Engine knocking/squealing

[Cong405]

First let me say I own a 1991 318is and I'm no mechanic but can do most of the basics (oil, brakes, belts, and rotors change).

The other day I started my car and heard a slight knocking sound coming from the motor. I then checked the oil and it showed a little less than half on the dipstick. I didn't think too much of it since I was planning to drive home (22miles drive) to change my oil anyways and I didn't think it matter much if it was slightly less than half. While driving home that day, I didn't hear any knocking at all.

Before starting my oil change, I parked the car for a few hours and didn't drive anywhere till I had to drive my brother to the bus stop which was 4 blocks away. So while I was driving, I heard noises coming from the motor but this time it was louder. When I got home and parked my car in the driveway, I notice that the knockings sound got louder and this time I also heard squealing sound like a loose belt.

So I decided to let the engine cool off and change the oil in hopes that my problems will go away. I also took off my AC belt, thinking that the squealing is probably coming from that since I did install the belt not too long ago. After completing my oil change and removal of the belt, I started the engine and the squealing got even loud and it idles rougher than before. I notice after i changed the oil, my fan clutch spun very slow and then all of a sudden stopped. I then turned off the motor and started it again and the problem was the same but this time the fan clutch didn't spin at all.

So now my problem is that I'm not sure what's wrong with the car nor how to fix it. I think it's the fan clutch that is causing all this but I'm worried that the low motor oil had something to do with it too. I've been searching the forums for days trying to see if anyone else ever had the same problem but didn't find anything. I was hoping that someone could give me some advice and input on what to do and how to diagnose the problem.

Thanks ahead!

[llll1l1ll]

Y'know, I'm probably wrong in this guess, but take a look at your motor mounts. When mine went bad, the engine didn't necessarily knock; however, I could feel every bit of engine in the car. Also, the fan stopped moving because it was getting smooshed against something else.

Granted, I don't know the 318 engine.

[tonywonder]

your fan could be broken but i dont think its the source of your problem. what type of oil do you use? is the pulley that the fan is attatched to spinning or is the whole unit just not spinning altogether? squealing is usually a belt or the alternator. hows your battery?

[xwill112x]

check your engine mounts, then fan shroud. shouldn't hurt it to have half a qaurt low unless you were driving like you were on the track..

[Cong405]

Thanks for the input r3v. I'm going to check this weekend.

your fan could be broken but i dont think its the source of your problem. what type of oil do you use? is the pulley that the fan is attatched to spinning or is the whole unit just not spinning altogether? squealing is usually a belt or the alternator. hows your battery?

I use Pennzoil 15w-40. I'm not too sure about my fan, I'm going to have to check this weekend. My battery should be fine since it's only over a year old.

[tonywonder]

dino oil ay? well its possible that this has gunked up in your lifters and is causing the knocking noise. its also possible buildup is preventing the chain tensioner from doing its job so your chain might be making the knocking noise.

people recommend different oils for this engine because of its age but ive only used synth oil on it, mostly because thats what its suppose to use. you should change your oil again and use a synth oil. the synthetic oil will help clean all the buildup out from the tappets and tensioner, and should quiet your engine. let it run at idle for a bit it might take a little to clear up.

ive also heard of using, i believe, 1 quart mixture ATF with your oil change to help clean it out. do a search on that.

you should also check out M42club.com they have a lot of information there.

[delatlanta1281]

Waterpump going?

[TrentW]

Waterpump going?

My first thought also.

[Cong405]

Thanks for the input guys. I'm going to check all that this weekend. Hopefully I'll figure it out.

[call me jack]

it sounds to me like your water pump is going, considering your fan runs on the same pully (at least on m20s, right?) and since the water pump is ceasing up, the belt would probably be slipping on that pully, hence the squeal.

I don't think your oil came into play at all in this. I would check your heat, and your temp gauge. fix the squealing, and then move into the knocking, if it's still there.

[Cong405]

I'm thinking about ordering the water pump kit from pelican. I hope that fixes the problem.

Quick question: Which thermostats is most recommended, 88 degree or 92 degree?

[tonywonder]

you should pull the water pump to see if thats the issue before ordering. get the pump with a metal impeller and 88deg therm by wahler. might as well check all your hoses while your at it. if the water pump unit ceased there wouldnt be any coolant flow and your engine would get hot.

if you say the fan stopped spinning then a ceased pump is the only thing that makes sense besides the fan itself being broken.

you could always remove that belt altogether and see what happens. dont run it too long but that should tell you if the knocking is from the pump or not.

did you manage to pinpoint where the knocking is coming from?

[call me jack]

you should pull the water pump to see if thats the issue before ordering. get the pump with a metal impeller and 88deg therm by wahler. might as well check all your hoses while your at it. if the water pump unit ceased there wouldnt be any coolant flow and your engine would get hot.

if you say the fan stopped spinning then a ceased pump is the only thing that makes sense besides the fan itself being broken.

you could always remove that belt altogether and see what happens. dont run it too long but that should tell you if the knocking is from the pump or not.

did you manage to pinpoint where the knocking is coming from?

it sounds like the pump hasn't completely ceased, but it starting grind and cause friction in the belt (spinning slower than that the alt, and the fly wheel) this would explain why the fan isn't spinning properly. But yeah, try removing the water pump belt, momentarily to see what happens.

[tonywonder]

it sounds like the pump hasn't completely ceased, but it starting grind and cause friction in the belt (spinning slower than that the alt, and the fly wheel) this would explain why the fan isn't spinning properly. But yeah, try removing the water pump belt, momentarily to see what happens.

So then the knocking would be from the pump intermittently ceasing? and slowing the rotation of the engine causing a rough idle?

[call me jack]

So then the knocking would be from the pump intermittently ceasing? and slowing the rotation of the engine causing a rough idle?

In a round about way, yeah, thats what i sounds like to me. Based on the information given, don't see how it could be anything more than that.

Now, if the car was at my house and went to inspect it, personally, i might find it's something else.

An audio/video clip of the car would probably serve the most value in further diagnosis. i wanna see how the fan spins.