Author Topic: M42 engine went south at 129K (Read 6072 times)

G-Man · « **on:** December 11, 2007, 02:45:46 PM »

My girlfriend was driving in Oakland, car dies at a stop light. Other drivers stop to help and push it off the road. It wouldn't start. She has AAA tow it back to her place. A few phone calls, I tell her to tow it to German Auto Sport in Berkeley. I just talked to them, they tell me the motor has no compression, pistons move but when they pulled the valve cover off, valve train doesn't move at all. I'm guessing the timing chain broke or came off sprocket. Unbelievable to say the least considering the mileage on the car (129K). It's common for M20 timing belts to break due to maintenance neglect by owners but this is the first time I've heard of a M42 timing chain breaking. Anyone have any other ideas of what happened? This sucks to say the least. Anyone in the SF Bay area have a spare M42 FS? If so, send me a PM. I sold my spare M42 from my 91 318i parts car last year. Little did I know this would happen.

G-Man

wrcarter · « **Reply #1 on:** December 11, 2007, 03:51:50 PM »

Heard about a sprocket coming off (or rather breaking) the crankshaft before.

volsBMWfan · « **Reply #2 on:** December 11, 2007, 05:24:26 PM »

There has been a couple of people on this forum that have lost there M42's in the same way. I found after mine did the same thing only i was turning about 6500 rpm when mine broke. Find a pre-95 M42 out of an e36 and swap it.

tjts1 · « **Reply #3 on:** December 11, 2007, 05:48:31 PM »

The timing chain, sprockets, guide rails and tensioner are all wear items just like a timing belt. You might be better off parting it out instead of fixing. Good luck.

sheepdog · « **Reply #4 on:** December 11, 2007, 08:42:53 PM »

Find a used motor. Cheapest and easiest fix.
If you are doing it yourself, I would consider going through the chain and replace the waterpump and thermostat before putting it back in. Biggest problem with these motors is that chain, otherwise they will typically last a long time.

G-Man · « **Reply #5 on:** December 12, 2007, 06:24:21 AM »

The car is in perfect shape, Bilsteins, H1/H4, etc.. I'll find a used engine and drop it in. Still looking for a lead on a used M42.

What all is involved in replacing a M42 with a M44?

Gordon

sheepdog · « **Reply #6 on:** December 12, 2007, 11:32:57 AM »

Quote from: G-Man;39312

The car is in perfect shape, Bilsteins, H1/H4, etc.. I'll find a used engine and drop it in. Still looking for a lead on a used M42.

What all is involved in replacing a M42 with a M44?

Gordon

Just a dual temp sensor, intake swap, and the belts or accessories are the biggest change needed it seems. The basic long blocks are pretty much identical.

RED IS 91 · « **Reply #7 on:** December 12, 2007, 05:44:23 PM »

If anyone can find a motor it will be you.........

Craigslist extraordinare

It just happened sitting at a light ?? No bang or nothing? That is weird ,I would think it would happen if you were high revving.
It might be fixable?

Sorry to hear about that .Good luck with the swap

sheepdog · « **Reply #8 on:** December 12, 2007, 06:23:12 PM »

Quote from: RED IS 91;39342

If anyone can find a motor it will be you.........

Craigslist extraordinare

It just happened sitting at a light ?? No bang or nothing? That is weird ,I would think it would happen if you were high revving.
It might be fixable?

Sorry to hear about that .Good luck with the swap

Fixable, maybe.
Trust me, it is WAY easier to just swap it.

Anytime the timing chain dies, it will be EXPENSIVE. The timing chain housing alone is over $300 and a ton of work to get to, you basically have to strip the engine bay and block to do it. If the chain, or a sprocket broke, you may as well consider the housing toast as well.

You can find a used engine for $400 or less. You MIGHT get half the parts needed to fix it for that. I got mine for $200. Get one from a yard with a small warranty and pop in a new t-chain tensioner and at least a new thermostat.

If you are going to fix it, do it right and basically do a minor rebuild. Pull the head have it checked and cleaned up, new lifters, change the water pump, thermostat, all new chain system including oil pump and t-chain housing... Basically anything that can die or have trouble within the next 150k.

RED IS 91 · « **Reply #9 on:** December 13, 2007, 10:18:35 AM »

Quote from: sheepdog;39346

Fixable, maybe.
Trust me, it is WAY easier to just swap it.

Anytime the timing chain dies, it will be EXPENSIVE. The timing chain housing alone is over $300 and a ton of work to get to, you basically have to strip the engine bay and block to do it. If the chain, or a sprocket broke, you may as well consider the housing toast as well.

You can find a used engine for $400 or less. You MIGHT get half the parts needed to fix it for that. I got mine for $200. Get one from a yard with a small warranty and pop in a new t-chain tensioner and at least a new thermostat.

If you are going to fix it, do it right and basically do a minor rebuild. Pull the head have it checked and cleaned up, new lifters, change the water pump, thermostat, all new chain system including oil pump and t-chain housing... Basically anything that can die or have trouble within the next 150k.

The only reason I said fixable was because of the low mileage on his engine.
I doubt he'll find a used motor with around 130,000 miles for $400.

Anyway, good luck with whichever way you go.

ejectorbed · « **Reply #10 on:** December 14, 2007, 07:31:28 AM »

This kind of problem seems to be more common than I thought before buying my '91 iS.
I had it for 2 months and it just died on me while doing about 3k rpm.
The engine had only done 107k.

car was in too good condition to give up on it.
Got an M42 from a '94 E36 that had clocked 78k.
I'm based in the UK and the engine cost me �290 including delivery...which seemed reasonable.

Swap was fairly easy to do, and I hadn't done anything like this in the past.
Basically just need to swap everything off the block except the head.
All manifolds, sensors, sump, crank pulley, hoses.
Took a weekend to do with an extra pair of hands. The car goes better than ever now.

sheepdog · « **Reply #11 on:** December 14, 2007, 11:56:38 AM »

Quote from: ejectorbed;39431

This kind of problem seems to be more common than I thought before buying my '91 iS.
I had it for 2 months and it just died on me while doing about 3k rpm.
The engine had only done 107k.

car was in too good condition to give up on it.
Got an M42 from a '94 E36 that had clocked 78k.
I'm based in the UK and the engine cost me �290 including delivery...which seemed reasonable.

Swap was fairly easy to do, and I hadn't done anything like this in the past.
Basically just need to swap everything off the block except the head.
All manifolds, sensors, sump, crank pulley, hoses.
Took a weekend to do with an extra pair of hands. The car goes better than ever now.

Until this site it seems everyone thought his motor was bulletproof. Unfortunately it does seem to have an issue, but now that it is known we can help others avoid these problems. This engine is not problematic, it just needs maintenance on something no one was/is aware of really.

G-Man · « **Reply #12 on:** December 18, 2007, 09:11:09 AM »

Sean at Autobahn BMW salvage in San Diego told me the following, I contacted him about finding a used M42 motor.

I bet you had a oil fed tensioner go bad and take out the timing rail. If the motor makes a racket in the first 1-3 seconds when it's cold... bad tensioner. I have seen this 4-5 times.

Questions is, what can be done to ensure the chain tensioner doesn't go bad??? Anyone else have any thoughts on what went wrong?

I found a used M42 in the SF bay area that came from a 91 318is that had been totalled in spin in wet conditions. The M42 donor motor has 160K on it. I asked the shop to put in a new timing chains, chain tensioner, water pump, thermostat, oil pump, , motor mounts, new hoses under the intake manifold and elsewhere. While the engine is out, check my clutch because my car has 129K on it and the clutch has never been replaced. Donor engine had 5 speed attached to it. Maybe donor engine has a good clutch that was replaced in the last 5K but that's wishful thinking. Anything else that needs to be replaced before motor goes back in?

G-Man

RED IS 91 · « **Reply #13 on:** December 18, 2007, 10:47:31 AM »

How much was the used engine

sheepdog · « **Reply #14 on:** December 18, 2007, 12:01:08 PM »

Quote from: G-Man;39668

Sean at Autobahn BMW salvage in San Diego told me the following, I contacted him about finding a used M42 motor.

I bet you had a oil fed tensioner go bad and take out the timing rail. If the motor makes a racket in the first 1-3 seconds when it's cold... bad tensioner. I have seen this 4-5 times.

Questions is, what can be done to ensure the chain tensioner doesn't go bad??? Anyone else have any thoughts on what went wrong?

I found a used M42 in the SF bay area that came from a 91 318is that had been totalled in spin in wet conditions. The M42 donor motor has 160K on it. I asked the shop to put in a new timing chains, chain tensioner, water pump, thermostat, oil pump, , motor mounts, new hoses under the intake manifold and elsewhere. While the engine is out, check my clutch because my car has 129K on it and the clutch has never been replaced. Donor engine had 5 speed attached to it. Maybe donor engine has a good clutch that was replaced in the last 5K but that's wishful thinking. Anything else that needs to be replaced before motor goes back in?

G-Man

I would pull the lower pan and check the pan bolts, but that can be done later. I would do it now though to make sure the upper pan gasket is still in good shape. Less chance of leaks later.

Also, the plastic coolant log under the intake and all vacuum lines.