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The Miser's Noisy Engine Cure? by Mark(The Miser)UK on 05 Nov, 2013 19:45
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This is the engine that survives despite my non conventional maintenance techniques. It was not quite so noisy when I first had it, but then the lower engine shield hadn't disintegrated then.
The problem with these engines; is that at idle they are able to vibrate different individual parts of the car at different frequencies or positions of the mounting brackets, from rear seats, rear doors, front doors, ash tray, tool box, front bumper; need I go on?
After peeling away the valve clash noise with a new head, I was left with this:
http://s1329.photobucket.com/user/Quantum-man/media/IMGP2506_zps61449767.mp4.html
Previously,
I rebuilt the injectors to a tighter spec, but that didn't seem to help...
Having ruled out injectors, by coasting down hill in 5th gear and at least some of the noise remaining despite fuel turned off, I then rebuild oil pump, and more recently Plastigauged the big ends, and checked the small ends.
All good, and so not replaced despite having the parts to hand.
It was a few weeks ago that I had an Eureka moment whilst lying in bed:
Could the trouble that seemed concentrated around #1 cylinder be due to the 'new' rings bedding in?
The frequency analysis, showed that the noise repeated every two rev. Syncronizing the video to a separated sound track, I was able to confirm that the noise was on #1 compression stroke @TDC, with some noise on#2 TDC....
The pic below is split screen of before 'Dremmel grinding of 'ridge' underneath, and after grinding above.
Both shots have been aligned so that the first peak being #1 cylinder.
Note that I only had time to grind and clean-up #1 and #4 bores, because I was working outside and we were due to have a storm by 3pm, and the head only came off about 1pm.
They are also not fully ground as light was bad. I thought what I'd done was sufficient to see if it was a cure for some of the engine knocking...
OK at first inspection I appeared to have made things worse.
It did seem to sound quieter, but I was going down with some mild flubug, so I could have been going slightly deaf.
Closer inspection of the two wave forms, led me to believe that the upper one was an improvement, but it was hidden because of auto volume levels... #1 noise had shrunk. relatively. Look closely at the second peak which is #3 injection. Now look at the wave form corrected below:
YES!Three different members of my family that I have visited have said that car has quietened down including my biggest critic of me and my car; my daughter!
I may soon take head off again and finish the job.
It's 3.30am, so I'm off to bed
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#1 by vako on 06 Nov, 2013 02:34
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my engine also had some excessive noise from the day i installed it in the car.... now when i tore it down i found that all the cylinders had ring wear and there wawe serious ridges on the top of all cylinders. i had to remove all the pistons using light tapping of a big hummer from underneath. but n1 cylinder was the hardest to take out... it needed few serious punches to be taken out. now i have rebored and installed new rings and pistons all round. hope noise levels will be decreased a bit
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#2 by 92EcoDiesel Jetta on 07 Nov, 2013 07:55
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Advanced way of looking at noise! Can't do that with a Stethoscope.
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#3 by smutts on 09 Nov, 2013 06:00
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I've used a freeware program "visual analyser" by sillanium software, which turns the computer into an ocilloscope, to do similar things, but depends on your soundcard. But with a decent microphone it can be very handy trying to work out when things are happening in the engine cycle. Also it is a fun toy, but I've found it takes a while to get the hang of it.
I'm enjoying Mark's habit of not taking things as gospel, also it is fun, now where did I put the popcorn?
