To rebuild now or later

[AJ2002]

Hello All, 

 

I am new to the forum as a poster.  But, I have been in the peanut gallery for a while!  Need help with a decision.  I recently pulled my first 2002 - it's a 76 - out of storage after almost a year.  I bought it and socked it away for a while (to avoid the wife) and until I finished building my garage.  Well it's out now and I am starting to work on it.  It's in fair condition.  Quite a bit over 100K miles.  Don't know exactly as the odometer stopped working.  Has not been driven much in the last several years.  I have probably driven it less than 20 miles.  I know the engine is a bit tired.  I did a compression test (warmed up) and got 145-130-140-140.  That 2nd cylinder has a pretty oily plug.  Not the worst numbers, but definitely not the best.  I plan to do a compression leak test.  Had a lot of popping on deceleration on my last spirited drive while working through the Seafoam.  Tested the exhaust today with air pressure and soapy water.  Found small leaks around 2-3 exhaust gaskets, at the down pipe flange, and not to mention a gaping hole at the flange before the resonator.  More interestingly, I had bubbles coming out in the middle of the exhaust manifold on the outside - obviously there's a crack.  I am debating should I just put a tired little engine out of it's misery and just pull and rebuild the thing?  I eventually want to build a performance M10.  Overall, I want to restore the car and keep it drive-able most of the time.  Thoughts? 

Edited December 11, 2018 by AJ2002
add more info

[ray_]

I don't think those numbers are too bad.

 

What  was the history before you bought it?

 

You might drive it around for a thousand miles or so, without being gentle, and check the compression again.

 

After getting the exhaust squared away.

 

Cheers,

[dlacey]

Dont pull it apart, these engines go on & on. Concentrate on Spark/Fuelling and exhaust - i am sure you'll find it will respond...

[AJ2002]

Thanks for the responses.

 

Ray - I know of a couple of owners. 

 

The guy I bought it from had it parked in his garage for a few years with very little driving.  The car spent a lot of it's life in New Mexico.  Not much rust comparatively.  Only about 4-5 spots that will required metal removal and patching - surface rust elsewhere.  In general needs TLC through out.  I tend to like the mechanical to be at least 7 out 10 - in my mind anyway.   I don't know what to expect as a 7 out of 10 M10 drivetrain.  As non-mechanical go, I like to stop the slide and improve over time.  I have an E39 530 coupe and 540 touring.  That has been my strategy.  Will see how it works out.    

 

dlacy - I do hope it responds over time.  At first it would not idle well.  Some timing adjustments, valve setting, new plugs and wires, and fiddling with the carb has definitely helped.  Maybe I should fiddle a bit more. 

[Mike Self]

2 hours ago, dlacey said:

Don't pull it apart, these engines go on & on.

+1.  My '69 has 226k miles on the original engine--drove it around all summer, including a trip to Pittsburgh from Dayton--ran just fine with only a semi-moderate oil thirst.  Your compression figures aren't out of line for a 100k mile engine.  Are you using 20W-50 oil?  M10s seem to like it for other than very cold climates.  And with all the sitting your car has done, some driving may loosen up some gummed-up rings or sticky valves and actually improve those compression figures.  For the oily plug in #2 cylinder, go one heat range hotter if it tends to foul (it's #4 on my 69's engine).  

 

For now, just drive and enjoy--enough to get hooked on it so when the engine really does need a rebuild, you'll be gung-ho to do it.

 

cheers, and welcome to active 02 ownership

 

mike

[Henning]

7 hours ago, AJ2002 said:

Thoughts? 

 

Yes. Mine is:

Without pictures of your car we can't give you any satisfying or qualified reply. ?

 

hen

 

Edited December 11, 2018 by Henning

[AJ2002]

Thanks, Mike.  I see you take yours on the interstate.  Do you have a 5 sp swap? Mine is wining pretty good at 55 mph.  But I suppose that bad exhaust has a lot to do with the noise and vibration level.  

 

Honestly, I don't know what oil is in there now.  I will try the 20-50.  Better sealing power I suppose.  

[02Pilot]

Fix the basics, make sure your fluids are good, and then go drive the thing. Hard. Get it hot, hit the redline, lots of throttle, for a good hour or so. Check everything over and do it again. Burn the crap out and see where you really are. As Mike said, you may well see improvements. Lightly used and babied M10s are rarely at their best.

[Stevenc22]

Yeah I restored and fixed everything except my engine and drove the car for for 4 years before I pulled the trigger on my build motor.

 

Get the rest of the car in good condition before messing with the motor.

[Conserv]

On 12/11/2018 at 4:22 AM, AJ2002 said:

Thanks, Mike.  I see you take yours on the interstate.  Do you have a 5 sp swap? Mine is wining pretty good at 55 mph.  But I suppose that bad exhaust has a lot to do with the noise and vibration level.  

 

Honestly, I don't know what oil is in there now.  I will try the 20-50.  Better sealing power I suppose.  

 

AJ,

 

The engines were designed to rev. And even though overdrive transmissions had already been around for decades, BMW’s engineers never made an overdrive transmission available from the factory on an ‘02. Why? because everything that happens on an ‘02’s M10 happens above 3,500 rpms.

 

Yes, if your daily driver is turning 2,000 rpms at 70 mph, an occasional drive in an ‘02 — 4,000 rpms at 70 with my ‘76’s original 3.90 differential — may seem a bit...busy!  But deal with your exhaust leaks so you can actually drive the car now! The more you drive it, the less you notice the...busy-ness!

 

As stated above, make certain you have 20W-50 oil in the car.  Feel free to overhaul the carb (Solex or Weber), if it’s not been overhauled in the last 4 years or 40,000 miles — hint, odds are that it’s not been.

 

Even when you do a “performance build” on a 2002, there are elements that could carryover. One thought is the following. There is a strong movement towards the electronic “123 distributor”. Find some of the long, endlessly-raving threads discussing it on this forum. If you think it might appeal to you, buy it now. You can tune it to your car’s current state, and it will eliminate a common “high-mileage M10” ailment: the distributors are worn, have lots of slop, and have lost their original advance/retard curves. When your engine has new pistons, higher compression, a hotter cam, etc., you’ll just use the 123’s app to adjust the curve for the “new M10”.

 

Welcome to ‘02’s, and don’t be afraid to rev an M10. I contend that anything less than 2,500 rpms is lugging the engine and no one wants to do that.... ?

 

Regards,

 

Steve

 

Edited December 12, 2018 by Conserv

[AJ2002]

Thanks everyone for sending comments.  All perspectives are welcomed.  This is my first adventure into a high revving fun machine.  I was driving my Ram truck this AM at 70 mph and 1.5k in revs.  All low end grunt machines. ? Same would be true of my 540 wagon.  I get a bit more revs out of the 530, but not much.  Anyone one of those vehicles at 3.5-4k revs in final gear would put me in jail.  So I am living through your comments until I can get a well functioning 2002 on the road. I get frightened something will fall out the thing at 4k revs. ?

[02Pilot]

Not revving the engines in your other BMWs is a crime. Every BMW I've owned, most of them daily drivers, saw the redline almost every time I got the engine up to temperature. You don't have to stay there, but a good blast of throttle now and again is nothing to be afraid of, and you're missing out on the best part of the power band.

 

And if something falls out of your M10 at 4k, it was going to fall out anyway. But I'm willing to bet that everything will remain firmly attached.

[evil02]

  With the caveat that your carb's air/fuel mixture is good. You can sit at redline all day. Keep in mind, the rev limiter is there protect the engine but, like being on an airplane at 10,000 feet with no seat belt sign on, you are free to rev anywhere between 0 and redline! 

 

 ALL my vehicles see redline every time I drive them. Some, many times a day. All have reached 100k+ miles without issue.

 

  ALL manufactures have a redline that is set far below what the engine can take. They put it in a place where the engine just doesn't make anymore power so, might as well shift and fall back into a rev range that does make power.

[xr4tic]

you bought an 02 that had been sitting for a while, then parked it for a while yourself?

 

The engine isn't where you want to start.  Get it running the best you can and just drive it.  I'm sure you will find all sorts of things that need to be taken care of, plus it will give you a better indication of what kind of engine build to go with.

 

If you drive it and think that another 20-30HP is all you need, then you can focus on rebuilding your engine or you may think it's woefully under powered and decide an engine swap is in order.

[Mark92131]

Cracks in your Thermal Reactor manifold is the perfect excuse to replace it with a nice IE shorty header and stainless steel exhaust.  If your 1976 hasn't been desmogged, its a great time to lose all that baggage.  Here's a list of things that need to go...

 

Mark92131

 

Smog removal

 

1. Buy a used early exhaust manifold, (no emission ports), or a Tii manifold or a non-thermal reactor manifold and plug the emission ports, or headers, or the IE Shorty Header.

2. Pull the Thermal reactor (smog manifold) off, 8 nuts, plus the bracket to the passenger-side engine mount, disconnect the hoses to the EGR filter (rear) and Check valve (front), toss in neighbors pool, (actually someone may need it because they crack).

3. Remove your alternator and battery, you will need clearance for the EGR filter and smog pump.

4. Unbolt the EGR filter from the intake manifold (2 bolts), remove the hoses (one is connected to the intake manifold, the other to the divertor), and vacuum lines from the EGR Valve.  Slide the EGR Valve and filter into the space vacated by the alternator to remove.

5. Buy the EGR blocking plate on the FAQ store, to plug the hole in the intake manifold (or use one of those rubber expanding plugs)

6. Remove the Dashpot for the Solex carb from the intake manifold, if it is still there, if you have a Weber carb, it is probably gone

7. Remove the T1 Temperature switch between 3 & 4 on the intake manifold (keep, they are expensive)

8. Remove the Diverter Valve (between the EGR Valve and the Pump), 3 hoses and bracket

9. Remove the Air pump, belt, and mounting brackets, (under the battery tray), it takes some wiggling to get it past the sway bar.

10. Replace the Alternator and battery (leave battery disconnected for now)

11. Remove all the smog components attached to the firewall (3 electro-magnetic valves (red, white, black), 2 relays, (speed & choke), the Control valve (round with 3 vacuum lines), the EGR Relay (looks like an aluminum cigarette pack).

12. Plug the 3 open ports on the intake manifold from unplugging the smog stuff.

13. Run a single vacuum line from the carb port above the port on the intake manifold, (passenger side of the carb) to the advance port on the distributor, plug the retard port on the distributor, (underneath).

14. If you have an electric choke or idle jet shut-off circuit, it might be powered off of the emission wiring harness (blue sheath wire bundle connecting all the firewall smog components), you'll need to power those things separately to remove the smogharness (run wires off the + side of the coil)

15. To remove the smog harness, trace the blue sheath wire bundle to the fuse box, remove the screw for the fuse box and pull it up, there should be two wires connected, disconnect both of them.  The push-on connection at fuse #12 should be used to connect to the + side of the coil.  If you have a coil with an internal resistor (blue, aftermarket) run a straight wire from fuse #12 to the + side of the coil, if you have the original black coil or red, you need to harvest the resistor wire from the smog harness (still connected to the coil), or use the older external style resistor that mounts on the firewall.  Either way, trace the smog wiring harness back to the coil and remove it completely.  If you need to harvest the resistor wire on the + side of the coil connection, peel back the blue sheath to expose the clear resistor wire and remove it and then splice it into your new wire running back to the fuse box.  The only thing connected to the coil will be the wires from the distributor to the - side of the coil and your new wire from the fuse box #12 to the + side of the coil.  If you have Pertronix, those wires will also be present.

16. Reconnect the battery and start the car

17, Set the dwell and timing

18. Reset the carb to best idle using the idle jet screw, set the idle speed and enjoy.