Author Topic: E30 M42 rebuild - expectations and realisms (Read 7990 times)

91318isguy · « **on:** July 03, 2009, 03:34:39 PM »

Hi everyone,

Anyone here rebuilt their M42 for the E30? I know of the one moded, which I would gladly take your advice. I'm looking at how much (best case scenarios, I already know the worst cases) I will at LEAST be looking at spending getting 1 OEM quality M42 out of 2 M42's at my place.

I already have ideas about what I will need to get new, but if anyone could provide me a list of parts I will HAVE to get new(I know there will probably be quite a bit that is obvious and I probably know already, but I won't be offended. The more detail I have now, the more likely this will end up coming out well in the end).

Thanks,

91318isguy

B318M42W · « **Reply #1 on:** July 03, 2009, 05:06:57 PM »

perfect time for a stroker...

DesktopDave · « **Reply #2 on:** July 03, 2009, 05:45:41 PM »

New gaskets, seals, chain case parts and tensioner. I'd probably do the valve seals & have the guides checked by a decent performance shop. I'd be tempted to balance the crank & pistons too. I'd definitely clean out the ports a little, but not to hog them out...just a cleanup.

I'd also totally gut every piece of rubber in the engine. New coolant, fuel & vacuum lines. Maybe even an engine mount or two.

+1 on the stroker, it's the best time to think about that. It's also a good time to think about new seals on the tranny, guibo, mounts, etc...and new relays, O2, fuel pump.

You'd have a great new engine, built to your specs, that'll run another easy 100,000 miles. It'll cost you $3-4k to do it right. More with a stroker. Try to find a BMW with less than 100,000 miles and you'll know why it's worth it.

derek9702 · « **Reply #3 on:** July 04, 2009, 11:00:50 AM »

I just got done doing a stock rebuild. I had everything checked out/rebuilt (crank, rods, head, etc.) at the machine shop. I also replaced all timing guides/components, gaskets, hoses, etc.

It ended up costing me around 3000-3500. That also includes replacing a piston and 4 valves due to my timing guide exploding:D

91318isguy · « **Reply #4 on:** July 06, 2009, 07:52:59 AM »

Quote from: derek9702;74790

I just got done doing a stock rebuild. I had everything checked out/rebuilt (crank, rods, head, etc.) at the machine shop. I also replaced all timing guides/components, gaskets, hoses, etc.

It ended up costing me around 3000-3500. That also includes replacing a piston and 4 valves due to my timing guide exploding:D

Derek,

Why so much. Did you replace every jot and tittle that made up the engine or just the required components. I'm hoping to get out under 2k. Did you find that you had to go to BMW for most of your parts or did you get them from other sources?

derek9702 · « **Reply #5 on:** July 06, 2009, 08:14:24 AM »

No...nothing special. I did have Metric Mechanic modify my main caps to accept the full thrust bearings. The stock M42 only has half a thrust bearing.

Other than that, I replaced the oil pump assembly and the complete timing system (timing case included). I figured I only wanted to do it once.

For my parts, I used pelicanparts and Tischer BMW.

91318isguy · « **Reply #6 on:** July 06, 2009, 11:57:24 AM »

was the cost so much because of having to replace a piston and valves? So the moding probably is what cost you. I'm really not looking for someone to lie to me, it's just I have a hard time reasoning why it would cost 3k just to rebuild. I know it'll probably be around 1k for the head gasket set (120), timing chain and components (90 for the chain, about 250 for the other parts), water pump (75 from Bav Auto for metal impellar version), oil pump (250 from BMW), oil pan (upper and lower) gaskets. Now the new vacuum lines I would see costing a bit (I would say close to $200). New main bearing should only run me about 80 (Bav Auto).

I'm going to be pulling the oldest motor (red chassis) first to clear the way for the other car to be put in the basement. Anyone here ever manufacture the cam positioning tool or know of a good substitute?

derek9702 · « **Reply #7 on:** July 06, 2009, 02:35:46 PM »

Take the info for what it is....i have no reason to blow smoke....it is what it cost me to properly rebuild it. I'm sure I could have just done it for less, new bearings/gaskets/timing components and been done with it, but I only wanted to do it once.

This was/is a stock motor. The piston and valves did add some to the total, but this also included the head being rebuilt, the crankshaft checked out and mangnafluxed, rods rebuilt, engine balance, and the block checked out and honed. You will also have to replace the head bolts and main cap bolts, as these are TTY bolts and can only be used once.