RENEWING THE TURBO GASKET
1 Here, Chris at Parkside Autos is looking to see where the noise is coming from while we rev the engine. The sound is definitely coming from the turbo area and not down near the intercooler.
2 The upper engine covers were detached, along with the air filter side intake housing and the Maf-to-turbo pipe – all held by 5mm Allen bolts. This is relevant to the four-cylinder 520d models, too.
3 We undid two 10mm bolts and pulled the alloy intake boost pipe from the turbo. There’s a rubber seal on the end which invariably leaks oil – boost charge contains oil droplets and lingers around the joint. Ours was a bit oily, but no worse than normal.
4 We detached the plastic pipe from the MAF to the turbo – it’s a push-fit onto the turbo. The red square indicates the location of the turbo-to-manifold gasket and it didn’t look right. Our engine has had the cast-iron manifold fitted prior to us, replacing the crack-prone steel originally fitted to E60/61s.
5 Up top, the pollen filter housing and rear bulkhead trim panel were removed, along with the steel inner wing braces. With those out of the way, we could start removing the filter housing.
6 The upper filter housing is held by 5mm Allen bolts – now is a good time to replace the air filter. The three red squares show where the turbo retaining bolts are accessed once the three rubber grommets have been removed.
7 There is also this steel protector plate to stop the grommets from melting and dropping out. On all M57 and M47 (2.0) diesels, it clips in from underneath the air filter’s lower housing and can be fiddly to refit. It goes in pointed-end first and is then pushed upwards to locate it properly.
8 This is one of the bolts holding the turbo. The correct type is a non-magnetic high-tensile bolt with a serrated head, requiring a 12mm multi-point socket torqued up to 50Nm. Ours had been replaced with 16mm bolts, presumably supplied with the turbo kit.
9 Here, Chris undoes the first of three turbo-to-manifold bolts and they all came undone easily. Our car was converted from a steel to iron manifold, but the bolts are the same (part no 11652243402). The turbo won’t fall off because the lower bracket is still bolted on.
10 As it’s not held by studs, the old gasket slid out easily. It had clearly failed and was showing black exhaust soot marks. We were worried that the iron manifold flange might be slightly warped, but the new one went in fine and shows no sign of blowing.
11 Luckily, Parkside Autos had a new gasket in stock. This was coated on both sides with copper grease, before being slid into place and the bolts torqued up. Never use exhaust paste – the excess will go rock hard and get sucked into the exhaust turbo vanes.