Topic: Help.. help..overtightened oil drain plug and developed a crack in oil pan

[coolgoose]

Hi guys.....I did a stupid mistake and over tightened the oil drain bolt under the engine on my 72 CB750. Now, it has cracked in two place. Please see the attached pictures for more details on the cracks.

How can I fix this? What options I have? Any suggestions guys 

Thanks a ton in advance!

[SOHC Digger]

Replace it.  They are plentiful enough on ebay.

[Stev-o]

Here and on sale!

http://www.ebay.com/itm/honda-cb750-1969-76-oil-pan-03456-/290642387159?pt=Motorcycles_Parts_Accessories&hash=item43aba2e0d7&vxp=mtr#ht_564wt_689

And get a gasket.  And a torque wrench!!

[CafeDawg]

+1 on SOHC Digger answer.  Did the same thing to mine a month ago got a replacement for$25 on ebay gasket for $12 had it fixed in no time.   Also gave me a chance while the exhaust was off to fix a few holes.   Good luck.

CD

[coolgoose]

Thanks a lot for the advice guys. I just bought the one in ebay from the link posted by Stev-o. I will also get a gasket and torque wrench.

Thanks again for the sound advice. I was thinking of going down the epoxy route..but probably that would not have been the right way.

[Grey]

you don't need a torque wrench. what you need is a crush washer on that bolt first! That's why you broke it. Don't McGilla Gorilla the bolt.

[70CB750]

My K0 came with the oil plug hole welded shut. Now I understandwhat the PO most likely done.

I took the pan off for my first oil change, drilled and tapped new hole and put it back. It works fine like thise, only the bolt is SAE and not metric.

[coolgoose]

Thanks everyone for responding back. This time I will be very careful when removing / installing the drain plug 

[LesterPiglet]

I wouldn't use a torque wrench. Just use your common sense and don't over tighten.

[Stev-o]

I wouldn't use a torque wrench. Just use your common sense and don't over tighten.

Too late, if he uses a torque wrench he won't have this issue again.

[killersoundz]

I wouldn't use a torque wrench. Just use your common sense and don't over tighten.

Too late, if he uses a torque wrench he won't have this issue again.

Not true. A used crush washer forms a wedge like shape which when tightened down is very likely to cause a crack. The crush washer must be replaced

[Accolay]

I wouldn't use a torque wrench. Just use your common sense and don't over tighten.

Too late, if he uses a torque wrench he won't have this issue again.

Some of us had zero experience with mechanics until one of these Hondas landed in our lap. I never worked on anything until I got my bike.

[MCRider]

Thanks a lot for the advice guys. I just bought the one in ebay from the link posted by Stev-o. I will also get a gasket and torque wrench.

Thanks again for the sound advice. I was thinking of going down the epoxy route..but probably that would not have been the right way.

If by torque wrench you mean to tighten it to the recommended torque, I would ask you to reconsider. The recommended torque is 25ft lbs +. IMO this is too much for this application.  First you should always use a fresh crush washer. YOu need to feel it crush. Then as with all crush washer applications, like this, spark plugs, oil tank plug, tappet caps, oil filter bolt, one should toghten it by hand. Then put a short wrench on it like a 6" or 3/8 drive ratchet, and give it a skosh more to crush the washer then stop. If it leaks later, give it another skosh.

There have been many threads, one just recently of stripping or breaking this hole. My Clymer says "be careful not to overtighten ir they will be difficult to remove next time" followed by 25-29 ft lbs!  Way too tight in my opinion. That makes it one of the tightest bolts on the bike. In a puny aluminum boss.

The oil tank can take it a little more, but I'd still go easy on that as well

[70CB750]

Tighten lightly and give it more if it leaks. It will not spray oil more like a drop of oil or two. Just wipe it off with a rag and tighten it more.

On my Dana 300 I use silicon tape onthe thread to keep it dry. Steel plug in Al case needs extra attention.

[coolgoose]

Thanks for the great info on torquing the oil drain plug MCRider. I wish I was bit more careful while tightening it in the first place. Anyways, I learned from my mistake and I would never forget this.

Thanks 70CB750 for suggesting silicon tape.
 

[Mercutiojb]

Hey, that's the one I was going to buy!

Here and on sale!

http://www.ebay.com/itm/honda-cb750-1969-76-oil-pan-03456-/290642387159?pt=Motorcycles_Parts_Accessories&hash=item43aba2e0d7&vxp=mtr#ht_564wt_689

And get a gasket.  And a torque wrench!!