M-TDI Vanagon Suddenly Blowing Huge Clouds of White smoke

[?Waldo?]

IMO the two most feasible reasons for the cam timing to fail are that either the sprocket slipped on the cam taper or a foreign object got into the timing belt causing the belt to jump time.

Regarding the cam slipping: the cam taper and matching taper in the sprocket should be cleaned with brake parts cleaner before each installation. Failure to do so risks oil residue on the taper which will significantly reduce the force required to cause it to slip. The factory torque spec for the cam taper is also fairly low. I know one individual who purchased a rabbit new from the factory and had the cam sprocket slip prior to anyone ever loosening the cam sprocket. I also worked on one engine recently where someone had foolishly used loctite on the cam bolt. The loctite on the bolt will not prevent the cam sprocket from slipping but it can prevent the bolt from achieving proper tension on the sprocket on the next installation if the threads are not chased to clean out any residue. Whenever installing a cam sprocket, as mentioned, I clean the tapers with brake parts cleaner, I make sure the cam bolt threads easily, and I do a final torque of 45 ft-lbs rather than the Bentley spec of 33.

Regarding foreign object getting into the belt: in the earlier pics in this thread, it can be seen that the engine does not have the correct lower timing belt cover. I believe the lower cover (if it can be called that) shown in the pics is from a 1.5 or possibly an early 1.6. It leaves a fair amount of space around it for foreign objects to get into the belt. The rear tires also throw things toward the engine. It is quite feasible for an object to find its way in there and cause the belt to jump a few teeth.

This is the correct lower cover and it does a MUCH better job at preventing things from getting into the timing belt.

https://www.ebay.com/itm/324464609161?hash=item4b8b990789:g:6psAAOSw7sRgD03w

[RolandD]

Don't forget to replace the lifters also.

Roland

[daltonhawk]

Thanks for the link to the timing cover. I just bought it. Besides being incorrect, it is also pretty chewed up. I was hoping there would be some timing marks for the crank sprocket - there were they’re gone now.

I do live on a gravel road so there’s a constant stream of crud getting kicked up.

I’ll be careful about inspection, cleanliness and torque on the cam bolt when I put it back together.

[daltonhawk]

[?Waldo?]

The cam typically survives fine unless the contact is even more dramatic and it snaps into pieces. Yours is still in one piece so it should be fine. You could replace just the 4 valves and 4 lifters. You'll need to replace those 4 valve stem seals and it would be good to at least hand lap the new valves into the seats. That's probably ~$100 in parts which is considerably less than a head. To complete the job you'll also need various other parts like cam seal, head gasket, manifold gaskets (assuming you remove them), head bolts, etc...

[daltonhawk]

Some people seem to be of the opinion that if the lifters are replaced the cam should also be replaced so the new surfaces can wear in together but maybe it’s not super important? I was wondering if my lifters should be replaced just due to wear, copper starting to show through.

Partsplacellc.com has rebuilt heads for $800 plus core and they seem to have a generally favorable reputation. I’d rather spend $100, I just don’t want to put it all back together and wish I’d spent $800 in a year or two.

[?Waldo?]

I've replaced the lifters without replacing the cam multiple times on the VW diesels and I have never had an issue. YMMV.

[daltonhawk]

Well I got the engine/trans out without too much trouble.

Now I know why the TDC mark was in the wrong spot - the clutch plate was rotated off by one bolt hole. When I move it one hole the mark lines up with the mark I made. Something must be missing from the empty holes in the flywheel that would key it? Dowels? The clutch looks pretty used up so I’m glad I pulled it apart.

[old_man]

[turbotype1]

Not sure about bolting the flywheel one any different than it is.... The bolts have one located offset from the others
_________________

[daltonhawk]

[daltonhawk]

Here is a picture of a flywheel from the classifieds. It has three roll pins installed- mine doesn’t have any. Does anyone know the correct size off hand?

[?Waldo?]

There should be three dowel pins between the flywheel and pressure plate that allow the pressure plate to be bolted on only one way.

You might consider getting the TDI Vanagon input shaft and running the dual-mass flywheel in order to reduce the stress on the transaxle.

[daltonhawk]

[?Waldo?]

The DMF comes as a complete kit with flywheel, clutch disc, and pressure plate. The Luk 17-050 kit is from the Mk4 TDI and costs ~$200 shipped. You need the TDI Vanagon input shaft as the splined area that engages the clutch disc is larger OD to match the TDI disc. The TDI Vanagon input shaft can be had for ~$100. There is minor clearancing required in the bell housing and the nose of the stock starter needs some attention as well in order to avoid pinching the flywheel. The diesel vanagon intermediate plate also does not fit with the TDI flywheels. A completely flat intermediate plate is available also. You would also need to add a TDC mark to the flywheel as the mark on it is not correct for the Vanagon installation.

[daltonhawk]

Ok thank you for the details. I’m thinking it over. I do have an identical spare new clutch so it wouldn’t cost anything to go that route but anything that would make it smoother and more reliable is good.

[old_man]

[MarkWard]

My flywheel in the classifieds includes the roll pins.
_________________
☮️

[11BC2]

[?Waldo?]