Chevy Water Pump Leak

Water Pump Leak Repair

I have a problem with a water pump leak. I have replaced the original with a new pump, but I still have a leak I suspect around the gasket between the waterpump and the engine block. Any suggestions? I was very careful to clean the surfaces and evenly tighten the six bolts in a rotation first finger tight, then to 11 ft-lb, and finally to 22 ft-lb. Is 22 ft-lb the right final torque or do I need to re-torque after the engine has been through a couple of temperature cycles?

Solution:

I would check the intake gasket for leaking and running down,looking like its the waterpump, as far as I can tell you are doing everything right ,if need be I would put a pressure tester on the cooling system and pump it to 20 lbs and looking very closely at the intake.

all I can suggest is to put a little sealant on the bolts,11ft lbs the first pass and 22 ft lbs final pass is the correct specs.no I wouldnt torque it to 28 ft lbs as you are asking ,.let me ask this,Is the coolant leaking in the same spot with the new pump as it was with the original pump?I would inspect it more closely as the heads bolt to the block right there and it may be that the head gasket is leaking (,just a suggestion) If it is leaking in the same spot or there is apparent leakage where the head joins the block,check for the head gasket,it seems that there was a problem with some of the heads on these motors ,...guy..

Bulletin No.: 06-06-01-019B

Date: June 12, 2007

INFORMATION

Subject:

Information on Gradual Coolant Loss Over Time With No Evidence of Leak Found

 

Models:

2004-2006 Buick Rainier

2001-2006 Cadillac Escalade Models

2001-2006 Chevrolet Avalanche, Blazer, Silverado, Suburban, Tahoe, TrailBlazer Models

2001-2006 GMC Envoy, Jimmy, Sierra, Yukon Models

2001-2004 Oldsmobile Bravada

2005-2006 Saab 9-7X

 

with 4.8L or 5.3L VORTEC(R) GEN III, GEN IV V8 Engine (VINs V, T, M, B, Z - RPOs LR4, LM7, LH6, L33, L59)

Supercede:

This bulletin is being revised to include engine RPO L59. Please discard Corporate Bulletin Number 06-06-01-019A (Section 06 - Engine/Propulsion System).

Some vehicles may experience a gradual coolant loss over time. A very low percentage of cylinder head(s) manufactured with an embossed Castech logo may develop a porosity crack in a very specific area.

Inspect the cylinder head assembly to determine if the casting was manufactured by Castech. This can be accomplished by inspecting for their casting logo located on top of the intake port, under the rocker arm support rail and in the spring deck cavity portion of the cylinder head.

If the cylinder head(s) are Not a Castech casting, follow normal diagnostic procedures in SI to determine the cause of the coolant loss

it could be that the head has cracks and that may be causing the head to leak near the waterpump,

if all of this does not show any leak then perhaps get another pump

I will always use form-a-gasket on waterpump bolts,just put a tiny bit on the thread near the end of the bolt,the thread in the block sometimes goes into the water chambers(depth),also I was just working on a chevy with the 5.3liter motor and looking closely at where the head joins at the block and it is very close to where the waterpump bolts to, also too ,the intakes leak on quite a few of these motors ,so check very closely 

Water Pump Gasket Operation:

Normally a flexible material that's placed between the water pump and engine block to prevent external coolant leaks. Certain styles of water pumps require a backing plate gasket to seal off access to the impeller and shaft assembly.

To replace a water pump gasket:

Remove the water pump. clean all remnants of the old gasket off of the engine. be careful not to gouge aluminum parts.

A water pump often has a steel plate bolted to its back. The plate gasket sometimes dries out during shipping. If this happens the bolts will be loose, causing a leak.

Before installing a new pump, it is a good idea to remove the bolts and cement both sides of the plate gasket.

When replacing a pump, be sure that all gasket material is thoroughly removed and that any o-rings, hoses, or gaskets are not damaged or forced during assembly. Be sure that the screws that hold the cover on the back of the pump are tight.

Use sealer to glue the gasket to the water pump. Sometimes a chemical gasket is used.

Be sure that the surfaces of the pump and block have been cleaned of all oil and coolant so that the chemical can stick.

Paper gaskets are generally the only gaskets, other than retorqueable head gaskets, that require the use of a sealer. Paper gaskets are found on timing covers, water pumps, water outlets, fuel pumps, and some carburetors. Several manufacturers make tool sets for cutting the holes in paper gaskets.

When replacing a damaged gasket, gasket paper can be purchased in sheets. A gasket can be roughed out by holding the paper against the part and tapping on it with a ball-peen hammer.