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View Full Version : I overtorqued my connecting rods


Camaro865
12-31-2011, 09:58 AM
i'm in the middle of freshening up a kawasaki fh500v engine and i took the connecting rod caps off to inspect them. long story short putting it back together they got torqued down to 8 or 9 ft pounds, book is 52 inch pounds, so just over 4 ft pounds.

the rods are aluminum, would it be safe to just take the bolts out and re torque or would i be better off with new rods? besides this they are perfect with no wear. i dont know if i'm being too critical with this or not, i just dont want to have any problems down the road.

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unkownfl
12-31-2011, 11:47 AM
Get new bolts or studs

piston slapper
12-31-2011, 04:34 PM
Replace the rods.
If they come loose there won't be anything to rebuild.
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BigFish
01-02-2012, 07:06 PM
I wouldn't replace the rods, what for?? Just get some new bolts ( ya really don't need to tho) ****** the threads in the rod and bolts with some carb cleaner/contact cleaner and use a drop of RED locktite on the bolt threads and a drop of oil under the bolt heads.

Patriot Services
01-02-2012, 07:12 PM
IMO I think you'll be fine. I would check clearence with old school plastigage at the factory torque setting to make sure the bolts didn't stretch or distort the threads. Red locktite will keep them from loosening.
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piston slapper
01-02-2012, 07:30 PM
My concern is that the aluminum threads were torqued over twice the recommended torque.
If the threads pull loose, all the locktite on the bench won't stop the bolts from coming out.
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jsslawncare
01-02-2012, 08:48 PM
I'm an engine machinist that turned full time grass cutter, REPLACE THE RODS! You doubled the torqe spec. You can't recon the small engine rod like you can a auto rod. The big end will be out of round. But, the rods are too cheap for what it would cost if the motor were to sling a rod. REPLACE THEM and make sure you put the caps on in the right direction.

unkownfl
01-02-2012, 09:50 PM
BTW you shouldn't be using that big of a torque wrench.

Restrorob
01-03-2012, 10:11 AM
replace the rods.


replace the rods!

x3............

Patriot Services
01-03-2012, 11:28 AM
The more I think about it changing the rods would be your safest bet. Your already tore down this far. Guaranteed if they failed it would be when you need the mower most. Plus failure will window the block for sure.
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Camaro865
02-03-2012, 08:02 PM
just an update:

i was just going to re torque and go with it but after i did that i noticed the rods had a good amount of play on the crank so i went ahead and got a couple new ones. they probably either distorted from the overtorqueing or the oil that was there made the play un-noticible. either way the engine runs and sounds pretty good for an older motor.

Sawil
02-07-2012, 05:36 PM
Always replace rods if rod cap bolts have been over torqued. The proper torque is not only important to get the best holding strength out of the bolt, it also minimizes bearing surface distortion.
Here is an experiment for you.
Get an old crank and rod.
Torque the rod to spec and turn it. It will turn.
Now over torque by 50%. (does it turn now?) (With Drag?)
You have just damaged the rod. It is more cost effective to replace than to have a down machine yet again.