Hey guys,
I've been dealing with a lot of oil consumption from my 74 2.3. I was assuming bad exhaust valve guides. I just replaced the cylinder head. The combustion chambers were very clean, tops of the pistons very clean, spark plugs nice and tan, virtually no ridge at the top of the cylinders. Engine has good compression, runs very smooth. I do have a over rich carburetor condition with a Weber carb which I need to re-jet. Lots of soot in the exhaust tip, I'm thinking from unburned fuel. I figured if it was rings, there would be a lot of crud in the combustion chambers and on the pistons. Before I decide to do a ring job, I was thinking that maybe the rich mixture is washing down the cylinders, thinning and burning the oil. Maybe that's why the chambers were so clean, too much raw gas? Any thoughts? I do get black smoke between shifts and when I put my foot in it. I didn't want to put too much more time into it as next summer it gets a V8 as I just bought a bunch of Mustang II V8 parts and an 8" rear for it.
Joe
Quote from: Pangra74 on November 11, 2009, 01:52:52 PM
Hey guys,
I've been dealing with a lot of oil consumption from my 74 2.3. I was assuming bad exhaust valve guides. I just replaced the cylinder head. The combustion chambers were very clean, tops of the pistons very clean, spark plugs nice and tan, virtually no ridge at the top of the cylinders. Engine has good compression, runs very smooth. I do have a over rich carburetor condition with a Weber carb which I need to re-jet. Lots of soot in the exhaust tip, I'm thinking from unburned fuel. I figured if it was rings, there would be a lot of crud in the combustion chambers and on the pistons. Before I decide to do a ring job, I was thinking that maybe the rich mixture is washing down the cylinders, thinning and burning the oil. Maybe that's why the chambers were so clean, too much raw gas? Any thoughts? I do get black smoke between shifts and when I put my foot in it. I didn't want to put too much more time into it as next summer it gets a V8 as I just bought a bunch of Mustang II V8 parts and an 8" rear for it.
Joe
Joe,
If the Soot and Black smoke are all you see on acceleration, and between shifts,it most likely is running way Rich. Blue smoke under hard acceleration or between shifts is likley Rings that aren't seating anymore. If the Compression is good and within percentages between cylinders, I doubt it's the rings. Perhaps there's a PCV or crankcase vapor issue that's causing the Oil to be burned in combustion, but masked by the Rich mixure so it washes the plugs down and prevents the Blue Smoke from Showing up. OR worst case : porous or cracked cyl head near oil gallery pressure or return drain hole, and oil is drawn into combustion chamber, diluted with Fuel (making it's presence hidden) and burned then.
A Head gasket sealing issue could cause this also. If you leakdown test the motor, and all is good, run the engine with a leaner jetting and even set up a Temporary Open breather. If the problem shows up with blue smoke at the exhaust then... well ,time to disassemble the engine, and really check for casting issues or rings not seated.
Pintosopher
PCV system seems to be ok. I replaced the valve anyway. Just changed the head and gasket and it was doing the same thing before that, except with wet oil on startup in the exhaust. That's why I thought it was valve guides. All of the cylinders looked equally clean when I took it apart. If the oil galley was leaking, I would think it would show up in the rear cylinder as that's where it comes up to the head. I need to check that metal box where the pcv hose attaches to at the side of the block to see if maybe it's plugged, but I would think that oil would come out the dipstick if the crankcase was plugged up.
This thing drinks a quart in about 125 miles and I don't see tons of blue smoke or any leaks like you would think you would. I get the black puffs from the wasted fuel and a greyish color on hard acceleration.
thanks for your comments.
Joe