doabarrelroll

Definately rod bearing noise. Change those bearings NOW or you'll be regretting the purchase of the car itself! This type of sound killed my 16v engine.

Yarf

Have you performed a compression test?

whalebird

Any metal shavings stuck to the drain plug magnet at oil change?

St3mpy

I have not performed a compression test. And to be honest, I didn't even notice a magnet on the drain plug.

I think I may have access to compression testing tools, I may do it within the next couple of days.

944Ross

Not to start the flame game, but you need to run 20w50.

Rods knocking make a noise twice per revolution. Lifters are once per rev. Here is a good example of rod knock: http://www.youtube.com/watch?v=H1_goqYytHU

St3mpy

I ran the car with the cam tower plugs off. The cam looks like it's getting plenty of oil. Obviously I can't see the lifter galley, but when I had the cam tower off I made sure it was clean. Does the lifter galley have different oil feed port than the camshaft?

I also took a video using a PVC pipe against the open ports. Against the 2nd plug from the rear the noise sounded loudest, but it didn't seem like it was coming from the cam tower itself. It's starting to sound like my knock is in the head somewhere. When playing the video in slow motion, it's easy to single out the knock sound. In slow motion, it sounds almost like a "gallop" sound, as in "tap TAP, tap TAP, tap TAP". The problem is, I don't know how acurate the camera's microphone is in slow motion.

Anyways, that's the only update I have for right now.

St3mpy

Ok ran a compression test today. The rubber plug was worn, but this should give a general idea. The numbers are 140 140 145 140 give or a take a couple of psi due to blow-by. I used a stethoscope, and it definently sounds like it's coming from #3. The tap was loudest when pressed against the intake manifold.

Any thoughts? Do you think it could be a weak valve spring? Its hard for me to feel for valve float when this is the only 944 I've driven.

St3mpy

Just an update: I took my last final today (yay!) so, some time in the next few days I'm pulling the engine and hopefully get to the bottom of this! Question: How far forward does the engine need to move to clear the torque tube? I don't have a hoist anymore, so I'm going to try to use my support bar to lower it down instead.

John_AZ

Congratulations of finishing finals.

Just a couple of thoughts.

If the cam housing scored your lifters, why put good used INA lifters in a bad cam housing?
Cam housings are cheap on ebay or elsewhere. Maybe $50.

Next, your compression numbers seem OK. Did you remove the DME/Fuel pump relay when you did the test (per Porsche). If not, your numbers may be a little off with the gas washing the cyl walls.

I agree with all the previous opinions.

GL
John

Tedro951

I think I read where you pulled the inj connectors, but try pulling the #3 plug wire off the dist cap or plug and see if it changes.

pnbell

Ok Congrats on finishing up your finals! Now get to the bottom of this for me!! HA HA

As I said a while back, I have replaced:
Lifters, Rod Bearings, Exhaust Gaskets, and had no change in my similiar noise. Mine seems louder sometimes, and quieter others... inconsistant.... at this point i am just goin to wait for my car to BLOW UP, and then fix it!! ha ha

But Seriously, i hope you find the problem as it may shed some light on mine! Good Luck!

St3mpy

I actually did buy a new cam housing off eBay for 25 bucks (cost me more to ship the thing), so that will go on when I pull the engine. My power steering rack is leaking, so I bought a used one off eBay as well. That's one of the reasons why I decided to just go ahead pull the engine, by installing a new rack I'm already half way there.

And to answer your question, no I did not pull the injector plugs. This was my first time doing a compression check, I should have thought about that. I'd imagine my numbers are actually higher.
I'll keep you posted!

St3mpy

Just an update, I pulled the engine this morning, although I had to drive back up to Auburn today and will be up here/around Atlanta until Saturday. When I get back I'll clean and disassemble the engine and figure out what it is.

In case anyone is curious, using the support bar to lower the engine worked fine. I used an old strut bearing placed under the "turn handle" to ease the friction. I'm not sure how well that setup will work to raise it back up though.

St3mpy

Ok, so I got the engine on the stand today (took 2 guys to lift it) and started tearing it down. At first nothing struck me as obviously wrong. Then closer inspection revealed that the intake valve on #3 is gunky, while the rest are clean. I haven't removed the valve yet (not quite sure how I'm going to do it), but at this point I'm thinking either bad valve spring or bad valve seat. If you look at some earlier post, you'll see that the noise was loudest at the #3 intake.
One thing that gets me is how are my compression numbers good? It must be a slight leak that only arises during combustion.

I'll post some pictures in a minute.

So far I've removed the head, I'll get to the lower end once I figure out why this intake valve is dirty.

Here's a link to the album: https://picasaweb.google.com/St3mpy/...eat=directlink


Here is the gunky Number 3 intake valve:



And the rest:
Number 1:



Number 2:



Number 4:

St3mpy

90% Sure I found the Problem!!!!!

And the verdict is....














Bent intake valve on #3!
I pulled the valve and chucked it in my drill. Sure enough, there was a slight wobble. I did spin another valve just to make sure my drill was true.


I said Solved-ish because obviously I won't know until I get it back together.