Thread: Sleuthing a knocking 300 tdi

Finally got mine all back together yesterday, the knock is gone!

New pistons, rings, big ends mains, the head looks almost brand new in the water galleries, so I'm guessing it got cooked, destroyed the head, and they took a punt on the rest being ok with a new head fitted.

I don't rebuild motors very often, and I always forget just how much work it all is in between, especially when you keep finding extra problems as you go!

Cheers
James

Good to hear. Even more fun underneath getting oil dripped in your eyes.
300tdi's can actually sound good with a bit of TLC.
Terry

Originally Posted by rover-56

Good to hear. Even more fun underneath getting oil dripped in your eyes.
300tdi's can actually sound good with a bit of TLC.
Terry

As in with good servicing ? Or as in with a few mods?
Cheers
James

Oh, I was thinking good servicing, mine has had a bad start in life with no oil changes by the 1st owner for at least 50k km according to the 2nd owner. 300tdi's seem to be prone to knocking noises anyway and I don't think crappy servicing helps. I have heard some really sweet running tdi's so I know quiet running is possible. Mine isn't one of them.

Personally i think the 300tdi is at the engines design limit at ~85Kw. They can be made to go with pump tweaking but I think at the expense of service life.
Terry

Originally Posted by rover-56

Oh, I was thinking good servicing, mine has had a bad start in life with no oil changes by the 1st owner for at least 50k km according to the 2nd owner. 300tdi's seem to be prone to knocking noises anyway and I don't think crappy servicing helps. I have heard some really sweet running tdi's so I know quiet running is possible. Mine isn't one of them.

Personally i think the 300tdi is at the engines design limit at ~85Kw. They can be made to go with pump tweaking but I think at the expense of service life.
Terry

I've actually got another one, only done 31000 from new, it's also noisy, I think that's one of the trade offs of having a direct injection diesel, but before pilot injection became the norm, they are pretty noisy at idle, diesel knock I guess.

Cheers
James

I think there is a difference between normal direct injection diesel noise and the knocking that comes out of some 300tdi's.
Probably to do with assembly clearances, I have known 2 300tdi's that were really sweet sounding, one was in a S1 Discovery, and the other was in my previous Defender before this one. I know that engine came out of a Discovery. It got me wondering if quieter engines were fitted to Discoveries, I don't know.
The noisy ones don't seem to die earlier, my current one is clattery, but had done 300k km and is easily capable of pushing the Defender up to more than a true 130kmh.
Terry

Maybe, but you may also find that some of the higher km engines are actually quieter than the tighter low km ones.

My experience is not related to a 300tdi but i have two Isuzu 4BD1's, both with aftermarket turbos. One (an older '85 version) makes a lot of engine noise but easily outperforms the '88 version in my Perentie which is extremely quiet from an engine noise POV.
I believe engine noise is directly related to injection timing along woith other things. The more advance, the more noise I am told.
The joys of diesel.