The S65 Engine
An M car is a pure concept of performance and built with that in mind. Some may think that they are “race cars for the street” and in some ways they are. The 2008-2013 M3 with the S65 combined more modern features than the M3 it was replacing, yet BMW wanted to retain the brute force in the engine, opting for a 4.0 liter V8, instead of a turbo charged engine found in the other models of the 3 series. The S65 is no doubt an iconic M engine. It’s high revving, loud, and immersive. Is it reliable though? As these generation M3 are coming down to a point of relative affordability, what can you expect in terms of repair and reliability?
With owning any M, be prepared for expensive parts and labor. If you are not comfortable with this, the N54 engine may be a better fit, because you will see here, one part that fails in this engine is $600, not including labor. These are the top 5 S65 engine problems.
Top 5 S65 Engine Problems
- Rod Bearings
- Throttle Body Actuators
- Idle Control Valve
- Valve Cover and Gasket
- Oil Cooling
S65 Rod Bearing Failure
This will no doubt be the first thing that comes up when you google the S65. The deadly rod bearing failure. The rod bearings in the S65 have a tendency to wear out prematurely, which could end in engine failure. This seems to be the number one issue that numerous forums call out.
The only solid objective information you can count on is that less than <1% engines have failed from rod bearing failure and that it has not correlated with miles or even tracking. Everything else is subjective interpretations and inconclusive. – Rajmun340
It seems that the effect of this issue has affected a small amount of the engines, yet it makes all owners nervous. The larger S85 V10 engine has the same issue. If you are concerned with this possibly fatal problem, switch out the rod bearings with aftermarket like these. Most forums have been saying to replace them every 50-80k miles, and gives peace of mind. To help further, have your oil analysed after the oil changes to check for any wear.
S65 Rod Bearing Failure Symptoms
- Engine ticking sound at idle and in the 1,600-2,000 rpm range (usually most noticeable at idle)
- A hole in your engine from it blowing up
- Engine completely seized and not turning over
Replacement Cost: approx. $2,500 for parts and labor. We recommend replacing these every 60k miles. The alternative is a $25k repair bill for a completely new engine!
Here is a clip of the noise:
Throttle Body Actuator Failure in S65 Engines
These are prone to fail in this V8, and the mileage reported for the failures vary. So these will go out in the engine and the way you find out, is when you M goes into limp mode, you lose engine power, and the DSC and EML lights illuminate. There are two of these actuators on the engine, and they are costly at approx $600 each. Then factor in labor which has been quoted on a few forums for nearly $1000. It is not a cheap fix. There is not a specific reason they go out, but some have speculated it is due to the plastic gears in the actuators. I know, plastic gears in a $600 part.
If you are relatively handy, and think you can DIY it, here is a link to a great DIY breakdown. I would consider it to be an intermediate difficulty and expect it to take around 6 hours. Let us know if you have ever done this fix.
S65 Throttle Actuator Failure Engine Codes:
- Fault Code: CDC0 – Throttle Value Actuator CAN Message
- Fault Code: 2B57 – Check At Lower Top
- Fault Code: 2B21 – Predriver Check Throttle Valve Actuator
Replacement Part: https://www.bmwpartsfactory.com/CONTINENTAL-VDO/82/13-62-7-838-085
Replacement Costs: $1,100 for parts, $1,000 for labor
Idle Control Valve
You will know if you have a faulty Idle Control Valve as soon as you turn the car on. Rough start and idle fluctuations are the symptoms of this, plus engine lights and error messages. It will also more than likely put your can into limp mode. Not a fatal issue, but can turn a weekend drive into a headache pretty quick.
S65 Idle Control Valve Failure Symptoms:
- Rough idle
- Irregular idle RPM’s
- Hunting or continually fluctuating idle RPM’s
Don’t confuse bad spark plugs or ignition coils for a bad idle control valve. A bad control valve will usually be throwing off a check engine light. Additionally, unless your spark plugs are really bad, you will likely only experience a few misfires, rather than a consistently poor idle, although bad gapping can cause this. If your S65 is slow to start, misfires under acceleration, or won’t start in the cold, then it is likely a spark plug and ignition coil issue instead.
Replacement Idle Control Valve: https://www.bmwpartsfactory.com/GENUINE-BMW/9/13-41-7-838-024
Valve Cover and Gasket
Affecting many other BMW engines, this is a typical issue across the board. Owners notice that the gasket leaks a small amount. Some replace just the gasket, others replace both. Keep in mind that this is a high performance engine that gets hot. Over time, the gasket and the cover tend to warp. This leads to oil leaks.
Symptoms are oil stains where you park the car, and oil on the engine. It is normal and I would keep an eye on how much oil the engine is consuming and leaving on the ground. If adding oil more than once a month, definitely go get them checked. The gasket is not very expensive, at $180 or so for the gaskets and spark plug tubes. The cover is quite a bit more though at $675 per side.
There are DIYs for this one here, and again it is more of an intermediate skill level.
S65 Valve Cover / Gasket Failure Symptoms:
- Oil leaking from the valve cover
- Cracks in the valve cover
- Spark plugs covered in oil
- Smoke coming from the engine due to hot oil leaks
S65 Valve Cover Gasket Replacement Part:
- S65 Cylinder 1-4 Gasket
- S65 Cylinder 5-8 Gasket
- Spark Plug Tube – you need 8 of these if you are doing both gaskets
Make sure you also buy the bank 2 gasket if it is failing as well!
S65 Valve Cover Replacement Part: https://www.bmwpartsfactory.com/GENUINE-BMW/9/11-12-7-848-154
At this point, I’ve got to nitpicking. This will only be an issue if you are taking your M to the track. The issue is that the oil can get too hot when running the car hard. When this happens, the car will go into limp mode. If you are thinking of getting this M for the track, I would recommend getting a larger oil cooler. It will ensure you keep the temps down to a manageable level.
Summary of the 5 Common S65 Engine Problems.
Overall, this engine doesn’t have an overwhelming amount of issues, and I had to dive deep and start nitpicking to get to 5 common problems. The issues it does have are common and known. The S65 is a great engine, the parts are just expensive, as with any M car.
Some advice I found from browsing numerous forums.
- Let the car come to temp before you get on it. Don’t rev the engine past 4,500 rpm before it has had time to warm.
- Keep an eye on the oil and change it 4-6k miles. Check old oil after every oil change. If it is dirty, you probably have an oil leak, if it has lead in it, change your rod bearings
- Drive it more. Don’t let the car sit for days and weeks. These cars are meant to be driven and driven hard. Enjoy your car, don’t be scared of it.
- Find a service center you trust. This is the case even if you don’t have an M. Good service centers want to help you enjoy your car.
- Have at least $1500 put aside for repairs. It will happen.
Overall, I would consider this to be reliable, but keep in mind what the engine was derived from. It is a performance engine and needs attention. Change out the bearing rods if you’re worried about it, and keep an eye on the oil. This will help ensure long life to the engine. If you are one who has been looking to jump into a E9X M3 due to them becoming somewhat affordable now. I would say jump on in. Make sure to look over the maintenance records, and do a pre-purchase inspection.
If you are thinking of buying an M3, check out our buying guide.
S65 Reliably Score: 2
1 is the best, 4 is the worst.
Overall there are no huge flaws to the design and with proper maintenance it will run well over 100k miles. Look at examples here. One has 190k on it. It does need attention, and will repairs will be expensive when needed.
What are your thoughts or experiences with the engine? Let us know.