Early 944 Interesting Engine noise?

[ParkerY]

Hi everyone,
My 84' 944 has picked up this engine noise recently. It almost sounds like a knocking noise but noise intensity does not go up when I rev up the car.



https://youtube.com/shorts/s9NPcyCt25c

I have uploaded the noise on youtube. My guess is I need to change the Camshaft's cheesehead bolt? Was wondering if anyone had a similar issue.

[Slam]

Did you reuse that cam bolt? If so, yes, it's backed out and that sound is your rotor hitting the inside of the cap. The cam bolt is a one-use torque-to-yield bolt.

[Jfrahm]

Does the frequency go up when you rev, just not the intensity?
It sounds a little bit like lifter tick but could be the ignition rotor, I've heard that knock with a misaligned cap.

If it's sat a long while it might be lifter tick.

[Monkey Wrench]

if its not the cap maybe pull the plugs and turn it by hand to see if you feel anything?

could the cam be mis- timed and the valves touching pistons?

would looking in through the plug holes reveal any tell tale marks on piston tops?

if a cam lobe is gone that might make valve adjustment change but others here are more experienced with the valvetrain adjustments

draining the oil to have a look for metal could be easy enough, if it all looks good and clean and doesn;t ned changing then maybe just refill with fresh and skip the oil filter swap if its ok,

a magnetic oil drain plug is a good idea, and probably not very expensive. I put one in my old volvo and it does catch stuff, I remove the magnet from the dibit in the plug and clean it on each oil change it gives me an indication. last time I was a bit suprised how much fine metal debris it caught. I hqve a lathe so I could machien a little dibit for a small rare earth magnet maybe but you can just buy them I think.

you can stick magnets to the filter if you like then move them when you do a filter change, if you remove them before it may suddenly release a bunch of stuff. you cant really see what it catches very easily.

im cleaning a machine right npw, unrelated, a pipe threader, the oil pump is clogged with metal.

I use a plastic bag over my magnetic pickup tool then i can poke that around, see what it collects then remove any metal it attracts by simply removing the plastic baggie. then im not trying to pull fine metal dust from the magnet itself. maybe not so helful here but its a good trick. you can put one into a bucket of oil to see what it attracts. if a cam lobe went south you might detect metal in the oil let it settle than fish around the bottom with that. if no nmetal great , if you find very much its a sign of something bad that needs to be adressed.

I made one up out of a hunk of solid core house wire with a good magnet taped to the end, its bendable and helps even for dropped fasteners. I can coil it up and put it in my toolbox. that will go places where the radio antenna tyoe of tool won't bend into. handy and cheap. ( like me ;-)

[Stoneguy]

I had a noise like that a while back. Remove your power steering pump belt and run it. See if it goes away. Mine was the pump. I have since rebuilt it and it's all good. Hard to tell where it's coming from in a video.

[Monkey Wrench]

probably not this but I had some noises from a waterpump bearing in another vehicle, they tend to go unnoticed until the thing gushes, and then you are stuck somewhere, pulling belts off will elimiate that too. and give the WP pulley a wiggle and a roll to "feel" the bearings maybe?

it sounds like a deisel in the video. maybe valvetrain clatter? the sound seems to relate to the engine RPM , to me. if it seems to be coming from there maybe get the gasket and remove the cover. a mechanics stethosecope might help or the screwdriver to the ear trick or put a clean 1/4" hose in your ear and listen through that at vearious places.

if you stand and listen to the frequency and also look at the while labels ont he belts you might see a relationshop between the belt's rotational frequency itself and the sound, sometimes that helps to tell if its related to the belt, check if thebelt is "slapping" sometimes new belts have a bad joint and then they wiggle and slap about. Ive seen a few lately that I put on and then removed and tossed aside because of belt slap. manufacturing defects. the belts run at a differrent RPM than the engine, but their frequency is related to the engine RPM

ive seen engines that had a hydraulic tensioner that sound a lot like that until the oil pressure is up. chain slap maybe but its not using a chain. still you might check oil pressure?

I think ive seen 944 posts where rad hose touched the fan and it cut the hose and gushed I guess after they had replaced the hose. If I remember right it had rubbed and cut the hose.



I dont think its an exhaust manifold leak but theat can make a sound perhaps similar. to me it sounds like a metallic knocking sound. anyway if so you might feel a little "wind " bnear the gakset if it is leaking ( when not too hot)

Im guessing the engine can be run for a short time with the valve cover off, but Im unsure. it may splash a little or maybe there is reason to not try that. with the cover off , if it is the valvetrain it may become obviously louder. others might know if thats possible.

let us know what you see, maybe the distributor as first noted. Just some guesses. im curious what it is.