One cylider low compression

CesiumClockTech · #1 04-17-2011, 05:34 PM

I have a 02 Ranger 125,000 mi 2.3engine 16V 5 Speed Manual Transmission, 2 wheel Drive. OBDII reader says "Misfire indicated in 3rd Cylinder" and 3rd cylinder input port has more carbon than the other ports

Spark Plugs have spark and Injectors are injecting but have no way to know how much

Compression Test Cyls: 1,2,4 180 Dry/270 Wet, Cyl 3 50 Dry 60 Wet
Is this an indication of bad valves or something in the block?

Doctor Wily · #2 04-17-2011, 05:55 PM

certainly could be something of that nature. either one of those. could be valve, rings, block, etc. best thing would be to perform a leak down test and see where it's going.

cylinder at TDC of COMPRESSION stroke. put compressed air into the cylinder using a connector like what you used for your leak down test. it can't have the valve in it though it has to flow (the air)

once you have the air going into the cylinder check the intake, the tail pipe, the radiator/coolant tank and crank case for the sound of air escaping.

heard from:

Intake: intake valve
Tail Pipe: Exhaust valve
Crank Case: Rings
Radiator/tank: head gasket, block, etc etc.

Good luck and keep us posted!

CesiumClockTech · #3 04-18-2011, 09:03 AM

Thank you for answering fast
I was hoping not to go there since I don't have a compressor big enough and I don't trust the Mechanics in this area as far as I can throw them and I already took the Head cover off but will put it back together for the leak down test

Trying to decide if I should replace the head or give the truck to son in
Florida where they don't have emission inspections

Doctor Wily · #4 04-18-2011, 09:48 AM

:-o

I definitely would do a leak down before tearing into the motor. It shouldn't take TOO much air to do leak down i wouldn't think? Oh well none the less do you see anything that seems off? Did you take just the valve cover off or the entire cylinder head? I am going to assume you took just the valve cover.

I wouldnt replace the head until we know exactly what is leaking. Once we know for sure what is wrong we can make decisions based off that evidence. It would suck terribly to replace the head just to find out there is a crack in your block that is allowing compression to not exist.

If you can try that leak down and lets find out where the air is going.

Cheers!

Wily

Guest · #5 04-18-2011, 10:47 AM

Something isn't right with the numbers. The difference in compression should only be 20 psi at best between a wet and dry compression test.

If the engine that you have is anything like the 1.8 Mazda engine, your going to find that one of the exhaust valves in #3 is damaged. (missing a small piece from the valve face. "burnt") Not a big deal. Just need to replace the valve, and of course, the head gasket. You may want to think about whether or not replacing just one valve is a good idea. After all, the valves all have the same use on them. Its only a matter of time before more valves fail. It might be years, or it might be a few miles before the next one lets go.

The best I know, no one has figured out why the #3 drops a valve. I'm not even sure many have put this together yet, but I have personally had 4, 1.8 Mazda engines lose one of the #3 exhaust valves, and have heard of several others.

It'd be interesting to see if this valve failure is being carried over into the Ranger engines. Anyone else have stories of exhaust valve failure?

Did a scan tool really state that one cylinder had more carbon than the others? I find this interesting, I mean... how could this be measured?