Jinma Water Pump Torque Question

   / Jinma Water Pump Torque Question #1  

erj

Gold Member
Joined
Mar 19, 2008
Messages
261
Location
Buckley, WA
I'm having to replace the leaking water pump on my Jinma 284 with Y385T engine. When I ordered the parts from Harold at Affordable, he did not have any torque info and simply said to make them 'snug'. I am not sure what that means. I have a torque chart that gives settings based on the type of bolt. However, those chart settings seem like they are low for the task that the bolts perform. I don't want to put this thing back together only to take it apart again.

See attached picture-
A is the box that encloses the thermostat. The bolts (a) are Class 8.8 M6x1.0. The chart recommended torque for that type of bolt is 8ftlbs.
B is the water pump. The bolts (b) are Class 8.8 M8x1.25. The chart recommended torque for that type is 19ftlbs.

Does anyone out there have better torque information?

RonJ
Water%20Pump%20Torque.jpg
 
   / Jinma Water Pump Torque Question #2  
That sounds about right for that size bolts. Remember that property class 8.8 is not, nor nowhere near a SAE grade 8 bolt. Property class 8.8 is at the bottom of the spectrum for marked fasteners (relatively soft low carbon steel). You could jump up to a 10.9 or 12 if you wanted to really reef up on them, but then there is concern about pulling the threads in the castings.

I like your belt, by the way.:thumbsup:
 
   / Jinma Water Pump Torque Question #3  
When I replaced my oil pump I tightened an 8mm bolt "snug" and snapped it off, it ruined my day. Ever since then I use a torque wrench on every fastener on reassembly and a torque chart if the manual doesn't have a spec. The torque of 19 ft/lbs sounds exactly right. With a 1.5mm pitch, the mechanical advantage on a foot-long wrench is over 60 to 1, at 19 ft-lbs those bolts are exerting over 1200 lbs of sideways force each. That's plenty to hold the water pump on.
 
   / Jinma Water Pump Torque Question #4  
Thats more sophisticated than I usually get. I would grab my 3/8 ratchet ( it's about 8" long instead of 12" ) and tighten them to pretty firm hand pressure. I'm betting with the loss of leverage with my 4" shorter ratchet and even more leverage loss due to my hand not exerting all the force at the very end of my ratchet I'm right around that toque rating. I pulled the deflector off the mower deck and it was installed with 14" MM head bolts. They were rusted and they all 4 sheared off. It took pretty firm pressure on a 2 foot lever. Before you think I'm a terrible mechanic these bolts had nuts on the other side so I didn't care if they sheared off.
 
 
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