Engine Knock

[Mbl35]

We just had a bedplate put in under warrenty at the dealer.

06 e350 box ambulance. A peice of the bedplate was broke off

were the oilfilter housing bolts to. Anyway when this thing came back like a month later with no reverse lights, oil pressure gauge drops to zero at times and a diesel leak. I repaired the diesel leak-copper fuelline gasket had a nail line in it causing a fine stream. I pushed on the oilpressure switch connector with a long screwdriver and that temporarily stoped the oil pressure gauge from dropping oh AND MOST IMPORTANTLY A HOLLOW SOUNDING KNOCK SOUNDING LOUDEST FROM THE AIRFILTER AREA. It went back to the dealer and they repaired the oilpressure switch/guage concern and some loose brackets

and nissing bolts from the ps pump etc. But now when i came in last nite to find it in the bay with a note saying no revberse lights. It had a check engine light with trans codes and all bank 1 glowplug circuit codes and the knock was still there!

Starting with the no reverse lights problem, verifying the chasis circuit being good at the relay i went to the trans snake at the pcm following rearwood to find the little 2 pin connector that connects to the engine harness unpluged-ok checked it and rev lite problem fixed. On to next concern-or should i say problem...glowplug, i see the glowplug harness connectors have a shitload of tape wrapped around them. Also bank 1 glowplug harness is installed backwards.

Now being so irate-i snake my hand from the rear of the engine

and unwrap the tape and yank the glowplug harness out and rnr

, glowplug test proves out-fixed. On to next problem-transmission, i inspect wiring down to trans main connector at trans to find a caves in pin and so flattened that i did'nt attempt to straighten it. I rnr inner trans connector harness and test drive 25 miles all Pass-runs like new now EXEPT(sorry for the long rant but i'm pssed off man)FOR THE

KNOCK AT IDLE! I also checked for loose crankpulley bolts etc.

and all are tight. The dealer said to remove the brakebooster

vacuum line and see if it goes away, i did that and not likely. That knock was not present before the bed plate repair. Though i would like to know if anyone has experienced a knock like this from the left front of the moter and i t seems to get louder the longer the engine idles.

[Bruce Amacker]

My experience with a knock coming from the air filter has usually been valvetrain related: valve tip trashed, rocker broken, crosshead, seized guide, etc. How's the balance graph and IDS compression test? How about killing the cyls one at a time and see if it changes? I might suggest an oil analysis if nothing else checks out (Napa/Wix 4077, $14). The scope wizards would use a pressure sensor in the intake manifold to graph out intake manifold pulses, indicating a mechanical problem but I've only done this a couple of times. The sensor is called First Look.

 

AND MOST IMPORTANTLY A HOLLOW SOUNDING KNOCK SOUNDING LOUDEST FROM THE AIRFILTER AREA.

 

Good Luck!