Late Model Flathead Blow By

G

guy1unico

Well-known member
My late model flathead just started having blow by out the passenger side tailpipe. The moter was totally rebuilt about 4 years ago. I don’t drive it but to Burger stop 10 miles and sometimes to my office 30 miles. What do you think, should I be concerned? Is there an additive I can put in the oil (Royal Purple) or fuel that might help or do I just need to driver it more?

Thank you

Guy





 

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What do you mean exactly by "blow by" ? Smoke ? What color ? Need more info. How does the engine run ? Has coolant level dropped ? Run compression tests on all the cylinders. Could be problem(s) with head gasket, valves and/or rings ......
 
dr brown has the right idea, when having engine problems always start with a compression test, will save you a lot of time and trouble, engine trouble shooting 101, if the smoke is gray its burning oil, if its white it passing water thru the engine, if its black engine is running to rich, check all of these one at a time
 
What viscosity are you running for oil? If you do have true blow by and your compression test checks out rethink your oil choice if you are running heavyweight oil.

I was told by a Hastings Piston Rings engineer that we can overwhelm the ability of the rings to maintain a "seal" against the cylinder wall. She explained to me that the rings when faced with too high a viscosity (too thick) the rings can sometimes actually hydroplane on the film of oil on the cylinder wall. This leaves oil to get past the rings and thus be burnt in the combustion process.

If this is what you're experiencing I suggest 10W40 oil alone, no other additives. It would be nice if it was that easy. Right? Believe it or not there is a good chance that's all it is.

Good luck friend.
 
I can say that it is not Blow-By. Blow-By is exhaust gases comes out of the crank case
through the breather
 
if you have white smoke out of your tailpipe, that is coolant, the motor id producing steam. If the smoke id blue it means that your burning oil. If it is black then the motor is running to rich burning to much gas
 
Just a "Kick a dead dog" idea. Get can of Seafoam (any auto parts store, walk-mart, target, etc). Pour half the can in the gas tank and half in the crankcase. Maybe save a few drops and pour down carb while running. Might fix problem (and of course, might now), at least temporarily. I had oil burning smoke out of both tailpipes two years ago. Seafood fixed it at least for now. No more smoking.
 
I'll do the compression check and let you know.
I use Royal Purple 10W - 40
what about a stuck valve... would the car run different...it now runs normal but smokes out of the right side off all the lights.
 
I think you need to drive it harder and longer. Seriously. Get the oil hot, let the rings seat. PS how many quarts did you put in the pan?
 
Strongly recommend the compression test. Again, what color is the "smoke" ?? Assuming (1) the engine is running smoothly under routine conditions and (2) the exhaust emission pressure patterns [puffing sequence heard and felt on your hand] and the emission of exhaust condensate appear SIMILAR AT EACH of the two exhaust pipes ....

.... then IMHO if this "smoke" is something new and you have made NO CHANGE in the oil you historically use, or the oil level you maintain in the crankcase, suspicion points toward an internal problem such as (a) coolant leaking thru the head gasket to be vaporized in the combustion chamber, (b) a hung-up or broken piston ring, or (c) even a dreaded crack in the block. Watch your coolant and oil - do levels drop abnormally or are they contaminating each other ?? Unsure about carb adjustment as that would likely affect the entire engine and not just the RH cylinder bank. If the engine is running smoothly and the two exhausts sound and feel normal (i.e. no distinctive "popping" at the RH one), I don't think at this time that a valve hanging up.

Keep us posted.
 
Like has ben said . Take it for a long run on the slab. 60 or 70 mph. if temp don't come up put some stats in it. 180. deg. Like they say[ blow the cobs out of it].If it blows all the water out you have a bigger issue.
 
Compression checked out fine...it should, the motor has low miles maybe 1800 since built 4 years ago. Added an 1/8 of a can to the carb (running a center 48 only) and 1/2 a can to the oil...the gray smoke has decreased 90%...that is really good...do you think I need to add more to the oil or just take it on more long drives?
What would a long drive accomplish that going around 4 city block revving it up slowing down revving up etc. etc. I just dont want to get out there on a long drive see a ton of gray smoke again and have bigger problems in the middle of no where....what do you think...do I have to worry at all?
 
Put a good load on the motor.
Find the steapes hill and let it work hard for a while.
If it gets better just out and give it a good joyride.
The smallest sign of white smoke and loosing water...back to the garage.
 
ah, the good old days when you took the car for a drive with some heavy accelerating to blow out the carbon, etc. that builds up in city driving.....put some longer miles on it as others have said.....helps to keep sludge from building up, too....have fun and driiiiive.....Mike
 
My flathead has no oil filter. Would an oil filter keep this from happening on a low mileage flattie? At $10 per quart I hate to change the oil every thousand miles.
 
I have an '48 F-1 with no filter and have no problems. I just completed a 1500 mile trip with no problems. I change oil about 1500 to 2000 miles and have no issues. I use 10W40 oil. I have put 10,000 miles on it and it was used when I got it. I don't know the mileage on the engine but, I think it was low mileage when I got it.
 
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