[Esixty1]

Guys, my 08 e91 335i is a bit ill. She's about 110k miles with dubious service history, which maybe says it all... I was going WOT in 2nd or third when the half engine light came on and it went into limp mode. I parked it up and when I came back to it about 2 hours later, it wouldn't start. Had it flatbedded home and plugged in the computer and there were a few errors...I've probably saved them somewhere. Anyway, did some research and troubleshooting, after which I swapped out the vanos solenoids and tested the cam position sensors, but no joy, haven't been able to start it properly since. Since then I've been getting error 2a9a (intake cam position error) and the usual 3100 boost cut error to safeguard the engine. Swapping cam position sensors from intake to exhaust makes no difference to the error.

Anyway, I've kinda come to the conclusion that I'm likely looking at cam ledge or maybe timing chain related issues, particularly given the mileage and maybe infrequent oil changes. Now there is another engine that I could pick up at a reasonable price (it would be an exchange unit and likely sans turbos, injectors and all the other bits. The question is, if i were to swap out the engine, how much of a mission is it and what would I need in terms of replacement parts such as gaskets etc? She's an automatic BTW. If I spent the money instead on fixing this one, are there other maintenance related Ice issues that will get me down the track?

Thanks in advance for any help on this.

[robthewrench]

You should find an indy shop and ask them to quote or estimate the labor both ways. The show probably won't quote the cost of the replacement engine, as that depends on what they can find, but would quote the labor. This would give you an idea of the cost difference to fix or replace the engine once you add in the cost of the used engine.

Note, due to electronics, you'll need to find an engine from a pretty narrow range of 07 to 09. Going outside this range means either custom coding or engine management and more cost.

I would only swap a used engine if the 08 335 is your dream car and you'd put more money than it is worth into it. If you pull the engine, you'll want to replace the turbos and waterpump. Its a large job.

Get the costs from an indy and then start thinking about which way to go.

[ctuna]

Likely to need a Walnut Blast for starters.
If it wasn't maintained this could be a major
issue along with possible sludge build up.
and maybe turbo's,coils and injectors.
We can't get a 335 wagon in the US wish we could.

[Esixty1]

Thanks guys. So I'm aware of a spare engine at a reasonable price and, if I went down that route, I'll probably swap it out myself, with the help of a very capable friend. The questions really are, if i stick with and fix up the engine I have (outside of the usual walnut blasting, turbos, injectors, hpfp items, which seem to be almost regular maintenance items on these engines) am I going to have internal issues, like worn rings, bearings, valve stem seals, guides etc, or is that stuff going to be ok for another 50k plus?

Of course, if i go the replacement engine route, it would be remiss of me not do the turbos, hpfp etc while it's out right? Which means the price goes up :-/

[ctuna]

Well only you know how much you thrashed it .
If you been beating on it and the timing chain slipped
or something like that maybe you do need a knew one.

[robthewrench]

How many miles on the donor engine and how was it treated? Used engine swaps are only a good idea if you can gauge the general health of the used engine, and/or get a warranty to go with it.

Even Jasper will only give you a 12/12000 warranty on a rebuilt engine.

[Esixty1]

The donor engine has about 75k on it but no service history on that one either. I haven't checked the warranty side yet but it is probably only 3 months, if not less.

I've sent the car to the garage to be looked at...they are seeing the same error i got (2a9a) and telling me I need a crank position sensor. Not filling me with confidence but told them to go ahead and replace it. We'll see how things look next week. If that doesn't sort it, I'll probably get it back home and get to work on pulling the cam cover off and checking the timing gear followed by the cam ledges...it's only time and money :-/

[Esixty1]

An update...as expected, the crank sensor failed to fix it. While it was at the shop, I asked them to do a compression test and they found it to be 0 on cylinder 1 and a couple of the others apparently! Last time I was cranking it over a couple of weeks ago, it did make a horrible noise at one point and I was thinking shit, I hope that's not valves hitting pistons... It's pretty hard to imagine what else it could be that would cause it to have zero compression. I'd welcome anyone to tell me otherwise.

If that's what has happened, I can only assume the crank bolt has come loose, or there's been some other catastrophic timing failure. It's back at my house now and I've got the tools required to whip the cam cover off and check the timing and crank bolt, so hopefully I'll have a better idea by the end of the weekend.

[Esixty1]

Cause identified...the crank bolt had backed out completely and basically fell out into my hands. So it's probably safe to say I'll have some bent valves.

[ucdbiendog]

wow. sorry to hear