Re: 8n Hydraulic pump exhaust valve

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Posted by Tim Daley(MI) on September 14, 2017 at 04:42:27 [URL] [DELETE] :

In Reply to: 8n Hydraulic pump exhaust valve posted by Kenny on September 13, 2017 at 20:16:33:

HiYa Kenny-
Part Number 8N-640 -Valve Assembly, Hydraulic Pump, Exhaust, doesn't look like it is repopped by anyone. CNH (Case New Holland) isn't a reliable source for parts any longer, in my opinion, and if they do stock them, you will pay beaucoup bucks for them. Heck, they no longer even make the MC-134D Hydraulic Oil. If Dennis Carpenter doesn't make it, probably no one else does either. Why do you think your exhaust valve is bad? Do you have leaking issues there? Have you had the whole pump pulled out, taken apart, cleaned thoroughly, then rebuilt? All parts will wear but this is one of the more robust features on the pump. If it was prone to a high failure mode, it would probably be repopped new already. I'm just saying. Look at the parts breakdown in your MPC. There are several other parts in the assembly that can fail -a cotter pin, a spring, 8N-642;stem, and a retaining pin. If you have done all that and you can visibly see leaking, chances are the pump bore is worn out-of-round and that is the root cause of the leaking. Best case scenario then is to replace the whole pump. Find a used one and rebuild it while it is out then reinstall. New pumps are sold but pricey -over $600 -and I do not know what the track record is for the new aftermarket pumps. Second case, involves finding a used original pump as well and try swapping out the Exhaust Valves only. To me, that is a lot of work to chance. If I'm pulling the top cover and dropping the pump, I would either do a complete rebuild of the original or rebuild another used one and then swap them out. I'd avoid buying a whole new pump, but that is just my opinion. Pulling and rebuilding the hydraulic pump is a pretty basic, straight-forward job. It just involves a lot of time and work.

Tim Daley(MI)

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