another engine knock

[fixitall]

I have a 2000 passport, started engine on a cool (40 deg) morning to find a loud knock, no previous warning, oil full. checked and found posts refering to timing tensioner, removed timing cover and inspected, everything looked good. pulled tensioner and checked seemed very tight. Decided to replace tensioner belt and water pump. I used a Honda pump and tensioner and Goodyear belt. installed it and noise seems almost louder than before. Knock is pretty consistent, when you rev engine noise will cut in and out, thats why i don't think its a rod bearing. Checked oil pressure with mechanical gauge, a good one, and have 40 psi at idle cold. Put a stethescope on it and sound is loudest at tensioner. Any idea's?

[Ramblin Fever]

Did you use an OEM tensioner and timing belt? If not, you may be off a tooth and/or perhaps the tensioner is bad....it can happen.

[amigo-2k]

Did you try to run it with the S-Belt off to narrow down the sound? It could be the S-belt tensor.

[Cat Fuzz]

Are you sure you replaced the tensioner and not the tensioner pulley? The tensioner is a hydraulic piston that is pressurized. If you took off a good tensioner, you would have needed a vise to recompress it for installation.

[amigo-2k]

Cat Fuzz is right, I watched the Isuzu video on how to replace it and it shows using a vise.

[fixitall]

Right now it doesn't have the front cover on it, i bolted on the balancer and ran it to try and track the noise. I did replace the tensioner, or hydraulic pusher as Honda calls it, I did not replace the tensioner pulley or bracket, but i did remove the bracket pivot bolt and cleaned it, made sure it fit well and rotated smoothly. I double checked the timing marks, one source from this website and from alldata, i'm sure they are right as it runs very well. There is no serp belt on it right now and I just ran it a little while ago. It sounds like one solid single tap per rev at idle, when revved it almost sounds like multiple taps. The noise almost always goes away right when you let off after revving, and when you hold steady at any rpm off idle the knock stops for a second intermittently. the noise does not go away as rpm increases, I took it to 3500 and still knocking. Has anyone here seen one or more of the cam followers collapse completely making a loud tap or knock. This is not the typical lifter noise these make, i've heard lot's of those. the trucks only got 90k on it and runs good.

[amigo-2k]

You may want to post this on http://forum.planetisuzoo.com/

There are a couple of Isuzu techs there that would weigh in.

[fixitall]

Just pulled the pass side head and found piston was hitting cyl. head. Looks like bad rod bearings. Time to pull it and rebuild it.