Stoutness of the M52 6-cyl engines

[FramelessMonk]

Hi,

Just wondering the reliability of this engine? Does it have the similar gasket issues (vcg, ofhg, oil pan) like the newer n52 series engines? The buying guide sticky on this forum didn't mention any engine issues to look for which is ODD for used BMW guide.
Also how are they in responding to power mods (not force fed). I think I read about something about manifold upgrade from m50 engine.

[Muzz258]

Yes the M52BXX engines have the same gasket issues (VCG, OFHG, oil pan).

The engines are very reliable and long lasting as long as you regularly feed it new oil and don't over heat them. Z3 M52BXX engines have aluminium blocks and heads, which don't like being over heated. They have a tendency to pull head bolts due to the weaking of the block after being over heated. Over come by using time-serts.

BMW did a good job at getting the power out of the engines at the design stage. You are not going to find an extra 30 hp cheaply like you will with an old Chevy engine. Allow for small gains with each modification and expensive parts. The M50 inlet manifold is one modification that helps. Other can talk about the HP gained and the shifting of torque from low/mild to high bands. There are cam shaft mods that people do. There is also an individual throttle body (ITB) kit available from RHD in Australia. https://racehead.com.au/product-cate...tle-body-kits/

Please note that the Z3's also come fitted with the M52TUBXX and M54BXX engines. These are duel VANOS engines. The inlet manifold changes (fit M54B30 manifold) work for the M52TUBXX engines. Leave the M54 inlet manifolds alone. Cams changes help a little. The ITB kits also fit the M52TUBXX and M54BXX eninges

Then there are the Z3M's with S50, S52 and S54 engines depending on where in the world you source your car from and how old it is. They don't really need any tweaking, but some do. Others can talk about these engines better than me.

[ZGator]

N52 (106k) and M52tu (161k) owner here, M52tu does not burn a drop of oil after 161k miles if that means anything to you, did do VCG on both engines at about 100k for maintenance reasons.

the N52 burns a slight bit according to the digital dipstick - about 1/2 quart per 10k miles.

for the m52 I changed the vanos seals and VCG - just for maintenance.

I have never had issues with either with the OFHG like so many others. I always wonder if it is from people over torquing the oil filters - but others think it is the gasket material.

I have always done about 1 year 8-12k miles oil changes for both cars.

The N52 is on original electric water pump, while the Z3 water pump failed around 60k.

However the N52 has had ignition issues and even a bad DME, I would rate both engines as reliable with slightly different issues.

[Schreier]

My M52 has been very, very reliable. It's 20 years old now and 126,000+ miles and doesn't burn any oil that I can perceive, or at least per the 3K mile/ annual oil change interval.

These are stout motors that can take a lot of abuse, if the coolant system is replaced every 15 years or so, and good-quality oil and filters are used.

Naturally-aspirated power gains are hard to achieve on this motor without a large investment of cash, which is why many people jump straight to forced induction and never look back. Motors in this family with 3-liters and above of displacement tend to suffer from harmonics at higher revs that can destroy the oil pump, which tends to put a ceiling on NA gains for those motors. The smaller 2.5 and 2.8s don't suffer from those harmonic issues. And of course you can get around that somewhat with a dry-sump system, if you're willing to put down $4-6K on such a solution.

Having said that, most people are happy putting a header, custom exhaust, and M54/M50 intake manifold on, flashing a tune, and calling it a day. If you are feeling more adventurous, you can always drop in a different cam, install ITBs, or even have your head ported by a professional.

It's all about what your goals are, and how much money you are willing to spend.

[BimmerBreaker]

Ive never heard of the oil pump issue only being on the larger displacement engines. I know it occurs from high rpm driving - do you have a source showing the issue doesnt affect smaller displacement engines? Why wouldnt it? Why would the oil pump care about engine size? Its chain driven...

[gdavid]

Ive never heard of the oil pump issue only being on the larger displacement engines. I know it occurs from high rpm driving - do you have a source showing the issue doesnt affect smaller displacement engines? Why wouldnt it? Why would the oil pump care about engine size? Its chain driven...

It is my understanding that the s52 crank (same as m54b30) has harmonic issues at high RPM that contribute to oil pump failure. An ATI damper is an expensive solution, keeping the rpms at stock limit is pretty effective. I put a M54b30 damper on the stroker I built but it is not tracked.

[rf900rkw]

All modern engines have issues where eventually the plastic cam cover gasket and oil pan and oil filter / oi l cooler adapters leak. Judging an engine by that is silly. The M52 block is *the* block used by the guys building 1000+ WHP dyno queens.

Yes, the oil pump nut comes loose when the rev limiter is bumped up past a critical harmonic. It appears 7100 on the S52 is the sweet point where the whip gets bad enough to shake the nut right off. Thayer had a video up of his failing on the dyno.

[Schreier]

Ive never heard of the oil pump issue only being on the larger displacement engines. I know it occurs from high rpm driving - do you have a source showing the issue doesnt affect smaller displacement engines? Why wouldnt it? Why would the oil pump care about engine size? Its chain driven...

As others have said, it's about harmonics that generally come out on the 6-cylinder rotating assembly when the stroke is beyond a certain length. Only seems to meaningfully affect 3.0 and above displacement. Shorter strokes and thus smaller displacements don't seem to generate the same harmonics, and mostly seem safe to spin somewhat past factory recommendations.

Sample size of one, but I recently took off the oil pan of my M52TUB25 as part of a front subframe refurb and fiddled with the oil pump while I was in there. The oil pump nut was still torqued to factory specs. This was an engine that survived a "money shift" a couple of years ago, and generally spun up to 6,200 for a short period every week on average. However that might not be enough to generate meaningful harmonics.

But all that is to say NA power going to be capped by the harmonics on your larger displacement M52s. Capped to what, you might ask? Don't know.

[Hasbro]

Timely thread for me, also. I'm picking up a 98 2.8 in a month or so and plan to "gently increase power" to use as a long term road/autox car while building a less civil Boxster. A presentable car that can do it all and last decades.

-I would like to increase torque/whp by about 10 torque/15 whp without sacrificing mid range (street) performance.
-Pull no more than 200 lbs.. Easy enough and equal to approx. 10+ whp.
-Lighten up some of the revolving weight; wheels, smaller crank pulley, clutch/flywheel etc.
- Go from approx. 18.5lbs/whp to 15.5lbs/whp
-Better handling and noticeably more pep, maybe a tick under 6 secs. from 0-60?

[Remotion]

You will have absolutely no problem. I have 30% more power than my M52B28 was stock and it has been revved at least 10000 times to over 7200 rpm in last 12 years. Zero problems ever. Starts to eat slightly oil now, about 2dL in 5000km. I change oils&filter every 7-10000km.
My S50B32 was also completely problem free (sadly only part in that car) whilst it was often driven at 250-280kmh speeds.
Also M50B25 before that was solid companion for 250000km's, daily over 200kmh in that thing. Not a single problem ever.

In Finland M50 or M52 is most often used turbo project engine also.