OM601 blowing blue smoke? Replace valve stem seals on W124 W201
Short answer: If your W124 200 D or W201 190 D (OM601) briefly puffs blue smoke after a cold start or after prolonged idling and oil consumption is rising, hardened valve stem seals are often the cause. The remedy is a new valve stem seal set – e.g. Elring 914.819 (comparison number A 102 050 00 58), NOS in original packaging, for 14,90 €.
Many owners of a Mercedes 190 D or 200 D know the picture: in the morning after starting, a bluish cloud hangs behind the car, and after a few minutes everything is back to normal. At the same time, oil has to be topped up more and more often between oil changes, even though there is not a drop to be seen under the engine. Before you think about an engine overhaul, it is worth taking a look at a small, inexpensive component: the valve stem seals of the OM601.
Symptoms
| Symptom | Likely cause |
|---|---|
| Blue smoke shortly after a cold start, disappears after a few minutes | Hardened valve stem seals – oil runs down the valve stems into the combustion chamber while the engine is stationary |
| Blue cloud when accelerating after idling or coasting downhill | Valve stem seals (vacuum draws oil past the valve guides) |
| Persistent blue smoke under load, high oil consumption, low compression | More likely worn piston rings or cylinder walls – not the valve stem seals |
| Oil pressure gauge reads conspicuously low, but the oil level is correct | Different cause: check the gauge or sender – see W124 oil pressure gauge faulty? |
| Oil consumption rises, but there are oil stains under the engine | External leak (gaskets, shaft seals) – fix these first |
Causes
Valve stem seals sit on top of the valve guides and wipe the engine oil off the valve stem so that only a hair-thin film of lubricant reaches the combustion chamber. They are made of elastomer and work continuously in a hot, oily environment. Over decades and many heat cycles, the material loses its elasticity: the sealing lip hardens, cracks, or no longer sits cleanly against the stem.
Long periods of standing, as is common with classic cars, make the problem worse. While the engine is stationary, oil collects in the cylinder head, seeps past the leaking seals and burns off at the next start – hence the typical blue cloud right after starting. Another factor is wear of the valve guides themselves: if a valve has too much play, even a new seal will not stay tight in the long term.
Testing it yourself
- Document oil level and oil consumption: Measure precisely over a few hundred kilometers how much oil has to be topped up. At the same time, make sure the engine is not overfilled.
- Check for external leaks: Inspect the engine from below and around the valve cover. Oil loss to the outside is cheaper to fix and must be ruled out first.
- Observe the smoke pattern: Have a cold start filmed after the car has stood overnight. A brief blue cloud that disappears quickly points to the valve stem seals. Persistent smoke under load points more to piston rings.
- Check the crankcase ventilation: Clogged hoses increase the pressure in the crankcase and can also push oil into the intake tract.
- Test the compression: Even, adequate compression values on all cylinders speak against piston ring wear and strengthen the suspicion of the valve stem seals.
Solution
If the suspicion is confirmed, the valve stem seals are replaced. For this we offer the genuine Elring valve stem seal set 914.819 – NOS, i.e. new old stock in the original Elring packaging. In the product data, the comparison number A 102 050 00 58 is listed. According to the manufacturer, the material is FPM, a heat- and aging-resistant elastomer. Price: 14,90 €.
When replacing them, also check the play of the valve guides. If these are worn out, a cylinder head overhaul makes more sense than just new seals.
Elring valve stem seals 914.819
Mercedes OM601 · W201 190 D · W124 200 D / 200 TD · NOS, original packaging
Comparison number: A 102 050 00 58
14,90 €
View productYou can find more parts for your car in our categories W124 and W201.
Compatible vehicles
| Model series | Model | Engine |
|---|---|---|
| W201 | 190 D | OM601 |
| W124 | 200 D | OM601 |
| W124 (station wagon) | 200 TD | OM601 |
Information according to the product data. Please compare the engine code and part number before ordering – if in doubt, we are happy to help.
Another typical diesel issue with these models is load-change judder: W124/W201 Diesel jerks on overrun? Check the linkage damper.
FAQ
How do I recognize worn valve stem seals on the OM601?
Typical is a bluish cloud of smoke directly after a cold start or when accelerating after prolonged coasting or idling, which disappears again after a short time. In addition, there is a measurably rising oil consumption without any external leak.
Is blue smoke always a sign of faulty valve stem seals?
No. Worn piston rings, a clogged crankcase ventilation system or an overfilled oil level can also cause oil burning. If the engine smokes continuously under load, that points more to piston rings; a compression test provides clarity.
What is the part number of the valve stem seal set?
The set offered here bears the Elring number 914.819. The product data additionally lists the Mercedes comparison number A 102 050 00 58.
Which vehicles does set 914.819 fit?
According to the product data, for the four-cylinder pre-chamber diesel OM601 in the Mercedes-Benz W201 190 D as well as the W124 200 D and 200 TD. Please compare the engine code and part number before ordering.
Does the cylinder head have to be removed for the replacement?
Not necessarily. With a valve spring compressor and a method that holds the valve in the cylinder, the seals can be replaced with the head installed. Without suitable tools and experience, we recommend leaving the job to a professional.
KFZTeile-Thot is a specialist business for tested and refurbished Mercedes parts with its own test benches and can point to over 1,000 positive eBay reviews. Not sure whether the set fits your engine? Call us at +49 179 8991069 (Mon–Fri 8 am–6 pm) or write to us via the contact form.