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LBZ Water Pump Replacement

19K views 12 replies 5 participants last post by  SoCalMike 
#1 ·
I think it's about that time. Truck has been loosing coolant I didn't know about until the warning came on. I park on the grass so never saw a puddle. Popped the hood and smelled coolant and its leaking from the water pump area. Started parking on concrete. Sometimes it leaks out after I kill the engine. Upper and lower hoses collapse after I shut engine off too. I added about a gallon of coolant and it seems to have stopped leaking momentarily. Truck is not overheating. I've probably driven it over 500 miles since I discovered it.

What are yalls thoughts? Pump going bad? I see write ups on other engines. Is the procedure pretty much the same for the LBZ?
 
#2 ·
'area'?
Look to the weep hole for coolant residue.

Don't follow the old utoob vid on the LB7 where the guy uses a hammer and chisel to break loose the fan. nono

Get the lisle wrench for it
and the socket/flywheel lock to remove the balancer.

LIS-43560 36 & 47/1-7/8" Turning Wrench 1 $17.00
LIS-22100 Flywheel Holder/Socket Duramax 1 $28.35

Don't forget to replace the short bulk hose crossover, on the front, down below the T-stats. Easy as pie with the front tore off...major PIIA otherwise. Be ready to also replace the O-ring on the pipe piece that feeds it too.
 
#4 ·
'area'?
Look to the weep hole for coolant residue.

Don't follow the old utoob vid on the LB7 where the guy uses a hammer and chisel to break loose the fan. nono

Get the lisle wrench for it
and the socket/flywheel lock to remove the balancer.

LIS-43560 36 & 47/1-7/8" Turning Wrench 1 $17.00
LIS-22100 Flywheel Holder/Socket Duramax 1 $28.35

Don't forget to replace the short bulk hose crossover, on the front, down below the T-stats. Easy as pie with the front tore off...major PIIA otherwise. Be ready to also replace the O-ring on the pipe piece that feeds it too.
FYI the short hose is 1/2 Inch heater his. Not 3/8.....

I just did this job 2 weeks ago. If you have questions let me know.
 
#5 ·
Note: The collapse of the top and bottom hose is usually caused by a sticky coolant reservoir cap. Clean it with hot water, or replace it.

The water pumps usually last a little over 100k miles. Does sounds like your pump is gone. Contact Forum Supporting vendor for quality parts and competitive prices. [list at the bottom] Merchant has a new pump with a welded impeller, as some have come loose in normal operation.
 
#7 ·
It's the original pump and I just hit 180K so I guess its overdue!
 
#11 ·
Are you sure on the 74 ft lbs?
Thought it was more than that.

I used a monster 3/4" rated for 600 ft lbs (no cheater needed), but can't remember the setting used.

It all falls into the nightmare dream you care not to remember. >:)
But I do remember the 'snap' feel, resonating thru my shoulders and spine, once that balancer broke loose. :nerd:

Hey, but when it's all over....the sense of accomplishment outweighs the pain and all of the strange body bruises seen in the mirror every morning (and having to explain their source to the other half). haha:
 
#12 ·
Yes sir.1st step Torque to 74ft lbs. 2nd step 105 degrees.

And to break the harmonic balancer bolt loose you put the hood to the service position. Use the flywheel locker and 36mm 12 point socket on the balancer bolt. 3/4 breaker bar and put a 5 foot cheater bar on it. This way you won't have to kill yourself loosening the bolt. Trust me that bolt it tight even with the 4 foot 3/4 inch breaker bar.......
 
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