Knocking / tapping noise

[aevansgatech]

I know this topic has been touched some, but I am hearing a pretty loud knocking/tapping noise coming from the top of the engine. I have seen that a couple possibilities are low oil pressure/level and something internal like a crank bearing. Below is the information I've gathered so far:

Oil Level/pressure
I did do an oil change this spring and put Rotella 15W-40. I have goot oil pressure (55lb running, a bit less once warmed up) and checked the level. I'm wondering if the heavier weight isn't making it to the top end and reaching the cams.

Internals
This is a possibility, but I didn't do any major work on it over the winter and did not have the pronounced knocking beforehand.
If a crank bearing or rod is knocking it would be new
-Note: I have about 97k miles on the engine but it has had timing belt serviced along with other maintenance roughly 5k miles ago.

Other / Environment
It has been a bit chilly this spring, so I haven't had a nice warm/hot day to see if the issue goes away. I'm wondering if the thicker oil and cool temperatures is causing a lubrication issue.

Any other ideas would be appreciated!

[samakijoe]

This is a gadget that will pinpoint the problem. Great for locating bad bearings, tappets, etc .
https://www.amazon.com/Lisle-52500-Mechanics-Stethoscope/dp/B0002SQYSM
It will be the best $10.00 you ever spent...
Lots of other places to get one.

[aevansgatech]

I did notice on the drive home that the noise is greatly diminished (almost gone) once the temps got up to 65 outside and engine warmed up.

So there was a big difference between cold start 35 degrees outside and warm operation 65 outside. I'm pretty sure it's not getting the oil up to the cams quick enough. Weak oil pump? Try going back to a 10W oil?

[djape1977]

check if your camshaft pulleys are plastic. if yes, change them immediately

[76was124]

Hi Andrew,

Some things to check could include: valve clearances, engine knock, exhaust leak, cam pulley bearings, distributor rotor,

The stethoscope:samakijoe recommended works well to isolate where exactly the noise is coming from. You just move it along and touch the various parts until the sound is loudest. A wooden dowel, or large screwdriver held to your ear work too, just avoid moving parts and also avoid the distributor and spark plugs/wires with anything metal.

You can also get a stethoscope for $5 at the local 1 and Done tool store (HF)

[sptcoupe]

You should also consider pulling the cam box covers off (very easy) and check to see that you don't have a worn cam lobe. This is a common problem because of the lack of zinc in modern engine oil.

[spider2081]

check if your camshaft pulleys are plastic. if yes, change them immediately

Just witnessed this on a Spider with less than 100,000 miles on it. The noise occurred most when idling and was kind of intermittent.

[aevansgatech]

check if your camshaft pulleys are plastic. if yes, change them immediately

Just witnessed this on a Spider with less than 100,000 miles on it. The noise occurred most when idling and was kind of intermittent.

Do you mean literally check if the two pulleys are made of plastic? The engine is all original and I expect them to be metal. Maybe I'm missing a reference to something here..

[djape1977]

some twincam fiats had plastic pulleys from factory. this was done for only couple years total. check if your car has plastic pulleys. if it does, loosen the cam belt and you will find one or all pulleys to have play in the center. change for all metal pulleys asap.