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Alloy water pump housing

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Does anyone have any experience with the new alloy (aluminum) water pump housing. I got mine in today from Rimmer Brothers (seems all the vendors in Britain now carry these) and it is quite a nifty piece. It is an exact duplicate of the original cast iron piece that is already on the car, but about 1/3 the weight. The only real issue that I can see about this little beauty is the spot where the three 5/16 short studs that hold the actual water pump on is about 1/4+" thick and is cut with SAE fine thread, just like the original. Now that would be fine if it were cast iron, like the original, but this doesn't seem like much to hold a big, heavy water pump turning at speed with a taught belt attached to it. Get the picture? I cut some new studs out of all-thread and stuck them in with thread sealer but am quite concerned that this might not hold. I could just see my water pump spinning off at 70mph. Am I being just an old worry wart or is this a possibility? I've written to several of the UK vendors and hope to catch a reply. Piman, any experience in this area? Hate to bolt everything up without an opinion. Thought of even putting in a thin all-metal locking backup nut from the inside but this might well interfere with the flow the the water spinning inside. Hmmmmm.

Bill
 
Hello Bill,
I have no experience of this item so far, but if the thread depth is only 1\4" that seems too shallow for a 5\16" stud.
However, I would be surprised if the vendors would sell this item if it had not been thoroughly tested, so perhaps the type of the aluminium (alloy) is a high strength grade.
The way I would go is to fit a thread insert, probably U.N.C. and make up new studs. By the way I don't like the quality of steel in the 'all thread' that we have here in the U.K. and would rather look for a higher grade fastener.

Alec
 
Bill,
Good observation about the thread length. You generally want at least one full thread diameter of engagement in aluminum (5/16 dia. = 5/16 length of thread) to generate full strength in a joint. That would be using a heat treated bolt, which all thread isn't.
I just ran the numbers on your combination and it works up that there is about.16577 square inches of shear area in those threads. If we assume that the aluminum has a 40ksi strength that comes out to a tensile strength of 6,630 pounds per tapped hole. That should be plenty to hold that pump in place.
This is based on using all of the threads in the hole, not allowing for any chamfer at the ends.
Hope this helps.

Dick
 
hey,if you have the housing, slip in an aluminum pump as well and cut even more weight.less weight is good!
rob
 
Hey Rob,
I acquired the aluminum housing from Rimmer and because it was new to me and no one that I knew had ever used one, I was a bit leary of the durability. Well, I emailed a few companies in England and got some quick and reassuring responses that the item was indeed of a superior quality. It installed well, exactly as the original cast iron unit it replaced. The only issue was the connection on the bottom back of the housing that connected the return stainless steel water line to the housing. I ordered a connector from two vendors and both were the same and neither would make the connection. Luckily the old one that I had was in fact stainless itself and worked fine. I tried sourcing out an aluminum water pump but to no avail and as I already had a new iron one, I just reinstalled it. I figured I saved about 4 pounds in weight. Kinda cool.

Bill
 
bill,
racetorations in the uk has aluminum water pumps. not cheap but cool stuff usually insn't. i hope you went with one of the modern waterpumps with the much improved impellers. if not you can get an impeller from them also.
this is too much fun.
rob
 
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