One of these things is not like the others..

[Mercguy]

One of these things doesn't belong... [biggrin]

187425

187426

I believe it's called #4 inlet kaput.

Yesterday afternoon, I got in the car, it started fine- all vitals OK... drove up the driveway and got mail from the letterbox, headed down the road and half way down the hill the engine note just went bunk. like I'd dropped 2 cylinders and all the power.

Barely managed to turn it around and limp back up the hill to the driveway, rolled it down the drivway into the shed and then left it till this morning.


I was thinking I'd punched a hole through a piston or dropped a rod - it wasn't a pleasant noise. I've probably torn an engine mount as well now... It was a pretty nasty vibration.
Since I 'knew' the motor was buggered, I thought I'd suss it out and see which cylinder it was, so went about cracking lines and checking fuel, then checking which cylinder.
Turned it over a couple of times briefly and it sounded like one injector was a dud or I'd done a rod.

While cranking it over I thought I might be in with a chance when cracking #4 made no difference to the idle note, so shut it off and went to pull the injector, but had trouble accessing it due to the firewall.
Pulled the rocker cover to get better access and was greeted with the above image.

Certainly can say I have never broken a rocker in my life until now.
So a Chance find, and I'd half figured I'd have to pull the rocker cover as next move after making an attempt to replace injector #4... which obviously doesn't need to happen now.


Now I know it's not piston slap noise I thought I was chasing some weeks ago.
The irony is, these rockers were checked less than 1000km ago and adjusted to factory spec, along with an oil flush and new filters There was no evidence of any crack in a rocker - I actually had the whole top end cleaned down because I was considering doing the stem seals....
The noise I was originally chasing I thought was piston slap, and so I checked / adjusted valve lash clearances to eliminate that from the equation, in order to further diagnose.

unsure how to proceed from here - apart from the obvious replace the rocker shaft and rockers.

Head off? find more problems? or new rocker shaft and chance it...

Motor has 130K on it.

bit noisy up top, stem seals need doing... If the valves or pistons are buggered, then it's going to have to come out and the $ spend might not be worthwhile and tip me over the scales.

Have a d2v8 auto sitting here as a potential donor...

Have a spare OM606 that is also tempting me...


Still need to figure out what other troubleshooting / diagnostics can be done to eliminate a full-on teardown.

Ideas? I'm all-ears.

[Tins]

Broken rocker on one of these usually means a slipped timing belt or the tensioner has gone awol. They are an interference engine, however as the valves are not angled in the head they usually survive. Def check the timing belt IMO. Then just replace the broken bits, paying attention to the bronze 'slipper' in the lifter. The rocker, pushrod and slipper all tend to be sacrificial.

187428

[Tins]

Broken rocker on one of these usually means a slipped timing belt or the tensioner has gone awol. They are an interference engine, however as the valves are not angled in the head they usually survive. Def check the timing belt IMO. Then just replace the broken bits, paying attention to the bronze 'slipper' in the lifter. The rocker, pushrod and slipper all tend to be sacrificial.

187428

Oh yeah, mine sounded like it had dropped a valve. No power. But the bloody thing kept going. I love TDi's.

[TonyC]

One of these things doesn't belong... [biggrin]

I believe it's called #4 inlet kaput.

Yesterday afternoon, I got in the car, it started fine- all vitals OK... drove up the driveway and got mail from the letterbox, headed down the road and half way down the hill the engine note just went bunk. like I'd dropped 2 cylinders and all the power.

Barely managed to turn it around and limp back up the hill to the driveway, rolled it down the drivway into the shed and then left it till this morning.


I was thinking I'd punched a hole through a piston or dropped a rod - it wasn't a pleasant noise. I've probably torn an engine mount as well now... It was a pretty nasty vibration.
Since I 'knew' the motor was buggered, I thought I'd suss it out and see which cylinder it was, so went about cracking lines and checking fuel, then checking which cylinder.
Turned it over a couple of times briefly and it sounded like one injector was a dud or I'd done a rod.

While cranking it over I thought I might be in with a chance when cracking #4 made no difference to the idle note, so shut it off and went to pull the injector, but had trouble accessing it due to the firewall.
Pulled the rocker cover to get better access and was greeted with the above image.

Certainly can say I have never broken a rocker in my life until now.
So a Chance find, and I'd half figured I'd have to pull the rocker cover as next move after making an attempt to replace injector #4... which obviously doesn't need to happen now.


Now I know it's not piston slap noise I thought I was chasing some weeks ago.
The irony is, these rockers were checked less than 1000km ago and adjusted to factory spec, along with an oil flush and new filters There was no evidence of any crack in a rocker - I actually had the whole top end cleaned down because I was considering doing the stem seals....
The noise I was originally chasing I thought was piston slap, and so I checked / adjusted valve lash clearances to eliminate that from the equation, in order to further diagnose.

unsure how to proceed from here - apart from the obvious replace the rocker shaft and rockers.

Head off? find more problems? or new rocker shaft and chance it...

Motor has 130K on it.

bit noisy up top, stem seals need doing... If the valves or pistons are buggered, then it's going to have to come out and the $ spend might not be worthwhile and tip me over the scales.

Have a d2v8 auto sitting here as a potential donor...

Have a spare OM606 that is also tempting me...

Still need to figure out what other troubleshooting / diagnostics can be done to eliminate a full-on teardown.

Ideas? I'm all-ears.


This 😁

Tony

[Mercguy]

The pushrod is still dead straight, so I'm hopeful there's been no piston to valve contact -

impossible to know if the rocker breakage was simply down to a catastrophic failure or if there is some fatigue cracking. The images don't give a clear indication of either - and the dull spot in the face of the crack appears that it may simply have been as a result of that few hundred metres of driving.
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Now I will need to check the valve tip and rocker and borescope the piston for telltale marks.

The issue I have been chasing for a couple of months is what I believe(d) to be piston slap - and my money was on #3 as being the culprit - but it is so damn hard to tell on this somewhat noisy engine. By that I mean, abundance of noises all the time and everywhere. It's not a quiet motor - by that I mean as quiet as I think it should be- if I'm drawing comparison to the v8 or to any of my mercedes engines. There is a noise that I'm heaing which is obviously contributing in some way - Stuff like this doesn't just 'happen' without some precursor. It's got a higher pitch note, not the low end thunk that a rod bearing has. and yet not quite like a nailing injector, but it could almost be... such a hard sound to describe - and difficult to chase around the engine bay - in fact it's more audible from within the cabin than in the engine bay where all the other clatter noise mask the source.
have checked with a stethescope also, and there's no nastiness down near the mains caps or low on the side. I can hear the injectors firing, and #2 and #4 are a little noisier than 1&3, but that's hardly a cause for serious investigation when it's not 'that' kind of noise.

But it has been down on power and I put that down to the turbo journal bearing / shaft not spinning as freely as it should be - it's only pumping about 12psi at 3500 under load which is a lot less than it should - and it's slow to respond (probably choked with carbon from all the different p.o's maintenance)

Timing belt was literally done by the guy I purchased it from not long before I bought it. Now I will pull it off and check everything after seeing your images.
Good excuse to get a few new parts onto the front end anyway, and I now have an excuse to put the 200tdi exhaust manifold and a different turbo -

but if I stick a camera down the bores and find any marks on piston crowns or scuffing - it's game over for the tdi and the 606 will go in.

[Tins]

Been open a while, but this is what happened to mine. I think that maybe the rods might have bent because I drove it a bit further than you did....

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[Mercguy]

Yeah - I'm going to have to do some vehicle location swapping and prep the shed for a bit of a longer term outcome.

Just looking around I see that a replacement head isn't exhorbitant, but I am seeing all the ancillaries on the engine looking like they need replacement as well... and that's a bit disconcerting.

So compression test, borescope and fingers crossed...

But the 606 is lurking. and dollar for dollar (rebuild tdi bits or 606 conversion cost) the 606 would ultimately be cheaper to drop in than a possible tdi overhaul. Going to have to do the needful first to simply keep that 'decision' as being a necessary one and not just use this as an excuse to swap it in.