PAXJ01

How much engine knocking is too much and how much is normal?

Gee oh Dee

No knocking is normal. Ticking is normal, knocking is bad.

BuckB91XJ

Is your noise coming from head/valvetrain/cam area? This is normal....or is it coming from the block/piston/crank shaft area? This is very much bad. For example, my Cherokees 4.0 HO motor has had a lifter tick since I've had it 185K miles to 265K miles. It still runs like a scalded Jackalope to this day. So far (knocking on wood) the bottom end has stayed tight. I do the oil changes religiously every 3K miles.

TheJerm

Look into a loose torque converter or bad flexplate before you go and replace the motor.

cruiser54

Knocking under load/power is the worst.

highmileage

even if coming from the valvetrain it could be bad. The east coast uses alot of ethanol in the gas mixtures (hence no chevron stations). Exhaust valves get beat to death

Firestorm500

When the last knock is when a rod comes thru the side of the block, you know it was too much.

Gee oh Dee

1991Jeep_Man

Eh, but it's a 4.0 so it'd still run. Besides, a big gaping hole in the block and a broken rod is very fixable. All you need is some channel locks and vice grips to straighten the rod, then just JB Weld everything Good to go!

TheJerm

I can attest to this when a friend hydrolocked and broke a rod in half. Threw another rod and piston in cause it was laying around and drove it. 2 cylinders were not making any compression due to bent rods and a crushed exhaust is what finally killed it while offroading.

DFlintstone

Pax, as the jerm points out. You REALLY want to check those torque-plate to converter bolts. There is a little panel, sort of 1/2 moon shaped on the front of the bell housing by the pan. Comes off easy with small bolts (screws). Up in there there are bolts through the torque plate, (with the teeth) through to the Torque converter. I forget...5-17mm? anyway you need to rotate the engine to check them all.

Also if the top starter bolt is too long it will knock as the torque plate hits it. The end of the bolt would be shiny.

While you are there check that your engine/bell-housing bolts are OK.

THEN you can start to worry if it's still knocking.

PAXJ01

lol JB Weld fixes everything!

97XJ

I too have the ticking noise,going to check flexplate bolts tomorrow,sounds like it is coming from lifters from the top and sounds like rod from the bottom,but some days it won't have any noise.sounds like a diesel engine,has 177,000 but been running strong.

darknezz

you havnt said what kind of knocking?


mine does a second of rpm timed knocking type sound at a cold startup. never, ever any other time. lately its developed a valve ticking at totally random times.

97XJ

my bolts were loose on flexplate,tightened them up and tried to check flexplate for cracks with flashlight,mine is steady ticking(sounds like diesel) speeds up with rpm and goes back to a stead tick,was wonder if anyone has tried to replace rod bearings,if it wasn't knocking real bad? found out after I bought the jeep the guy I got it from pulled the oil pan and replaced oil pump with high volume. Sorry,not trying to highjack other posts