I remember on the N54 engines that people used to go on about having to clean the backs of the inlet valves insitu using ground walnut shells etc under pressure to clean off the (I think) baked on deposits that don't get washed off by fuel (as it's a direct injection). And this was often recommended around the 50,000 mile mark.

Haven't really seen much discussion about that issue with the B58 engines. has something changed in the design that prevents this happening?

Good question. I am curious about this as well. Unless they added some kind of supplemental fuel injection system (I believe Toyota does this) then I can't see it NOT having an issue with carbon build-up eventually. You might not have heard much because most people's cars on here are under 5 years old and may not have the mileage on them in order to notice a difference.

Hasn't really been an issue, they changed a lot with the n55 and onward and the issues seemed to disappear

I recently traded in my +120k mile X3 35i with the N55, and never felt the need to walnut blast. Still had plenty of power and efficiency, was averaging 20mpg with a heavier foot than the norm. I also pushed the engine to redline a few times a month for fun, figured it was keeping the engine breathing nicely. The B58 is a much more advanced engine looking at the details and updates they made from the N55, I don't foresee carbon buildup being an issue. Looks like they made changes that should prolong the rear of the head gasket as well, especially with less heat soak temp changes since the B58 retains heat for longer to increase efficiency and minimize wear on parts.

I haven't seen any newer N or B engines needing carbon blasting anytime soon. I've replaced B46/B48 engines with up to 30k or so on them and have never seen a single bit of carbon buildup in the intake ports. I don't specifically know what they're doing but it's definitely improved over the N54 days.

freshxdough wrote

I haven't seen any newer N or B engines needing carbon blasting anytime soon. I've replaced B46/B48 engines with up to 30k or so on them and have never seen a single bit of carbon buildup in the intake ports. I don't specifically know what they're doing but it's definitely improved over the N54 days.

Just out of curiosity, what are the reasons you're seeing b46/48 engines for needing replacement?

brettl wrote

freshxdough wrote

I haven't seen any newer N or B engines needing carbon blasting anytime soon. I've replaced B46/B48 engines with up to 30k or so on them and have never seen a single bit of carbon buildup in the intake ports. I don't specifically know what they're doing but it's definitely improved over the N54 days.

Just out of curiosity, what are the reasons you're seeing b46/48 engines for needing replacement?

Plastic Engine coolant line between the cylinder head and coolant expansion tank fails then the engine overheats because the customer usually drives it WAY too long resulting in engine overheat check control messages and engine temperature faults for cylinder head reaching 178C (352F)

You definitely get a check control message for coolant low and engine temp too high and to pull over by the time this happens. I blame some of this on customer neglect by not pulling over and getting it towed.

Should this plastic engine coolant line be preventatively replaced at a particular age/mileage?

satz wrote

Should this plastic engine coolant line be preventatively replaced at a particular age/mileage?

I mean personally I'd probably do it but you need a specific setup. Usually only happens in the f30 330i or f32 430i. In the X3 it's a different coolant hose part and coolant routing so it's not affected.

freshxdough wrote

I mean personally I'd probably do it but you need a specific setup. Usually only happens in the f30 330i or f32 430i. In the X3 it's a different coolant hose part and coolant routing so it's not affected.

Thank you