|
|
Title: Lower Radiator Hose Comes Off
Problem: A 350 GM small block engine had a rebuilt water pump installed. Before installation, the rebuilt water pump was painted to match the color of the engine block. Then the vehicle was driven about 1-2 miles. At this time, the lower radiator hose came off of the water pump inlet tube and all of the engine coolant came out. This happened several times even after new hose clamps were installed and checked for proper tightness. What could be the solution to this problem?
Solution: Two things caused this problem to occur. First, look at the photo to the left. Notice that there is a small metal lip cast into the water pump housing at the start of the input tube, as identified by the yellow arrow. This lip helps to hold and seal the radiator hose to the water pump inlet. This is necessary so that as the pressure in the cooling system increases to around 14 psi, the radiator hose will not leak or come off. The metal lip is cast into the inlet tube housing of the water pump. Note that in the photo, the lip only goes part of the way around the water pump inlet tube. This was caused from a flawed water pump casting. So only a small part of the lip was used to hold and seal the radiator hose to the
water pump.
Problem: A 350 GM small block engine had a rebuilt water pump installed. Before installation, the rebuilt water pump was painted to match the color of the engine block. Then the vehicle was driven about 1-2 miles. At this time, the lower radiator hose came off of the water pump inlet tube and all of the engine coolant came out. This happened several times even after new hose clamps were installed and checked for proper tightness. What could be the solution to this problem?
Solution: Two things caused this problem to occur. First, look at the photo to the left. Notice that there is a small metal lip cast into the water pump housing at the start of the input tube, as identified by the yellow arrow. This lip helps to hold and seal the radiator hose to the water pump inlet. This is necessary so that as the pressure in the cooling system increases to around 14 psi, the radiator hose will not leak or come off. The metal lip is cast into the inlet tube housing of the water pump. Note that in the photo, the lip only goes part of the way around the water pump inlet tube. This was caused from a flawed water pump casting. So only a small part of the lip was used to hold and seal the radiator hose to the
water pump.
The drawing to the left shows a sectional view of how the lip is used to hold and seal the radiator hose to the water pump inlet tube. As the hose clamp is tightened, the radiator hose is secured to the right of the cast metal lip. This makes it difficult for the hose to slip off. With only a partial lip and the increased pressure in the cooling system, the radiator hose easily slipped off, causing all the coolant to come out.
A second problem also occurred. The owner painted the water pump housing to match the engine block color. The paint on the water pump housing inlet tube made the cast surface very slippery. With the cast metal lip partially gone and the surface very slippery, the radiator hose easily
came off when the coolant pressure increased to
its normal level.
If the water pump housing is painted, make sure the surface where the radiator hose touches the water pump is not painted and has a rough cast iron surface. Also, make sure that when a rebuilt water pump is used, it has a full cast metal lip. In some cases, an enhanced cast metal lip may be ground into the casting using a hand grinder. Be careful not to grind too deep into the casting, possibly causing the casting to weaken. If this doesn’t work, you will need to purchase a new water pump that has a full cast metal lip.
Back to Troubleshooting Clinics
A second problem also occurred. The owner painted the water pump housing to match the engine block color. The paint on the water pump housing inlet tube made the cast surface very slippery. With the cast metal lip partially gone and the surface very slippery, the radiator hose easily
came off when the coolant pressure increased to
its normal level.
If the water pump housing is painted, make sure the surface where the radiator hose touches the water pump is not painted and has a rough cast iron surface. Also, make sure that when a rebuilt water pump is used, it has a full cast metal lip. In some cases, an enhanced cast metal lip may be ground into the casting using a hand grinder. Be careful not to grind too deep into the casting, possibly causing the casting to weaken. If this doesn’t work, you will need to purchase a new water pump that has a full cast metal lip.
Back to Troubleshooting Clinics
|
|