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L-98 water pump replacement


Well-known member
Jul 25, 2001
2008 Silver Coupe
I am going to replace the water pump on my 90 L98 BEFORE it goes out.At 105,000 miles and some play in the pump, why not?
Anyhoo,does anybody have a respectable (or ridiculous)opinion on the so called 'High Flow'water pumps available.I've always been one to replace OEM parts with OEM parts,but she runs hot in traffic and heats up real quick at the red lights.I've already installed the manual fan switches from Mid-Am.They do fine job but since I'm replacing the pump anyway,I hoped I could get a few valued opinions.

BTW,Idler pully gettin'a little noisy as well.Probably replace it while I'm there.

Comments Please!! THANKS!!
I have always used the stock pumps on the C4. The stock pump is a really nice aluminum piece.

We use to have a lot of problems running warm. I did several things that made the difference. One, I replaced the radiator (probably about time at 150K miles-and the sides were splitting) with a stock unit.

I have our fans set where on runs as long as the engine is on and the other cycles with the a/c. We also cleaned out the massive amount of leaves and crud stuck between the radiator and condenser. I also replaced the fan motors as they were not pulling as much CFM after 10 pluse years and 150k miles.

Still running the stock pump and keeping cool in the Florida heat with the a/c blasting and bumper to bumper traffic. In fact, I had put a high performance low degree thermostat in the car. I need to bump it back up to a 190 stocker as the car won't heat up enough to stay in closed loop when running down the highway. We hardly break 190 in traffic.

Like I said, if you have never pulled the dog house off over the radiator and condenser, you are in for quite a surprise. There will be tons of junk stuck in there.

Hi there,
I agree, stock unless you are racing, its that simple.
They only flow as well as the rest of the system, consider the restriction of the thermostat, lines, and radiator??
I would stay stock, and if you get it installed at a GM dealer, you can get a lifetime warranty with it also.
Best toyou, c4c5
Thanks folks.

Bought the pump today (FRI.)and tensioner as well.Good price at Young Chevy in Dallas.$165 for pump,$45 for tensioner.(It ain't *what*you know,......)
Doghouse is checked regularly for debris.Personally I think we should be compensated by our municipalities for street cleaning.It doesn't take long for the trash to pile up in there.
Went with stock pump,will install myself.Last time I let some one else work on it,well....
I took it in for auto trans fluid service and to have the horn checked,When I returned to pick it up,I was informed that I would need a complete steering wheel assembly(!)About $800.00 as I recall.


I took a look for myself and discovered that the *fingers * on the back of the button,which reach down and push the contacts together,had bent to the point that they didn't reach the contacts.

Exit to Parts Department...

"I need two horn buttons for a '90 Vette"
"That will be $10.00 sir "
"*Really*?Hey,thanks man."

Exit to Service managers office....
(Very polite)"Hi,how are you?Great.Hey,I had my Vette in the other day for tranny service and to have the horn diagnosed and you guys wanted to replace the whole steering wheel."

"Yes sir,I'll look into that for you"

He leaves,comes back a few minutes later.

"Yes sir,I just talked to the tech on that job and he says your contacts have gone bad and we don't sell the contacts seperately,GM sells the steering wheel as a whole unit,except for the air bag.We will reinstall the old airbag for you"

Gosh,wasn't that kind of them to install my old bag at 'no additional charge'?

"So you are telling me I am forced to buy the whole steering wheel assembly to make my horn work,you don't just sell the parts?"

"Yes sir"

At this point I take one of the unobtainable parts out of my pocket and show it to him.

"That's not entirely correct,I just purchased two of these horn buttons for $10.00"

He gives me a blank stare and then says,

"Yes,but it is the contacts that are bad sir"

"Do you guys have a Corvette specialist?"

"A Corvette *specailist*?"

"You know,a person who works ONLY on Vettes"

He thinks my statement is quite funny.

" ha ha,no,ha ha ha no,no,no.No Dealer has a person who simply specializes in Corvettes.The techs work on all the models.Ha ha ha..."

"Well,let me give you a lesson in diagnosis my friend.( I pull out the button with the bent fingers)This is the old button from my Vette.See how the fingers are bent?This is why my horn doesn't work.These parts are readily available and they cost $5.00 a piece.NOT $800.00.I have to wonder at this point,how many people have you charged $800.00 for a complete steering wheel assembly when all they needed was one or two five dollar buttons?"

He gives another one of his blank stares.

I add "The dealer at XXXX Chevy has TWO guys who don't touch anything but Corvettes.Wouldn't that make them specialists?"

He says nothing.He knows he has been BUSTED!

I am still polite with him as I inform him that these kind of customer service practices are what gives the dealers a bad name.
And then I leave without getting anything that even resembles an apology or an offer for a free oil change or a free cap or SOMETHING to make up for his IDIOTIC SERVICE MANNER.

Why do dealers F*** them selves out of future business by doing these kinds of things?

It is hard to find a good mechanic.So I have become one.It's just that I'm lazy,and can afford for someone else to do the work.But no one can afford to be ripped off.So I'll just do it myself.

Just had to share an experience.
Talk with ya later.

Oh, Thanks for the input on the high flow pump!!
Taking a break from water pump installation.I haven't had this much fun since my last root canal.
Wow, this thread is really giving me something to look forward to. I can hardly wait till it's my turn! Gotta love C4's. If it's not alternators, it's water pumps.

Alternators,eh?I *might*be able to help you.What kind of problem are you having?Well,that's kind of a dumb question actually,but it's a way to start.I suppose you are replacing them often?
Hi all! IMHO, C4's run way too hot and literally cause everything under the hood to fry. Alternators weren't meant to be subject to such heat. Playing with the chip, 160 degree stats, (still debatable if it is good for the engine or not) all these things are a bit of help but they don't vent properly. I am really looking forward to adding my hood heat extractors and once for all will find out what kind of a difference it makes. Unfortunately, that is my winter project.

Tried it. It basically means your fans are running all the time, and everything under the hood gets covered in grit and dirt. Got to be a better way to cool these cars.

Gordan Killebrew suggests removing the weatherstrip on both sides of the clamshell,in front of the doors where the hood comes down.He says in his book'Top 50 Questions From Corvette Owners'it improves underhood cooling.He also notes that from '92 on,the factory did not put these strips in.

Almost thru with water pump installation.!!

NOT. :(
Richard, thanks for keeping us up-to-date with your water pump installation, and be sure to do a follow-up when you are finished. Don't be afraid to vent your frustration here if need be. :gap

I have a feeling that I'm gonna be digging into the front of my engine soon to repair/replace some things (like stripped threads on both the a/c compressor and the air pump :eyerole), so I'll be very interested in what's involved with the deeper you go. ;)

Good luck!
Well,I had to stop about 11:00 AM to go work on my new store.Still trying to get it ready for Grand Opening on Saturday.I just got home.

I have removed all obstacles,if you will,and I think I may have introduced new cuss words to the English language in the process.The large bracket for a/c has a special name that I won 't repeat in this forum.

I did get the new pump mounted,before I left earlier.

I have the Chevy Factory Service Manual (Mid America,about a C-note and some change)DON"T WORK ON YOUR VETTE WITHOUT ONE.The best Hundred or so that you will spend if you DIY.
However,I do wish they had included more detailed illustrations in some procedures,like ,..oh uh...THE WATER PUMP R & I MAYBE!!

It is going to take me a couple of days at this point to finish.I,ve got a million (ok,a few)things to do to take care of ME.
I've got a sweet little 86 MR2 that I drive when the Vette is being perfected.Not as fast by a long shot,but still a lot of fun to drive.
I've also need to buy hoses and replace them while I have it in it's COOLANT SYSTEM MAINTENANCE MODE.It would be just plain stupid not to replace these items at this time.

Hey,can ya think of anything else I should be checking on the Vette while I have it torn down to this stage?
Actually,the most difficult task was the removal of all parts needed to access the water pump itself.

Naw,the lower bolts on the A/C compressor were really the most *challenging*(meaning -#@##$^%*)

I hope I can remember what order things will need to go back on sinc e I have to put it on the back burner.Admittedly,I am the WORST about tightening up bolts or installing parts,only to have to loosen/remove them because I neglected(forgot) to include a step first.GGRRRRRR.
rdgfx3 said:
I think I may have introduced new cuss words to the English language.

:L I hear ya brother! My neighbors are afraid of me! :L

As for "anything else I should be checking", definitely change your coolant hoses and any other otherwise hard-to-reach hoses while you're in there. I'm doing the vacuum hoses as well; they are badly deteriorating at some of the ends on mine, so I'm sure there are more places they're weak. :eyerole

And don't forget to check all the electrical connections that would otherwise be inaccessible. ;)

Don't forget to replace the formed little heater hose right under the throttle blades. Also, get some high quality hose clamps to replace the factory, and or get some of the factory clamps from you dealer if you want it to look original.

Here is how I do this job.

1. battery disconnect
2. intake tube off
3. belt off
4. there are four crazy super long thin (10mm heads) bolts that run from the right inner fender to the driver side holding the compressor to the mounting bracket. I think the center inner fender skirt piece needs to come out, then you pull these four bolts. This lets you swing the compressor out of the way to gain access to any lower bolts.
5. Air pump valving bracket bolts
6. Hoses
7. that crazy large plate on the front of the pump
8. Pump
9. clean gaskets
10. Repeat.

** I left out the part about cleaning the wounds, pinching off the artery while applying the bandaging! :r
69MyWay said:
4. there are four crazy super long thin (10mm heads) bolts that run from the right inner fender to the driver side holding the compressor to the mounting bracket. I think the center inner fender skirt piece needs to come out, then you pull these four bolts.

:confused Ya got me there Chris! What exactly are you trying to say? :L

It would be easier if I removed the skirt and that is what I will do on reassembly.
Well after reading all this I am not sure I am looking forward to having to replace mine ....what really scares me is no one has mentioned if it is a six pack job or a case job...:L :L :L
It is not THAT bad.
Replacing the right side bank of spark plugs on the L-98 is harder IMHO.

BTW,I am stalled until I get the hoses.Lower hose and both heater hoses are backordered.
This wasn't a job I expected to fly through.I have the time to wait and most important,another cool car to drive while the coolest car is down.
rdgfx3 said:
Replacing the right side bank of spark plugs on the L-98 is harder.

I hear ya there brother! People have all kinds of ways to approach those plugs when changing 'em. :L


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