Renault Modus - are they generally ok?

GolfBravo

Any modern turbo diesel engine can prematurely die - turbo life is significantly affected by user habits and maintenance.

The two biggest turbo killers are dirty engine oil (caused by poor maintenance) and not allowing the turbo to cool down with the engine idling.

Turbo bearing and seals depend on a good flow of clean oil to keep them cool - the exhaust turbine gets red hot - and particles in dirty oil stick to oil seal lips.

Sudden stops at motorway services are especially bad - you cruise at 70mph, you spot the services sign, brakes on, pull up at the pump and switch off. The turbo is still red hot - turbos spin at tens of thousands or rpms. With the engine off, there's no oil cooling the turbo so the oil behind the exhaust side seal cooks until it's carbonised. When the turbo is spinning, the carbonised oil erodes the lip of the oil seal.

So when you buy a used turbo diesel it is essential that it comes with a complete service history, preferably from a reputable dealer/garage. Many garages can stuff up even such simple procedure as oil change (e.g. not draining old oil properly/using a suction pump to partially remove old oil).

Even one missed oil change can kill the engine - you get a lot of crude stuck inside the engine block, and when you eventually replace the oil all the crude is flushed out but stays in the engine. The last thing you want to do is to disturb crud/built up carbon as it then gets pumped through the turbo causing wear to the journal bearings.

The main problem with Renault turbo diesel engines is their extended service range (designed to please fleet managers) with their engine oil sensors.

And BTW, French turbo diesels are indeed superb, and that includes both Renault and PSA (Peugeot/Citroen). They simply need proper maintenance and common sense when driving.