xj motor knocking

[bad company]

i did a radiator flush  and know my motor is knocking any advice on why or how to get it to stop?

[SteveTheFolkie]

Kinda doubt the two are connected  - perhaps just having done some work on the vehicle you're more sensitive to the noises the engine makes - the 4.0 has many virtues and quite a few flaws - one of the flaws I've heard of is rod knock - the bearings get worn - try an oil change - perhaps a heavier viscosity - see if that helps.

[bad company]

thank you

[SteveTheFolkie]

I gave this some additional thought and decided more information was needed -

1) under what circumstances does the engine knock (idle, steady load, when you're on the gas)?
2) with the hood open can you tell where the knocking is coming from?
3) how's your heat?

I ask these questions because it's quite possible that I was wrong earlier - if you've got an air bubble in the cooling system that can cause a rather odd knocking noise- also a water pump a bearing on the way out can knock - to check the water pump - with the ENGINE TURNED OFF try to wiggle the shaft - there should be no lateral movement.  To check for air spend some time bleeding the cooling system - it can take a bit to get it done correctly -

Steve

[(Tattoo) Jack]

  You didn't say under what circumstanis the engine Knocks. I didn't change the oil in the WJ for a while and one day, with an hour to kill, thought "why not try one of those Jiffy/Qwik lube places", well the next day I (WJ) ended up with a Lifter knock. So are my 2 connected...  I THINK SO, anyway... you could have a Lifter that won't fully expand. If the knocking happens when you first start it up and then quits (ur lucky) then it's likely (but not 100%) a Lifter. Lifters make a higher pitched, tinny sound whereas Rods make a deeper, thudding type of sound.

  JM2C's

[SteveTheFolkie]

Good ones Jack - yet another possibility - if it's a tick more than a knock and it varies with engine speed is a cracked header OR a leaking exhaust gasket - I've spent hours chasing down valve train issues before only to discover an exhaust leak as the culprit ...

[bad company]

it happens as so as i start it and gets faster as i accel. to me it seems like it is comeing from the valve but went i took the cover off it dosent looki ilike anything is wrong

[SteveTheFolkie]

does it go away at some point?  If so it could be a collapsed lifter (they're hydraulic - normally oil pressure forces them to "full height" - if they're dirty or clotted up the oil doesn't do it's thing - typically until the engine warms up and the crud gets loose.  If that's the case then some "top oil" (Marvel's mystery oil or something similar) may fix the problem.  The fact that a visual exam didn't reveal any broken valve springs is a good thing - give it a shot - follow the instructions to a "T" - and change your oil and filter after the treatment - maybe it'll fix up the situation for you!

[bad company]

no i dose it until i shut the truck off