Engine overheating gearbox knocking - 2002 Jeep Liberty

Rod bearings are certainly a cause of knocking sound in an engine. You drive it hard? Don't change the oil, or let the oil run low? Have a whole lot of miles on it?

I'd guess that its related to the double gearbox removal. There are four engine/transmission mounts: one on the top side of the engine, one on the top of the transmission, and two on the center member. One or more might be loose or separating. The top engine mount is a common problem. Could also be loose sway bar mounts, or strut bolts on the uprights.

you need check your thermostat and check your fan clutch

Try shifting into first without pressing the gas. If it is a slow decline before engine dies this is normal. If its a dramatic engine death, your clutch is to blame, if it still makes noise then its the gearbox. If you have a Mr. Clutch Autocentre near you they will test your gearbox for free as will many reputable transmission shops.

A gearbox will not "knock" in the usual sense, that is said of an engine running on petrol which is a lower octane than it needs. The sound is more of a light rattle or pinging.

If your manual gearbox has had the wrong oil in it for only a week or 2 and has not been thrashed, it is unlikely it has been damaged at all. Just drain and refill with the right grade.

If an auto gearbox, using the wrong oil can cause damage, as it may be far too thick. Drain and refill 2-3 times with the correct grade, running the engine until warm, but not driving around, in between. Then go for a drive without thrashing the car, and see if you can notice anything abnormal.

If you can, take it to an auto trans shop for advice.
Then

Hello, With so little information, I would HAVE to assume that this is a rod knock. Does it make noise in neutral too? Or only when you drive it. Try to put it in neutral and step on the gas....Does it still knock? A rod knock means you need to rebuild that motor. A rod knock can usually happen from beating on the car or a timing belt slipped a couple of gears. I would check your engine oil level, not transmission. Because low levels of engine oil can create this sound too. Good luck and feel free to write me back with much more detail so that I can further assist you.

As you've already realised, this is serious. The engine is more than likely totally shot. Maybe a broken valve and punched a hole in a piston. Broken piston rod maybe. It's been overheated and also probably blown the head gasket and warped a head. You're looking at a complete engine re-build already. I think I'd just buy a rebuilt long block and start fresh.

Sound like a blown head gasket. Changing the knock sensor will not remove a knock. It's a sensor.

firstly i would take it back to the garage i got it repaired at. but does the knocking get worse the faster you get or is it only on turning on full lock? if its when turning could be a faulty CV joint, could be that the driveshaft is not located back in the gearbox correctly, i would take it back to the garage

Very simple.... I had this problem and it drove me Crazy.... your gearbox engine mount is gone. When you look at it it will look fine but when under load it moves. creating the knocking noise..

Use a crowbar (Very carefully) to move the engine to check.