Thread: 300 Tdi Injector Clamp Nut Tension

Hey Deano , been there done it. When I snapped one of mine I almost had a heart attack, for a moment I thought I had snapped a molded part of my new c.head off!!

After a fair few bolt snapping incidents whilst changing my CH, I always try to use new bolts where possible and look at torque settings as a guideline.

For the clamps I stepped up through the torque settings 5,10,15 and when getting up to torque if the next click didn't come quick enough, I just left it!

One of mine made it 24Nm and others I only dared get close... I suppose they fatigue from all the heat exposure over the years. All new ones and you probably would get 24Nm on them all no probs.

Matt

oh btw, I still have three of those studs in my old CH if you want me to post them... should be same part number 300tdi/200tdi?

I stretched all of mine before I bothered looking up the torque setting!!
New ones were good for 24Nm

Thanks guys. New ones are pretty cheap and Roverlord is only 1 days post away.

Frightened the crap out of me too. I had visions of having to remove the head to extract the remnants. , and after all that bull**** 60 degrees plus 60 degrees plus 20 degrees and similiar crap with the rockers for heavens sake, talk about making a simple job difficult......................

Never been more thankful for my usual pedantic thread cleaning and using gallons of anti sieze, stud remnants came out easy with a gentle tap from the cold chisel.

Deano

Or, if its Sunday and you just broke the stud and need to use your TDI for work on Monday. Go to the auto parts store that's open, buy a packet of high tensile M8 bolts with the same amount of thread as the stud. Cut the head off and clean up the edges, then use it as a stud. Fits fine with no issues. I think the narrow shoulder of the original stud might be a failsafe for over tightening in the alloy head, ie the stud will break before it pulls out of the alloy. Whatever the reason, the home made stud is still there after 100k kms. Simon

Binned my 3/8" drive torque wrench today, just doesn't feel right. If I torque up fairly quickly it 'breaks' cleanly and feels good. If I torque up slowly it 'hangs on' and doesn't 'break' till way over tension. I reckon this is what may have happened with the injector stud(s).

Deano

Originally Posted by DeanoH

Binned my 3/8" drive torque wrench today, just doesn't feel right. If I torque up fairly quickly it 'breaks' cleanly and feels good. If I torque up slowly it 'hangs on' and doesn't 'break' till way over tension. I reckon this is what may have happened with the injector stud(s).

Deano

Dry threads might have been binding up. Have you tried the torque wrench in different circumstances, or with some loctite on the threads? Its easy to reach apparent tension if the nut sticks in place too early.

Originally Posted by DeanoH

Binned my 3/8" drive torque wrench today, just doesn't feel right. If I torque up fairly quickly it 'breaks' cleanly and feels good. If I torque up slowly it 'hangs on' and doesn't 'break' till way over tension. I reckon this is what may have happened with the injector stud(s).

Deano

Dig it out post it up and I'll service it for you.

Dont use high tensile bolts, the OEM studs are shanked so they do break before you overtighten them and kill the head. If they snap off before they hit 24NM then they have been over tensioned previously.

on a standard sidchrome 13mm ROE spanner I pull upto 40NM without too much effort so they are quite easy to over do, just like the bolt for the cran case ventilator, the rocker cover bolts and the dreaded centrifuge oil filter on the TD5.

Typically its not the butcher that does them up too tight the first time that has the problem but the guy trying to do the righty afterwards that does.