Water Pump Hardware 48 Flathead

Skipper Mc/Louisiana

Skipper Mc/Louisiana

Member
Hello,
What is the size, thread and length, for the bolts that are used to install the water pumps on a 1948 V8? Is stainless hardware recommended for the bolt inside the water pump? Thanks.
 
Yes to stainless for the bolt inside the pump and don't forget some anti-seize on it as well. Not sure of the length but I'm sure someone will be able to provide that info.
 
I've never had a bolt in the water pump not come out, and none were stainless. Anti seize is a good idea, you should be running a corrosion inhibitor of some type in the cooling system.
Martin.
 
evidently 42 merc you have never tried to remove a bolt inside the pump with the head rusted nearly off, a $1 stainless steel bolt is worth a lot more than that to save hours of fustration trying to remove a rusted bolt
 
Maybe it was just a bad dream, or more like a nightmare, when I tried to get those inner water pump bolts out of a 59ab engine that I planned to have rebuilt. The 9/16" hex heads had rusted down to something close to a 1/2" hex. I drove a metric size socket on to what was left of the hex, heated the area inside the pump around the bolts and the heads snapped off of both bolts. This allowed me to get the pumps off, and by luck there was just enough of the bolt shank left to grip with vise grip pliers. I heated that area around the bolts a couple times and applied some candle wax. I was never so happy when they began threading out. After that, its been stainless steel bolts with anti seize on threads for any of those internal water pump bolts that I install
 
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John and Mr coast,
From your experience the bolt can be an issue it seems. As I said, I haven't had the displeasure, so could go either way. Thanks for input.
I do still think though, if your running an antifreeze/summer coolant (which contains a corrosion inhibitor) and change it as specified by its manufacturer) and anti seize on threads, you can use a regular bolt, and it won't be an issue.
Stainless bolts, normally A2 are not good mounting hardware, they gall up and seize quite easily if not cover with anti seize, and snap or round off easily.
There maybe decent quality stainless bolts, not A2 sold for the purpose, that would be better.
I font think it's a needed thing with good coolant.
Martin.
 
Be careful about the length if you are replacing all the water pump bolts, they are not standard length and some will bottom out. ..B.
 
Scooder, you are right, stainless wont take as much torque as a steel bolt, but the difference is slight, steel bolt 3/8 x 16 is 31#,stainless steel 3/8 by 16 is #29
 
3/8-16 and I believe the correct length is 7/8". In some cases a 1" bolt bottoms out before tightening. G.M.
 
Thanks everyone for the replies, I will be attempting removal of the old pumps (in about a week) and already see rusted bolts inside the water cavity. I will replace the hardware, and be sure to not use bolts that are too long. Thanks for the great advice!
 
Skipper Mc/Louisiana said:
Thanks everyone for the replies, I will be attempting removal of the old pumps (in about a week) and already see rusted bolts inside the water cavity. I will replace the hardware, and be sure to not use bolts that are too long. Thanks for the great advice!
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Make sure you use a 6 point socket so you don't round the heads. G.M.
 
God its a stupid idea having those bolts inside a water jacket ..
But as dumb as having the crank seal on the inside on a Y block..
 
The pump mounting bolt in side the water jacket broke when starting to loosen it. When changing out a water pump one side at a time, can the engine be supported with a jack under the oil pan? I prefer not to have to pull the engine. Thanks.
 
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