what's making this engine noise? (E30 content)

Problem: My engine (~130K miles) started making clacking noises about two months ago that increases with rpms. They get WORSE when the engine warms up. The noise is not a deep thud/clunk but a rat-tat-tat clacking. One import shop adjusted my valves and told me that sludge had blocked the oil spraying onto the cam and rocker arms. They put some sludge remover into the oil and told me to drive it 1K miles and then they'd do an oil change and that would clear up the noise. The noise only got louder after 150 miles so I had it towed to my BMW guy, who just listened to it and said it was a blown piston/bearing and the noise was piston slap. He recommended replacing the engine.

EXCEPT that piston slap and worn bearings are supposed to make clunking noises not clacking noises, and they're supposed to decrease (not increase) as the engine warms up. Does piston failure sound right or should I get a third opinion? What else could it be? This sucks.

could be a valve tick....
did they adjust the lifters when they adjusted the valves?

well first off, does ur car feel like it is losing alot of power, cause then it could possibly be a blown piston. You probably have a bad valve or a few bad valves. Valve ticking is very common in e30s, but it shouldnt be exremely noisy and it shouldnt get increasingly or decreasingly worse with engine warm up

No, it's not apparent that I've lost a lot of power. I don't know if the first guys adjusted the lifters too, but I'll ask tomorrow. But believe me, this sound is not a "tick-tick-tick" it's a very LOUD 'RATTITY-RAT-RAT-TAT', like when a moving fan runs against a piece of paper. But what hangs me up is that the sound is not at all deep and clunky. The PelicanParts.com website says this about piston slap:

It is a dull-thud clunk that can be heard every two rotations of the crankshaft. Piston slap is most commonly heard when the engine is warming up, before the piston to bore clearances have decreased due to the pistons expanding.

As far as I know worn bearings sound about the same.

Location, location, location.

If you can isloate the area from where the noise is coming from you can pretty much determine the cause.

you said it sounds like a fan hitting something. did u check to see if something is rubbing up against the fan or something else

H2O pump or alternator. I've heard both make a similar sound.

Originally Posted by lordofthewaters

H2O pump or alternator. I've heard both make a similar sound.

Yeah, except I'm talking LOUD here--like a clanging clatter, not a small sound.

Bad bearings will make significant noise. But I'm not sure what you mean by loud. Like louder than the exhaust at speed, or louder than the valves at idle. Methinks we need a vid here.

if the shop is not specializing in BMW they could have not got it right the first time, it is not unusual to have to take a couple shots at the valve adjustment process. sometimes they just miss the adjust or don't retighten the nut enough and they come loose again and the lash goes....good luck....cliff

have u tried the fan hitting the distributor cap, when the engine is warmer the fan turns faster explaining why it increases when warmer engine, at higher rpms the fan is turning faster, which also explains it, that is happening to my far, but less intense so i keep the car at low rpms

make sure the fan is not wobbling and that the top radiator hose is securely pulled back to the valve cover side, any of these things could cause what you say...I'd have to actually look at it to determine the actual cause, but if it's that noticable it can't be that hard to figure out...might be expensive to repair but the diagnosis can't be that hard....just get in there and look....good luck...cliff

I don't see how the fan could be hitting the dist cap. The diameter isn't big enough. Sounds like the cowl is loose maybe.

the diameter IS big enough

Originally Posted by faviolosky

the diameter IS big enough

Yes you are right. That was me having a brain fart. I mean to say that the fan shouldn't be thick enough to make contact, if that makes sense. When you did the new clutch did you make sure that the fan was sitting on the correct side of the clutch? If incorrectly assembled it could make the plastic fan sit closer to the block.

it (fan clutch), when the engine coolant is hot, makes the fan spin faster at low rpm and slows down as the rpm gathers...that's the point of the clutch....while idling at 650 rpm the fan needs to spin faster than at 3500 rpm....it's the point of the fan clutch ...cliff

did I just see this? do you know what that represents? my goodness...just trying to help...cliff

Originally Posted by stevehecht

Problem: My engine (~130K miles) started making clacking noises about two months ago that increases with rpms. They get WORSE when the engine warms up. The noise is not a deep thud/clunk but a rat-tat-tat clacking. One import shop adjusted my valves and told me that sludge had blocked the oil spraying onto the cam and rocker arms. They put some sludge remover into the oil and told me to drive it 1K miles and then they'd do an oil change and that would clear up the noise. The noise only got louder after 150 miles so I had it towed to my BMW guy, who just listened to it and said it was a blown piston/bearing and the noise was piston slap. He recommended replacing the engine.

EXCEPT that piston slap and worn bearings are supposed to make clunking noises not clacking noises, and they're supposed to decrease (not increase) as the engine warms up. Does piston failure sound right or should I get a third opinion? What else could it be? This sucks.

I think I have a similar problem with mine. I can't describe it as well in words, here's what the dealer's SA put: "grumbling/whinning noise. ... engine needs to be warm" (to hear the noise). The noise is quite annoying.

First time I took it in (few weeks ago) they changed the "tensioner pulley". According to them this fixed the problem. Five minutes later as I drove off, the noise came back. I was away for a couple of days so I couldn't take it back.

Today I had an inspection done and I pointed to the same problem. This time around the "P/S pump noise, grinding noise" is listed as the problem. They ordered it and I should have it fixed by next Thursday. It can't be the alternator because that one let me down a month ago so they put in a new one at that time.

I'm "lucky" with this being a "certified series" so I don't have to pay for these parts. The guys at the dealership are great too. And I don't know why, but I still love this car.

If anyone wants to hear the noise, I recorded it with my phone and put it here (you'll need QuickTime or Real Player):
http://cid-e8ab8d5920b3c5cc.skydrive...se.aspx/Public