Should I transplant an M50/M52

Post Sun Nov 21, 2010 9:09 pm

At some point in the new year I want to replace the M20B20 in my touring. It's got 200000 miles and leaks oil like a sieve.

The question is, should I simply dump an M20B25 into it or go for something more modern?

As far as I can see from the posts on this board there's not a great ecomony gain to be made out of running an M50/M52, which surprises me really, especially on the VANOS versions. I'm not after huge power, so although I'd like to get modern it's a little hard to understand why I would go to the extra effort.

Someone convince me.

Reasons for sticking with M20:
1) It's my first engine swap, although I'm pretty capable.
2) I would imagine insurance is non-trivial for the non-standard swap.

Reasons for going with M50/M52:
1) Bringing the engine up to date has got to make the car cleaner, smoother, more economical... right?

Post Sun Nov 21, 2010 9:13 pm

m50 because i had a e36 325i with 109k and history and the m50 was sweeeeet bit more economical than the m20 that i have now and it was sooooo smooth compared to the e30 but that is the modern touch would a e30 really be a true e30 with a m50?

Post Mon Nov 22, 2010 12:54 pm

Can I ask a different question, how much trouble is it getting insurance for a M50 2.5 converted E30?

I've got about 8 years no claims (since I moved back to the UK) and a clean license, but beyond this are there many insurers who simply won't touch it?

Thanks

Post Mon Nov 22, 2010 2:23 pm

I was getting good 30+mpg with my M50 non vanos in my E30 touring.

The driving difference between the M20 and M50 is massive, the M50 feels so refined and works so well in the E30 all most like it should have been there to start with.

Insurance is no problem, people like Adrian Flux, Sky insurance (advertise on dw) and various other speacilists all insure these no problems

If your capable an M50 swap will be a doddle, if you have all the bits its no more harder then a few bolts!

I have a full drop in conversion here for sale that if your capable could fit easy in a day

http://www.e30zone.net/modules.php?name ... highlight=

Post Mon Nov 22, 2010 2:35 pm

Thanks Phil, I don't want to drag this forum into a factional fight between engine evangelists, but I guess if it's economy I'm after I should probably go M52 (although I don't really need the 2.8 ).

VANOS is a must I would have thought, at least single VANOS.

Post Mon Nov 22, 2010 3:56 pm

No problem,

just my 2pence, having driven all types of the M5* iv never noticed a real difference in the mpg, Iv always prefered the non vanos engines due to the simplicty and easy running of them.

However I would think it better to go on the majority vote!!

Post Mon Nov 22, 2010 4:12 pm

Agreed that vanos engines have slightly more to go wrong, but given an engine of equal capacity the vanos surely must be more efficient through the range. Is this really not your experience?

No particular reason why I would go M52 rather than M50 vanos though.
2.5 is the same stroke and bore on both engines, what are the differences between the two? Head design? Component material?

I know that M52 is an alloy block, apart from the weight what's the advantage? Thermodynamic efficiency?

EDIT: answer my own question:
http://www.e30zone.net/modules.php?name ... uble+vanos

Post Mon Nov 22, 2010 4:44 pm

From Wikipedia:

VANOS Performance
Single and Double VANOS systems due to age and mileage are commonly seeing performance issues as well as complete failure of the VANOS piston seals. Another common effect is a rattling sound coming from the upper valve train assembly. The original seal material was found to be inferior for the application and tends to break down within 75k - 100k miles. VANOS Seal & Rattle kits are available to address these shortcomings. VANOS repair does require special tools that can be rented or purchased from a variety of vendors.

Has anyone on here actually seen these issues and are they hard to resolve? As this is the first I've heard of any problems.

Post Mon Nov 22, 2010 5:31 pm

gudgeon wrote:From Wikipedia:

VANOS Performance
Single and Double VANOS systems due to age and mileage are commonly seeing performance issues as well as complete failure of the VANOS piston seals. Another common effect is a rattling sound coming from the upper valve train assembly. The original seal material was found to be inferior for the application and tends to break down within 75k - 100k miles. VANOS Seal & Rattle kits are available to address these shortcomings. VANOS repair does require special tools that can be rented or purchased from a variety of vendors.

Has anyone on here actually seen these issues and are they hard to resolve? As this is the first I've heard of any problems.

Danthe sells the replacement vanos seals.
As said does require special tool to do the job so not very DIY friendly.

Post Mon Nov 22, 2010 5:59 pm

Special tool is only needed if you are timing up from scratch or if your not very competent.
You can keep the timing spot on with paint marks just to change the seal, you need to be aware of what is going to or might turn when you take it apart.

You probably wont even notice the effects of failed seals as its a very gradual process, but the longer you leave it the more damage it will do to the vanos unit, when the seals have shrunk/hardened the piston is contacting the bore (rattle noise) and making grooves, scratches etc.

Couple of vids (twin vanos in vid but its the same issue with single) -

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