TheSamba.com :: View topic - DIESEL 1Y post-mortem and warning

Tue Jul 26, 2016 8:08 am

My 1Y decided to die a horrible death in Hell’s Canyon 1000 miles away from home:

This engine was made by VW Mexico with only 25k miles on it. Available as a “factory overrun” long block 3 years ago (spring 2013) for $2,200. This post serves as a warning to any who are running an engine from the same batch.

In Riggins Idaho I took off the top cover and saw this:

WARNING: The following photos are not for the faint of stomach!

It looks like a valve stem was bouncing off the head:

This isn’t where your valve should be sitting:

My mechanic measured the camshaft bolt torque at 12½ lbs, and suggest it “self-loosened” over 25k miles.

A close examination of the camshaft drive sprocket revealed a tapered surface mismatch with 2 regions of contact and one of non-contact (darker is the wide end):

This sprocket was the original that came on my Vanagon 1.6NA diesel. Since the 1Y was sold as a long block, it did not come with the matching sprocket. My mechanic simply bolted on the old sprocket which was alleged to fit.

A close-up of the center region shows the arc of slippage as the sprocket flexed:

These scratches probably happened just preceding the catastrophe.

This shot shows the conical sprocket surface only contacted the camshaft on the outer (small end) 10mm of metal just in front of the bolt:

Bordering that region was a groove that looked suspicious, suggesting that the metal fatigued and cracked.

A close up shows the sprocket was close to breaking:

These were new engines sold through parts dealers without any warrantee. I know of one other person who lost the same engine at 5,000 miles from the same kind of failure. My suspicion from the start was that these industrial engines were quality control rejects and subsequently resold by dealers as a “factory overrun”. This confirms my suspicion. Any who are running the Mexico 1Y engine are forewarned to upgrade your cam sprocket ASAP.

Tue Jul 26, 2016 8:25 am

Gnarlie! :shock: I'm sad to see this happen to you as you are one of the best resources for repairs and keeping our aging diesels running.
I hope you get back on the road soon. Sending you good vibes from Florida! 8)
jeff

Tue Jul 26, 2016 9:18 am

Sorry to hear of your breakdown. In considering what direction to go, you might consider that you can turn your 1Y block into an mTDI.

Tue Jul 26, 2016 9:37 am

Gnarlie, so sorry to hear about this! I know the time an effort you've put into your van, and appreciate all you share here. Hope you recover and are back on the road soon ...

I have the same engine from the same batch, but mine was purchased as a 'complete' engine from the somewhat dubious Overland Parts, and included almost everything from the valve cover to the oil pan: water pump, IP, timing belt and all sprockets, etc..

Are you sure that the 1.6NA camshaft sprocket (069109111) is incorrect for the 1Y?

BrickWerks says:
"This fits way too many models to list, but the ones we care about are all the T3 and T4 Diesels 4 and 5 cylinder, and Caddy Diesel and Petrol models.
Some LT's, and even the common 1.9 TD/TDI engines fitted to T3s - AAZ, AFN, 1Z, AHU"

Another online vendor claims:
"New Camshaft Sprocket for 1.5, 1.6, 1.9, 2.5 Diesel Engines and 1.9 TDI (AHU/1Z) Engines for an 77-83 Cabrio, 92-97 Eurovan, 85-99 Golf, 79-99 Jetta, 92-97 Passat, 82-85 Quantum, 77-84 Rabbit, 80-85 Vanagon, 82-84 Audi 4000, 78-86 Audi 5000."

I realize the 1Y is a bit of an odd beast used in few vehicles, but if not the 069109111, what is the correct camshaft sprocket for the 1Y?

Best wishes for a speedy recovery!

Tue Jul 26, 2016 10:22 am

That's a real bummer. It would be good to have someone check the cam taper on a brand new 1Y, but then again it might just be reduced to that batch, as mentioned.

Tue Jul 26, 2016 10:56 am

As far as I have seen, the cam sprockets interchange from 1.5 through mk3 1.9TDI.

When I use a cam sprocket and cam that have not previously been matched together, I use a bit of fine valve grinding paste and gently check the match of the tapers. Every time the cam taper is separated, spray both surfaces with brakeclean to make sure there is no oil residue that has found its way onto the surfaces. I also always recommend torquing to 45 ft-lbs vs. the factory spec of 33 ft-lbs. I also give the cam bolt a tap with a hammer just to make sure it is properly seated between the initial torquing and the double-check.

Tue Jul 26, 2016 12:48 pm

What happened? ...did the cam sprocket slip off?

...really sorry to hear about this :(

Tue Jul 26, 2016 1:04 pm

It's often hard to tell what happened first. I would say it is likely that cam slipped, piston hammered valve, valve head broke off... but it could have happened in a different order of from a different cause... e.g. cam timing was not set correctly, piston lightly tapped valve, valve stem broke...

Tue Jul 26, 2016 1:18 pm

That is a bummer, sorry. What do the other 3 piston tops look like? If the gear slipped on the camshaft I would expect valve contact on all 4 pistons, not just 1.

Mark

Tue Jul 26, 2016 1:20 pm

Andrew A. Libby wrote: It's often hard to tell what happened first. I would say it is likely that cam slipped, piston hammered valve, valve head broke off... but it could have happened in a different order of from a different cause... e.g. cam timing was not set correctly, piston lightly tapped valve, valve stem broke...
I remember GN mentioning he drives without a timing belt cover......... I HOPE that didn't have anything to do with the failure?! ...or is it obvious from the pics that the cause was a defective engine?

Tue Jul 26, 2016 2:43 pm

The cause was not necessarily a defective engine, unless the camshaft taper was not up to specs. It may be that the difference between the 1.6NA sprocket taper and the 1Y cam taper is within acceptable VW tolerances. My accusations of a quality control reject is speculation, but in any case we should be aware that sprockets may not fit properly and result in a wrecked engine.

Andrew:
You said it. Checking the contact of the tapered surface should be mandatory. Block is probably not salvageable. The valve was forced down through the conrod which is bent and the crank is not turnable. Matt Pollard thinks the piston mushroomed and expanded the cylinder halfway up. In any case there is a gouge in the cylinder wall from a loose valve.

I believe what caused this breakage is metal deformation of the mismatched sprocket. The bolt remained at its initial tightness but the sprocket moved inward enough to allow it to slip. The area of deformation would be the thin pressure region between the crack and the edge. Ideally the pressure should be distributed over the entire conical surface.

We are installing a Quality German AAZ at this time so I should be back on the road soon. Thanks for all your sympathy, this has been a Vanagon adventure.

Wed Jul 27, 2016 6:13 am

It looks like it dropped a valve. The other Mark asked if there were marks on the other Pistons from the valves hitting the piston. That would indicate if it had jumped time.

Wed Jul 27, 2016 8:18 am

I am interested because I also have one of the very engines in question. My point is that if the failure started in the valve train that could mean the camshaft itself became more difficult to turn and that would put more turning force on the timing gear. That would make the gear more likely to slip on the shaft if the shaft was suddenly more difficult to turn. Looking at the multitude of hammering marks on that one cam lobe makes me think the camshaft faced extra turning resistance for a while, in sharp pulses, at that lobe. That extra pounding resistance could have caused the gear to loosen and slip, assuming it did.

So my question remains, what do the other piston tops look like? Did they also get enough valve hammering to think that the failure began with the gear having slipped or do they show much less contact damage which could indicate the gear slipping occurred later in the sudden failure?

Mark

Wed Jul 27, 2016 9:23 am

There are valve hammer marks an the other 3 pistons, but #1 the valve broke and got sucked down into the cylinder.

This breakdown was not terribly dramatic. It sounded and felt like a piece of rubber was coming off my tire. I shut off the engine, pulled off the road and looked but nothing was wrong. If at that time I had known to adjust the valve timing backwards and bolt the sprocket down I could have continued driving with little damage. But instead I started driving back to the nearest town. The noise got worse and the engine stopped turning.

I believe the forensic evidence shows an obvious mismatch between the two tapered surfaces of the camshaft and the sprocket. All the pressure of the timing belt was carried on the outside (small end) of the cone, causing metal flexing and fatigue where the cone eventually cracked. Even if I had bolted the sprocked down tighter,it is likely the sprocket would have broke off at some point in my trip.

I’m not sure what the solution is at this point, but Andrew’s advice to check the surfaces makes good sense. It may be that some engines have a more standardized camshaft cone than others, and sprockets from some engines fit better than others.

Wed Jul 27, 2016 9:51 am

The huge number of scattered strike marks on the one cam lobe indicates to me the engine was run quite a while after that one lifter came to pieces. But I don't see nearly enough strikes in the piston and combustion chamber areas for me to assume that valve contact preceded the lifter failure. That is why I wanted to see the magnitude of the valve contact evidence on the other pistons. If the gear slip came first and started the chain of events I'd expect more evidence of piston valve contact repetitions, at least on the same scale as the number of cam lobe hits.

One of the things I generally do with my diesel engines is to put paint marks on all 3 pulleys that turn with the timing belt so that when the flywheel timing mark is in position I can expect all paint marks to also line up to their respective references. Then if I ever have any question as to the timing having jumped I simply turn the engine by hand until the flywheel TDC is lined up for #1 and then look at the marks to verify the pulleys are still timed correctly to each other. This issue with the poor cam gear taper matching would mean my method falls short, since the gears could all be still in proper timing with each other and the crank while the camshaft itself has moved badly out of time.

Mark

Wed Jul 27, 2016 10:23 am

I took a picture of one piston, but the survivors look like this:

Mark, in fact the AAZ we put in uses the very system you describe. Each alignment of the 3 rotating shafts is scribed with a set point. Its really a much better system. My donor engine is a ’92 AAZ and the pump is a ’97 from Giles and my mechanic made it all work together. New engine runs pretty good from what I can tell.

Wed Jul 27, 2016 1:49 pm

Gnarlodious wrote: My donor engine is a ’92 AAZ and the pump is a ’97 from Giles and my mechanic made it all work together. New engine runs pretty good from what I can tell.

Wow that was FAST! CONGRATS! :) :)

crazyvwvanman wrote:
One of the things I generally do with my diesel engines is to put paint marks on all 3 pulleys that turn with the timing belt so that when the flywheel timing mark is in position I can expect all paint marks to also line up to their respective references. Then if I ever have any question as to the timing having jumped I simply turn the engine by hand until the flywheel TDC is lined up for #1 and then look at the marks to verify the pulleys are still timed correctly to each other. This issue with the poor cam gear taper matching would mean my method falls short, since the gears could all be still in proper timing with each other and the crank while the camshaft itself has moved badly out of time.

Mark

But if you would be in serious doubt, and were taking the trouble to hand-rotate the engine to TDC, then why not just simply hand-rotate to TDC, and then just do one complete hand-rotation of the entire engine to be sure?

Sat Jul 30, 2016 1:37 pm

Good to hear you're back on the road and with an AAZ !

Same thing happened to my 1Y but mine didn't skip the timing (as near as I can tell, since sprockets, belt etc were still intact) it just sucked a valve, destroyed head, #1 piston / conrod, broke the intermediate shaft and tore three huge chunks out of the block.

I will be firing up my new AAZ very soon.

Sat Jul 30, 2016 1:40 pm

Sorry to hear it. If you still have that sprocket I would be curious what you see if you examine the inside conical surface closely. My guess it the same thing happened to yours as did mine, the sprocket didn’t fit the camshaft properly.

Sat Jul 30, 2016 11:00 pm

Wow!
We went through Idaho last week and decided against Hell's Canyon (or was it the other one?). Our unfortunate tow home last summer was from Santa Cruz--Van Cafe is very nice but won't touch diesels. The pump bracket went loose after some local guys welded the downpipe back together, later I found they had removed the bottom muffler bracket that shares bolts with the pump bracket...in the end if was the same type of damage.
My JX came from Quality. I would treat any of their engines as cores--please go through it before driving far.