235,000 mile N54 valve cover change

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Mar 29, 2010
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I’ve been chasing down some weird driveability issues for a while, even taking my love it/hate it 335 to a shop. (Gasp!). They diagnosed out of spec crankcase pressure but wanted $2200 to change the valve cover to freshen up the pcv. I bought the parts for $250 and did the task yesterday. Took about 4 hours and really wasn’t the easiest job, harder than I remember when I changed the cover gasket about 5 years ago. The vent hose was very brittle, it broke when I tried to unclip It. It was probably broken for a while.


Hopefully that explains why the top end is so grimey. Pcv probably hasn’t been pulling as much as it should. The splashed areas look fine but the still areas… yikes.

Car has 235,000. OCIs are usually castrol 0-40 every 5-7500 miles. Driving is very urban, extensive idling, and many short trips in a cold climate. Doesn’t burn any.
 

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Joined
Dec 28, 2011
Messages
3,357
The N54 puts a smile on your face when the twin turbos scream but isn't the most reliable engine. From the pics and the images, I'd say you have done a great job keeping it up at 235k. Changing the pcv was a must do. Hope you get it to 300k. Did you ever get a weep by the oil filter?
 
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Mar 2, 2004
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Kentucky
Doesn't look that unusual to me. Those surfaces that have caked on carbon deposits probably don't receive a lot of oil splash since the cams are covered, so what does get on there tends to stick and harden, is my first thought.

I've never seen covers over the cams like that, I wonder what purpose they serve? How are the valves actuated?
 

antonmnster

Thread starter
Joined
Mar 29, 2010
Messages
1,132
Location
Minneapolis
The N54 puts a smile on your face when the twin turbos scream but isn't the most reliable engine. From the pics and the images, I'd say you have done a great job keeping it up at 235k. Changing the pcv was a must do. Hope you get it to 300k. Did you ever get a weep by the oil filter?
Twice. And the oil cooler thermostat gasket too. And, since I was in there, all new pulleys and the belt since they are right below the oil leak and apparently they don’t like to get soaked with oil. All the parts are around $150 so no reason not to.

and you’re right about the n54. It’s absolutely sublime with a dual personality: 100% torque at 1800 rpm pulls like a V8 with no drama, or can scream at 7500. It’s too enjoyable to replace. And I love that “paid off” feeling.
 
Last edited:
Joined
Dec 28, 2011
Messages
3,357
Twice. And the oil cooler thermostat gasket too. And, since I was in there, all new pulleys and the belt since they are right below the oil leak and apparently they don’t like to get soaked with oil. All the parts are around $150 so no reason not to.

and you’re right about the n54. It’s absolutely sublime with a dual personality: 100% torque at 1800 rpm pulls like a V8 with no drama, or can scream at 7500. It’s too enjoyable to replace. And I love that “paid off” feeling.

You have done well, enjoy it!! I totally get it. That is one of the engines that just give and give. Even the MPG at high speeds is excellent. Imagine that engine without the many minor but costly and PITA fixes?? That would be something.
 
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Nov 10, 2018
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virginia
I had one I kept for 200k. Valve cover gasket is a pain mainly because of the injectors and of course being a BMW every gasket leaks before 100k miles. I ran a MHD tuner, upgraded intercooler, intake and 30% ethanol tune and it ripped but they aren't built to own outside of a warranty. Besides the oil filter and valve cover leaking by 70k, the turbos had to be replaced under warranty at 70k miles, the water pump went out around the same time and this all before I did any modifications. I bought it cause it had everything i wanted in a car: RWD, forced induction and a manual transmission but never again.
 
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can scream at 7500.
They fall flat on their face after 5000rpm. Not as bad as the single turbo N55 but the N54 mitsu turbos have no top end or ability to make top end boost. I take that back. At STOCK laughable low boost (been a while but I think around 7psi) they are linear. Tuned for what the turbos are capable of boost starts falling off after 4500ish rpm and top end is non existent compared to the low and midrange.
 
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Aug 30, 2004
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For this reason, I was always told to replace the entire cover (not just the gasket) on the N54/N55 motors when there is a valve cover leak.
 
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Looks pretty normal for the mileage. Some darker areas for sure, but overall not bad. Have seen much worse.
Thanks for the pics, great job saving $$$ on a relatively easy job.
 
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