I was out driving my runabout yesterday minding my own business, it was a nice day and the car was running great. All of a sudden (a short time after a hill) it started knocking loudly, I shut her down. Oil smoke and hot oil smell (now that can't be good). I dropped the inspection pan this morning and took a look inside. Found no loose or obviously broken parts, no babbit material in the pan. Crank looks to be in one piece. Cylinder walls look great. Everything seemed to be where it was supposed to be. :-) The engine still turns over with the hand crank. The drained oil smells hot. This car is new to me this year and this is the first time I've had to open my T engine. Any ideas on what the problem might be? I tried using the search function, but for some reason it is not working for me this morning.
Maybe a magneto magnet let go?
I use Google to search the forum, just include MTFCA in your search string, like so:
engine knock mtfca
Ernie: what year is the car? Is there an external oil line going to the #1 Bearing? Is the oil line clear & not crimped? If there is no external oil line is the internal line clear? I would check the # 1 bearing real close since you said this happened just after a hill! Good Luck
Overheating? Does it have a moto-meter that showed otherwise?
Thanks for the quick responses! The engine is a 26/27. No external oil line. I will check the internal line, good thought. No moto-meter, but no steam either, I will check that too. The engine is really clean inside, no sludge build up, but that does not mean the oil line is not clogged with band material.
It's possibly overheating. When the engine gets too hot, the pistons expand and they start to bind in the cylinders. If you continue to run before cooling off, the engine will seize.
The other possibility would be lack of oil to the front of the engine. I would suggest that you take the cap off number 1 rod bearing and check the clearance and also the condition of the babbit. Be sure to look at the top of the bearing, the part in the rod itself because that is where the most wear occurs. Also try to clean out the oil line if you can. It can be done from the bottom front of the engine. Hard, but doable.
Before you tear everything down, you might want to start it up and see if the knock continues while cold.
Going uphill causes the flywheel to move farther from the magneto coils, so it would be unlikely that the magneto would be the cause, but you can't rule that out either. Sometimes the actual cause won't be evident until you pull the engine.
You can also remove the center main cap and inspect it for wear. Loose main bearing knocks tend to get worse when the engine is pulling hard. They also lessen if you retard the spark slightly.
Another possible cause would be piston slap, but that usually is worse when the engine is cold. You can check that in two ways. One is to observe the rod bearings while turning over the engine slowly with the crank. If they move front to back as the piston goes up or down, your rod is bent causing the wristpin to push the rod either forward or backward as the crankshaft turns. This would also be more noticeable at slower speeds. If you pull the head off, you can turn the engine with the piston up and see if you can rock the piston back and forth side to side by hand. It should not move sideways noticeably. That will cause a knock if it does.
Good luck. The last thing to do is pull the engine and take everything out for inspection, but if you do, be sure to repair everything that is wrong, so that you don't have to pull it again very soon.
Couple questions that may lead to good answers
what color was the smoke?
Where was the smoke coming from?
front of motor?
back of motor?
Fred, that was 6 questions you are only allowed 5 questions per day. I looked that up in the Forum rules. It is in section 8 paragraph 12 page 64.
Ah, Dean, you forgot to read sub paragraph 12B which allows sub-questions on the same part (engine considered one part here).
Ain't April 1 fun???
Ernie, I would really check for a broken crankshaft very carefully, although I will admit that is a "worst case" scenario.
Hmm, is a "scenario" where the fat lady sings at the beginning of the opera??
Here is an update. I got a little more time to work on the old girl (the car, not the wife :-) ) and found no coolant in the radiator. I should have checked that first, but I guess the oil smoke and knock through me. That part looks to be an easy fix, new hose. So it looks like overheating may have been the start of the problem. Thanks again for all the responses! Should I button her up and try her again or does overheating cause other problems I need to check for?
It would be good to try it again after you add coolant. The worst problems caused by overheating are in the cylinders. If the pistons expand they will get scored as well as the cylinders. also the rings might loose their tension. Sometimes the actual shape of the pistons changes from slightly oval, which is how they are manufactured to round. When that happens, they will rock back and forth. If you are lucky, maybe none of that happened. So try starting it up and driving a short distance. If no loud knocking, you are lucky. You should also check both the coolant and oil more frequently, because the overheating could cause oil consumption and blue exhaust. You will notice the blue exhaust especially after you slow down such as going downhill to a stop, and then when you start out, you will get blue smoke. That smoke is an indication of ring problems. Also check the radiator for leaks. This will also include the hoses, head gaskets and if it has one, water pump.
Ernie, Ernie, Ernie.....Check your oil level, water level and gasoline level on a regular basis. If you are really lucky no major damage may have been done. Once every 2 months or so, because I live in a humid area here on the Texas Gulf Coast, I also drain a ounce or two of gasoline from the valve below the gas tank and drain on my carburetor. Preventive maintenence on these older cars is a must and will save you grief and time in the long run.
No point dwelling upon the damage that could have happened, because you may have escaped it. If you did escape it, you are to be commended for a rapid shutdown...and you're a lucky person indeed.
Maybe buy a lottery ticket today?
I suspect you dodged a bullet. Fill it with fresh coolant, change the oil, and try it out.
The lessons best learned are the ones that are accompanied by a panic shot of adrenalin.
"no point dwelling" good one Dave! Vince
It just slipped out...