3.0L engine compared to 2.0L

G

Grizzly9

Member
Hi Guys n Girls.
I have been without a Z4 for 3 years now. I am itching to get a 3.0L next instead of a 2.0L that I had before. My main concern with the 2.0L is that the thermostat housing was prone to cracking as well as the expansion tank because they're made out of feckin plastic.
This means that they may regularly need replacing which helps BMW make a profit. My query is, does anyone know if there is minimal difference between the two engine component parts? I would have thought that the bigger engine would be more sturdy/robust due to the increased bore size and hence operating temperature /pressure.
Any input much appreciated as I'd love to experience the 3.0L .
 
Grizzly9 said:
Hi Guys n Girls.
I have been without a Z4 for 3 years now. I am itching to get a 3.0L next instead of a 2.0L that I had before. My main concern with the 2.0L is that the thermostat housing was prone to cracking as well as the expansion tank because they're made out of feckin plastic.
This means that they may regularly need replacing which helps BMW make a profit. My query is, does anyone know if there is minimal difference between the two engine component parts? I would have thought that the bigger engine would be more sturdy/robust due to the increased bore size and hence operating temperature /pressure.
Any input much appreciated as I'd love to experience the 3.0L .
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Hi, I’m not sure if the 3litre has much of a bigger bore if at all? It’s extra capacity is largely due to 50% more cylinders.
The expansion tank splitting is a common theme on the larger engine as well, they’re not that expensive are they?
I wouldn’t let it put you off the car :thumbsup:
Rob
 
Thanks Rob,
I didn't realise we're talking 6 cyl instead of 4. I don't think the tank and thermostat are that expensive but I remember I had to replace at least one of them within 2 years of renewing.
I'm looking at this one on eBay as it seems a peach of a deal with just the ABS to sort out.
https://www.ebay.co.uk/itm/2003-BMW-Z4-3-0I-2DR-CONVERTIBLE-MANUAL-NON-RUNNER-SPARES-OR-REPAIR/192892755322?_trkparms=aid%3D888007%26algo%3DDISC.MBE%26ao%3D1%26asc%3D20140328180637%26meid%3D049534f770e644ee9ba7a5797249a34c%26pid%3D100009%26rk%3D1%26rkt%3D2%26mehot%3Dpp%26sd%3D333166795238%26itm%3D192892755322&_trksid=p2047675.c100009.m1982
Steve.
 
Maybe someone close by can take you out or let you try the 3.0 SE or the 3.0 SI.

I had the 2.5 and knew as soon as it went that the next Z4 would be the 3.0 SI.

Just do it as you will not regret it. *







* Unless you buy a lemon!
 
IIRC the expansion tanks are the same across the range so nothing in it there. Although they are prone to cracking they're usually good for 8-10 years first. There's a number of threads on here regarding the overall reliability of the N42 2.0 and its more than fair to say its not BMW's finest hour and if you can get either a 2.2, 2.5 or 3.0 then I'd go for that.
 
Go for the 3 litre N52 engine if you want the real deal.

After my S54, it’s hands down the best engine I ever owned. Not to mention it’s BMWs lightest 6 cylinder due to it being made of magnesium. :thumbsup:
 
The abs will be because it's been standing and the likelihood of it having a manual roof is up there with rocking horse do do.
And worrying about an expansion tank because it's happened before is silly, I have a 2.0 and a 3.0 sitting on my drive neither of which have faulty tanks.
 
R60BBA said:
Not to mention it’s BMWs lightest 6 cylinder due to it being made of magnesium. :thumbsup:
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The difference in weight between n52 and m54 is negligible.
The block itself is marginally lighter (its only partly made of magnesium), but the auxiliaries are heavier (electric waterpump, valvetronic etc).
iirc the weight difference is 10kg or so. (BMW even lists the n52 as heavier, but thats shipping weight)

What the n52 and m54 mainly set apart is fuel efficiency imho (apart from the extra 30hp/15Nm)
 
I have a 2.5 n52. It is a ridiculously smooth engine. I’m very impressed with it. Wanted a 3.0 but lots of them weren’t upto standard. The n52 is the engine to go for. It’s very reliable. Thirstier than your 2.0 obviously but it’s a bloody sweet engine
 
GuidoK said:
R60BBA said:
Not to mention it’s BMWs lightest 6 cylinder due to it being made of magnesium. :thumbsup:
Click to expand...

The difference in weight between n52 and m54 is negligible.
The block itself is marginally lighter (its only partly made of magnesium), but the auxiliaries are heavier (electric waterpump, valvetronic etc).
iirc the weight difference is 10kg or so. (BMW even lists the n52 as heavier, but thats shipping weight)

What the n52 and m54 mainly set apart is fuel efficiency imho (apart from the extra 30hp/15Nm)
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What I stated is a fact man, it doesn’t need to be delved in further. :rofl:

Not to mention I am talking not just out of research, but from experience as I have owned both.

Here’s a question for you to consider: did the M54 win as many awards as the N52? :tumbleweed:

OP, get the N52 if you can, it also sounds better and is smoother. :thumbsup:
 
Not dissing the N52 but the M54 3.0 is a good lump as well and I would look at both depending on mileage and price
 
Zoomer said:
Not dissing the N52 but the M54 3.0 is a good lump as well and I would look at both depending on mileage and price
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M54 isn’t a bad motor at all.

Apart from the fact that it likes to drink oil lol.
 
R60BBA said:
Zoomer said:
Not dissing the N52 but the M54 3.0 is a good lump as well and I would look at both depending on mileage and price
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M54 isn’t a bad motor at all.

Apart from the fact that it likes to drink oil lol.
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Mines actually really good on oil but I don’t do too many miles a year.
My dad would have said it a good indication of it getting round the engine if it’s using a bit :poke:

All of the six cylinder cars are good and all can have issues. I wouldn’t swap mine just to get 30bhp more but if I’d seen an si for the right price before I purchased mine I would have gone for it.

The only thing I definitely wanted was a 3.0 litre. Relative had a 2 and got lots of issues so ultimately swopped it for a 3.0 litre.
 
Zoomer said:
All of the six cylinder cars are good and all can have issues. I wouldn’t swap mine just to get 30bhp more but if I’d seen an si for the right price before I purchased mine I would have gone for it.

The only thing I definitely wanted was a 3.0 litre. Relative had a 2 and got lots of issues so ultimately swopped it for a 3.0 litre.
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100% agree.

No point swapping an M54 for an N52, but if in the market looking for a new car, an N52 at the right price is a better deal. :thumbsup:
 
Rather than worry about which engine is better I'd be more concerned about how and why both lower rear suspension arms got so badly damaged they needed replacing at MOT a couple of years ago - rear end shunt maybe?
 
Just find a nice car in budget whether it a n52 or m54 and go from there. The m54 does use lots of oil generally speaking unless the ccv is knackered but you can get issues on the n52 with those as well. In fact in the reliability stakes I think the m54 edges it. It's certainly cheaper to fix when it does go wrong, just compare water pump prices for example. Plus the m54 sounds nicer too but again there isn't alot in it. I also be very careful using industry awards as a measure of how good/reliable an engine is, the N42 won plenty and we all know that can have more issues than the m54 and N52 put together!
A bigger issue for most would be post vs pre face-lift spec in terms of seats, lights, steering wheel and interior grey/black plastics. The series of engine really is a minor factor for many buyers.
 
R60BBA said:
Here’s a question for you to consider: did the M54 win as many awards as the N52? :tumbleweed:
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I don't know.
All I know is that the m54 made Wards best 10 engines 3 years in a row and the n52 2 years in a row.
But winning awards is just someones opinion who connects a prize to it

Btw the potential oil consumption from the m54b30 can be largely solved by swapping the 0w30 or 0w40 oil for 10w40.
For mine that did the trick.
With our mild climate (especially the mild winters) that's no problem at all.
 
If you do go for a 3.0L, the M54 and N52 have different torque characteristics. The N52 produces max torque at 2500rpm vs 3500rpm for the M54, I much preferred the increased grunt of the N52 at low rpm and I imagine this is part of the reason why the mpg is superior. As stated above the M54 sounds marginally better in terms of induction noise.

My only issue with the N52 was the hydraulic lifter tick that occurs if the car does short journeys. It does not cause any problems but is very loud and embarrassing to listen to. Two of my three 3.0si engined cars have had the issue
 
When I'm looking at cars over 10 years old and multiple owners, the choice is dictated by condition, mileage, history and how it drives, not just the engine spec'. The best car I could find for my budget 9 years ago was a 2.5 M54 with low miles, perfect history and drove very nicely. It's never caused a problem, when my indi serviced it he said it's one of the nicest he's seen recently, when I MOT'd it the other day the guys were 'bigging up' the condition. It's done under 50k miles, been meticulously maintained not seen rain for years and is sorned over winter. My point is, despite all this it wouldn't fetch as much as an average 3.0 that would need a lot spent on it to come close, so beautiful bargains can be had slightly lower down the engine food chain. Price wise, the 2.5SI N52 is the current bargain sweet spot IMHO.
 
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