So, I've been working on this cylinder 6 misfire for the last week. I was told by a Land Rover specialist in the Portland area to use Engine Restore to see if it could help with a possible collapsed ring. I put that in on Sunday, 3 days ago.

Yesterday, I started noticing a slight low-end engine knock. It comes on about 10-20 seconds after startup and is intermittent. It will get louder and quieter at random times and occasionally disappear completely, for a short time.

I had the oil changed, (full synthetic 10W-30, same weight as previously used) and it didn't change. I drove straight from changing the oil to another shop for a different reason and he told me to pop my hood because he wanted to check my oil because it was knocking like it was out. He checked it, it was spot-on and when I restarted it, the knock was gone.

Started it a couple of minutes ago, after sitting for an hour and the knock is back.

Any thoughts?

 

Shut it off. Dont drive it until you can confirm you have proper oil pressure in all cylinders.

Note. These trucks seem to be happier running on a 40 weight oil. Most of the members on here, including myself, opt for 5w/40 in the winter and 15w/40 in the summer.

What year is your truck?

 

Thanks for the reply. It's a 1999.

 

So, I was just on my way to have the oil pressure tested and while I was at the ATM, the knock was pretty loud at idle. As I drove off, it went away. Giving it gas is definitely changing it. Any thoughts on why that would be the case?

The shop didn't have time to get me in and my buddy is out of town that has a tester, but it would be nice to get a couple of scenarios so that I can research them a bit.

Any other thoughts on what would cause this if it's affected by rpm's?

I'm really, really starting to rethink buying this truck. I've only had it about 2 and a half weeks. Maybe time to take my lumps, sell it and get a Land Cruiser.

 

Check your cats, when they start to fall apart the catylist inside them rattles around and sounds like a rod knock.
With the engine off tap on the cats with a hammer, if they rattle they are bad.
The best way to check them is to drop the y-pipe, start the truck and see if the knock goes away.

 

Does your oil warning light come on at bulb test at startup? If lamp was out, the low oil pressure switch would have no way to tell you that you had bad pressure at idle.

 

Thanks again, guys.

When you start it up, there is a rattle that sounds like it may have been coming from the cats. I'll check those to see if they could be the cause of the new knock.

Also, the oil light does turn on at startup. Are you saying that I shouldn't need to check oil pressure if the light isn't indicating that there is a problem?

If you use a scanner, does that give any information about oil pressures on these trucks?

 

No a scanner will not give oil PSI because the ECU does not get a oil PSI reading from anything, the oil switch is just a on/off switch, pressure over "X" light goes out.
If the oil light is not common on anytime the engine is running your oil PSI is fine.

 

So, I'd like to assume that the oil pressure isn't a problem, since I'm not getting an oil light. I have a guy coming to do a pressure test over the next few days.

Also, after crawling under the truck while having someone else work the accelerator, the knock does not go away above idle. It was just being masked by the Flowmaster exhaust. After briefly banging around under the truck, it doesn't appear to be cats.

So:
1. Knocks after 20-30 seconds of being started.
2. Knocks throughout rev range.
3. Knock sounds like it's coming from passenger side of motor, (still difficult to differentiate between top or bottom, but sounds more like bottom.)
4. Knock only started after using Engine Restore (possible coincidence).
5. Knock is intermittent whether warm or cold, but is always present.

Any other thoughts on it?

Sorry, guys. 20,000 miles ago, the previous owner did new heads, new radiator, new a/c pump, fuel injectors rebuilt and tuned, new water pump, new ps pump, new belts, new O2 sensors and new motor mounts. I figured I'd at least have a month before needing to sink money into this truck.

Thanks for any help. I'm too broke right now to take it 2 hours away to a shop that deals with Rovers.

 

Some are able to remove plug wires one at a time, to isolate which cylinder is involved, the idea that less power on that connecting rod makes the sound change. Some are able to use a broom handle or mechanic stethoscope to poke around and "hear" where the knock is from. Maybe try swap to 20W50 oil and see what that does for the noise. Bearings can be replaced in the truck, there is a write up in the tech area.