Engine Rebuild

#41

Wow, I’m about a week late replying to the original post, which now seems a totally different topic. Here’s my $.02 on the question of whether an average guy can rebuild an E30 engine and what to expect in the way of cost. I can’t address the horsepower gain. Take this for what it’s worth as this is my first post here.

I bought a mileage unknown '87 325is back in the summer, knowing it was leaking oil from possibly every seal and not running smooth, but thinking it was probably OK. I figured for $800 I couldn’t go too wrong. When I took it to the local BMW mechanic, I was told the head was “bad”, “toast”, etc. and that it would cost over $1800 just to rebuild the head. Not what I wanted to hear for what was intended to be relatively cheap track car (I doubt I’ll ever get to the point of really racing it, but want to do several HPDEs a year and figured I’d build to Spec E30 standards).

After the mechanic declined to buy the car for parts, I swallowed hard and decided to move forward with the project and rebuild the engine myself. I bought a remanufactured head (much cheaper than getting it done locally), got an engine hoist and stand off Craigslist and began the process of pulling the engine. I had a Bentley manual and whatever DIY articles I could find on the internet. I took notes in the manual, labeled and numbered every electrical and hose connection with different colored electrical tape and took digital photos every step of the way to hopefully allow me to get it all back together.

The bottom end of the engine was in remarkably good shape, as I hear they usually are. The cross hatching on the cylinders looked very good as did the crank bearings. Even so, I decided to go ahead and pull the crank and pistons and get them and the block checked out by a machine shop before buying any rebuild parts, not wanting to get deeper in the hole.

Everything checked out fine and I’m now in the process of putting it back together. The machine shop charged about $250 to get the cylinders honed, the pistons and some other parts cleaned, the crank polished, and new wrist pin bushings put in the connecting rods. The parts to rebuild the bottom end of the engine cost another $400, including new crank and rod bushings, connecting rod bolts, wrist pin busihgs, piston rings and gasket set. So for about $650 you can get the bottom end machine work and parts to rebuild it. This doesn’t include head gasket set, head bolts, etc for the top end.

I’m now in the middle of putting the engine back together and have the pistons and crank installed. Should get the oil pump and pan on this weekend and then the head, mainifolds, etc.

I’ve enjoyed the process, learned alot about my car and hope to have a running Spec E30 by Christmas. (I’m doing the suspension while the engine is out.)

#42

That’s awesome. You are the man. Where in the SE are you?

#43

High Point, NC

#44

I just got done doing my motor and while I have rebuilt motors before this was the first time for one with fuel injection / computer. Suggest taking your time, use painters tape and sharpie and label everything before tearing it apart, get a disposable camera or two and keep them nearby and take pictures of stuff. Use baggies to keep your nuts and bolts sorted and labeled. Take your time, clean the parts (especially threads) and replace wear items as you go. You’re in Spec E30 so you’re already a smart person :wink: and have people to call on for advice, so have a good time with it. If your experience was like mine you’ll be very happy, satisfied and proud when you’re done and you’ll have a much better understanding of how it all works and be less intimidated next time something needs to be worked on.

#45

Here is the conclusion on my first effort to rebuild an M20 engine (really any engine).

As mentioned above, I decided to try to rebuild this engine after being told the head was shot on my proposed cheapie track car. I bought a rebuilt head for less than 1/4 the price quoted to rebuild the existing head, so I didn’t get into rebuilding the head. I did pull the engine, tear it completely down, and had the internals checked by a machine shop before buying the parts to do the rebuild.

Once the internals checked out, I started the rebuild and installed new bearings, piston rings, engine and trans seals, oil pump, water pump, windage tray, timing belt, etc. and did the Spec E30 suspension while the engine was out of the car. I did the engine reassembly myself with the help of a friend who has a little more experience with this kind of work.

We fired the engine on Jan. 15. After turning it over some with the coil wire off to get the oil pressure up, we connected the coil wire and the engine fired immediately. Didn’t even need the fire extinguisher we had handy in case of the worst.

After resolving a brake problem, I’ve been driving it around the past couple of days to break in the motor. So far I only have about 70 miles on it, but it seems to be running pretty well. I’m keeping my fingers crossed that it stays that way.

This is definitely a project that someone with minimal experience can accomplish. I agree with the prior post. The key is attention to the details. Take your time and clearly label every connection so you can get it all back together. That helped tremendously, as did the hundred plus digital photos I took, labeled and saved on my laptop.

Overall, it was a fun project. Now I’m looking forward to having some fun with the car.

#46

thanks for posting this - what was the most complex mechanical project you had tackled prior to the engine?
cheers,
bruce

#47

Congrats on the rebuild. If you don’t mind my asking, how much did it cost you in total?

After I started this thread, I chose the cheap way out and wanted to hope for the best. I’m doing a reseal only refresh (more or less) all for around $400. In addition to every seal and gasket (minus head gasket, left that on the block), I’m doing new rocker arms and a crank scraper. New water pump and timing belt as long as I’m in there. Still trying to keep this cheap so I’m doing as little as I HOPE is necessary. She was a real leaker…

Progress thus far is 95% torn down and everything has been Simple Greened. Banging out the rocker arm shafts with a wooden dowel and the head still on the block is a PITA, but it’s coming. The only hurdle left is the front crank shaft seal as I’m not sure how to get at it without having the engine roll over on me.

The decision for just a reseal was easy when I got the compression and leak down numbers from the guy who sold me the engine (~160 psi, <5% leak down across the board). Digging further revealed the head had been off relatively recently as the rockers were all etched with their proper location and the head casting has a 2001 date on it.

I’ve found this job to be a lot easier than I expected. A few bumps along the way, but overall pretty straight forward.

#48

I worked on a local stock car team for a few years, but that was 25 years ago when I was in college. We didn’t do any internal engine work in-house. As close as I got to that kind of work was adjusting the valves on the straight 6 Chevy engines we ran. We rarely had to pull an engine, and when we did, it was in a tube frame car, so there wasn’t much extraneous stuff to deal with, such as wiring harness, injectors, etc.

#49

I would liked to have done my car on the cheap. I was hoping to just replace seals, belts and hoses and have a servicable motor, but the bad cylinder head started me down a slippery slope to more expense. Since I was pulling the head anyway, I decided to go ahead and pull the whole motor so I could get at the seals more easily. Then, since I already had the motor out, I decided it would be silly not to go ahead and replace the bearings and rings since the odometer wasn’t working and I had no idea how many miles were on the engine (although the crank bearings and cylinder walls looked pretty good).

The rebuilt head cost me $450. The machine shop work to hone the cylinders, polish the crank, clean the pistons, install the new wrist pin bushings, resurface the flywheel and media blast the intake was about $270.

I spent about $1000 on new engine parts, including all new bearings, gaskets, piston rings, head and crank bolts, engine and trans seals, oil pump, windage tray, hoses, etc. That doesn’t include the ignition parts, thermostat, belts and other miscellaneous stuff. I also sent my injectors out to get them rehabbed. A couple weren’t working at all. That cost another $100. I also put in a new clutch kit (why not?).

I put on a full Spec E30 suspension while the engine was out, including Ireland sways and camber plates and SS brake lines.

My “cheap” track car now is not, and I don’t yet have seats, harnesses or a cage. But, I figure I’ll come out about the same financially as my buddy did on his car because I’ve been able to do all the work myself, and I have a fully rebuilt engine instead of one with 200K miles on it.

#50

2-2 part questions…

Did you do a crank scraper? How was the install?

Did you do rocker arms? Do you also need to do rocker arm shafts?

#51

I put in an Ireland Engineering crank scraper. Install was not too bad, although when I tightened down the oil pan, the crank then hit the scraper so I had to take off the pan and make a minor adjustment. I just bent the scraper tray away from the crank in the spot where it was hitting.

I bought a rebuilt head, so I didn’t do anything to it other than adjust the valves.

#52

Randy87is wrote:

[quote]
My “cheap” track car now is not[/quote]

“cheap track car”. That was a good one :laugh: I thought mine was ready to go racing, and still ended up spending another $2500 last month on stuff needed to complete the car and me.

DB