W204 Engine warning light and cream in filler cap

[DonVitto]

Just an update, I had the timing chain and thermostat replaced, along with a service and a couple of other things. Total cost £1,600 inc VAT so not too bad in the end all things considered.

I've cut down on the super short journeys and I take it out for a long run every weekend. Oddly though, I'm still getting some moisture under the oil cap. Not as much as before (although it could have been building up over time) but a very thin layer of "cream" on the underside of the cap. It's not really alarming because it's minimal, but it never used to happen. I've left the cap off a couple of times to try and encourage it to evaoprate. Could this just be left-over moisture from the short journeys and cold weather, or is it more likely there is a small leak somewhere?

 

[markjay]

A coolant leak into the oil will (a) manifest itself on the dipstick, not on the filler cap, and (b) it will also cause a reduction in coolant level in the coolant expansion bottle.

If you still experience condensation in spite of long journeys, the engine top breather might be blocked. When this happens, it tends to trap moisture in the top part of the engine (and if pressure builds-up it could eventually blow through the camshaft cover seal and cause an oil leak).

But I would just give more time. See how it goes.

 

[DonVitto]

A coolant leak into the oil will (a) manifest itself on the dipstick, not on the filler cap, and (b) it will also cause a reduction in coolant level in the coolant expansion bottle.

If you still experience condensation in spite of long journeys, the engine top breather might be blocked. When this happens, it tends to trap moisture in the top part of the engine (and if pressure builds-up it could eventually blow through the camshaft cover seal and cause an oil leak).

But I would just give more time. See how it goes.

Thanks for your reply. I should be honest - the journeys in the week are still short (school run) but not as short as during lock down. This time the car at least gets up to temperature, if not for long. But with that said it's no different to how I've been driving it over the last 5 years. As you suggest, I'll leave it for now and keep an eye on it. Thanks for all your advice.