Tapping sound from engine...

[abellia]

Hope someone can help with this. When I initially start my car the engine is pretty quiet but once the engine is at normal operating temperture I hear a tapping sound from the engine. I performed a valve adjustment but that didn't seem to work. Although I could be wrong, it really sound as if the tapping is coming from the fuel injectors and doesn't sound like it's being caused by anything metal. I have not read anywhere that fuel injector noise increases with operating temperture. The car idles and drives fine.

Other potential useful info - Car has approx 65,000 miles, have changed all belts, water pump, pulley, ignition rotor, fuel pump and spark plugs within the last year. I use redline 10-30W synthetic oil. Can some please provide some insight as to what may be causing this. Thanks...

 

[nadroj]

Check oil level other than that i dont think i would worry about it, my e30 ticks my freinds e30 ticks .

 

[Big Daddy]

Try some injector cleaner, it could be a dirty injector. By the way you do not mention the model?

 

[abellia]

It's a 325i convertible & I added oil recently & have used Redline S1 cleaner.

 

[epj3]

You will never ever get rid of the tapping sound. It's the nature of the car and it'll only get worse as the car gets older and tolerance become more and more out of spec. These cars have noisy injectors, nothing you can do about it. Dirty or not, they will be noisy. It has a noisy valvetrain, in fact there are a few spots in the valvetrain that can make noise... between the cam and the eccentric (rocker), between the rocker and valve, and then of couse the rocker can be out of spec on the shaft it sits on.

You're just going to have to live with it until you put an M50 in the car.

 

[jrt67ss350]

It's likely entirely normal. The six cylinder e30s tend to have very loud fuel injectors. You've done all the right things as far as maintenance goes, so I probably wouldn't be too concerned especially since you say that the car runs fine. My fuel injectors are the loudest part of the engine at idle, and mine has 300,000 miles on it.

 

[abellia]

"between the cam and the eccentric (rocker), between the rocker and valve, and then of couse the rocker can be out of spec on the shaft it sits on."

Can any of these be fixed without much hassle?? I'm not an A+ mechanic but all of the work stated in my initial post was done by me so I think I should be able to handle it.

 

[emanriv@yahoo.com]

when was the last time you checked or serviced the timing belt , it's possible that it needs replacement,

 

[jrt67ss350]

"between the cam and the eccentric (rocker), between the rocker and valve, and then of couse the rocker can be out of spec on the shaft it sits on."

Can any of these be fixed without much hassle?? I'm not an A+ mechanic but all of the work stated in my initial post was done by me so I think I should be able to handle it.

The play between the cam and rocker and between the rocker and valve are "fixed" by doing a valve adjustment properly. I put "fixed" in quotes because the interface between the rocker and cam and between the rocker and valve are designed to have a certain amount of space between them, and adjusting the valves sets the correct amount of "play" between these parts. The play between the rocker and shaft that the rockers rotate on could only really be fixed by replacing both of the rocker shafts as well as all of the rockers. I believe you have to remove the head to do this.

If your car only has 65,000 miles on it, there is no realistic way the rockers and shafts are out of spec. The valvetrains and injectors on the M20 are noisy - it's just the way they are.

 

[abellia]

I replaced belt less than 5k miles ago. If it was the belt why would the sound differ between hot and cold temperture? Additionally, the noise existed before I changed the belt. The ticking sound can be heard from approx 15 feet when the car is up to temp. I think that's a bit excessive.

 

[jrt67ss350]

15 feet with the hood closed or with the hood open? If you can hear it with the hood closed, then that's not normal.

 

[abellia]

15 with the hood closed. I am now starting to worry....

 

[emanriv@yahoo.com]

yeah mine taps also but i cant hear it from 15 feet away. that's pretty loud.

 

[abellia]

I really appreciate everyones input. But the question I need to answer is why only when the engine is warm. When I first start the car it's fine. I gather from above that I should rule out the fuel injectors. I am going to do another valve adjustment. Slightly expanding metals with increased heat may be causing it (i guess). Any advice or "trade secrets" on making sure I do the valve adjustment correctly?

 

[jrt67ss350]

I don't think this is probably anything to really worry about. Fuel injector clicking usually can't be heard from 15 feet away with the hood closed. Valvetrain noise probably could if it was bad enough, and the fact that the car does it only when hot helps support that.

Rotate the crank clockwise with a socket and breaker bar until the number 1 cylinder (the one at the front of the engine) is at top dead center (both the intake and exhaust valves should be fully closed and cam lobes will be pointing approximately downwards). Measure the clearance between the valve stem and the rocker adjusting eccentric with a feeler gauge. With the engine hot, the clearance should be 0.30mm (0.012 in) and with the engine cold, it should be 0.25mm (0.010 in). If there is more slop than this inbetween the valvestem and rocker eccentric, then leave the feeler gauge in there, loosen the locknut and rotate the eccentric with a small allen key to take up the slack. Then tighten the locknut back down. Slide the feeler gauge out and then recheck the clearance to be sure it's right. That's really all there is to it - no big secrets.

I've read that setting the valves cold is the best way to do it, but if that's not working, then you might try setting them with the engine hot.

 

[equate]

Heat shields

 

[epj3]

Yea it's definitely valves. I can hear an m20's valves when i'm behind them in traffic, including ones I know are in spec. My e30's valves were audible through under passes while going slow speeds.

 

[echothreezero]

Often the valves are noisier when adjusted properly. Some people I know have eliminated the noise by tightening then up past spec and what do you know, a few thousand miles down the track they have worn cams etc and the noise comes back - this time with a power loss due to the cam wear. It's better to have them noisy and adjusted properly than quietly wearing out your cam.