Hello Scotty and community, I have a 2005 Mazda MPV 3.0 v6 (Duratec 30) Automatic with 200K miles.
I replaced the timing cover gaskets as well as the timing chain tensioners. now when I turn the engine over by hand it makes a clunk - clunk noise.
I checked the timing as the service manual says, and the marks on the gears match up (as far as I can tell).
I also checked the combustion chambers with a bore scope, and I didn't see any contact of valves with the pistons for all 6 cylinders.
Here is an audio recording of me turning the engine over by hand (with the spark plugs removed).
https://www.youtube.com/watch?v=m2PcV6zsgPc
I did a compression test (with a weak battery and a junky tester which kept popping out) here are the results:
Cylider 1 : 135 psi
Cylider 2: 149 psi
Cylider 3: 134 psi
Cylider 4: 169 psi
Cylider 5: 131 psi
Cylider 6: 169 psi
With that much compression there is no way that the valves are bent.
The noise seems a lot quieter after the test:
https://youtu.be/9ZVDl9MTaXU
The Car runs and runs well.
Thank you for all of your help and dedication, sacrificing from your time to help.
You said you replaced the tensioners but you didn't say if you replaced the chain and the guides. Most tensioners operate with spring pressure and oil pressure.
If you're 100% sure that the pistons and valves haven't made contact then I'd recommend installing a full timing kit.
I'd guess that it's very hard to find what maybe causing that noise, and I personally do not know what sounds an engine should be making before it's first startup when you only replace the tensioner (DEFINITELY would not start it).
As @Doc has said, the tensioner use oil pressure to push the chain, and as I understand it, as it's an old chain that's probably already a bit stretched the tensioner may not be able to tension it using only the spring. But I could be wrong, this is nothing more than a guess.
I only replaced the timing chain tensioners, as I didn't want to mess with re-timing the engine. I was thinking of doing a compression test, as if the valves are bent the car is basically totaled anyway, and if there is no compression it will verify the prognosis.
If the compression test results are good (And I'm unsure cause there's quite a bit of variance, not enough to indicate bent valves - but probably enough to indicate quite a lot wear and tear), then I'd just replace the rest of the timing kit. I think it's almost certainly a timing system noise...
To me it sounds like the tensioner isn't installed properly and or it's skipping or jumping at top of stroke. Car worked before you did it? Triple check everything is in time. Make sure the tensioner is installed properly and adjusted accordingly. Remember if it was fine before and is doing after you messed up on install.
The car worked before the repair.
I torqued down the tensioners with a torque wrench and they are holding the chain.
My thought is that they need oil pressure to extend perfectly. But I'm not sure.
Almost sounds like the chain is "catching" on the edge of the shoe tensioner (if you replaced the chain guides) and flicking it!!
I only replaced the tensioners, since I didn't want to mess with re-timing everything. I used zip ties to keep tension and cut them afterwards.
When doing a timing chain, you are supposed to replace all the components in a kit, not just one part. At 200K miles, the chain is probably stretched beyond the capability of the tensioners and guides. It should have been changed at around 100-150K miles.
OR is the cover installed wrong? Sounds like the cover could be getting caught.
It makes the noise without the cover installed as well