Was driving home yesterday at about 50 mph. Check engine light came on and then started flashing. Could definitely feel a misfire. Pulled over and could hear a steady tick coming from what sounds like the drivers side valve cover. Tried to drive it again, found when I got above 2500 rpm, the noise slightly lessened and the check engine light stopped flashing. Limped it home, got the code reader, found a few codes. P0300, p0305 and another code that didn't have a number, just the description of misfire with low/ empty fuel. The low fuel light had just come on, so I put gas in in, no fix. Got an inline spark checker, got spark on #5. Compared to a few other cylinders and they all look the same. Thought I may have a lifter issue due the noise and that as rpm increased(and oil pressure) that the misfire went away. Pulled off the upper intake and valve cover on that bank. With the valves in the closed position, I pressed the rocker arms, and they are all nice and tight. Valve springs look good. Replaced spark plugs and wires a few weeks ago. What else should I be checking? This one is driving me nuts

 

Should probably add that it's a 1999 d2

 

If you have spark, then you know it's either a compression or fuel issue. You could have a hole in the piston, broken rings, a failed injector, or you could have a valve that's only slightly bent. It is possible that at higher RPM, there's enough compression for combustion. That sometimes happens with less severe compression leaks.

 

Checked the piston with a boroscope, that looks good. I'll have to get a compression tester and verify that though.

 

It's good that the piston looks alright. A leak down test would really be the best way to check out the cylinder. A compression test will only tell you whether it's down on compression or not. A leak down test will tell you where the compression is leaking.

 

Oops i meant to say cylinder leak down test. That's the mission tonight. After a little YouTube hunting, I found another disco making the same noise. A lot of guys complain of slipped liners making this noise, but wouldn't there be other symptoms to go along with this? Coolant loss? Overheating? Mines not doing either, but I'm trying to rule out other possibilities. Thanks for the input so far. This is my daily driver, so I need to hurry and figure this mess out. Here's the link to that YouTube video. Sounds just like mine. To me it sounds like it's coming from the drivers side valve cover area, but sound travels, so I could be wrong.

 

I had a tick just like that in mine. It was a cam bearing that had fallen out of the block and was riding on the cam. It would come and go and sometimes I think it would get wedged between the lifter and the cam, because it would occasionally misfire on the cylinder where the bearing was.

 

Good to know. This one misfires all the time at idle, check engine light flashing. Above 2500, misfire lessens but the noise stays. It's a little quieter, but still there

 

Got the cylinder leak down tester on the engine. Not looking good. 100% leakage on that cylinder. Not coming from the valves. Pretty noisey at the oil fill. Pulled the lower intake and gasket off, found small chunks of head gasket sitting all around the lifters for that cylinder. Going to pull the head off, guessing a slipped liner at this point. With all the metal head gasket chunks in the engine, I'm not even going to chance it. Time for a new engine. What engine swap options do I have at this point? I see d1's with Chevy 5.3/6.0 swaps. Diesel swap may be more simple but finding parts here when it breaks seems tricky. Give me some options guys!

 

Well, that sucks! I haven't done an engine in mine. I have, so far, gotten around replacing mine by simply not driving it much! LOL!!
I'm sure someone will be able to point you in the right direction. If you don't get a reply here, maybe start another thread specifically for replacement engine options.