1955-1962 Chevrolet 235 261 Water Pump Adapter Leaking Coolant

[djjc76]

Hello Everyone, first time posting here but long time lurker. I have been struggling to get a tight seal between the water pump adapter that relocates the water pump up a little higher to the radiator. I have a 261cui Chevy Engine with a 1954 Chevy truck water pump. The water pump to adapter plate is no issue. It is sealed very well with no coolant leaking. The issue I have been having is between the plate and the engine block, leaking on the bottom edge of the plate. I have removed and replaced the plate with various gasket configurations about five times and still the same issue. I have first tightened the bolts that hold the plate directly onto the block and then torque the top ones per the instructions. Perhaps I shouldn't even use a blue gasket at all and simply use RTV only between the plate and the block? Please advise! Thanks.

Juan

[Pre68Dave]

Give me a call Juan, my number is on the bottom of the installation instructions you got with the adapter.
Dave

[djjc76]

Give me a call Juan, my number is on the bottom of the installation instructions you got with the adapter.
Dave

Hi Dave. Wow, so sorry. I never received a notification from your reply. Yes, I'll call you soon. Thank you.

Juan

[Deve]

Another issue Juan, or maybe it's just me.. it's entirely possible, but I ordered a waterpump from one of our vendors that stated "Short Shaft Waterpump" and it was touted as the one to use for fitting the new 235 into an older truck. Those do NOT work for me. The fan still hits the radiator. The pictures you shared with me confirmed (to me anyway) that you have the wrong waterpump. Again, I hope I am wrong. The ONLY waterpump that I find suitable for this conversion is the AW108N available at Rockauto.com for $65. This has the narrow pulley and you use the 216's old fan for this. The 6 blade fan you are using is part or all of the problem. The AW108N is a 1953 waterpump and it works very nicely with Daves adapter but the waterpumps bolt pattern for the fan blade is perfect for the old 216 but wrong for the newer style 235 fan. If anyone has other information that makes me wrong.. please interject because I want to get this right.

I know for a fact that I am right about everything fits perfectly if you use the AW108N and a 216 fan with Daves Adapter plate.

[Pre68Dave]

Deve, he has the correct pump.

[Deve]

Turns out after consulting with Dave there is only one correct pump for the narrow pulley that works with the adapter plate and fits in a pickup with the radiator in the stock position. It uses the 216 fan which is a nice compact design that does not create clearance problems. The AW108N from rockauto.com is the correct one. If you purchased a 'short shaft' water pump from the vendors that has the new style 235 fan bolt pattern, you will be disappointed. I have a box of waterpumps I have purchased from the vendors advertised as 'short shaft' and "allows for proper fitment for the new style 235 and the stock radiator location" and NONE of them fit unless you press off the hub and shorten the shaft more, or move the radiator further forward. If there is some secret I do not know about, please let me know!

[mfahrbach]

Juan, that is one BEAUTIFUL looking engine!