When we take the rocker cover off a TDI, we're looking right into the heart of the engine: the camshafts, roller rocker arms and hydraulic lifters. You can usually tell straight away whether the engine has been running on the right oil and whether it's been changed on time. In the photo, you're looking at a TDI cylinder head from our workshop. I'll show you what we check and what its condition tells us about the engine.
What's inside the cylinder head of a 2.0 TDI?
- Two camshafts – one opens the inlet valves, while the other opens the exhaust valves.
- Roller rocker arms – these transfer the movement of the camshaft lobes to the valves.
- Hydraulic lifters – these take up the clearance between the moving parts, keeping the engine running quietly.
- Valves, springs and valve seats – everything needs to seal properly.
On common rail engines, the injectors also sit in the cylinder head, between the valves. That's why everything has to be spotlessly clean when we're working in there. There's absolutely no room for careless work.
What problems do we see most often in a TDI cylinder head?
Why do camshaft lobes wear out?
When you drive with old oil, or oil that doesn't meet the correct specification, the camshaft lobes and rollers start wearing down. Your car no longer pulls as well as it used to, becomes harder to start and sometimes starts rattling too. It's a well-known problem on some TDI PD (Pumpe Düse) engines, especially when oil meeting VW 505.01 hasn't been used. See why I'm always going on about using the right oil?
Why do hydraulic lifters rattle?
You start your car on a cold morning and hear a rattling noise from the top of the engine. After about a minute, it goes quiet. Often, the hydraulic lifters are responsible because they can't fill with oil quickly enough. But if the rattling carries on after that, we need to investigate something more serious.
Why is oil leaking around the rocker cover?
Over the years, the rocker cover gasket hardens and oil starts seeping out around the edge. At first, it looks like a tiny leak. It's not immediately dangerous, but please don't leave it like that. Get it sorted before the oil reaches the hot parts of the engine.
How do we repair a TDI cylinder head?
- First, we measure the oil pressure and run diagnostics. We want to be sure the problem really is in the cylinder head and not somewhere else.
- We remove the rocker cover and carefully inspect the camshaft lobes, rollers and hydraulic lifters. We're looking for every little sign of wear.
- If the camshaft is worn, we replace it together with the rocker arms and hydraulic lifters. Fit a new camshaft against old, worn rocker arms? You'll soon be back with exactly the same problem.
- We tighten everything to the specified torque using a torque wrench and fill the engine with oil that meets the correct specification. There's no guesswork here.
Don't replace just the camshaft if the rocker arms and hydraulic lifters are worn too. Otherwise, you risk having to do exactly the same repair again before long. I'm telling you this because I don't want you paying twice. At the end of the day, that expensive mistake comes out of your pocket, not the workshop's.
Advice from Kris Mladenov: Change your engine oil and oil filter every 10,000 km or once a year, whichever comes first, regardless of the oil used. That's the cheapest insurance you can give your TDI cylinder head. A few oil changes done on time will cost you far less than repairing worn camshafts.
If your TDI is rattling, doesn't pull like it used to or you're seeing oil around the rocker cover, bring it to Das Auto Service. We'll take a careful look, find out where the problem is coming from and tell you what actually needs doing. No replacing parts blindly.
The right oil from our shop
Genuine Longlife III FE 0W30 engine oil 5L
Genuine LongLife III engine oil for common rail TDI engines. Using oil that meets the correct specification is important for protecting the camshaft lobes and hydraulic lifters from wear.
View in our shop
Genuine Volkswagen SpecialD 5W40 diesel engine oil 1L
Genuine 5W-40 engine oil meeting the required specification for older TDI PD engines, where the camshaft lobes are under the greatest load.
View in our shopRead more
- Complete engine rebuilds
- Diagnostics at Das Auto Service
- 2.0 TDI: The vacuum pump that leaks oil
- 2.0 TDI with balance shafts: The oil pump problem
- Compression, leak tests and borescope inspections: How we check engine health
- 1.9 and 2.0 TDI PD engines: The legend and its weak points
- Oil leaks from the rocker cover and sump
Frequently asked questions
Why does my TDI rattle when it's cold?
It's often the hydraulic lifters. They can't fill with oil quickly enough. If the rattling doesn't stop once the engine has warmed up, we need to find out where it's coming from. Don't ignore it.
Can I replace just the camshaft?
Not if the rocker arms and hydraulic lifters are worn too. In that case, we replace them all together. Otherwise, the new camshaft could wear out quickly, and you'll end up paying for the same repair again. I don't want that happening to you.
How can I protect my TDI cylinder head?
Use oil that meets the correct VW specification and change the engine oil and oil filter every 10,000 km or once a year, whichever comes first, regardless of the oil used. Don't rev the engine hard while it's cold. It's that simple.