my car just redefined 'lumpy idle'

[Randell]

my car has always had the typical M30 idle (smooth, then a little blip and then smooth again). last year it got worse though, i was sitting in the car idling for a few mins while my girlfriend grabbed something from the corner store, and it started to run rough.. i've had my mechanic look at it numerous times but he insists it's fine. i've got used to it so it doesn't bother me anymore.. it's just a slight rumble but nothing major.

but last night i let my tank run down to 20km range (i kept forgetting!) and then filled it up (premium, i've got an EAT). started it back up again and it was ROUGH. it feels like there are stones in the engine, the whole car rocks and the engine thumps.. so i started to drive home and it was smooth as silk. stop at a stop sign and it starts to rumble away again.

i drove it to work this morning and it was ok for the first few mins, then it started again. it is pretty severe, i'll get a video of it tonight. it's fine off idle.. no improvement in park or neutral.

any ideas what this could be? engine mounts? low compression? the ICV is only 6 months old..

this car knows when i've got a bit of spare cash!

[M-what]

At least you have experienced a smooth idle. I am still searching...

Sounds like the junk at the bottom of the fuel tank were stirred up and some of the small particles got by the fuel filter and has now gunked up the injectors. Drive it for a while, and if it don't improve try injector cleaner.

Same thing happened to me with my e30 M3 when I ran the tank too low. But it cleared up after few days.

[Rustam]

evap purge valve stuck open?

[632 Regal]

I would do the basic maintenance items like plugs/ wired and the such, then advance to the fuel filter(s) etc... after you do the plugs and stuff remember to do a computer reboot.

Are you getting any codes from the stomp test?

[BillionPa]

gas made it bad eh...

fuel pump relay? (get a new one)

vacuum leak? (would wreck havoc with idle)

charcoal canister? (get a new one)

dirt in new ICV? (just clean it out)

dirty valves?

[sKilled]

I'm no genius, but how about the Shogun reset? Before you go spending money, it's free innit.

[ThoreauHD]

I'm going to pick engine mounts for 500 dollars.

[Randell]

thanks for the suggestions everyone. unfortunately a rough idle was only the beginning. i jumped in this evening to leave work and *bing* coolant level. so i called a friend and he came out to rescue me with a couple of bottles of distilled water..

but.. it still wasn't finished with me.. i filled it up, turned the key and heard a sound that would make you all feel sick.. it kinda sounded like the leg of a large animal snapping.. it came from deep within the engine and left us both standing there staring into the engine bay in silence...

i didn't dare start it again although i'd say the major damage has now been done.

i will get it towed on monday to my mechanic, and will probably leave it there as some sort of display, $2 entry... 'come and see the red beast of terror, hold your wallets tight!'

[onewhippedpuppy]

Ouch, that sucks. Hopefully it sounds worse than it is.

[Ausmpower]

Uh Oh!!..... Blown head gasket or cracked head?

I just hope that noise wasn't a rod snapping as the engine tried to compress raw water.....

If it's toast speak to Roger at the Beemer motor workshop in Maddington (he may be your saviour!)

Ross

[Randell]

Uh Oh!!..... Blown head gasket or cracked head?

I just hope that noise wasn't a rod snapping as the engine tried to compress raw water.....

If it's toast speak to Roger at the Beemer motor workshop in Maddington (he may be your saviour!)

Ross

yep, i imagine that's what hydrolock would sound like.. the oil is clean, the coolant had to go somewhere... :(

[Gearhead]

Did you hear this noise while cranking, or did the engine "catch" then the noise? If while cranking, I would think that a hydro-locked cylinder(s) would cause the starter bendix or flywheel/flexplate to fail before a rod or crankshaft snapped.

[632 Regal]

hydrolock is not a good thing, I believe it is time to look into another engine. you must have a big crack in the head for it to dump that much via gravity.

good luck!


yep, i imagine that's what hydrolock would sound like.. the oil is clean, the coolant had to go somewhere... :(

[s_ribbens]

Still, check the motor mounts. When they fail they can certainly make some awful noises. Not ruling out the other comments, but don't want to exclude more simple things to check out first.

[Jon K]

Ok - reread the post apparently you had more issues lol.

Def sounds like a leaking gasket if it was real lumpy etc and your coolant is low. Good ol' M30 cooling system for ya! Anyway, the SNAP could be a number of things... could be the cam snapping which I would think is most likely. If a cylinder is full of fluid and the engine cranks the cam tries to turn but can't push the valve down the cam takes a lot of pressure on the lobe and I believe your camshaft is hollow like most other BMWs... CRACK. Sucks because it happened, but the good news is that M30 camshafts are more popular than grass. I would pull the valve cover and check it out. Then i'd do a leak down and pressure check the cyls and all that good stuff.

[Morgenster]

Uh Oh!!..... Blown head gasket or cracked head?

I just hope that noise wasn't a rod snapping as the engine tried to compress raw water.....

If it's toast speak to Roger at the Beemer motor workshop in Maddington (he may be your saviour!)

Ross

Now that sounds like a horrorstory. I'd be mortified to find out something like that, but wouldn't something else give before the crankshaft or pistonrods?

[Jon K]

Now that sounds like a horrorstory. I'd be mortified to find out something like that, but wouldn't something else give before the crankshaft or pistonrods?


Yeah - cam shaft

[Ausmpower]

M30 cams are solid..... Well mine is in my '90 M30! and so was the cam in my E12 M535.

I'll wager on a rod or wrist pin...... Seen it twice before (No, not my cars!).

It usually goes crank, crank, fire....... CRUNCH! Damn!

The head will have to come off anyhow to fix the crack or corrosion that caused the failure in the first place.

best case = reconditioned head, worst case = sick bottom end.

If you need a hand Pm me I'm in the northern suburbs.

You wouldn't believe me if I told you that I just turfed a useable E28 M30 head but we're moving house and I had to off load some excess beemer stuff.

Gave away a compleat, clean, (rust free!!) set of E12 front doors and a blown dogleg 5 speed too.

That head might have saved you some $$.


Ross

[Ausmpower]

Did you hear this noise while cranking, or did the engine "catch" then the noise? If while cranking, I would think that a hydro-locked cylinder(s) would cause the starter bendix or flywheel/flexplate to fail before a rod or crankshaft snapped.

Usually you wouldn't strip the starter drive or the flywheel (it's manual) the starter would just stall from to much load.

[joshua43214]

Did you hear this noise while cranking, or did the engine "catch" then the noise? If while cranking, I would think that a hydro-locked cylinder(s) would cause the starter bendix or flywheel/flexplate to fail before a rod or crankshaft snapped.

I have seen quite a few cars with bent rods from hydrolocking. Usualy it will make a loud knock, like someone hit the engine with a hammer. and poof, bent rod, engine will even run sometimes once you clear the hydrolock, then you can listen to the wonderful sound of the rod scraping on the cylinder wall.

No matter what, someone is going to hand to turn the engine over or start it to diagnose it. Pull the cam cover off and make sure the cam did not break, then pull out all the plugs and roll the engine slowly over by hand. shine a flashlight into the plug holes if you can and see if you can see anything odd. Usualy when a rod or wrist pin breaks, that piston will tend to stick a bit rather than go down, then drop abrubtly, or you can prod it down with a long thin screw driver.

Something is already broken, you won't hurt it any more turning over by hand if you use common sense. Luckily by the sound of it, the engine stoped instantly, so if you do have a broken rod, there is a good chance the cylinder is still ok and you can maybe just toss to rods and pistons in ontop of repairing the original cause.

[Randell]

the car turned about twice and then it was a loud sudden SNAP sound. very distinct, it was like a huge bone snapping and it kinda echoed through the carpark... i'm hoping the block is still ok, i don't think i can afford a new engine! the cam lobes were quite worn and i think the head gasket job done 80000km ago (before i owned it) was very shonky , so i was expecting something to happen eventually..

the car is in a very poorly lit under-building carpark at work, i couldn't really see anything and i don't feel like going back this weekend as there's nothing i can really do for it.. i will get it towed to my mechanic on tuesday, he can rip it apart and tell me the damage.. if the block is damaged the car is going to sit for a very long time, as i don't have the money for a new engine at the moment.. if that's the case i'll drop by auto classic Ross and you can take me for a spin and remind me what it's like! i'll be driving a holden astra for the time being, which is a nice car but it's nothing on the bimmer

i had a dream i went back to the office and it started fine and i drove home and was overjoyed, then i woke up ... :( :)

[sKilled]

Don't feel too bad, the Astra was engineered by Opel, another (albeit inferior) German car company.

[Morgenster]

I am so going to check coolant level every week from now on. Brrr...
Real sorry about your car Randell. Hope the damage is minimal.

[genphreak]

Wow, dude I feel for you.

If we can be of help over here in Sydney, just let us know.

M30s come up 2nd hand every now and then, and you can always buy a 735i cheap on eBay... part the rest of the car and you can make the money back. It can be a fun thing to do if you can keep your **** together throughout the process.

I'd pull the plugs where she is and see if there is indeed coolant in a cylinder, if so you know the cause. The noise could be a piston or pin, but it may well have cracked a bore- not wanting to be a devil to you, but it is quite likely. Given the motor is quite old, you may do well to get a whole new motor and have your mechanic make the best they can out of the two and a new gasket set. A check of the cam condition and the head yours has might help you work out what is up, but a real cheap way is to get another motor you know runs, drop it in with no pull down and worry about the details like souping it up a bit or replacing something here or there, later on when you have some cash.

In this hasion, with the spare parts hanging around from the left overs you should be right later on, and avoid paying for a complete rebuild by the hour .i I'd definately try to get away with a straight forward engine swap instead if the money is tight. Costs can balloon real easy in Australia on these cars.

:) Nick