Thread: 300Tdi injection pump

you know you can change the head seal without completely dismantling the pump or even removing it right?

Don't need to loosen the bolts. Just remove the two nuts and bolts holding the pump to bracket + 3 flange bolts. It is possible to do the oring pump in. It is easier (and I think faster) to do it pump out (not removing the head of course). It is on stroke (i.e., fully compressed) at TDC.

Originally Posted by Blknight.aus

you know you can change the head seal without completely dismantling the pump or even removing it right?

Thanks Dave,

Yes, I do know it can be done without dismantling the pump. I have detailed notes & photos explaining how to thoroughly clean the pump/head, release the head bolts but do not remove it, cut the old o-ring and fit the new one by stretching it over the head etc.

I've also been told this job is incredibly difficult to do in-situ, especially for a first-timer. Would seem to be very difficult to ensure cleanliness without removing the pump?

Thanks again.

Originally Posted by damienb

It is on stroke (i.e., fully compressed) at TDC.

Thanks Damien,

Not sure if I'm understanding the bit above tho'. Are you saying TDC is the best spot to do the o-ring replacement or that at TDC ("on stroke"), there is extra force on the head and this is not the best position?

Sorry, but dumb questions are my speciality...

Both (except TDC is the best spot). When the pump is on the bench, keep or put it on TDC by inserting a 9.5mm drill bit into the timing hole, which will fully compress the springs and keep things from falling out when you back the head out. Once the bracket plate is removed, the long bolts can be reinserted for o-ring replacement.

"Hmmm, yeah, they look the same to me."

Originally Posted by Leo109

Thanks Dave,

Yes, I do know it can be done without dismantling the pump. I have detailed notes & photos explaining how to thoroughly clean the pump/head, release the head bolts but do not remove it, cut the old o-ring and fit the new one by stretching it over the head etc.

I've also been told this job is incredibly difficult to do in-situ, especially for a first-timer. Would seem to be very difficult to ensure cleanliness without removing the pump?

Thanks again.

Not really it just sounds hard.


Id call it 3/5 spanners if nothing goes wrong rebuilding the pump when you get it wrong...

Hi guys,

Removed the pump this morning without any major dramas - just took a while taking it very carefully. Carefully plugged all open ports and gave it a very good wash with degreaser and blew it dry with compressed air - looking all nice & clean now. Then left it in the sun during lunch to dry fully before attacking the distributor head o-ring.

But when I bought it in to the bench, there seems to be diesel weeping from the large three-sided nut in the middle of the dist. head, between the four delivery valves. Could this be my leak, instead of the head o-ring?

If so, can I replace the o-ring under this nut without causing major upset to the pump internals? (My notes cover only replacing the big o-ring between the head and the pump body so I'm very cautious about undoing anything else.)

If it can be removed (or loosened it enough to stretch a new o-ring over it), how do I do so? A 1" ring spanner is just too small and a 27 mm or 1 1/16" too big. I could maybe butcher my 1" ringie with a die grinder to make it fit but don't what to do that if there's a better way.

Have no vehicle in running order until I get this pump back on, so prompt help would be very much appreciated.
Thanks,