300Tdi sudden noise

Drove to work, kept revs at around 2K. The noise went momentarily, then came back and gradually got worse. Oil light flickered at idle, and I checked and found the oil on the low side of normal. Put a litre in so it's slightly overfull now.

And the noise is now sounding more like a knock.

Thanks for the link to the dropped cap.

What sound does a damaged injector make? With the stethoscope each injector sounds different. The vacuum pump and lift pump don't sound adventitious with the stethoscope.

Do fueling issues make any similar noises? Ie under fueling?

Engine Temp on the low 70s still.



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The noise seemed to get worse after a short drive with an occasional low whistle from around the turbo. So I stopped and had it flat bedded home. The ex-mechanic on the tow truck thought it sounded top end, so I may need to go searching for one of those lash caps somewhere in the system, but still need to explore other possibilities.

Another thought.
About 3000kms after a timing belt change, the engine started to make a slight tappet/knocking noise.
it was more of a background noise and seemed to be more noticeable around the exhaust side and from below.
turned out the injection timing was a little too far advanced.
we reset the timing with the locking pin and the noise went away.

Quote:

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Originally Posted by Michael2

The noise seemed to get worse after a short drive with an occasional low whistle from around the turbo. So I stopped and had it flat bedded home. The ex-mechanic on the tow truck thought it sounded top end, so I may need to go searching for one of those lash caps somewhere in the system, but still need to explore other possibilities.

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The list of possibilities could be quite long.
Start eliminating the ones we know now before looking for more.
The lash caps are the prime suspect, find them. Then eliminate the rest of the possibilities as posted earlier, they are your most likely culprits.

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Ouch!!!!

I took the head & timing cover off today in order to investigate.

There was a No.2 Inlet Valve mark on the top of No.2 Piston. No groove or indentation.

No damage or shards in the valve guides, no evident damage to the cam.

The valve was straight and seated properly.

The timing was spot on.

Putting downward hand pressure on the top of No.2 Piston and backing the crank a bit revealed a very slight "dup" sound and I could feel it drop. Wouldn't have been a millimeter, and not visually discernible, but evidence of Big End or Gudgeon damage.

I priced the parts (Big Ends, Mains, Seals, Head Gasket, Pistons, Crank) $2.5K in parts for a rebuild, plus several days of my life.

TRS had a crate motor that had been put in a disco and done about 10K km for just under $5K delivered, with ancillaries (minus timing cover). I need the car for work, so that's my easiest option. Hopefully it will arrive tomorrow.

That means I've got a new Injector Pump with less that 100km on it that I'll be putting up in the markets section next week. PM me if you need one.

Thanks to everyone for their replies, it certainly gave me a logical plan of action to proceed through with the diagnosis.

Quote:

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Originally Posted by Michael2

Ouch!!!!

but evidence of Big End or Gudgeon damage.

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Possibly both.

Rebuilt my Tdi a few months ago, sported a cracked piston, found when replacing the head gasket.

All big ends were cactus, (only around 100,000km old) and gudgeons needed rebushing and reaming.

Too much advance/too much fuel = too high cylinder pressures, even though EGT's were never excessive (IMO)

Rick tell us more. What was your plunger lift at ? How much boost were you running ? A few weekends ago I changed out the head gasket on my engine with 850 hours since rebuild. On rebuild had used 20thou OS pistons in bored honed pots matched to each piston. Engine shop also teamed and fit the rods. Crank was 10thou US ground on the mains all quality shells throughout. Cam new shells linished and fitted. Engine run in by getting up to pressure and settled then run hard
Anyway have been running advanced and 20psi plus but keeping get under 600.
Symptoms of HG leak into pushrod gallery so I popped the lid the other day. Anyway changed composite out to MLS gasket and blow by has reduced BUT all four pots had visible but not palpable verticle drag lines and honing barely visible. Not sure where to go really will just keep flogging her but kinda want a plan. I have abother block in shed which I could get machined and built up but not sure what else to do to get better outcome.
Oh and I can't see me turning the tap down ?

S

I never measured the plunger lift before Steve, only bought the adapter for this rebuild and just didn't bother checking before doing the timing belt.
The last belt change (115,000km prior) I used the calibrated drill bit, removed and used a slightly smaller one pushing the adjuster in the desired direction and it went better. :angel:

I've seen 750* a couple of times, but mostly kept it under 700-720 with the probe in the EGR pocket.

Boost is 16.5-17psi, measured at the turbo outlet.

Honing marks were still well visible, and although the tiniest of lips at the top transition the hone marks were still there, just.
It was in an frame rebuild as I needed to get it all back on the road ASAP I just kept going.

I have some shots of the ACL 780 bearings, the top halves were stuffed, bottom halves looked new.
King were fitted this time around as that's what came in the Bearmach box.

Gudgeons were just too loose, the slightest of movement/wobble, so I rebushed them.

Ring gaps checked and all were absolutely spot on out of the box, which surprised me no end.
Rod weights were within 1g of each other, I think pistons were within 3g, 3 were within 1g so I evened them up.

The head was a Turner 'Performance' head that IMO looked like they'd let the work experience kid at it, (and the head wasn't clean, grinding dust in the ports, swarf in the head) so out came the die grinders and burrs and about four-five hours later I lapped the valves.
Just couldn't help myself. :D

I went to turn the star wheel back a touch but couldn't find my old notes (after three moves in eight months, five moves in eighteen months. Don't ask....)
So left alone and decided to not bury the foot as deep until I find the file, but....

The thing goes harder than it ever did, blows less smoke, EGT's are lower on any given hill and I'm using less boost at any given speed on a given piece of road.
Better ring seal ?
More air flow with the modded head ?
New injectors ?
Or more probably, the combination.

BTW, I went with an MLS gasket as I was going to go VNT with 20+psi boost and was pedantic about getting the deck clean, used a flat block, white spirit then methylethylketone and the bloody thing started weeping oil from the pushrod side after a week or so, I'm guessing from the oil feed to the top end. :(
I have two gaskets sitting here, one composite and one MLS but I'll probably hold off until Christmas, too much happening ATM.