oil pan bolt size

Can anyone tell me off hand the length and thread pitch of the oil pan bolts (head is 10mm). Was under the 'vert doing some split loom replacement and discovered I have one missing. Would prefer not to pull another one out to check the size so I can go buy a replacement.

KDirk

KDirk.

OK, someone will probably beg to differ but, it appears that the thread is 5/16" x 18. The threaded portion, measured from the bottom of the flanged head is 11/16". The length measured from the bottom of the flange to the very end is 13/16". The overall length measured from the top of the bolt head to the bottom end is 1 and 9/64". The head itself is, as you said, 10mm.

I had a similar issue yesterday while working on my '97 GMC truck. I buggered up the threads in the crankshaft for the harmonic balancer when I used a puller to get it off. I wanted to chase the threads so i wouldn't muck up the bolt putting the balancer back on. Thinking it was metric, since I was using metric tools to do the work, I tried using a metric tap to chase. Couldn't get it started. Upon closer inspection of the bolt and some measuring I became aware that it was a standard bolt size and thread. (sheesh!) So glad I stopped and checked it!

Some time ago, I read somewhere the reason for this mix and match of metric and standard bolt sizes but now can't remember.

John F.

Ah great. I was hoping it was metric thread as I can buy a metric head bolt with metric threads, or SAE head bolt with SAE threads. I know the hardware store will not have a 10mm head bolt of any sort with standard threads. Which leaves using a mismatched head size (I hate doing stuff like that) or trying to get a spare off a junk car. How stupid.

Thank you for the size verification however.

KDirk

KDirk,

Your welcome.

Another note on the oil pan bolts. The three located at the "point" of the pan are a different. They are a smaller diameter. Don't know the size of hand but the screw into the timing cover instead of the block. Hopefully it's not one of these that you need.

John F.

Kevin when you come up you can get at Gibson's. There are lots of cars with bad motors...

Ah great. I was hoping it was metric thread as I can buy a metric head bolt with metric threads, or SAE head bolt with SAE threads. I know the hardware store will not have a 10mm head bolt of any sort with standard threads. Which leaves using a mismatched head size (I hate doing stuff like that) or trying to get a spare off a junk car. How stupid.

Thank you for the size verification however.

KDirk

John,

Luckily the one missing is not one of the oddballs. It is in the middle of the long side closest to the radiator. Luckily there is no leaking due to this one missing.

Dave-

That is my plan, naturally. Not sure how I'll get to the pan since I can't jack the car in the yard, but will figure out something.

KDirk

There is a Black '90 Riv in the yard with a bad motor jacked up right now. They do put the car up on doughnut spares for us junkers.

KDirk,

If you can wait a couple of days to replace it, I can send you the one I just measured out on Tuesday. Should get it Fri. or Sat.

It'll be awhile before I do anything (if ever) to the engine it came from.

Won't cost you a dime.

As with "Nucular" energy, it's "... too cheap to meter".

Oh yah, if it means anything, the bolt came from the original engine pulled from my '90 Reatta last June.

John F.

John,

that'd be great if you are so willing. No rush, it isn't leaking (thankfully). I just did the pan gasket, this one must have backed out on it's own (despite the fact I torqued them all to spec). Guess some thread lock will be in order.

Will send pm with my address.

KDirk

KDirk,

I've got it ready to go. All that's needed is the address.

I've been using blue LocTite on all pan bolts. So far, so good.

John F.