The Stovebolt Site Forums The Shop Area Engine Shop didn't smoke, now it does

When I brought my 49 3600 home a month ago and fired it up, it didn't smoke. After the teething pains of a complete tune up and valve adjustment it's been running great. I've done 2 hot oil changes. The valves were set at .10 and .20 cold after my fist attempt that had them too tight and I haven't readjusted hot. The Rochester is running rich and my plugs have some black soot, but no sign of oil fouling.( by the way, if any one has a main metering jet for a 49 W-1 I could try out my other carb!) It has been putting out some blue smoke while running for a week now. Not just when you start it up, but some blue smoke as it is driving, and the more RPM's the more smoke. It's using about 3/4 qt of oil a day (between 10 and 25 miles of driving). I did put a quart of transmission fluid Slowly down the carb about 2 weeks ago and have soaked the valve guides in transmission fluid/MMO when I did the valve adjustment. I haven't done a compression test yet and I'm not sure that that would tell me why it's smoking, but I can do one. I have a good running 235 that I had originally planned to put in later, so I can always do the swap, but I'm wondering if you guys have any other ideas. I plan on doing a hot valve adjustment and pulling the plugs and soaking the cylinders with transmission fluid mixed with MMO, but thays all I can think of to do. I din't want to O/H the 216 and I really didn't want to do the swap till fall...

I think your plan to add MMO to the cylinders is a good idea.

I'd drive it for a bit after clearing out the MMO, then do a compression test - both dry, and then with oil added to the cylinder.

Did you add the transmission fluid BEFORE the smoking started? I believe that too much detergent in the oil can clean an older motor too well and cause smoking and oil consumption to increase.

The transmission fluid was poured slowly down the throat of the carb. Before both oil changes I added a quart of MMO and drove for a while , then did a hot oil and filter change.

Getting an older, high-mileage engine TOO clean can lead to oil consumption problems. Sometimes, the carbon buildup behind the rings is the only thing holding them into contact with the cylinder walls. One thing I've used to check engines is a "cylinder leakage" test, where air pressure is put into a cylinder at the top of the compression stroke, through the spark plug hole, and listening for leaks at the carb, exhaust, and oil filler. This checks valves and rings, and can also be used for head gasket testing by looking for bubbles in the radiator. Get the cylinder close to the top on the compression stroke, lock the crankshaft with a vise grip on the flywheel, or put it in high gear and set the parking brake firmly, and use an old spark plug shell with an air line fitting brazed into it to pressurize the cylinder. Listen at the carb, exhaust pipe, and oil fill hole for leaks. Repeat the process for all cylinders. I'm going to guess you'll find pressure getting past the rings into the crankcase. Time for a ring job, or a full overhaul!
Jerry

I did ck vaccume whem I tuned it up. It was 17" at idle. Do you mean ck it while driving?? I will do a compression test, both wet and dry, but that will only tell me the compression rings and valves, right, not how the oil control rings are doing?? HR, what you say makes sense. Now, should I pour my blend into the cylinders and let it soak, or leave it alone? I don't want to make it worse!

While I don't usually reccomend "fix-in-a-bottle" additives, some of my friends have had some success with something called "Engine Restorer". It's a product that's added to the oil, and supposedly fills scratches, worn areas, etc., in the cylinders, and allows rings to seal more effectively. It's a temporary fix at best, and might squeeze a few more miles out of a worn engine and reduce the oil consumption. Don't add any more cleaners, you'll just create more clearance, and increase the tendency to pump oil past the rings. You're looking at a complete teardown and inspection soon, and probably a rebore job, new pistons, etc.

Cylinders don't wear at the same rate from top to bottom, with the majority of the wear happening in the first inch or so of piston travel at the top. If you re-ring an engine with taper-worn cylinders, the rings must constantly change diameter to try to maintain contact with the cylinder walls. This results in the rings losing their tension quickly, and translates to very short ring life. If the cylinders are worn more than .005" different diameter from top to bottom when you measure them, it's time for a rebore and new, oversize pistons, and the corresponding oversize rings. This straightens out the wear, and gives the new rings a straight cylinder to run in. Years ago, rings wore faster than the cylinders, so an engine could benefit from a re-ring job if the cylinder taper was not excessive. With improvements in ring material and manufacturing processes, I haven't seen an engine made in the past 15 years or so that could be a candidate for a successful re-ring job without reboring. If your engine has the original pistons and rings, it MIGHT take a re-ring job, but don't count on it!
Jerry

Ok no more cleaners in the oil. I've been running 10/40, maybe I'll change to 15/40 or 20/50, it is summer in MO after all. The engine restore seems like something to try,(if you're into fixing 55 yr old trucks, what's a couple of dollars on fix in a can)
I will do the valve adjustment cause I don't like to leave something unfinished. The truck runs great and I'm using it as my daily driver(I'm been putting off the trans locked in park in my daughters 85 Volvo) it's only 5 miles to work, so I can make this work for a while. I'm still puzzled why the spark plugs aren't fouled with oil The dwell is 33, timing is on the mark with the vac advance disconnected, new cap, rotor, wire, condensor etc. The truck did run hot before the smoking happened, new w/p, radiater, thermosta, hose's, flush etc. thanks for all th replies.
Dave

Running hot can cook piston rings, and result in loss of the tension against the cylinder walls. That might have been the last straw on a ring set that was close to its lifespan already. Hope it didn't score the cylinder walls at the same time!
Jerry

Sounds like you have either lost a ring or have a hole in a piston, probably the rings. Try the Restore, I've had some success with it. But if the engine is worn too bad it wont help. Sounds like it's time to swap the engine.