Recently acquired low-maintenance girlfriend with deferred-maintenance convertible, 8/2011 build date (on the car), with 106k and a history of regular oil changes, low & high pressure fuel pump replacement & VANOS solenoids. That's it.

I'm accumulating the parts to go through the engine one time to make it safe and reliable. I'm trying to address anything that could be fatal first, then the nuisance stuff later. What am I missing? So far I've got:

• PCV diaphragm & spring
• a timing chain (cold treated), guides, tensioner, crank cog, bolts and seal kit
• tools to secure crank & cams in service position
• OE mfr Water pump (Saleri?)
• water pump pulley
• alloy coolant pipe
• alloy thermostat housing (from Maxpeeding Rods)
• two into one wiring adapter for newer style thermostat housing to older harness
• new oil-cooler-to-block seal
• new turbo oil lines - braided feed, stock return
• Shop vac adapter for walnut blasting the intake valves (never touched)

My scanner shows low and high pressure fuel pumps in spec. I don't hear the timing chain death rattle, yet.
Is the exhaust-cam-driven vacuum pump a common failure? My understanding is that leaks reduce the already small amount of oil to the pump, it seizes up, shears the cog bolts off of the exhaust cam, and then, game over. So is this just an N14 issue, or does the 18 share this weakness?

How real and/or frequent is the exhaust valve breakage? Valve stem seals? low tension oil control rings? Holy cow, that is an inexcusably long list.

So, in terms of a known issue causing instant engine death, did I miss anything?
Thanks,

Brian C.

 

How often were the oil changes done before you “inherited“ the car? This will determine your path forward.

Few and infrequent oil changes will be the cause of many failure in the N18 engine. The best thing you can do is switch to 5000 mile synthetic oil changes. Mine lasted 200k+ miles with 5000 mile oil changes, and 10k mile filter changes. I never replaced the vacuum pump, timing chain, the oil filter housing seals, or the turbo lines. Also never had it walnut blasted.

From your list, I would delay the water pump and thermostat until they start showing signs of failure. The water pump will start to weep, and the thermostat will fail open and throw a code.

I would also skip trying to repair the PCV and just get a new cam cover.

 

Yeah, sound advice here: it seems like you're replacing a lot of things that may just be fine. Like, I haven't heard of significant timing chain/guide issues on the N18 (I think that's one of the things they improved?) so I wouldn't preemptively replace those unless you've got obvious issues. I'm pretty sure the death rattle was more of an N14 thing. Turbo lines should be fine unless leaking, I'd think, just make sure you've got the retrofit shield Mini added to protect from heat.

A straight-up cam cover replacement isn't a bad idea. Also there have been a few revisions of the turbo bypass valve and the earlier ones could be problematic, so that wouldn't be nuts to do if it's original. Beyond that I'd just replace stuff if/when it has issues.

One important maintenance item (if automatic) would be to change the transmission fluid. It's a "lifetime" fluid, as long as you define that as "lifetime of the warranty". It's not a bad job, you just need an ATF pressure filler, and you can remove the pan in the car if you remove the lower engine mount and shift the engine forward a bit. Do a search: lots of details on this.

 

Alas, I believe the oil changes were closer to 10K intervals, but at least they were all done with synthetic oil. The replacement PCV diaphragm & spring were less than 20$ and can be replaced in under 5 minutes, so until anything else rears its head, that's a start. Why change the cam cover if the PCV is serviceable? Does it have some internal valving or other function that falters with age?

As for the rest, I suppose I can pressure test the cooling system as it came into my life at the MIN level. Before it's next oil change, I'm tempted to add something like GUNK engine flush, then drain and refill with new. There does not appear to be any comingling of fluids between oil and coolant, so that's something. It has finally stopped raining in NorCal, so I'll crawl under and around inspecting for any leaks, especially the oil filter housing gasket.

A transmission flush and fill with new gasket is on the list, I have a fluid pump and all sorts of adapters for that job. I've done it a couple of times on my old 955 Cayenne Turbo and D2 A8, so ich sprechel Deutsch car maintenance generally, I'm just trying to understand the specific quirks of this engine. Thank you.

 

I could very well be wrong but I think with the OEM valve cover you can't change the diaphragm. I know with the one that came on my 2012 CS it didn't seem possible. YMMV.

I call that stuff "engine kill", and I would strongly recommend you stay away from it.

There are two types of engines. Ones without significant sludge, they don't need engine flush. And then ones with significant sludge, in those the flush can break the sludge free and plug your oil pickup. I personally know someone who killed a Miata engine that way.

 

The best thing you can do to clean an engine is to change the oil more often, and change the filter every time. Skip the engine flush. 10k mile oil changes aren’t the worst thing, as long as the oil level never went too low and was topped off as needed. Still, I would start going 5k miles.

You can change out just the PCV diaphragm, but there are oil passages in the cover that can become clogged and plugged as the oil ages. Again, regular oil changes will help.

Really, the biggest issues with these engines can be avoided by regular oil changes and proper maintenance. Too many of the accessories are bolted to the block and rely on oil passages for lubrication and gaskets for sealing. Keeping fresh oil in the engine will keep the passages from clogging, which then protects the gaskets from being over stressed by higher oil pressures.

Can you tell I’m a fan of regular oil changes yet?

I reiterate, my Clubman with early build N18 engine ran for over 200k miles on the original turbo, vacuum pump, timing gear, oil filter housing, cam cover, never had a walnut blast…. I RELIGIOUSLY changed the oil every 5000 miles, changed coolant every 2 years, and never let an engine code go ignored for more than a couple days. These engines can take care of you, but you have to take care of them.