Would anyone know what this tapping is under my beamers hood?

[Titius Justus]

Im guessing next step is to jack the car up, take the oil pan off and have a gander at the bottom side...

Yup. I've heard quite a few in my time. Heck, I've even thrown 2 myself. I'd bet my money that you have the genuine, good 'ol fashioned rod knock (RK). I'm just hoping your crank is OK and you can get by with popping a new bearing in.

Out of curiosity, the car had no knock when you test drove it? Typically a bearing failure would follow a loss of oil supply, such as extreme cornering or high RPM's when low on oil, or neglecting to change the oil.

[hatefuel66]

Thanks for the input Titus, Yup quite weird, tested the car and it drove awesome. Got the car back from where it was being sold which was about 30 odd miles. Did the standard checks before leaving there. Oil, coolant, tires. I was informed of the infamous power steering leak. Did maintenance a couple of days later. Changed out oil, replaced radiator and water pump. The previous radiator didn't have any issues as such just the bleeder plug was damaged and was rtv's all around it. Changed out trans mission fluid. Now this may be the indicator of high rev's. I drained the ATF out, changed the filter and noticed only about two quarts drain out. Think it holds about 7 quarts normally. While driving it back i didn't notice any high rev's but the car did feel a bit weak. Never had driven one previously so it was quite hard to have a reference of if the car is naturally sluggish or if there is a problem. 1.9l for cyl, To my delight today i went to pull the plugs and discovered that the forth cylinder plug wont allow a spark plug puller to slide over her. Little but frustrating. So I'm going to drive this til it dies and get my hands on a new engine. Will be taking a look at the underside with the pan off. Should have been an indication that the 2nd owner just drove it for 10.000 miles then decided to sell. Excuse he had was he developed skin cancer and the convertible had to got. Never did get to meet him so who knows if that is true or not. Bought an obd reader today and plugged it up and its missing on cyl 3. as long as the crankshaft is not scuffed i should be able to pop in a bearing from underside? Heard all sorts of horror stories. When you get lemons make, ummm lemon juice. Any other alternative engines which could go in a z3, Those m44 with low miles are hard to come by. closest I've seen is 1700 bux for one with 70.000miles.

[Titius Justus]

I have heard a knock similar to this before which wasn't anything typical; it was on a 98 Mustang GT.

On the Ford 4.6 liter V8 that year, in an effort to save weight, the coolant passage was molded into the intake, right next to cylinder #1 port. Well, in the infinite wisdom of Ford, the intake was composite and over time it cracked - in between the coolant passage and #1 intake runner. One day when I went to start it up, it had a knock. I swore it was a rod. It came out of nowhere, and the engine was always well taken care of so I was stumped.
After removing the engine and pulling the oil pan, it was obvious what happened. Coolant leaked into #1, when the piston came up on compression stroke - well, water doesn't compress, so something had to give. That would be the connecting rod. It bent the rod, causing it to pull the piston further down into the block, and interfere with the crankshaft. Every time the piston came down, the crankshaft counterweight were smacking it.

Nice one, Ford.

[BimmerBreaker]

Z3's got M52s, S52s, and S54s. I think an N52 would be cool swap, or at the very least an S52... M44s are lame.

Keeping it slimbody and doing an S52/S54 would be cool

[hatefuel66]

1.9L pretty lame, lol had a friend come in from out of town so hes gone and am back on it. Wel that was a fun job pulling the oil pan! Needed a new gasket anyways. Just scrubbing the heck out of everything and then I'm going to pull the bearings out and inspect them. The pan had no inkling of filings. Though there might be some signs as the oil was changed out and not flushed. Going to try and keep this up to date as there are so many forums with out a conclusion or an ending to the story. Sooo this leads me to my question. While i have the oil pan down I'm going to change out there bearings. Once all back together if its still there what could it be. Basically trying to trouble shoot the issue in advance. Thanks peeps. Going to get the go pro out and shoot video. Nothing on the m44 on youtube...

[hatefuel66]

Right so I got all the way down to the bearings, Obviously I went straight for cylinder 3 :P Not a crazy amount of up and down. Little bit of wear on the bearing shells. No scoring on the shaft. Going to get my hands on a plastigauge and get the tolerances.

[hatefuel66]

Just to give anyone looking at this a thread a heads up, replaced the bearings and am now having an issue with oil pressure. Must add from me looking at the bearings i feel they did not needed to be replaced but went ahead while i had it open with access. So in saying that it is most likely a lifter. Living and learning appreciate all the help that was given on this thread.

[BimmerBreaker]

So lets recall what happened:
Ticking noise
Forum says its bearings, despite no proof of such
You check bearings
Bearings are fine but in the process of checking them they have not been re-seated properly now causing oil problems, probably eventually leading to bearing failure

Like some kind of messed up self-fulfilling prophecy

[hatefuel66]

Lol Reposted on the other thread I started. Rather embarrassing mistake on my behalf. So looks like the bearings are sitting pretty. Had another slip up as well, metallic pinging in time with the motor. This is the point after everything I want to just face plant the wall while shouting obscenities. Just like the oil cap i walk away for a while, come back with a cup of coffee and a smoke and ponder. The pinging was the bracket for the spark plug cables mounted on the side. So touch wood bearings are fine. So I think I've really trouble shot it to the lifters.

[325bob]

I can't fathom how a lifter noise can be changed by pulling a plug wire, which has been a method of diagnosing which cylinder has excessive rod/piston pin wear (a knock)for decades, sorry if is the piston pin ,as that requires head removal. "PINGING" is a term usually use for detonation, which could be that cylinders problem if it has excessive carbon buildup, and,of course would stop with the wire pulled, but is rarely evident at idle.

[BimmerBreaker]

"PINGING" is a term usually use for detonation

What is one person's pinging is another's ticking, is another's "light clunking" ...one can't trust someone's exact vocabulary when troubleshooting over the internet.

[325bob]

What is one person's pinging is another's ticking, is another's "light clunking" ...one can't trust someone's exact vocabulary when troubleshooting over the internet.

Amen, most posters can't spell "BRAKES", and also call "won't start" as "wont crank",lol.

[FuelCell250]

It's hard to make a good judgement call with a YouTube video, but that sounds very similar to my M44 before I tore it down. The noise didn't go away, but it drastically lessened when I unplugged the spark plug wire on Cylinder 4 (affected cylinder) while it was running.

Tore it down, bearings looked fine. I pulled off the head, and the cylinder was all scored up. It ended up being piston slap.

Here's the video if you'd like to check it out. Here's what the damage looked like, and here is how much it is costing me to rebuild it (about $1800 at this point, probably $1900 when it's all said and done).