2004 water pump noise

[Duramaster]

Just an FYI........... Last week I replaced a water pump on a 2004 C-4500 LLY (I know wrong area to post but it shouldn't matter) and the only way you can get a pump from GM for this year vehicle is to get a pump kit which is just the pump with no housing. You have to swap over the housing, no biggie. Anyway, the new pump has narrower gear teeth than the original one. Of course I did not see this the first time (or the second time) and when I got the vehicle back together it had a gear rattle in the front of the engine much like a poorly shimmed PTO on the Allison transmission. I ended up reinstalling the old leaky original pump AS PER GM PARTAC so that the customer can use his truck until GM can figure out what the heck happened. I guess that they have several cases of this across the country and have no clue as to how the mix up started. Needles to say, I got pretty good at replacing the pump three times later. The purpose of this post is just to get you to take a look at your pump gear teeth and make sure that you don't end up chasing the same noise I had.

[DmaxMaverick]

Good info! Thanks, D.

[Mark Rinker]

Clarifying - just 2004 LLY affected?

[Duramaster]

Well, so far this is the only one that I have come across. If I get a chance, I will try and ask the Parts guy at work.

[DmaxMaverick]

It would be interesting to find out which years are effected, and why.

There are only 2 Duramax water pumps, so far. 2001 - 2005 (LB7 and LLY), and 2006 - current (2006 LLY, LBZ, and LMM). I wonder if they got the stock mixed up? The pumps are similar, but don't look interchangeable. The gears are obviously different, though.

LB7 - LLY / LLY(2006) - LMM:

[Duramaster]

That's cool that you have the pictures. And yes, the pump P/N 19168888 fits 01 - 05 LB7/ LLY in the pickup and 03 - 05 LB7/ LLY in the Medium Duty. No word yet from GM TAC as to what the deal is.

[lafrance]

I have been through this whole problem for the last 12 months. I had the pump replaced on my truck with the ac delco pump which is the only pump available through gm. It comes without the housing. The gear is incorrectly machined resulting in excessive backlash and resulting gear train noise. I have had 3 pumps replaced one was an oem replacement with the housing no noise but lasted 1 year before it began to weep. Gm then had enough cores to run them through ac delco remanufacturing( JUNK) There are after market pumps available but that is a crapshoot. I have and am going to put in a original isuzu pump that I found through a gm dealer one of the last 4 in Canada. GM needs to fix this headache.
Lafrance

[Duramaster]

We just got another GM Warranty representative in today. He listened to the truckand then took the original pump with him. Hopefully he will come up with a resolution. I have two more pumps to replace but I don't dare until I know what's up with the current gear issue.

[Mike in OKC]

Hi I am in the process of installing a new AC Delco pump I bought from GM, in a 2005 LLY with 156000 miles. I had mine installed in the pump housing and bolted back on motor and was going to finish up tonight. Then today I read your post about the gear noise. So I pulled the pump back off tonight and inspected the teeth on the new and old pump. They did look different so I checked further. As far as I can tell the teeth on the old pump are about 1/32 deeper than the new pump teeth. The overall diamater on the old pump gear is approx. 3.599 the new pump gear is approx. 3.593. That is not much difference so I bolted just the pump to the block less the housing and checked the difference in the slack in the mesh of the gears between the new and old pumps. The old pump seemed to be tighter. I don't know if the dealer will give me my money back or if I will have to take the loss but it is to hard of a job to knowling install something that will cause trouble. Maybe I can get the old pump rebuilt. If you hear anything from the GM TEC on this subject please post it. Thanks

[dr.olds]

hey mike in OKC maybe we can swap info from time to time! im only 70 miles from OKC, here in Cushing USA!:cool:

[Duramaster]

A gut from GM came to the dealership this week, took some pics of the old pump, took the pump and is now looking into the isseu. SO............... My parts dept. gave me a pump from NAPA. It has the correct width teeth and it has no noise. BTW, the NAPA pump BOX says it is made in the USA. I don't know about the pump, but the box is labeled in the USA.

[Mike in OKC]

Hey Dr. Olds that would be fine with me. Also Thanks Duramaster I will check out Napa. Mike:)

[lafrance]

Just installed an original isuzu pump. Noise gone as described in previous post. Gear cut is wrong on the delco pumps. Returning to dealer for refund.

[More Power]

Losing a water pump, and certainly when losing more than one within a short period of time, could indicate a problem with cooling system overpressure. In an LB7, this could be due to a leaking injector cup seal or head gasket. In an LLY or newer, it could mean a leaking head gasket. Leaking, in that compression pressure is finding its way into the cooling system.

These water pump seals should survive 100's of thousands of miles without leaking if everything, pressure wise, is normal.

I recommend replacing the coolant pressure cap whenever replacing the water pump. A defective cap could be holding too much pressure, which puts too much pressure on the water pump seal. We frequently hear of water pump replacement within months of a reported head gasket or injector cup problem that resulted in excessive cooling system pressure.

The cap is supposed to vent at ~15 psi. I suspect some of them are holding more than that.

Jim

[Dmax affair]

Just wondering if there has been any updates to this problem? I have just replaced the water pump in my 2003 and have a noise coming from the engine, sounds like a bad bearing and doesn't start making noise until the engine almost reaches normal operating temperature. I did use a new gm pump kit and of course I never looked at the gears!

I also replaced the drive belt, idler pulleys and tensioner bearing so those items are good!

I can't believe that I need to tare into this thing AGAIN!

[More Power]

Bring the engine up to operating temperature, when you can clearly hear the noise. Shut the engine off, and remove the serpentine belt. Now start the engine again, to listen for the noise. The water pump is gear-driven, like you said, so the engine won't overheat without the serp belt, but all other belt-driven accessories won't be a factor in any noise you hear. If you can still hear the noise, and if you're convinced it's the water pump, it'll have to come off to inspect it.....

Jim

[Dmax affair]

Bring the engine up to operating temperature, when you can clearly hear the noise. Shut the engine off, and remove the serpentine belt. Now start the engine again, to listen for the noise. The water pump is gear-driven, like you said, so the engine won't overheat without the serp belt, but all other belt-driven accessories won't be a factor in any noise you hear. If you can still hear the noise, and if you're convinced it's the water pump, it'll have to come off to inspect it.....

Jim

Just did what you suggested and it sure is coming from the front of the engine. I gess the wp will be coming off. Damn all of that coolant!

[mattb5150]

Is there a new pump available form GM?

Matt

[Kennedy]

We did 3 different Duramax engine builds recently and all got GM water pumps. Mine is teh only one currecntly operational, but I have no signs of any odd noises.

[Dmax affair]

Changed out my AC Delco pump today with a new napa pump #42349. The gear on this pump looks just like the original pump gear, best of all the napa pump is nice and quite!

[mattb5150]

My water pump started to weep at around 150k miles a few months back. With summer temps I got worried I'd get stranded in the Sierra's somewhere with a bad pump so I took it to the local Chevy dealer and had them replace the pump for $1,200. As soon as I picked it up I noticed a whine almost like a leaking turbo hose above 2000 rpm, even when trans is in park. I took it back to the dealer and of course they spent the day diagnosing without tearing it apart. They are supposed to call the parts TAC tomorrow, guess they should pull the belt off. Is this the sound others have heard or am I barking up the wrong tree with a coincidence?

[DmaxMaverick]

About 60 seconds with a stethoscope, then a run without the belt should tell them all they need to know.

I hate those closed hood diagnostic procedures. They are the most expensive, time consuming, and least productive.

[Yukon6.2]

$1200 for a water pump replacment...OUCH:eek:
Not trying to date myself,but i remember when that would buy you a complete motor.
I thought 4-5 K for injectors was pricey
I really don't know how people can justify such expencive repairs.
It's like that with all brands,i was told a local guy just spent $1700 on a fuel pump for a toyota TuRD.
I can see having to pay big$$$ for a company truck making money,but so many daily drivers are costing their owners $$$ to haul just one person around.
Glad i can fix my own vehicals.though that is getting harder as i move up in build years.Guess it's time to get a few more donar rigs in the yard
Thomas

[mattb5150]

I'm sorry it was only $1100, the $1200 included installing a new pinion seal on the rear diff. $750 for labor and $ 263.80 for the pump. And I think that's good price for pump from the dealer.

Well they removed the belt, my idea, and the noise doesn't seem to be there, now sounds like I'm only hearing boost when I rev above 2000 rpm, should I hear boost even under no load? They claim the belt tensioner is making noise, the pulley does have some play and its got 150k miles on it. It's also got rough idle and an EGR code I'm wondering if the noise may be from the vacuum pump.

Matt