35i Engine Failure?

richardb · #1 06-22-2021, 01:59 PM

We sold our E53 a few months ago, and have been searching for an E70 35i for over 6 months. During that time, I have seen probably a dozen 35i for sale in the CT/NY area for $5-6k requiring a total engine replacement.

This is making me reconsider if a 35i is really a good idea. I haven't seen that kind of engine failure rate for any other models. Is there a widespread issue hitting these cars at 100k miles?

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Zulu95 · #2 06-22-2021, 02:12 PM

Having had an indy blow an engine last year I would guess it is failure to prime the oil system properly after draining the system.
Couple that with the VCG/OFHG oil leak contaminating the serpentine belt causing it to fail and enter the engine through the front oil seal behind the harmonic balancer you have two reasons for early engine failure.
Then you have the whole V-8 issues but that is a different model.

richardb · #3 06-22-2021, 02:19 PM

Interesting, I thought the N54 belt-eating failure issue was resolved with the N55?

Cyrix2k · #4 06-23-2021, 04:48 PM

It probably is due to loss of oil prime. I have a pet theory that not only does it happen during OFHG replacement (where early reports are from), but also after sitting for an extended period of time. The N55 uses a variable displacement oil pump for better efficiency and I don't think it's able to adequately prime the oil system after it drains down. The N52 also has a variable pump and the N52 in my old X5 blew up after sitting for an extended period. Naturally the N55 is worse since it's boosted. No oil plus boost = boom.

Quote:

Originally Posted by richardb

Interesting, I thought the N54 belt-eating failure issue was resolved with the N55?

AFAIK, N52, N54, and N55 all suffer from that.

Zulu95 · #5 06-23-2021, 04:57 PM

So just like the WWII Tiger Tanks we need to exercise our engines at regular intervals or they will seize up. Some things never change.

BMWHoochie · #6 06-24-2021, 10:32 PM

I have the N55 and love it. The only problems so far are some gaskets and a power steering pump.

The N55 is actually a pretty robust engine. The problem with the OFHG and cooler gasket are like others have said above. People fail to prime the system, and when cleaning the OFH people use crap like brillo pads, scotch-bright, and other towels that get into the oil passages and cause major issues from clogging Vanos solenoids, etc... or using a contaminated belt. When I did mine, I took the filter cap off and made sure oil was circulating before I connected the injectors back to the DME.

Also, I have seen pumps that can't clear air pockets, but that's rare. Check out the images below of what I found when I stuck an inspection camera in one after an OFHG job. It's crazy lol. This is why I don't use brillo pads, scotch-bright, and shop towels. Microfiber cloth is all you need. I even vacuum the passages before assembly. OCD FTW

You can get a crank seal guard for $60 and it will prevent the belt from being pushed into the front seal. It's worth the peace of mind. Even with preventative maintenance hoses can leak, and blow an o-ring and that's all it takes.

BMW gaskets leaking is not something new. I have yet to see a BMW engine without some kind of gasket leak. The HPFP, and other stuff like Vanos solenoids, water pump/thermostat are common replacements on higher mile engines as well.

It's a great engine. Keep up with preventative maintenance, and I recommend sticking with OEM for everything.

1. 5k mile oil changes
2. I do plugs/coils every 40k. I prefer Eldor coils over Delphi. ALL newer N55's use Eldor now.
3. Brake fluid, power steering, and coolant flush every two years
4. Transmission pan/filter/fluid every 40-50k
5. Front/Rear Diff fluid and drain/fill plug every 40-50k
6. Transfer case fluid and drain/fill plug every 40-50k
7. belt, and all pullies every 40-50k
8. Check hoses and for leaks every time you have the hood open

It might be overkill but if you order from FCP Euro you have a lifetime warranty on everything. Purchase the new stuff, send the old stuff back and you get a full refund including tax. Mostly everything on my X5 that matters is covered now lol. You only pay for shipping back.

Check out the shop towels and particles from scotch bright pads down inside the OFH passages. Most mechanics don't use an inspection camera before they put the housing back on, and this is what's left inside. Don't mind the date on the image. The image was from 6 months ago.

Good video for some common replacements on the N55
https://www.youtube.com/watch?v=rPUUNhjJjHU

Zulu95 · #7 06-24-2021, 11:09 PM

Back in the 70s my old style BMWs did not usually leak oil. The paper VCG was reusable with a little gasket cement. I was sometimes pulling the VC weekly to adjust the valves as I was pulling some big numbers just for fun.

Cyrix2k · #8 06-24-2021, 11:27 PM

Quote:

Originally Posted by BMWHoochie

Even with preventative maintenance hoses can leak, and blow an o-ring and that's all it takes.

I can validate that. My friend's N54 has eaten THREE belts and another friend's also ate a belt. Both of them lost a belt when their p/s pump bolts backed off (one had the bracket break in the process), one was from a coolant leak that hit the belt, and one was from an oil leak at the OFHG.