That's a really sensible idea... the passenger side timing cover comes off without too much hassle, would be worth pulling it off to confirm belt is tensioned correctly
Yes. I've just had the covers off to replace the cam gears (since I originally thought that was the problem. So had the timing belt off for that. Edit: If it had failed, why would it cause that sound?
I had a similar sound when mine failed, I guess it has something to do with the belt flapping around and not having enough tension on it putting odd forces on the idlers and cam gears etc.
Exhaust Valve Cover removed...more photos.. As the inlet valves cover removal proved unrevealing I moved on to the exhaust valves.....nothing there either (see below). A broken valve spring has been suggested, any thoughts on that? Engine seems to idle smoothly.
Update.. After a prolonged break from working on the car and a heap of annoying hold ups I've finally got around to getting a leak down test done. The results were consistently around 10% which is what would be expected from a newly reconditioned engine. So I guess that now points me to a deeper place in the engine.....Anyone know of anyway to test for a failed bearing? I guess I could drive it for a while longer and when it finally lets go, and then I'll know for sure
Someone else may chime in but I believe this eliminates excessive piston bore clearance as well. Something has come loose in the bottom end...
Just had a listen to that video Marcus, and that sounds like pinging to me. Double check your timing.
Sometimes if it is valve related you can hear it out the exhaust from the back of the car. Maybe get someone to listen at the back while you rev it. Also what about putting the car up on ramps and listen with a stethoscope to the sump area. Could the sump have been dented ?. Cheers Dave
Timing is good Graham. The noise is also louder now than when I took the video. It's a bit hard to reproduce the sound accurately with a phone video. It's a very clear hard tapping sounds now.
I'll check the sump Dave, but pretty sure there's no damage. I will check with stethoscope next time I have her back together.
Have you dropped your oil Marcus? Also do you have a magnetic sump plug by any chance? If you have spun a bearing your oil will be full of metal bearing/conrod/crank combo easiest way to know.
Tap, clack or knock? They are very different. Left or right ? front or back? Use a piece of garden hose up to your ear will help to locate the position. Tap sound - usually a lifter. Check the grade of oil or longish run in the car will sometimes clear. Clack sound - empty lifter or little end, maybe broken valve spring knock sound - (deeper tone to a tap) usually bottom end Left or right predominate position of the sound indicates heads Central indicates block area. Your initial video the sound came in under load/revs. Was it still there at idle? Is it now there at idle and gets louder with revs? what is the speed of repetition of the sound? eg every time a piston goes up/down or slower like a lifter Diagnosis of sound via text is very hard. I hope some of these thing can help locate what we are looking at. what ever it is it sound like a tech day coming up for an engine pull.
Definitely the next step Matt. I do have a magnetic sump plug so should see something there. I'm assuming there is still a "sliding scale" of failure? What I mean is this engine still idles quietly, and then knocks on acceleration. Might this be what I would expect to see early on before massive failure?
Somewhere between a clack and a knock . It seems to be coming from the front top of the engine, but I think I've excluded most of what would be the prime candidates. Not the VTC gears or timing pulleys....cant see any problems under the valve covers. Leak down test showed sound compression?? Running out of bits that can make that noise......unless I look deeper. Dropping oil next to look for metal.
Been thinking about this. This sound isn't unfamiliar. I have heard it in a few vg30's. I have never actually found the cause. But the engines still run fine. I wonder if the vvt oil valves at the back of the cams are opening under oil pressure when it revs. So either too much oil pressure, or the oil valves springs are screwed. Just a guess I spose but sound feasible.. Have you checked the oil pressure? maybe too high and relief valve is stuck closed. Could cause vvt springs to be over powered.
If you still have the cam covers off, check the lifters for cam slap. Turn the motor over by hand to get each cam lobe pointing away from the lifter. Use a screwdriver to push on the lifter. If the lifter is ok (full of oil) you will not be able to push it down with out a LOT of force. If the lifter is faulty it will feel spongy. Lifter should remain in contact with the cam at all times.
I appreciate the new ideas. Been at this diagnosis for a while now and I suspect it will end up being a big end or something equally as sinister, but I really want to be sure before I go to the trouble an expense of an engine pull/replacement (when I've done that twice already in the last couple of years). The oil pressure (as per stock gauge) starts at about 74% and drops to almost 0% when hot at idle. Engine noise is about the same hot or cold engine. Re: "vvt oil valves" I'm not familiar with these. I'll check the FSM. Now that I have all the timing gear back on and the leak down has been done, I'll also try cranking it with the plenum off to try to hear better where the noise is coming from. Maybe it will be easier to pin point that way.
