It happens about half the time in the morning start-up mode only. I'd rather hear my 'ol lady nag than that awful sound. (1) I wanna know if it typifies a larger bearing clearance than normal. (2) If it is probably the last bearing to get pressured w/ lube. (3) If I'm losing some bearing material every time it happens. It sounds like one rod only. I use 10-30 dino. It wouldn't be so bad if I could idle at a lower rpm upon start-up. These IAC's seem to be overkill, I realize you can't have motors dying on people when the A/C is on, etc. but I get tired of the constant revving the IAC causes. I put a flat washer in the IAC hose for awhile to tone it down but got paranoid and took it out.
Got a Wix filter, no Frams here. The idle is that typical 1200 rpm for the first couple of minutes when cold, also the typical 10 second lag after higher RPM for it to return to normal idle rpm. It's not constant. Thinner oil could be a possibility. I would like to know the percentage of 4.6's that dry knock. That would let me know if I've got a potentially overclearanced rod journal.
Originally posted by johnaec Amsoil 0W20 synthetic actually has better wear characteristics than their 5W30 synthetic, which has better wear characteristics than Mobil 1 5W30 synthetic. I don't know about Mobil 0W20 synthetic.
Actually, I double checked and that should have stated Amsoil 0W30. Also, Mobil 1 makes a 0W30, but according to ASTM D4172 tests, it has pretty poor wear characteristics: http://www.amsoil.com/lit/g1283.pdf
Note - the above doc is at Amsoil's site - I myself would like to see something more independent.
That said, I'm currently running Amsoil 5W30 synthetic in my Mark VIII and Mobil 1 5W30 synthetic in my T-Bird. 'Can't really tell much difference, even from the switch from Mobil 1 to Amsoil in the Mark.
My 90 with the 3.8 does that. It has 125k miles on it though. I am using Mobil 1 5w30 and the proper Motorcraft filter. I think(like 99% sure) that they have an anti drainback.
Annoying as hell and doesn't do it in the summer or if the temp is over 60 out. It can't be a good thing regardless.
01 F150 5.4L 4x4 and a 98 Mustang GT vert sitting engineless and without transmission or converter