Snapped rocker shaft, 300tdi

Hello,

I've noticed a slight knocking on my 300tdi for a little while, after doing some investigation I found the bolt securing the rocker shaft on cylinder 4 to be loose.

I tried to tighten it up but it wouldn't tighten at all, so I took the stud out to find it brought the thread out of the head with it as well!

I also saw that the rocker shaft was bent slightly above cylinder 4.

Is this a commen problem? And could I try to helicoil the stud hole first instead of trying to source a new head? Seems such a waste of time and effort to swap for the sake of one M8 thread not playing ball.

Thanks,
Mitch.

Happens, helicoil or timecert it

Thanks Fanatic. I'll give it a try.

Helicoil all of those rocker shaft stud holes, if its like the one I have I fixed one only and then the next one stripped out when attempting to put the shaft back in. All done now and secure, well worth the effort, no more surprises.

I had this problem on my 200tdi only my rocker shaft snapped. I helicoiled it and its been fine ever since.

Thanks for the advice everyone

Took the rocker assembly off last night. The shaft has broken between cylinder 3 and 4.



There are a couple of studs that felt loose so I will helicoil these, my only question is how to people gain access to Helicoil the stud at cylinder 4?



The bulk head seems to be in the way and there's no straight way of getting a drill in there. Does anyone have a little trick in order to get the job done?

Thanks,
Mitch.

I don't know a trick for your specific job . ihhttps://www.machinemart.co.uk/shop/product/details/rad-1-right-angle-drill-attachment?da=1&TC=SRC-90%20degree%20drill ihhttps://www.machinemart.co.uk/shop/product/details/clarke-rad-2-right-angle-drill-attachment?da=1&TC=SRC-90%20degree%20drill I need to drill in a tight space I use a 90 deg
Drill adapter there are two from machine fart . One is 24 the other is 10 ish.
the link didn't copy right is im doing this on a phone and getting attacked by twins but the info is nearly there if it helps.

I've now swapped the rocker shaft with a second hand item.

All went well, old one off, check the pushrods and they are all straight and fine, helicoiled the head, and fitted the new rocker shaft along with new valve caps.

I've gone to start the engine and now it will not fire. Just keeps turning over without event the slightest hint at firing!!

What do you think it might be?? First thing that comes to my mind is if the valve clearances are out as this is really the only thing that could have changed.

Quick video to show what's happening.

https://vimeo.com/125041118

snapped in exactly the same place as mine after i rushed fitting a new head and missed the end nut off the stud, I also thought mine was just bent until stripped lol, swopped for the spare rocker shaft i had and the valve clearances were completely different, guess there is quite a variation in the pedestals, 5 minutes to set n she runs better than she ever has.

Cheers Steve

I'll look into the valve clearances then mate, few people on facebook have said this might be the cause of it not starting.

MitchBaldwin said:

I'll look into the valve clearances then mate, few people on facebook have said this might be the cause of it not starting.

Click to expand...

Makes sense to check them whenever the rocker cover is off, mine have usually changed

I didn't really think changing the rocker would make such a difference, but then I've also replaced the Valve Caps as well at the same time.

Thinking about it now it's probably a mixture of everything has changed the clearances. Fingers crossed it works haha.

MitchBaldwin said:

I didn't really think changing the rocker would make such a difference, but then I've also replaced the Valve Caps as well at the same time.

Thinking about it now it's probably a mixture of everything has changed the clearances. Fingers crossed it works haha.

Click to expand...

fingers crossed you didn't make them too tight and they've bent something.

should have backed them all the way off then done them upon fitting

Looking back in hindsight yes I should have done that. Lesson learnt i suppose.

compression or fuel one is missing !, tight tappets will give you no compression, check clearances, check fuel by loosening an injector pipe.
check stop valve connection on injection pump has not come off.

Disco is now back up and running Checked all the valve clearances this morning and they where all out by a tiny bit, amazing how a little adjustment can make the engine run or not.

Thanks everyone for your advice.