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Posted by: atmadsen914 Dec 28 2008, 11:06 PM

I recently rebuilt a 2.0/4 motor and installed it in my 914. After getting many fuel system issues sorted out I finally was able to drive it a few times but after about 150 miles of driving. It developed a knock. I readjusted the valves and the knock seems to get better but never goes away. The knock is audible from idle to about 1500 rpm then smoothes out. When I roll the motor over by hand I can hear a knock on every cylinder.

The motor is basically stock with the exception of a web cam (73 grind).

I am about to pull the motor and start disassembling as the sound does not seem good. However after many hours of tinkering has not gotten worse.

Ideas? or do I just get to do it all over again?

Posted by: McMark Dec 28 2008, 11:56 PM

Slight valve/piston contact is a possibility.

Posted by: Jake Raby Dec 29 2008, 09:50 AM

Sounds like a worn lifter bore... OR the camshaft thrust bearings are zapped.

Or a couple hundred other possibilities. Get a video of the sounds and post it, I can probably diagnose over the net.

Posted by: Cevan Dec 29 2008, 10:02 AM

Well, you can't beat that for a response.

Posted by: 2-OH! Dec 29 2008, 01:47 PM

Same problem here until I realized...A. I used a 1.7 distributor and, B. Once you go to the Webcam 73, you can no longer use the book timing...

Make certain you have a 2.0 distributor and experiment with the timing until you loose the knock...Timing is a tricky thing so watch your temps...

2-OH!

Posted by: Brett W Dec 29 2008, 03:49 PM

If it is a mechanical noise, could be contact between the cam gear bolts and the oil pump.

Posted by: Phoenix 914-6GT Dec 29 2008, 03:52 PM

Glad we have people like these to help with this Hope between the powers that be you will get this licked

Posted by: atmadsen914 Dec 29 2008, 08:50 PM

Thanks for all the responces!

Jake I might take you up on sending over the sound. I will pay for the service of cource. But before I do that. I did use a 1.7 distributor. Is that an issue? And and I set it at the stock timing. Should I adjust that?

I relize this is like diganosing cancer over the phone.. in the dark.. with a bad conection.

Thanks for your help everyone.

Posted by: atmadsen914 Dec 29 2008, 10:03 PM

Here are two clips of the idle. 2nd has two revs in it. (they are the quiet spots) Notice as I shut it down it seems to be very loud.
Timing seems to not effect the sound.

Thanks again.


Attached File(s)
 clip2.mp3 ( 121.53k ) Number of downloads: 234
 clip1.mp3 ( 102.15k ) Number of downloads: 162

Posted by: brant Dec 29 2008, 10:33 PM

Ouch...

if that diesel sound is your knock then I think you had better not start it again.

I however am no expert what so ever...
still that sounds bad..

bump for Jake's expert ears

Posted by: atmadsen914 Dec 29 2008, 10:49 PM

My thoughts exactly! I assume it needs to be disassembled. I figured I would ask before I started over. Practice makes perfect.

As an FYI. I am using a mega squirt system and adjusting the idle mixture seems to make some difference. I assume at this point that this is a coincidence.

Posted by: Brett W Dec 30 2008, 01:41 PM

Pull the valve covers off and look at the rocker arms before you drop the motor. Look for anything out of the ordinary. Otherwise it is time to pull it apart and see what you see inside the case.

The dizzy won't make any difference in this case.

Posted by: Cap'n Krusty Dec 30 2008, 02:27 PM

You put the pistons in right side up? The Cap'n

Posted by: SGB Dec 30 2008, 02:44 PM

exhaust is tight? Those valves are RIGHT THERE at the exit from the head. They actually do go "tapitty-tap" in a distinct metal to metal way that is essentially muted by the rest of the exhast-
BUT-
If it does this on rotation by hand, there is something mechanical going on.
Did the rockers go back on OK? Sure those pushrods were seated when you set the valve adjusty?

Posted by: atmadsen914 Dec 30 2008, 04:34 PM

I wondered about this. As part of the project I installed a set of headers. They are very dificult to get tight. (angle of the bolts) So I am not 100% that they are tight as the need to be. Will that give you a for lack of a better description a dieseling at idle?

Because at speed the motor sounds perfect an builds good power.

Posted by: atmadsen914 Dec 30 2008, 04:35 PM

Rockers look perfect and have been holding adjustment perfectly.

Posted by: Mark Henry Dec 30 2008, 04:36 PM

What was the end play?
Keep rolling it over as you take it out and tear into it, just in case you get lucky.

Posted by: atmadsen914 Dec 30 2008, 04:37 PM

I sure hope so.

Posted by: atmadsen914 Dec 30 2008, 04:49 PM

My current theory is actually endplay. I fear the flywheel bolts have loosened. (I was not the one who installed them). As the sound seems to be very similar to when you roll the motor over on the bench without the fly wheel attached.

I have no play however on the front side but it is difficult to test with the motor in the car.

Just a theory at this point.

Posted by: brant Dec 30 2008, 05:41 PM

not questioning your abilities at all
but how was the end play when you first built it?

I had one with loose end play that I decided would be "good enough"
it was on the outside edge of the specifications
it broke the crank shaft in two
had a horrible knock at idle and deceleration
but under load the crank halfs would catch each other on the angled split and the noise would go away...

I hope thats not your situation but how was your end play specs when you did your build?

brant

Posted by: cwpeden Dec 30 2008, 06:08 PM

Don't mean to hijack, but this may shed some light...

I had a similar noise on one motor and someone described it as 'piston slap'. Anyone heard of that?

The motor was swapped out for another and never run again. Never diagnosed.

Posted by: atmadsen914 Dec 30 2008, 07:02 PM

It was .005 my book says .003 to .005 is ok.

But you never know. It is coming out Thursday. I will post what carnage occurred.

Then sell the parts and buy a motor from Jake.

Posted by: 2-OH! Dec 30 2008, 10:35 PM

OK, pull it if you want, but I had the same exact noise and problem...

Here's what I did to correct it:

1. Make certain the distributor is in correctly (which ever one you use)...Haynes manual...Mine wasn't

2. Make certain your spark plug wires are in the correct firing order..Mine weren't...

These two things will produce the noise you have...

3. A 1.7 distributor will run it, but with the Webcam 73, it will ping and Octane knock under acceleration...2.0 works wonderful...

4. I am still experimenting with the timing but I estimate it will be perfect around 13 to 15 degrees @ 3500 RPM, red line (27 degrees BTDC), engine warm...

5. Webcam will make it hard to idle...I ended up with a small orfice to create a planned vacuum leak...She idles like a rock @ 1100 and has wonderful torque right up to red line...Love that cam...

Good Luck !!!

2-OH!

Posted by: Brett W Dec 31 2008, 09:10 AM

Check the fan, but it sounds like it is flywheel, rotating assembly related.

Posted by: atmadsen914 Aug 8 2009, 08:26 PM

So over the last few months I pulled the motor took it most of the way down. Everything seems fine. Lifters wear is good. No lose rods. No piston slap. Compression is at 8.75:1. Put it back in fired it up and yet sound is still there. Idles like a drag racer. Loud and clacking. Above 1800 she runs just great. Seems like it was missing a little before (based on carbon on cyl # 2) but that seems licked. So I am pretty much back at square one.

Ignition seems like a good next step. What is the best way to go for a 2.0L distributors?

Posted by: norustscott Aug 10 2009, 10:07 PM

really, nothing loose or out of spec...wow ignition is unlikly, it may cause some pinging but what we hear is clunking and clatter. mechanical interference of metal parts.