possible rod knock?

**woggin** · 10-12-2009, 07:43 PM

heyas,

just wondering a few thing regarding rod knock, motor in question, 7mge

it has a slight knocking noise at idle, and anything below that, but above idle it doesnt 'knock' have read that it usually knocks til 2.5k or so, but this one only does it under 1000rpm, does this sound like the usual characteristics of rod knock or not?

The car had been sitting with a full sump of oil for about 3 weeks, then once we turned it on, we could hear this faint knocking noise, when under load(in gear and on the brake) it knocks, but as soon as you increase rpms above 1000 it goes away??

i dumped the oil, filled it up with clean stuff and it went away for about 10secs, then returned, the motor is quite noisy so its hard to hear exactly where its coming from!

thoughts?

thanx
wog

**Jin~Jah** · 10-12-2009, 10:20 PM

Since it's a 7m, it's definintely possible! if you've got a digicam, maybe post a vid of it running.

if the engine's not in top condition anyway i'd say drive it for a while and see if it gets worse.. it'll probably need some work soon anyway

what car is it in?

ed · 10-12-2009, 10:45 PM

best way to define rod knock ive found is to get the car driving, and find that point of 'no load' and see what happens.

by 'no load' i mean not acelerating or engine breaking, but the null point between the two where engine and gearbox are perfectly speed matched. if its noisy right on that point, and quiet on either side, its prob a big end

cheers
ed

**woggin** · 11-12-2009, 07:04 AM

its in a mx83, that seems to have been driven across australia without an airfilter, the entire motor was clogged full of shit, the PCV system was clogged from where it becomes metal pipe at the rocker cover all the way to the throttle body, head was full of sand and dirt, the overflow bottle had this thick (5mm thick) of the said dirt/grime, i assume the rad had been recod since it was clean as, spark plugs were loose, spark plug galleries filled with oil (some to the point where you couldnt even see the ceramic on the spark plug(where it connects to the lead)

dump all the fluids, cleaned everything we could, unblocked the engine from the nullabor, runs likea charm, then this happens,

ill get a vid over the weekend, it doesnt do it whilst driving, only under 1000rpm (load/unloaded)

**Robbos_Toyotas** · 11-12-2009, 11:21 AM

are you sure its a "knock"and not a tap? My 7mgte does this too, and it dissapears after idle... not bad but audible still - im going to take the rocker covers off over the weekend as i believe its a bucket/ shim problem...
my old 7mge that i cooked used to have a tap/ knock which didnt go away, peaking worst sound around 2.5-3krpm....which i believe was a gudgeon, that had been damaged from cooking the poor thing...has yours been overheated at all? big end knocks are generally pretty loud....and generally come from have not enough oil in the engine/ shitty oil....
blake