The BMW M52 engine is a naturally-aspirated, inline-six engine that the German manufacturer introduced in 1994. It succeeded the BMW M50 engine — the first to feature BMW’s VANOS technology — and shared much of its design and construction.
Over its six-year production run, the M52 engine was available in multiple versions that would make their way onto the E36 3-Series, E46 3-Series, E39 5-Series, and other models from BMW’s portfolio at the time. A high-performance iteration of this engine, dubbed the S52, would also power the second generation of the BMW M3 — the E36 M3.
Today, an M52-powered car has become an increasingly popular option for someone looking for a simple German-made daily driver or a project car that won’t cost you a pretty penny to tune or upgrade.
However, these engines are over a couple of decades old, and you’re bound to face some mechanical issues owing to their age. This guide covers everything you need to know about the BMW M52 engine, from the available versions, to what you should look out for when buying one.
Technology Behind the BMW M52 Engine
The BMW M52 engine, like its predecessor, featured a dual overhead camshaft, coil-on-plug ignition, and a knock sensor. It also used the same crankshaft and single-VANOS (variable valve timing on the intake shaft) system.
In most international markets, BMW decided to switch from using cast iron to using aluminum for the engine block. As a result, the manufacturer shed nearly 23 kg over the M50 engine.
The flip side to using the lighter aluminum alloy to construct the engine block was the lower strength and stiffness compared to cast iron. To counteract this, BMW coated the cylinder walls with a Nikasil (Nickel infused with silicon carbide) coating instead of the traditional pressed-in steel liners. As it turns out, this wasn’t such a great idea for the US market.
U.S. vs. International Spec
Unfortunately, the Nikasil coating turned out to be the cause of serious concern in North America. At the time, the fuel in our market had extremely high levels of sulfur. For reference, the government mandated that sulfur content in fuel was to be capped at 300 ppm by 2004. Today, that number is down to 30 ppm.
As BMW learned from the V8 M60 engine, the sulfur in our fuel would have an adverse reaction with the nickel in the cylinder coating, causing the cylinder walls to soften and resulting in an improper seal.
To avoid this, BMW decided that the M52 engine sold in the U.S. and Canadian markets would retain the cast iron construction of its predecessor, the M50 engine. The only exception would be the iteration of the engine used on the BMW Z3 Roadster (E36/7), which featured the aluminum cylinder blocks.
1998 Technical Update
In 1998, BMW made some updates to the M52 engine. The most notable changes included the addition of variable valve timing to the exhaust camshaft as well, making it one of the very first BMWs to feature double VANOS. Other changes came in the form of electronic throttle control and a dual-length intake manifold.
By this point, the manufacturer had realized the downsides of using Nikasil for the cylinder lining and replaced it worldwide with steel cylinder liners.
What Is the Difference between M50 and M52 Engine?
In most markets, the cast-iron construction of the engine block on the M50 engine was replaced by a lightweight aluminum on the M52 engine. As mentioned above, this wasn’t the case in the U.S. and Canadian markets that retained the cast-iron block. While the M50 engine was only equipped with single-VANOS, the M52 engine featured double-VANOS.
Apart from the above, the engines were broadly similar. They were available in similar displacements — 1,991cc, 2,394cc, and 2,494cc. The M52 engine was also available in a larger 2,793cc iteration.
How High Can an M52 Rev?
The stock M52 engine can rev up to 6,500 rpm, while the higher-performance S52 version has a 7,000 rpm redline. Owners who have tuned their engines to have higher rev limits have found that going above the 7,400 rpm mark with the stock internals does stress the engine out and can cause long-term damage.
BMW M52 Engine — Available Versions
Over its six-year production run, the M52 engine was available in three main versions — a 2.0L, 2.5L, and 2.8L. A 2.4L iteration of the engine was also sold solely in the Thai market. Of the three global engine models, only the latter two — 2.5L and a 2.8L — made their way to the North American market.
M52B25
The M52B25 displaced 2,494cc with an 84 mm bore and 75 mm stroke. Peak output figures were 168 hp at 5,500 rpm and 181 lb-ft of torque at 3,950 rpm. It was introduced in 1995 and would be on sale until 1998 when it was replaced by the M52TUB25.
M52TUB25
The M52TUB25, as the name suggests, is the ‘Technical Update’ version of the M52B25. The update brought double-VANOS, electronic throttle control, and a dual-length intake manifold.
While peak power and torque remained identical at 168 hp and 181 lb-ft, respectively, the latter was produced earlier in the rev band at 3,500 rpm instead of 3,950 rpm.
M52B28
The M52B28 was introduced in 1995 alongside the M52B25 as a larger-displacement and consequently more powerful version of the M52 engine. With bore and stroke figures of 84 mm, this was a ‘square’ engine displaced 2,793cc.
Peak output figures were 190 hp at 5,300 rpm and 210 lb-ft of torque at 3,950 rpm.
M52TUB28
The M52TUB25 is the ‘Technical Update’ iteration of the M52B28. While power and torque remained identical, they were produced at slightly different RPMs than the pre-update engine.
Peak power of 190 hp was produced at 5,500 rpm, while the 210 lb-ft of torque came in at a lower 3,500 rpm.
What BMW Cars Had the M52 Engine?
The BMW M52 engine made its debut in the form of the 2.0L M52B20 aboard the BMW E36 320i. It would go on to power multiple models in the 3-Series (E36), 3-Series (E46), 5-Series (E39), and 7-Series (E38) and select other models from BMW’s portfolio at the time.
The South African market also received an iteration of the engine on a non-BMW car — the Land Rover Defender.
Here is the list of cars that the BMW M52 engine powered in the U.S. and Canadian markets:
M52B25
The M52B25 powered the BMW 323i (E36) from 1995 to 1998, BMW 323ci (E46) from 1995 to 1999, and the BMW 323ti (E36/5) and BMW 523i (E39) from 1995 to 2000.
M52TUB25
The M52TUB25 was used on the BMW 323i and 323Ci (E46), BMW 523i (E39), and the BMW Z3 2.3i (E36/7) from 1998 to 2000.
M52B28
This version of the engine powered the BMW 328i/328is (E36) from 1995-1999, BMW 528i (E39) and BMW 728i/728iL (E38) from 1995 to 1998, and the BMW Z3 2.8 (E36/7) from 1997 to 1998.
M52TUB28
Lastly, the M52TUB28 featured on the BMW 328i/328Ci (E46), BMW Z3 2.8 (E36/7/8), BMW 528i (E39), and the BMW 728i (E38) from 1998 to 2000.
Is the BMW M52 Engine Reliable?
The BMW M52 engine is a reliable piece of engineering, and it’s not hard to find examples that are still in impressive running conditions after all these years. While international markets faced more complications with the new aluminum engine block construction, we benefited from the reliability and longevity of a conventional cast iron construction.
However, the M52 has been around for decades now. A pre-update version of the engine is nearing 30 years and is bound to have hundreds of thousands of miles on it. Understandably, this is going to result in some mechanical problems.
BMW M52 Engine — Pre-Purchase Inspection and Common Problems
The BMW M52 engine is a fine example of the tremendous inline-six engines that BMW used to design and produce. It only brought some minor improvements over its predecessor, the M50 engine, but it still had a lot to offer with regard to performance and reliability.
While the solid engine block itself has likely stood the test of time, the same can’t be said about the supporting systems like the then-newly introduced double-VANOS technology or the cooling system.
These are some of the most commonly reported issues on decently-maintained but high-mileage examples of the M52 engine:
Water Pump Failure
The M52-powered cars used a water pump that employed a plastic impeller. While the pump is designed to last you around 100,000 miles, the impeller has been known to fail sooner and require replacement. If there is an issue with your water pump or the impeller has failed, it can cause the engine to overheat.
If your impeller has to be replaced, you could consider getting a metal one instead of the OEM plastic component, as the former will last longer. Keep in mind that a cheap aftermarket one may also adversely affect the performance of your engine.
Cooling System Problems
Multiple BMW models at the time were troubled by cooling system issues. The one that supported the M52 engine had several cases of radiator-related failures. The most significant reason behind that was that the radiator casing and most of its components, like the coolant expansion tank, were made of plastic and have stood the test of time quite poorly.
A crack in the radiator housing, coolant tank, or one of the hoses can result in a coolant leak and overheating of the engine.
While inspecting a pre-owned M52-powered car, let the engine run for a while and check to see if the temperature reading settles at a normal level after a few minutes. If it rises abnormally, it’s best to avoid purchasing the car.
Valve Cover and Gasket Oil Leaks
An issue that affected the M52 engine and even the ones that followed was oil leaks from the plastic valve cover. The valve cover is exposed to high temperatures, and this would cause it to deteriorate and crack over time. The rubber valve cover gaskets suffered a similar fate as well. The prolonged exposure to multiple heat cycles causes the gasket to harden and eventually crack, resulting in an oil leak.
Luckily, an oil leak should be relatively easy to spot. If not on the floor under your engine bay, you should be able to see oil around the engine cover or in the spark plug bores. If the oil drips onto the exhaust or other high-temperature components around the engine, a burning smell may permeate the passenger cabin. This is a classic sign of an oil leak under the hood.
Keeping track of oil levels will also help you determine the possibility of a leak. An unexplained, sudden drop in levels very likely means there is one. Replacing a worn-out gasket is inexpensive and not very labor-intensive, but a valve cover will cost you a little more.
VANOS Failure
The BMW M52 engine was one of the first to employ double VANOS or variable valve timing on the intake and exhaust camshaft. Since this was still a nascent technology, it had some issues. While the system itself is less complex than it is in today’s cars, this also means that any problems might require you to have the entire thing replaced.
A faulty VANOS system can result in rough idling and a sudden, noticeable drop in performance, among other issues.
M52 Engine Demands Proper Maintenance
At the end of the day, the M52 engine, just like any other BMW engine, greatly depends on proper maintenance. Here at Bimmers.com, we offer one of the largest catalogs of Genuine BMW, OEM and aftermarket parts for the M52 and any other BMW product out there.
o find what you’re looking for, head over to our store and select your car using our car selection tool. Once you choose your vehicle, any search you do will only return parts that are a guaranteed fit for your Bimmer!
