TwoXJS

Hey, guys! Me again....This time with an actual request for help. Our 93's 2.5 has a knock to it. Not a tick, but a knock. First off, oil pressure seems good, 15-20 @ idle and up to 70 under power.

We've tried using some of that Motor Honey, which did help pressure, but nothing for the knock. I'm thinking it's the bearings for the connecting rods on the crankshaft (forgot their name ), but we'd apprectiate any other ideas.

I'm planning to take a video when it running to try and pinpoint where it's loudest. We don't have a stethoscope, so I'll try camera audio. If you guys think it's something else and have any ideas what to try, I'd greatly appreciate it!

DFlintstone

That would be the rod bearing. Tectonically I suppose it's the relationship between the rod journal on the crankshaft, and the rod inserts in the connecting rod. (those are relatively easy to change, but usually the crank is worn)

How many miles? Flex plate bolts on our aw 4's loosen and knock. You might check your clutch to flywheel bolts. A lifter can really make a hardy knock also.

I've dealt with a few bad rod bearings. Seeing a hill ahead, knowing I'm gonna need to put it to work is what made me sweat. There's a pretty clear relationship between putting it to work, and the "volume" of a rod knock.

Radi

Knock at engine speed or half engine speed? (got a timing light? It flashes at 1/2 engine speed)
Does the noise change when you rev the motor? Worse when you let off the gas? Any double-knocks?
Any difference between hot motor and cold? Idle or under load?
Does the noise change if you disable each cylinder one by one by pulling the injector plug? You can sometimes find the offending cylinder that way...

DFlintstone

Supper tip Radi. (Howdy Chuck). Yea, first loosen the plug wires on the dizy so you can lift one without getten zaped, (with the engine off), then with it running lift one at time and see if lifting one makes the sound quit.

Radi

Hey Don!
I've been pulling the injector plugs lately instead of the plug wires, got whacked pretty good on a GM HEI, even using chicken pliers it got me, lol. Problem with pulling injector plugs though is it sets a CEL unless you are quick about it.

DFlintstone

F L I N T S O N E Has no "cel" (except for those pesky dui's) (we Renix folk Drive with no light)

Man up Chuck! What's 45,000 volts? Funny coincidence I have this up for sale at the moment. > http://www.ebay.com/itm/151116956529...84.m1555.l2649

opie1988

My old 2.5 wrangler (1988) sounded like heck until it warmed up and was driven. I changed out the bridges on the valves and it sounded like new.

http://www.summitracing.com/search/p...jeep/liter/2-5

Carl48

Check the exhaust manifold for broken studs...very common on the 2.5...the resulting exhaust leak makes a knocking sound... although it usually goes away when the engine warms up.

TwoXJS

hey guys! thanks for the tips! It doesnt seem to change depending on temp's, but does SEEM to go away under power. Might just be we cant hear it over the engine, i'm not sure. It's married to the AX-5, so i dont know if the flexplate is still in play here.