Engine Rough Idle and Stall, Blue Smoke

[Matthew A.]

I know I posted about this under the "What did you do..." thread, but in the interest of sharing problems and making sure I'm on the right track I figured I should likely put it here.

I got the oil changed today. Nothing magical, just a drain & fill with a new filter installed (first person to bring a flushing machine near her is going to get flushed with it). 15w-40 as 20w-50 wasn't available. Worked out the mistakes they made that kept it from running (they'd failed to push the dip stick all the way in and had bumped one of the plug wires loose). Got it started back up and it ran....poorly. Engine was violently shaking, everything sounds louder and there is a blue smoke cloud pouring out of the exhaust. EDIT: Forgot to mention almost the entire time the oil pressure light is on as well.

Then she stalls. Get her started up again and she starts to sputter so I give her a little gas and find that she only quits when she dips below 1K RPM. Blue smoke is still violently pouring out the exhaust. At this point I'm thinking that the gaskets might be shot. There was some blue smoke before, but no smell of burning oil so it wasn't a cause for major concern at the time. Now I have my own smoke screen and a car that can't be safely driven until I get this fixed.

I'm thinking that the gaskets need to be replaced and while I'm at it I should be checking the piston rings and cylinder heads. In addition cleaning off the fuel injectors and valves just to be certain. Then re-timing her to make sure everything is golden. This sound like the right approach or should I be looking at another route to take?

[Mike W.]

15-40 is somewhat too thin, but it shouldn't be a problem yet where you are. I'm not sure what you mean by gaskets, but a blown head gasket doesn't manifest itself with blue smoke and generally doesn't blow unless it's overheated. Old hard valve guide seals, which it probably has, can lead to significant oil consumption, but running rough and not a dramatic overnight change. Excessive fuel from a leaky injector can cause problems similar to what you're describing. I'm troubled by the oil light, a new switch might be in order, they're cheap. Rings and bearings are rarely a problem, the head is much more fragile. Start with the basics, compression and fuel pressure, if you have too much fuel pressure it can do odd and not good things. Timing needs to be vaguely close, but nowhere near exact to at least run ok.

[Matthew A.]

15-40 is somewhat too thin, but it shouldn't be a problem yet where you are. I'm not sure what you mean by gaskets, but a blown head gasket doesn't manifest itself with blue smoke and generally doesn't blow unless it's overheated. Old hard valve guide seals, which it probably has, can lead to significant oil consumption, but running rough and not a dramatic overnight change. Excessive fuel from a leaky injector can cause problems similar to what you're describing. I'm troubled by the oil light, a new switch might be in order, they're cheap. Rings and bearings are rarely a problem, the head is much more fragile. Start with the basics, compression and fuel pressure, if you have too much fuel pressure it can do odd and not good things. Timing needs to be vaguely close, but nowhere near exact to at least run ok.

15w-40 is recommended by the manual for the temp range. I wanted 20w-50 (it supports a wider range) but no one carries it around here.

The change happened right after they drained old oil out and put the new oil in. Oil light is on if the car is (which is telling me it can't maintain pressure because there is enough oil in it) and the blue smoke tell me that it's leaking oil somewhere. There was some blue smoke before, but now it's more like a blue cloud. With the only change being new oil I have a feeling that something isn't sealing properly anymore. I'm pulling it apart tomorrow to get a better look at the heads and rings to make sure nothing is broken or ill-fitting and going from there with them.

Outside of that, I've ordered a head gasket set (Bavarian Autosport lists it as having: "Head gasket, Valve cover gasket (w/spark plug gaskets if applicable), Intake manifold gaskets, Exhaust manifold gaskets, , Valve seals, Upper timing cover gaskets/seals, Throttle body to Manifold gasket, Cold start valve housing gasket, Thermostat housing & cover gaskets, Temperature & Pressure sender seal rings. If applicable also Manifold to downpipe gaskets, Rear water nipple gasket, Throttle body water housing gasket, Cold start valve o-ring. " in there so it seemed like a good deal in general). It's the cheaper replacement and the if that solves the problem, great. If I've got cracked heads or problems with the rings, less great and I'll have to go down that road.

This time I'll take pictures as I go too. That way I can actually not screw-up and lose and/or misassemble anything and document the problem properly.

[GripGreg]

Glad to see you over here!
Our cars are single overhead cam inline sixes, with just one head.
Also, if you pull the head it's always best to have it rebuilt.
Make sure the auto machine shop knows the procedure.
Get a recommendation from more than one mechanic, okay?
And, if you tell the parts stores to buy Castrol 20/50, you'll definitley buy it!
Be a salesman? 10/40 is for newer cars!! If you can find Valveline 20/50 Racing oil, that would be good too.
But make sure it reads 'Racing oil'.
I use to use it in my Porsche. There's more to the oil story. 10/40 is too thin!
Good luck,,,,Greg

[Falkenberg]

As an addition to what Mike writes, I've also heard that an M30 can be very smokey when ignition timing is off, fuel delivery is not as it should be, etc.
Mine smoked a lot more when advance was too much.
Maybe an italian tuneup would help, if the old oil somehow left piston rings stuck, just thinking here.
But the oil light is a problem. Makes you think if the previous oil had stuff added to it. Does the engine knock down below? Maybe you have a problem with the lower end. Oh, did you ever take the valve cover off? Check if the 2 banjo bolts on the oil spray bar are still in place & tightened. If they are loose, you will loose a bit oil pressure there.

[Matthew A.]

As an addition to what Mike writes, I've also heard that an M30 can be very smokey when ignition timing is off, fuel delivery is not as it should be, etc.
Mine smoked a lot more when advance was too much.
Maybe an italian tuneup would help, if the old oil somehow left piston rings stuck, just thinking here.
But the oil light is a problem. Makes you think if the previous oil had stuff added to it. Does the engine knock down below? Maybe you have a problem with the lower end. Oh, did you ever take the valve cover off? Check if the 2 banjo bolts on the oil spray bar are still in place & tightened. If they are loose, you will loose a bit oil pressure there.

I'd be very surprised if I lost timing from an oil change, but I'll be checking that as soon after I get a timing light (local parts store is getting one in for me from Spokane).

I'd love to give her an Italian Tune-up but she doesn't even run properly. With the erratic idle followed by dying and the blue cloud mixed with the oil light the signs are that I've got some kind of leak internally that's keeping the pressure from building properly.

I doubt the previous oil had anything added to it beyond years of build up from sitting in the engine honestly. It was blacker than coal and a bit on the thick side, signs that it was well past due an oil change.

I spent some time digging through my Haynes book and under Erratic Idle and Oil Consumption the Head Gasket is listed. It's actually the only thing that's listed under both problems. I'm not saying it is the Head Gasket yet, but it does point me where I was already aiming: at the gaskets inside the engine block.

[GripGreg]

You said 'the book' says 15/40 is recommended. That's, of course for a new motor.
I don't think yours or mine is new anymore. 20/50 is what you fight for.
Please read my last post in the other thread.

[Matthew A.]

You said 'the book' says 15/40 is recommended. That's, of course for a new motor.
I don't think yours or mine is new anymore. 20/50 is what you fight for.
Please read my last post in the other thread.

When you look in the owner's manual the oil is not determined by the age of the engine, nor the mileage but the ambient air temperature that the vehicle will be operating in. SAE 15w-40 is for about -5F to 80F. SAE 15w-50 is for -5F to 105F. SAE 20w-50 is for 15F to 120F. Based on BMW's recommendations SAE 15w-40 is fairly ideal for where I live (North West Montana), but 15w-50 would be better.

If the oil is leaking into the pistons at the proper viscosity rating for regular use then the most likely cause is in the gaskets, rings or heads. Those are the things I'm looking into. Yes the engine is older, and is likely more worn but that would advocate reshaping the cylinders and likely plus-sizing the pistons to ensure proper seal-age and performance over throwing thicker oil into the engine as a stopgap.

[Matthew A.]

Delays due to breaking one of my ratchets occurred, but I got back on track and bring pictures!

First is the head gasket (warping/twisting occurred when separating it from the engine block where it was practically glued on place):


And a close up of some of the bits that didn't come off with the head gasket that I still need to carefully scrape off:


Here's what the fuel injectors look like:


And here's the valves (I'll get another shot of them when I get them disassembled, and yes that is the exhaust manifold. I couldn't get it off when it was in the engine bay because of those 4 nuts you can see which are completely frozen and were in danger of being stripped, so I disconnected the manifold from the exhaust itself and pulled it out that way. I plan on trying to get the exhaust manifold off though so I can make sure everything is clean and smooth again before it all goes back together.):


Here's a look at the pistons:


And here is a close up of one of them so you can get a better look at what I can see:


And finally a shot of the gunk that's coating the bottom half of the engine compartment rather thickly:


As soon as she can be driven to a car wash she's getting a bath.

EDIT: Forgot to mention that the head gasket is basically leaking oil, it's soaked it up pretty heavilly, and I've seen signs of gasket bits around one of the valve heads. Additionally all the gaskets, save 1, are basically fused into the parts they seal. The one came off nicely, and there was one that was missing on the intake and has been fixed with some silicone.

I've got a full head gasket kit that should just about cover all of this. It makes me rather glad I decided to get in there because the gaskets look ancient.

[Mike W.]

Don't even think of putting that thing back on without replacing the valve guide seals. Dollars to doughnuts they're crispy hard and leaking like a sieve. Check the head for cracks carefully too, but at first glance it appears to be ok, but a small crack could be starting.

[Matthew A.]

Don't even think of putting that thing back on without replacing the valve guide seals. Dollars to doughnuts they're crispy hard and leaking like a sieve. Check the head for cracks carefully too, but at first glance it appears to be ok, but a small crack could be starting.

I'm taking the valves out tomorrow so I can scrub them clean again, so that'll be something I can inspect. I wouldn't be surprised if you're right. The head itself looks okay, but I'll know more once I get all the residue of the old head gasket off. I want to clean the pistons too, mainly so I can ensure they aren't showing any signs of damage.

I'll also be looking at the valve gaskets tomorrow too. More pictures as things progress.

[GripGreg]

The piano top pistons are the ones mostly desired! I hope you got lucky!
You may not need new rings? These bottom ends are nearly bullet proof!
Some of us know of injector rebuilders!! Just ask.
Greg

[Matthew A.]

The piano top pistons are the ones mostly desired! I hope you got lucky!
You may not need new rings? These bottom ends are nearly bullet proof!
Some of us know of injector rebuilders!! Just ask.
Greg

I hope so on the pistons too. I haven't had a chance to check the rings yet so I don't know how good or bad everything in there is....yet. I'll be running a feeler gauge through there too. If the pistons themselves are good then I may just need to get larger rings to compensate for cylinder wear.

The injectors actually look pretty good. I don't see any carbon, cracking or signs of weakening on them. So that's one project down. Added gapping the valves because they were clicking to the list though. Plus it just seems like a good idea while I'm in there to do so.

[Mike W.]

The piano top pistons are the ones mostly desired! I hope you got lucky!

Greg

All US 528i's got piano tops. The problem is they're only a 2MM piano top. The old 2800 Bavs with 9:1 compression had 8MM or so crowns.

[Falkenberg]

I've opened up my '76 engine (with the INATs) and also a '77 2.8 engine (4A1), and I've also put hands on some pistons from a 633 (I think). The '76 engine has the highest crowns. The other 2 were kind of the same height. In the picture it is shown next to the 633 piston.