I need a crash course in E34/525i/M50

I went to look at a 95 525i tonight that was advertised as "body and interior in great condition, engine problem, runs but needs a head gasket". The body and interior were as good as advertised, if not better. The engine however, I'm fairly sure, needs more than just a head gasket.

I took compression readings on all the cyls, and they were all over the place, most alarmingly cyl #3 showed no compression at all. There was no sign of oil and coolant mixing, but definitely compression leaking to the cooling system. I didn't drive it to test the trans, because I'm not sure if I would be damaging the engine beyond repair, but if I proceed with this adventure / folley, I will at least drive it around the block before handing over money.

My best guess is that it has a cracked head, and a few minutes of google searching suggests that thats a known/common problem.

SWMBO really likes these cars, so my question is, should I run away screaming, or take the chance? It has just under 200k miles, (but aside from the engine looks and feels like half that), documented dealer service history for most of its life, 2 owners (relatives, in a family with multiple BMWs), and I could probably get it for well under a grand.

I would like to hear from someone who's actually done one. Could it be done at home in the driveway by someone with reasonably good skills? If I went through withh it, I would pick up a remanufactured head before I even start.

I would take the gamble. A head swap isn't that bad. Just make sure to get the timing correct and you are set. Given you can get the car for a steal, I would do it.

In reply to Cuda: Have you done an m50 with vanos swap? Thats the information I'm looking for.

Swapping a dohc head is swapping a dohc head.

To be on thethe safe side, I would make sure there's room in the budget for the engine to need more than just a reman head.

You may find it easier (and maybe even cheaper) to find a low mileage 325/525i engine to put in. M3 engine's fit. Just saying.

njansenv wrote: You may find it easier (and maybe even cheaper) to find a low mileage 325/525i engine to put in. M3 engine's fit. Just saying.

This is what I was going to say. Gaskets/head bolts/reman head, possibly chain guides and tensioners will all = more than a known good engine.

Vines Automotive in AL will even sell you a good motor with a warranty for a fair price.

You also have to take into account the transmission. Given the price, you might have a good project that's worth the work. I had 2 E34's in the past. The 525i put a dent in my wallet when the transmission went kaput!

The head will need to go to a machine shop - it usually runs about $450 for seats, seals and decking. Gasket kit is about $260 with bolts and all. You need special tools to time the VANOS (not really but it makes it so much easier...), eBay, $110.

Figure the while-you-are-in-there costs for water pump and hoses, etc... $1200 is where you will end up for the first one.

You can get a decent M50 for $750 to $1000. You can upgrade to an S50 for the cost of the motor and a chip for around $2-2.5k and you can go to an S52 for the same or a little more.

buy it and swap in a known good engine... and GPS has it right... and S52 in that would be a treat

After doing some research it looks like a complete engine swap is a viable option.

So what would make the s50 or s52 engine better than an m50? What would be needed to complete the swap? This isn't a hot rod project, just a daily driver, but if the swap resulted in a fuel milage improvement, or some other tangible benefit I might be up to trying it. What bimmers came with those engines?

Edit: it looks like "s" engines are from the M3s. Wouldn't the m52 be nearly the same engine with out the "M"car parts mark up?

Both require an oil pan swap from your current M50 and futzing with the pickup tube. No big deal.

S50 would require nothing else.

S52, swap manifold and a few sensors from the M50 to the S52.

S50/S52 both make much more power/tq than the M50. S50 is 3.0, S52 is 3.2.

My S52 in my E30 with a tune, Bimmerworld equal length headers, 3.5 MAF made 235whp with a weak headgasket.

An M52 with an M50 intake manifold would be within 15-20hp of an S50 for a whole lot less money. The M52 is a lot torquier down low than an M50, and with the M50 manifold it's at least as good as the M50 in the top end.

HappyAndy wrote: So what would make the s50 or s52 engine better than an m50? What would be needed to complete the swap? This isn't a hot rod project, just a daily driver, but if the swap resulted in a fuel milage improvement, or some other tangible benefit I might be up to trying it. What bimmers came with those engines? Edit: it looks like "s" engines are from the M3s. Wouldn't the m52 be nearly the same engine with out the "M"car parts mark up?

The M50TU, M52, S50US, and S52US are pretty much identical. The S engines use the same iron block and are just bored out a bit. The S cams are a little hotter, and the crankshaft has a bit more stroke. The S52 crankshaft is the same as the M54B30 crank, you can swap either of those into a M50TU or M52 to make those a 3.0L engine. The M20 through M54 all use the same size bore.The M52TU and M54 are aluminum blocks with dual VANOS used in the E46. There was also a aluminum block single VANOS M52B28 only used in the Z3. The main improvement over the years was mostly low end torque not top end power.

The easiest route is to use a single VANOS engine using your car's existing OBD1 management. There are various ways you can piece together a single-VANOS OBD1 3.0L that would be at least equivalent to a S50US using only M5x parts.

A great budget option is an M52 (found for ~500 in these parts), S52 cams (~2-300), use your stock sensors/oil pan, and chip your ECU to match (<$400). 210ish whp. I'm assuming the car is a manual car, if not...it would be a great time to fix that.

I bought it! for about half the asking price too. Since its auto trans I'm going to stick with the 2.5 engine, I found one with 100k miles for $550. I'll be going to check it out next week. If that one doesn't work out, there are some other prospects in the area too.

DAMNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN.

Did you at least give him a kiss?

I'm still looking for an engine, are the 325i m50 engines directly interchangable?

The oil pan and mounts are different. Pretty easy to check on bmwfans.info.

Also the front exhaust manifold is different, but the rear one is the same. Everything else seems to be shared.

they don't have any GM LS-based V8's where you live?

I have been lusting after a 5 series for quite a while now...nice score!

It's pretty fun to drive for a "big" car. I went to some track days in my 530i and had a blast. It surprised a lot of people.