Bolts snapping (1 Viewer)

[WCBlueSky]

In the process of replacing the rear main seal and resealing the retainer ring, I snapped the heads off two bolts that go into the retainer. They are flange-head M8×1.25, grade 5T. The FSM calls for 14 ft-lbs and a generic bolt chart says 13 ft-lbs. Torque wrench didn't click and just from the feel I don't think I got anywhere close to that before they snapped. Any ideas? Could they somehow be weaker after 25 years of sitting in the engine block?

 

[ceylonfj40nut]

Is it in-lbs? Don’t have the FSM handy. Common mistake if you confuse the two.

 

[voodu3]

I would guess that after 25 years of heat cycles that all bolts in and around the engine have started to deteriorate some.

 

[tominboise]

An M8 is a pretty hefty bolt. Even at the low strength grade used, it shouldn't have busted. Did they break in the root of the thread? Was there any corrosion? Were the threads clean? Did you put any oil on the threads prior to installation? Were the threads in the block clean?

 

[nukegoat]

Your torque wrench sucks

 

[Pippylongsausage]

I had a similar problem and it was old fpig on the end of the bolts causing them to bottom out in the holes and snap before they could reach the correct torque. Also my crappy hf torque wrench wouldn’t click sometimes. Get a feel for what the torque should be and if you feel yourself going past that stop and figure out what’s wrong.

 

[SNLC]

I had a similar problem and it was old fpig on the end of the bolts causing them to bottom out in the holes and snap before they could reach the correct torque. Also my crappy hf torque wrench wouldn’t click sometimes. Get a feel for what the torque should be and if you feel yourself going past that stop and figure out what’s wrong.

Don’t use a HF torque wrench.

some tools are worth a few extra bucks.

Cheers

 

[fjbj40]

Tq wrench is garbage!

 

[Pippylongsausage]

Actually I think it’s from summit but it’s a cheap one. A nicer one is on the Christmas list.

 

[baldilocks]

Tq wrench is garbage!

Even so, come on man........ let’s use common sense here.

 

[fjbj40]

Even so, come on man........ let’s use common sense here.

Unfortunately, common sense isn’t so common anymore

 

[baldilocks]

I would guess that after 25 years of heat cycles that all bolts in and around the engine have started to deteriorate some.

If this were the case, reusing head bolts , or any other bolts on the engine, wouldn't be a possible consideration.

 

[WCBlueSky]

Your torque wrench sucks

How dare you! My HF torque wrench is made from the finest Chineseium money can buy.

Alright, I ordered all new bolts from the dealer, I'm going to chase the threads with a tap, and check the calibration of my torque wrench. Thanks for the replies.

 

[BILT4ME]

My 96 FSM shows 15 LB-FT.

 

[western flyer]

I also vote torque wrench is bad. I had it happen to me.

 

[Rifleman]

I had a similar problem and it was old fpig on the end of the bolts causing them to bottom out in the holes and snap before they could reach the correct torque.

The bolts could be bottoming out like you suggest above, plus It may not be your torque wrench. Someone in the past may of over tightened those bolts with a air impact, thereby stretching them. Then when you went to tighten them to the correct torque, they just kept stretching until their heads snapped off.

One way to tell if they were bottomed out in the hole. If they were you won't be able to just unscrew the remaining part of the screw, you'll have to use vice grips, or drill it out. If it was bolt stretch, then the remaining part of the screw will only be finger tight, and you should/might be able to just unscrew it back out of the hole.

 

[bigredmachine]

did you use the right bolts and not use ones that were too long from somewhere else by mistake? at 15 ft/lb I would just tighten them with a 1/4 inch ratchet and call it a day, don't forget to use fipg on the plate

 

[WCBlueSky]

I checked the torque wrench I used against a couple other torque wrenches and it seems fine. I re-tapped out the threads and did a dry run with the new bolts and was able to easily get to the 14 FT-LB spec without issues. Not sure what went wrong last time but it seems fine now. Just need to put on the RTV and button it all up.

 

[WCBlueSky]

Actually I think the torque wrench was defective. It didn't click yesterday either and before I broke another bolt I stopped and got a different wrench. Sure enough it was way too tight. Took it back and got another one.