable on daily
driven cars, and anyone that tells you otherwise doesn't
drive their car daily.

Nab
Except for, um, me, at least. 80-200 miles a day, about 6 days a week.
Maybe the relatively few of us who [have] daily drive[n] Meziere H2Opumps are so rare, that Nab is statistically correct, but I'd be lying if I testify against daily driving my Meziere WP118HD.

A PROPERLY REBUILT & ALIGNED OEM-type mech H2Opump should at least work well, if not very well.
Many if not most of the problems with OEM-type mech H2Opumps are due to misalignments between the cam-driving spline, the spline key, and the H2Opump's driven spline.
Sometimes I wonder if several thousand miles using a badly rebuilt mech H2Opump, could make the next one look bad because the previous one did some sort of damage to the cam-driving spline and/or the spline key.
Anyone who has had two or more mech H2Opumps in a row fail them should either find out if there is something wrong with the cam-driving spline or the spline key … or the H2Opumps they bought.

Then again, anyone who's had two or more mech H2Opumps fail them, might not want to try another mech H2Opump, whether the problem turns out to be the cam-driving spline, the spline key, or a bad streak of craptastic rebuilds.

In my case, my spline key, and my cam-driving spline had somehow worn each other smooth, and the cost of switching to the Meziere WP118HD was about 1/3 the price of replacing my cam-driving spline and spline key (nevermind that Sunrise Chevy told me it'd take at least 4 days to get them to me).
The Meziere WP118HD and the Innovative Wiring harness both, beat Sunrise Chevy to the punch, so …

In my case, I do not regret daily driving my Meziere WP118HD.
Since my last mechanical one had no leaks of any kind, I gutted its mechanicals, transplanted the Meziere HD, and never had another complaint.
(Bonus: in the winter, with the engine shut off, the Meziere would give everyone in the wagon about 15min of hotass heat before I needed to restart the engine. Saved gas, probably ate into the battery's lifespan.)

Had my 1st replacement mech H2Opump performed properly, though, truth is, I can't think of a reason why I'd've bothered considering a Meziere.

Sometimes, there are times when neither choice is necessarily a mistake.
People who own Gen2 LT1 engines should be glad when they actually have options.
 

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Another advantage to an electric pump is that the water pump drive seal in the timing cover lasts much longer before leaking. At least mine do.
 

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I also firmly believe that electric water pumps should
only be used on race cars. They are unreliable on daily
driven cars and anyone that tells you otherwise doesn't
drive their car daily.

Nab
Nab, I would agree if the EWP was other than a Meziere. I have had my Meziere on for over 20 years and for 10 of those it was my DD. Yeah I always thought on a "street car" they were short lived but for me that has proved to be not true. Now 20+ years and 90+k miles later...still working. YMMV
 

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Used CSR pumps exclusively. Swapped it out after 10 years,and have it for a spare (never needed it). Do I drive mine all day,everyday? No,and doubt many of us do. I certainly could though. Drove 950 miles to NOLA in 2016,and drove it hard for the entire week. Then drove across Texas,N.Mexico,and Arizona for another week of 100+ degree temps. Then drove another 1500 miles home. Many of us have used these pumps,and few (if any) have ever converted back to mechanical.
 
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