Hey guys,I have a 94 525i with 257000 miles on it. Three days ago, I tried to start it up and it just clunked out and I tried to start and again and it did the same thing. It would only stay started if I kept pressing on the accelerator. The engine was making popping sounds and was "acting like it wanted to jump out of the car". I checked the spark plug wells and all by #6 had a good 2 inches of oil in them. I knew I was losing oil, but I thought I just had an oil leak at the bottom of the engine, so I had tried stop leak. Anyways, the spark plugs were burnt/black, so I replaced them and the boots. I tested the ignition coils and all of them produced a spark. I put everything back together and it still didn't start. I'm thinking a lot of oil probably got into the cylinders. I was thinking of using a siphon pump and trying to get as much oil out as I can (I don't know if this is even possible). I had put gasket sealant on the spark plug gasket and will get new grommets (didn't even know there were grommets) for the valve cover. I had already replaced both gaskets last year and they seemed fine when I checked this the other day.So I wanted to know what could be causing the car not to start? Could the timing chain have anything to do with it? Is there a way to check if the ignition coils are giving out enough voltage?Thanks!
If you don't have rubber washers on the valve cover, the domed nuts bottom out before they tighten down the gasket. Oil would have only got into the cylinders if you pulled the plugs before drying out the wells. Not sure how you tested the coils but I'd just stick a plug in the end of the coil pack, ground the tip, crank it and see if you get a spark. OK, a spark in air isn't the same as when it is in the cylinder but it is a fair indication. Black plugs sounds like it is overfuelling. But is that just the outside ring at the end of the threads or the centre electrode too?
That is how my dad tested the coils, but I don't think he grounded the spark plugs when he did it, so we might have to do that again. The electrode and the hooks/prongs (idk what they are called) that go above the electrode was black. We took as much oil out of the wells as we could. The electrode side had oil dripping from it.IMAG0229.jpgIMAG0231.jpgIMAG0236.jpg
i don't know how oil could have gotten pass the spark plugs. If it is overfuelling, what are the symptoms of that. The car stays started if it is continuously given gas. I was thinking of getting a compression gauge and testing the cylinders, since oil got in there. Honestly, I don't know what to try next.
Oil is going to get into the cylinders 3 ways. Either is got in there from the wells when you took the plugs out, you have worn valve guides or worn bores. With the last two, you would get blue smoke out of the exhaust at the very least when you fired it up and more than likely on the overrun too. Some call the ring on the insulator in the second pic 'the brown ring of death'. I wouldn't go that far but I don't think it is helpful. Either way, you need new plugs. But before you put them in, spin the engine to try to vent it of fuel and get rid of some of that excess oil. Maybe put a piece of card on top of the plug holes as it may make a bit of a mess. The plus side of having a bit of oil in there is that it will help compression. But it will not help ignition much. It is very easy to flood the M50 by running it for a minute or two when cold and then turning it off. It can be an absolute pig to restart if you do that.
If you have the plugs out, it will not sound like normal cranking - there is no compression going on. Do you mean it started when you put the plugs back in but you had to keep your foot on the gas to keep it running? If so, do that and get it nice and warm. Then treat it to what BMW call 'spirited driving' to clear away the cobwebs
Oh. Well, we did turn it a few times with the sparks plugs out, nothing came up out of the wells. Yes, it did start after I put the plugs and coils back on and it only stay started when I had my foot on the gas. I kept doing this for at least 10 mins on and off. Nothing changed. Maybe I have to do it for a lot longer. What is spirited driving?
Here's a vid of how it sounds.
https://youtu.be/QuykTUiO0nI
Oh and also, it keep revving by itself, you can hear it in the vid.
Also, I had looked into the spark plug wells and after where the spark plugs would sit, it was black. My dad said that's oil and it was probably too much in the pistons to produce a spark.
I had the same issue and the popping sound was actually backfiring through the intake. It blew the ICV hose off and kept it from starting. My solution was to clean up the spark plug wells, the spark plug tips, the inside of the coil pack boots where they contacted the spark plug, and reattach the ICV hose. Runs perfect now.
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