Trying to Diagnose a Ticking Noise that won't go away.

[SixerFixer]

I recently got my E30 on the road, and have been trying to diagnose a tick from what I believe is the top end of the engine:



Work I've done thus far to try and remedy the issue:

Timing Belt/Water Pump Replaced (timing marks line up perfectly)
Valve Adjustment (0.010in on cold engine)
New Valve Cover Gasket
New Exhaust Manifold Gaskets (manifold to head)
New Intake Manifold Gaskets
Rebuilt Injectors
New Vacuum Lines & Fuel Lines
New Spark Plugs (Gapped to 0.028 )
New Ignition Rotor

I haven't changed the plug wires or distributor cap, as they looked OK, but I ordered a new cap just to be safe. I also ran a compression test, and the results looked pretty good:

Cylinder 1: 162 psi
Cylinder 2: 170 psi
Cylinder 3: 170 psi
Cylinder 4: 170 psi
Cylinder 5: 170 psi
Cylinder 6: 170 psi

The compression difference on Cylinder 1 is so small that it didn't raise any red flags for me.

The sound appears to be coming from the motor itself, but just to rule out an exhaust leak, I ordered a set of exhaust manifold flange gaskets just to be on the safe side. The car runs great, and the motor makes excellent power, so I am at a loss. Any ideas? :)

[jlevie]

Your compression test results look great. A leak down test will tell even more.

In a case like this I'd use an automotive stethoscope to pinpoint the source of the noise and go from there.

Not trying to scare you, but a while back I diagnosed a car with an apparent tick from the top end that turned out to be a bad rod bearing. The stethoscope made it obvious that the noise was actually from the bottom of the engine. So it can be hard to tell where the noise is coming from by ear alone.

[SixerFixer]

After putting a stethoscope to the bottom end, I can confirm that the bottom end is quiet. I popped the oil cap off and put the stethoscope on the rocker arm shafts, and noticed that the intake side is WAY louder than the exhaust side. I am almost positive that the noise is coming from the intake side, likely from cylinder 1. I did a valve adjustment a while back, and cylinder 1 was in spec. Trying to diagnose this tick, I checked the valve clearances again, and they were still in spec. Could it be a bad rocker arm? I've never heard of them going bad without actually breaking.

[jlevie]

A worn cam or worn valve guides can be noisy.

[SixerFixer]

I never actually had a look at the cam (thanks for the idea!), so I had a quick peek while the valve cover was off. The #1 intake lobe has probably a 1/16" groove worn into it (!!!!), and the rocker arm has significant wear on it as well. I think I have found my issue!

Thank you for your advice, jlevie!

[ahlem]

Look carefully at the rocker pads to see if any have worn to a convex shape.
If so, they have a tendency to tick.

[jlevie]

I never actually had a look at the cam (thanks for the idea!), so I had a quick peek while the valve cover was off. The #1 intake lobe has probably a 1/16" groove worn into it (!!!!), and the rocker arm has significant wear on it as well. I think I have found my issue!

Thank you for your advice, jlevie!

You have found what is probably a major contributor to the noise. If not too badly worn the cam could be reground and blue printed, but a used cam in good condition is going to be less expensive. I suspect that probably all of the rockers need to be replaced and you need to make sure that the oil spray tube is delivering sufficient oil.

The spray tube could be plugged or engine oil pressure could be lower than it should be. The spray tube can be removed and blown out (or replaced). Temporarily replacing the oil pressure switch with a gauge will tell what pressures are being reached on a hot engine while driving. I get concerned if I don't see at least 10psi/thousand rpm.

[rock141b]

Had the same problem with my 88is ticking would not adjust out, so I pulled the head and found 2 worn cam lobes and thus 2 worn rockers. Had the cam redone plus two new rockers and all is well hope this helps.