Lately, we’ve noticed a growing number of valve failures being reported for certain VW and Audi vehicles, in particular those with the 1.9L diesel TDI and 1.8T gasoline engines.
After reviewing many cases of these failures, it turned out that the problem was not with the valves themselves, but with the method of cylinder head overhaul. Most failures occurred shortly after a rebuild, and appeared to be mainly attributed to the poor adjustment of the hydraulic lifters.
Best Practices
- Hydraulic lifters must be adjusted at the same time as any new valves are adjusted
- All parts should be installed in conditions of pristine cleanliness
- Each follower must be coated with an extreme pressure cam lubricant as used on the lobes
- Old engine oil must be drained and replaced with both new oil and filter, as old dirty oil will contaminate the new lifters, leading to early failure
- Hydraulic followers must be allowed to “settle” for a MINIMUM of 30 minutes, after the installation to allow the excessive oil in the hydraulic lifter to drain. If this step is not completed, some valves may make contact with the piston crown leading to an immediate fracture in the cotter groove on start up
- Engine must also be allowed to “settle” for a MINIMUM of 30 minutes when the repair is ready, then cranked over carefully for TWO complete cycles by hand to check for valve to piston contact. Ideally, it is recommended that the engine to be left overnight before restarting for the first time after the repair.
This post applies to the following VW Audi valves: 058109601C, 058109611E, 058109611M. However, these important best practices should apply to all work in the valve train area, and should be taken into consideration for ALL engines that use hydraulic lifters.
A BIG THANK YOU FOR YOUR BLOG “Best Practices for VW Audi Cylinder Head Rebuild”
I experienced exactly what you described…….One of the valves made contact with the piston crown and broke at the cotter groove……….but I STRONGLY believe my failure was from ANOTHER cause.
All parts were installed in conditions of pristine cleanliness.
Each follower was coated with an extreme pressure engine assembly lubricant. This lubricant was also used on the cam lobes, camshaft caps and journals.
Engine oil was replaced with both new oil and filter.
The engine was hand cranked for two cycles to check for valve to piston contact.
Spark plugs were removed, fuel pump was made inoperative by disconnecting the fuel line and removing the fuel pump fuse, The motor was then cranked using the starter, until the oil light went out. ( This is to ensure that un-burnt fuel did not enter the catalytic converter )
Spark plugs were then re-installed, fuel pump fuse re-inserted, and the engine was started and left to idle for about 30 minutes, until the “tappet noise” disappeared and the engine was running smoothly.
I note in your blog that you recommended that the engine to be left overnight before restarting for the first time after the repair.
I did not do this.
I believe that my broken valve stem was from another cause……
The valve stem failed at the cotter groove for one valve ONLY. The valve made contact with the piston, making a few small dents.
When I removed the head and carefully inspected the SPRING SEAT where the broken valve was, I notice a shiny mark at the side edge of the machined spring landing. I think it was from the spring being put in crookedly and up on the side. (Sorry that I don’t have a photograph to show you.)
I strongly suspect that I had fitted the valve spring incorrectly ( I BELIEVE that the spring base was not properly seated on the machined face of the head, but up on the side, when the collets were inserted)
It is a deep hole, and hard to see if the spring is seated correctly, unless you look very carefully.
This angled and incorrectly seated spring would, I suspect have put an extra stress on the top of the valve stem when the engine was running at higher RPM. The valve top broke at the ring groove after driving for about 300 metres. AAARGHH
I took the head to my local specialist with a photo of the Valve/Piston contact. He agreed with my opinion about the reason for the Valve stem failure at the collet groove. He also supplied a new valve, and refaced the head.
New head gasket and new head bolts were used ( of course )
Car has run for 5,000 kilometers with no further failures since repair.
Hope this adds to the knowledge base, and others may benefit from my experience.
Thank you for the piece of useful advise.
Mine is in the workshop, right now. Same problem. Battling to pay-up.
Holding thumbs that it is repaired properly and well.
Well done. Will speak intelligently, to the machenic (who seems to know it all and stubborn).
I wish I did the job myself.