N52 2.5 preventative maintenance

D

DJMC

Member
 Evesham
Putting this into Google AI I get the following: https://www.google.com/search?q=n52...8keUg3mw&csuir=1&mtid=eI5cavnUJMaohbIP4OrKsQY

Assuming this is roughly correct, if I buy a 23i with, say, 100k miles and want to take every precaution for future engine life what would be the main "critical' things to have sorted, if not done already (I'd always be sceptical they have been) and what are the likely costs at an indy or main dealer?

With these cars now dropping under the £10k mark the cost of maintenance (and road tax/insurance) is a concern.

Also, can anyone recommend a good indy near-ish to Worcester?

Thanks all.
 
Hello!

You can’t go wrong with an N52. Even at 100k miles, they’re very reliable engines.

That being said, you do have items that I’d consider consumables. VANOS solenoids like to play up for fun at any mileage and I’ve had them start failing at under 2 years old.

Water pumps are another that fail with minimal warning. People say don’t go beyond 100k without changing. Mine is on 142k with no issues or logged codes. I will do preventative maintenance in the autumn though.

You get your usual valve cover leaks and oil pan leaks but they’re not exactly bad. Valve cover/gasket leaks will cause running issues, so worth addressing.

People seem to go on about DISA valves but my E89 is on original units at and they’re going strong (tested with ISTA and observed fully operational).

Eccentric shaft sensors can and do go bad. If you’ve got evidence of oil in the connector then it is worth changing.

The only big ticket item that plagues all E89s at some point is the roof. Some say failure is a matter of “when” and not “if”. Wiring harnesses tend to break at fulcrum points and sensors do fail. The control relays can also go bad and cause the motor to over-run. Relays can be swapped out with ease and the Zed Shed do a preventative maintenance package for the roof harness and sensors.

Overall, they’re a very solid car with problems that are well understood. With the N52, you lower your potential exposure to engine issues.
 
The AI link makes the N52 sound like it'll explode any minute!

Specifically...

Oil Filter Housing Gasket (OFHG): When this gasket fails, it leaks oil directly onto the serpentine belt. The oil degrades the rubber, causing the belt to slip off and get sucked through the front main crank seal into the engine, shredding the oil pickup tube and destroying the engine.

Crankshaft Seal Guard: Install an aftermarket aluminum plate behind the crankshaft pulley. This cheap insurance policy physically blocks a failing accessory belt from entering the front main seal.

"Mickey Mouse" Coolant Flange: The factory plastic fitting on the cylinder head degrades and snaps without warning, causing instant coolant loss. Proactively swap it for an upgraded aluminum flange.

Electric Water Pump & Thermostat: Unlike mechanical pumps, the N52's electric pump fails completely without warning, typically between 80,000 and 100,000 miles. Always replace the water pump and thermostat together to save on identical labour steps.

When looking into an N52 engine bay, what visible signs are there that prevetative maintenace has been done, if any?

I'm building a check list. Please correct any errors/omissions:

1/ Check under and behind the oil filter for any leaks onto the block and down the front onto belt /s below.
2/ Look for a metal disc behind the crankshaft pulley. Is it a common upgrade?
3/ I now know where the coolant flange is - original black plastic, replacement silver metal.
4/ The water pump at the bottom front of the N52 seems inaccessible. Any indications of imminent failure or just replace it anyway if not already done at 100k? I'm guessing not... replace if not done already.
5/ Look for any other leaks from the front of the block.
6/ Valve cover leaks.
7/ Check under car for leaks.

Is that a fair list for engine checks to do when looking at a car to buy?

Roof-wise, I'm aware of required maintenance but I guess wires breaking is impossible to predict.

Reminds me of starting my E46 330ci cab decades ago to drive to dover and down to the south of France. "Boot open" warning on the dash stopped me putting the roof down. Drove all the way roof up (swearing). When I arrived I contacted BMW Emergency Services (they never came) and then found the broken wire by the boot lid hinge. Twisted the ends together... Solved it myself!
 
I think some of these issues are somewhat exaggerated, certainly based on my experience of owning 4 cars with N52s.

1/ I bought my 330i with a slight leak from the oil filter housing gasket and didn't get it replaced for another 8,000 miles.
2/ I've never looked, but never had an issue.
3/ Never had a problem
4/ The water pump on my first E86 died at 60K miles. The pump on my 325i died at 135K, but it may not have been the original. They both overheated in less than a mile. To avoid that inconvenience people often renew them as a preventative measure. I'm just playing water pump roulette with my 330i at 130K, although it may have had one before I bought it.
5/ Never noticed any leaks.
6/ My 330i had a new valve cover gasket fitted at 105K miles a couple of months before I bought it - the other 3 didn't leak.
7/ You'd do that for any car.

My 330i had a similar issue to your 330ci - a wire inside the boot-lid loom split.

The N52 is generally regarded as the least troublesome engine fitted to the E89!
 
Loved my 2003 330ci, but after 9 years and 103k my wife thought it was "dangerous" and it went, replaced by an awful Merc (sorry to swear).
But back then I was too ignorant to think anything might go wrong with the 330. I did have one issue with the gear lever not returning to centre. Gearbox out job and a grand at an indy worted that.
Just counting up... I've had (tongue twister coming up...) five four cylinder and six six cylinder BMWs. Seventh six on its way maybe, twelve total?
 
You're some way ahead of me then.

My first two were 4 cylinder turbo diesels (more swearing) but since then I've had six straight sixes - all N/A petrol. :D
 
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