Cracked Coolant Outlet Tube - ZR-1 Net Registry Forums

dzim · 05-07-2012

I am new to the ZR-1 Net Registry Forum and new to ZR-1's. I just purchased my 1994 ZR-1 in March so my "terminolgy" may not be perfect!

A little over a week ago, I noticed that my ZR-1 had an anti-freeze leak on the left front behind the power steering pump. With the help of my mechanic (and best friend), we did a cold pressure test and discovered the driver's side coolant outlet tube was the source of the leak. It seemed that the likely problem was the gasket between the outlet tube and the plenum. I ordered the gasket and a set of bolts from Jerry's Gaskets (who has been great to work with - thank you so much Jerry). When we removed the outlet pipe, we discovered the gasket was in perfect shape. However, the outlet pipe was cracked. I then ordered a new outlet pipe - again from Jerry's Gaskets and replaced the cracked outlet pipe, put on a new radiator cap, pressure tested the system, and refilled with anti-freeze. We actually re-used the original bolts and gasket as they were in great shape.

My ZR-1 has been in storage most of its life. The odometer currently reads 9,985 miles. I thank the previous owners for preserving it, but I plan to drive and enjoy it. After replacing the outlet pipe, I drove it 400 to a Corvette Show in Kansas City this past weekend. The car performed flawlessly and even received a Best of Class Award for 92 - 96 C4's.

In the last two months, all fluids in the ZR-1 have been replaced and the car has been completely detailed - inside, outside, and under the hood. I fully expected to have "some issues" with a car that has been in storage. If it would have blown a hose, it would not have shocked me. However, I did not expect to have a cracked outlet pipe.

As you know, the outlet pipe consists of a rectangular housing with an attached pipe that goes to a radiator hose at the front of the engine. The crack is not in the pipe. It is in the housing on the front shorter side of the rectangle. At this point, the housing would appear to be its strongest as the bolt holes are recessed from the front two corners. The crack is all the way through this portion of the housing and continues around the joint where the pipe is connected to the housing and finally ends on the back side of the housing.

I have no idea what would cause the housing to crack like this. If the bolts were over tightened, I would expect it to crack in the corners around the bolt holes. I also have no idea how the pipe is connected to the housing or what would cause that seam to crack.

I know "pictures are worth a thousand words" and I have sent pictures to a friend who has volunteered to help me by posting them.

I welcome your feedback and knowledge. If you have additional questions, I will do my best to answer them.

Thanks,
Dale Zimmerman
Lincoln, Nebraska
1994 Black Rose ZR-1 #113

05-07-2012	#1
dzim Join Date: Apr 2012 Location: Lincoln, Nebraska Posts: 21	Cracked Coolant Outlet Tube I am new to the ZR-1 Net Registry Forum and new to ZR-1's. I just purchased my 1994 ZR-1 in March so my "terminolgy" may not be perfect! A little over a week ago, I noticed that my ZR-1 had an anti-freeze leak on the left front behind the power steering pump. With the help of my mechanic (and best friend), we did a cold pressure test and discovered the driver's side coolant outlet tube was the source of the leak. It seemed that the likely problem was the gasket between the outlet tube and the plenum. I ordered the gasket and a set of bolts from Jerry's Gaskets (who has been great to work with - thank you so much Jerry). When we removed the outlet pipe, we discovered the gasket was in perfect shape. However, the outlet pipe was cracked. I then ordered a new outlet pipe - again from Jerry's Gaskets and replaced the cracked outlet pipe, put on a new radiator cap, pressure tested the system, and refilled with anti-freeze. We actually re-used the original bolts and gasket as they were in great shape. My ZR-1 has been in storage most of its life. The odometer currently reads 9,985 miles. I thank the previous owners for preserving it, but I plan to drive and enjoy it. After replacing the outlet pipe, I drove it 400 to a Corvette Show in Kansas City this past weekend. The car performed flawlessly and even received a Best of Class Award for 92 - 96 C4's. In the last two months, all fluids in the ZR-1 have been replaced and the car has been completely detailed - inside, outside, and under the hood. I fully expected to have "some issues" with a car that has been in storage. If it would have blown a hose, it would not have shocked me. However, I did not expect to have a cracked outlet pipe. As you know, the outlet pipe consists of a rectangular housing with an attached pipe that goes to a radiator hose at the front of the engine. The crack is not in the pipe. It is in the housing on the front shorter side of the rectangle. At this point, the housing would appear to be its strongest as the bolt holes are recessed from the front two corners. The crack is all the way through this portion of the housing and continues around the joint where the pipe is connected to the housing and finally ends on the back side of the housing. I have no idea what would cause the housing to crack like this. If the bolts were over tightened, I would expect it to crack in the corners around the bolt holes. I also have no idea how the pipe is connected to the housing or what would cause that seam to crack. I know "pictures are worth a thousand words" and I have sent pictures to a friend who has volunteered to help me by posting them. I welcome your feedback and knowledge. If you have additional questions, I will do my best to answer them. Thanks, Dale Zimmerman Lincoln, Nebraska 1994 Black Rose ZR-1 #113 Last edited by QB93Z; 05-07-2012 at 04:30 PM. Reason: add pictures