Advice & Opinions Needed: Blown HG - 98 M3/4/5 88k miles

Hi Guys,

I recently discovered I've had a HG failure. Very disappointing as my car only has 88k, hasn't been tracked and has been well maintained. I'm concerned the head might be cracked as well. Whats interesting is I believe the car never overheated. Spirited drives have lasted no longer than 10 minutes on back roads, and I've kept a close eye on temp on the highway.

Right now, the car is going in storage for the winter anyway as its a secondary car. The car also needs a throw out bearing, so I will need to replace the clutch as well when I fix the car. I will be doing the work myself. I'm looking for opinions on where to go from here. I have a couple of things in mind.

Option 1: Take off/inspect head. IF not cracked, have it decked. Replace HG, Reinstall with ARP hardware.

Option 2: Take off/inspect head. If not cracked have it decked. Replace cams with something aftermarket. Reinstall with ARP hardware. Install LW flywheel with clutch replacement.

Option 3: Take off/inspect head. If not cracked have it decked. Reinstall with ARP and a head spacer. Complete with a supercharger build. (I'm not sure if headspacers are available or recommended)

Option 4: Head is cracked. Purchase a rebuilt head, reassemble with ARP hardware.

Option 5: Head is cracked. Purchase/Install Euro S52B32. Repair NA motor in spare time, sell when complete.

This is my first experience with a BMW. I've owned the car for 3k miles, and while its the most fun car I've ever owned, its also been the most trouble. I currently have another money pit project, a mk2 GTI VR6T.

What I'm looking for, is to hear from people who have been in my shoes, gone with a set of cams, owned a supercharged car or a Euro swapped car, and the costs associated.

Thoughts and opinions greatly appreciated.

Thank you in Advance.

You're looking at serious money for a euro S52B32, so I'd probably throw that idea out right away. As far as whether or not to install cams and/or a supercharger, it depends on what you want to do with the car.

If it were my car, I'd just repair it to stock condition, but use ARP head studs.

My thought is I can recoup some of the costs by selling my motor/trans. I will definitely by using ARP hardware, as thats personally why I think the HG failed; probably on a downshift I didn't rev match well.

Whole lot going on here!

1) There was no Euro S52, only the S50B30 and S50B32. Using this engine will cause a bunch of regulation headaches, and isn't worth the hassle anymore.

2) IMO, you're better off implanting an S54.

3) If you're going to salvage THIS engine, I'd recommend taking it out to work on it.

4) Cams and S/C will change this car from great, to beast. Just use a thicker Head Gasket to lower the compression a bit.


What is your budget for this job? At the very least it sounds like you'll need a new HG. If you can do it all on your own and you take all winter it will be pretty inexpensive. Buying a new engine and doing cams/SC is going to bump this up towards $10k.

Sounds like fun, though!

Update: This guy is breaking (parting out for us yanks) his 97 M3.

Maybe he'll set you up with his engine. Make sure you get it 'long block' style.


Ugh, now that it's on my mind I can't stop looking into it. Here's another in the UK.

no such thing as a euro s52b32, its an s50b32

if I were you, stock hg and arp hardware, along with a supercharger build and never worry about it again

Originally Posted by petriej

Using this engine will cause a bunch of regulation headaches, and isn't worth the hassle anymore.

I agree that the S54 makes more sense, but just for reference, there are no emissions regulations to comply with in the OP's state of Michigan.