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MG MGA - Bolt Torque and diameter

The engine is in and running!!!

All I have to do is relearn its preferred tunings.

One item has come up and that is a dramatic oil leak at the front of the engine. I suspect it is a result of not tightening the front plate, timing chaing cover and oil pan nuts sufficiently.

I coulding find torque for those bolts spec'd in the manual; anybody have any suggestions?

Here's the heart of the question. The 5/16" diameter bolts seemed to snug up fine to a 20 pound torque setting, but the 1/4" bolts never got to even that degree of torque, they just kept turning and turning. I inspected the bolt threads and they appeared to be just fine and I have no reason to think the female hole is stripped.

After talking with a friend who is an engineer he explained that due to the smaller surface area of the 1/4"bolt it may take significantly more "turns of the screw" before they torque up.

Any similar experiences? Any comments? Thanks
T McCarthy

If you are trying to torque a 1/4" bolt to 20 ft-lbs, you have probably stripped it. That is way too much torque for a 1/4" bolt. The amount of torque a bolt can handle is proportional to size and smaller bolts require and can accept only lower torque. Here is one chart that shows the maximum torque for various bolt sizes.
Jeff Schultz

You're going to need some of these before you need that torque chart....
Del Rawlins

on a 1/4" thread, I use a 1/4" ratchet. When it is hard and tight without too much force, then it's tight enough.
dominic clancy

If it's not a question of torquing the bolts, it could be one of not centring the front cover correctly on the pulley shaft before tightening, resulting in oil escaping past the felt seal. Also, did you fit the convex oil thrower washer on the correct way round?

Steve Gyles

For small fasteners convert to inch pounds, 10 ft lbs = 120 in lbs, and use an inch pound torque wrench. Few foot pound torque wrenches have sufficient resolution below 20 Ft lbs.
Russ Carnes

This thread was discussed between 20/10/2008 and 31/10/2008

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.