jpitman2

Mate of mine once worked on an off shore oil platform. It had a crane on a pillar for lifting supplies and machinery off barges 100ft below on the water. The crane pillar was held down by some VERY LARGE BOLTS into the deck. Part of regular maintenance was to check the nuts on the BIG bolts. Seems they did it wrong, just applied specified torque without any loosening...over and over and over. One day the crane was lifting a large load off a barge, and the nuts just went elastic, and pulled off. The driver rode the crane 140ft to the water, and got away with a broken arm or similar. The threads on the bolts still looked servicable apparently.

I did have trouble the first time I pulled the block drains , but it was more a question of getting the wrench pull at the right angle. They were pretty tight, but they went in looser, and dont leak.

jp 83 Euro S AT 56k

hacker-pschorr

How about the oil drain plug? I was paging through the WSM and noticed

M22 - 60Nm
M20 - 50Nm

The idea of tightening a crush washer to 60Nm is odd enough, what makes this extra bazaar is the 22mm is the old style without the helicoil insert. Why would tightening a drain plug into bare aluminum threads be higher than the one with the insert?

WSM Volume I
Page 10-05

Ed Scherer

A little visual aid might serve as a good reminder to not torque the block drain plugs too much:

Block drain plug, seriously deformed crush washer, and new crush washer:




The crush washer wasn't crushed as much as it was totally reformed. I had to unscrew it from the drain plug. It didn't leak, though, and provided a few years of trouble-free service.

GlenL

Doesn't even look like the same part. Maybe it's not!

"Gotta make sure this doesn't come loose" is often the thought right before screwing things up.

I keep blue loctite handy to satisfy that impulse.

Snark Shark

Always to spec, or do you ever under-torque things that seem a little worn out, threads less than perfect?

Reddog2

Interesting discussion. I just drained my coolant this past weekend and reinstalled the plugs to torque spec (per WSM) with some anti-seize. I was paranoid about pulling the plugs out as they felt tight when I tried to remove and I was not the last one to put them in. I used the torque wrench in reverse at torque spec to try and ensure I did not break these bolts. - they came right out at or around the WSM torque ( assuming reverse reading is valid?)

Before I put coolant in, maybe I will remove again and re torque or hand torque to lower setting, with another new set of crush washers as advised - to ensure they will come out again next time.

Good thing I did not read the links here on broken bolt drains first. Sometimes too much reading leads to not enough doing - especially for us rookies.

worf928

Bump.

It's been over a year since this was on the front page and we've lots of new folks getting coolant on their faces.

docmirror

Just did my block drains a few days ago. Took the coolant bath. New crush washers and replaced plugs with 26Ft Lb. The removal torque was significantly higher, assuming due to long term fitment.

I torqued all the important stuff on the front engine job. Got the new pinch bolt on flex bumped up to 66 Ft Lbs. Checked the rear one before removal, and I could see someone had been in there. It was right up to mid-60 so I left it alone.

Only thing I didn't torque was the crank bolt, which is important, and I will go back and torque it when I get to the shop with the right tool. I just used my 24" breaker with a pipe over it. I should be 'close' to book on that.

BTW, putting anything, including white seal tape changes the torque value.

worf928

26 ft-lbs is the WSM spec, which is too high, and will result in your crush washers looking like Ed's above.

The block drains will seal at 26 n-m (19 ft-lbs) without distorting the crush washers.

worf928

Bump for C19 shelterers draining coolant themselves for the first time.

Mrmerlin

Nice Dave !

Rob Edwards

Decided to freshen the coolant in 1978 US #0021 today, may have come across a rationale for the original torque spec being 26 ft-lbs. M12x16 hex head bolts. I torqued them to 19.

worf928

Confused Rob I am. Didn’t we cover this: https://rennlist.com/forums/928-foru...l#post12265692

Wait... you postulate that the spec is due to using a M12 Hex-head bolt (which would be a 19mm hex-head) rather than the small-head drain plugs (M12 with 13mm head?)

Rob Edwards

Yes, this very early block has these bigass 19 mm-head M12 bolts (the driver' side drain is close to the boss for the lower bellhousing bolt and the clutch hardline is right in the way, was a PITA to get at), so maybe they switched to the smaller bolt heads for clearance reasons? Just a WAG.

SwayBar

Interesting discussion on torque wrenches.

I have 3 different torque wrenches, small, medium, large, and use them on every torque-able bolt/nut without fail using the factory specs. I do it only because I don't trust myself and believe in using the proper tool for the job - which my arm by itself is not.

The only time I've had a problem using them, was with 928 oil pan gaskets. With that said, I'll be ordering Greg's new pan gaskets so I can finally use a torque wrench properly during their installation.

As a side-note, I'm always a wreck while installing brand-new spark plugs - those crush washers always seem to take forever while waiting for the click of the wrench!