Well @ 445k the water pump started weeping, just replaced it @ 447,024. This on only had 236k on it when it started weeping. Org. lasted only 207k before weeping and I replaced it @ 209k. Not really a hard job, All Data calls for 8.6. I had it out and back in with a new fan clutch (Hayden) at about 11 hours. I also took the rad and CAC out and sprayed them down, also cleaned the condenser while I was at it. Also installed two 10 1/2" pusher fans on the condenser hooked to a toggle in the dash.. With the new fan clutch and 2 electric fans the A/C blows ice cubes @ idle. Org. fan clutch was toast would only roar at above 210 degrees and for 15-30 seconds in the a.m. (no roar at idle when warm... this was my main warm A/C problem at idle). I have only heard my fan at warm temps maybe 10 times in 447k, you would of thought I would have figured that out allot sooner.:(.

Tools and tips for water pump job.

1) Crank Bolt 36mm 12 point. needs to be re-torqued to 300 foot lbs.

2) MUST remove crank pully/damper to get the nut off of the stud....MUST!!!

3) If your new pump does not come with 2 little studs on it, get some from the dealer. Good luck getting them out of the old pump.:p:

4) Removing the main idler pulley bracket (big fan clutch one) will make moving the thermostat bypass pipe out of the way 100x easier.

5) Take a picture of the serp belt routing. This will aid in the install.

6) Make sure you have at least 5 gallons of coolant. I use the 50/50 universal long life from Prestone.

7) Remove BOTH battery grounds. or you will find out that the intake heater wiring harness is ALWAYS hot. Only wiring harness you have to move for this job.

8) When installing the turbo pipes output/blue to CAC, input/black plastic to intake/heater. Make sure the pipes are all the way down and that the bands are tightened to the correct spec. The bands also have a notch on them to let you know that they are in the correct place. I did not install the input tube correctly and it blew off the CAC the first time I got on it.:eek: I thought I blew something I had no boost/power and I was black smok'in like one of them pullin tractors at the county fair:D.

9) There are 6 rubber flaps/air dams. 2 between the condenser and CAC and 2 between the CAC and rad. and 2 in the front from the headlights to the condenser (these you will not have to worry about if you leave the grill on and the condenser in place). The 2 between the condenser and CAC are small and you must line them up for proper air flow. The 2 between the CAC and rad are larger and they must be lined up also. It is kinda hard to explain what lined up means but think of it as a ram air/tunnel system for the cooling system. The air comes in the grill and gets funneled by the front 2 flaps to just go in the condenser, not around it. Then the air goes to the CAC the flaps are in between the the condenser and CAC so that all of the air goes straight into the CAC. Then straight in to the radiator where there is 2 flaps between the CAC and radiator. If any of these flaps are misaligned the air will go out the sides and in to the wheel well area. So you may have poor engine cooling and poor A/C operation when the clutch fan is on. It will not be able to pull the air thru the designed ram air/tunnel properly and do its job correctly.

This job can be done by anyone with a little bit of automotive understanding. The only special tools needed are the 36mm 12 point impact socket and a fan clutch removal/install tool.

FYI. The crank pulley is not pressed on to the crank snot, remove the crank bolt and gentle pull the pulley/damper towards you, it should come off with no problems....It is heavy so don't drop it;)

Wow, pretty good. We just had our 2008 Savanna Cutaway's fan clutch take a crap at 60,000 miles and it wasn't covered under the 5yr 100k warranty. No fun, but its fixed now. We noticed right away because the fan comes on several times a day and stopped the other day.. Then it began overheating once it warmed up earlier this week. Replaced the clutch and did a coolant flush while at it and all is well once again.

so i suppose you have to take off the front end(grill. radiator, etc) to do any front end work on the engine?
got any instructions on disassembling the front end?

so i suppose you have to take off the front end(grill. radiator, etc) to do any front end work on the engine?
got any instructions on disassembling the front end?

You do not have to take the grill off, I did so I could clean the trans cooler and condenser and install the 2 pusher fans. There is only 4 bolts holding the grill on, 2 at the top (you can see when you lift the hood) and 1 behind each turn signal light. You also do not have to take out the rad. or cac to do the water pump but it makes it 10x easier plus you get a chance to clean them thoroughly. The cac and rad. come out in one pc. they are bolted to one another. To get the assembly out easily, (this is not in order :rolleyes:) remove the fan and upper radiator shroud and unbolt the lower radiator shroud from the radiator, disconnect the trans lines and upper & lower radiator hose from radiator, remove the air box and turbo pipes (input & output) and just pull it straight up. Keep a eye on the trans & oil dip sticks and the turbo outlet pipe (the aluminum one) so you do not rake the radiator fins.

When I change the serp belt and alt. I usually only remove the air box and upper shroud along with the turbo pipes. It only takes about 15 mins. It is about 10 bolts and loosen about 5 clamps.

You do not have to take the grill off, I did so I could clean the trans cooler and condenser and install the 2 pusher fans. There is only 4 bolts holding the grill on, 2 at the top (you can see when you lift the hood) and 1 behind each turn signal light. You also do not have to take out the rad. or cac to do the water pump but it makes it 10x easier plus you get a chance to clean them thoroughly. The cac and rad. come out in one pc. they are bolted to one another. To get the assembly out easily, (this is not in order :rolleyes:) remove the fan and upper radiator shroud and unbolt the lower radiator shroud from the radiator, disconnect the trans lines and upper & lower radiator hose from radiator, remove the air box and turbo pipes (input & output) and just pull it straight up. Keep a eye on the trans & oil dip sticks and the turbo outlet pipe (the aluminum one) so you do not rake the radiator fins.

When I change the serp belt and alt. I usually only remove the air box and upper shroud along with the turbo pipes. It only takes about 15 mins. It is about 10 bolts and loosen about 5 clamps.


What brand are those pusher fans you added? I've been thinking about adding those to mine. Are they hard to do?

They are the 10" TCI 827000 reversible fan. I got them from Jegs for 80.00 a piece plus the relay kit for like 25.00. You can use them as pusher or puller by changing polarity of the motor when wiring them up. They are 10 1/2" O.D. and they fit perfectly on the front of the condenser (one on each side of the trans cooler). No cutting/fabrication required, very simple/straight forward install. I wired them to a switch in the dash so I can control them. Some just wire it directly to the compressor switch, but then they will run when ever your compressor is running which really is not needed when cruising or using the defroster. I will take some pics with my phone and hopefully I can figure out how to upload them to this site:rolleyes:

They are the 10" TCI 827000 reversible fan. I got them from Jegs for 80.00 a piece plus the relay kit for like 25.00. You can use them as pusher or puller by changing polarity of the motor when wiring them up. They are 10 1/2" O.D. and they fit perfectly on the front of the condenser (one on each side of the trans cooler). No cutting/fabrication required, very simple/straight forward install. I wired them to a switch in the dash so I can control them. Some just wire it directly to the compressor switch, but then they will run when ever your compressor is running which really is not needed when cruising or using the defroster. I will take some pics with my phone and hopefully I can figure out how to upload them to this site:rolleyes:


Thanks for the info man.:thankyou2 Pics would be awesome.

Wow, I wish I had found this before pulling the water pump on this C5500 since it would have aleviated my anxiety thinking about pulling the crank pully. You can't imagine how suprised I was when the pulley came right off. So, 300 Ft-lbs on the pulley bolt and no mention of always replace on it so we will be good.

BTW, the water pump seal wasn't leaking, it was the housing that had a hole in it. Is cavitation a problem with these? The inside is completely ate up and through the housing, causing the leak. I have pictures if interested.

My clutch fan will stay on till about 45-48mph. Gotta get mine changed quick cause in town it kills the mpgs.

My clutch fan will stay on till about 45-48mph. Gotta get mine changed quick cause in town it kills the mpgs.

If you get a Four Season/Hayden clutch it will run at that speed to. I called there tech dept. about it and they said it is normal when cold to stay locked up at those speeds until it heats up. They said that the replacement clutch's for the duramax's will stay locked up longer and come on sooner then the factory ones.

Just want to give you a heads up on this as I just put one on about 8k ago and she loves to stay locked up till the engine gets to like 140 degrees (from cold of course) but once it gets there it will stay off till it gets to about 194 on the temp gauge. I was driving in some stop in go in NYC when it was 95+ out and she was a roar'in every time I took off from a light, which is every damn block in Manhattan. People where look'in at me as if I had a propeller on the van:D I did notice that know one jumped in front of me like they usually do driving down there, so that is 1+ and my A/C was throw'in ice cubes, so that is another positive.

Ok thanks for the heads up.

Great info, my 2008 seems to be weeping about a cup of fluid each day. This has been the last 4 days. If it is the water pump should I get a factory unit or buy after market? Or do I have a choice?

Great info, my 2008 seems to be weeping about a cup of fluid each day. This has been the last 4 days. If it is the water pump should I get a factory unit or buy after market? Or do I have a choice?

I always stick with OEM for components like this. I got a OEM water pump for mine from Rock autoparts for 155.00 plus shipping. Read my 1st post as I listed the gaskets needed for the job also.