oil getting black

N

nbrskn

Senior Member
my flathead is an 8BA, maybe 2000 miles on rebuild. Right from the beginning it turns the oil black.

The neighbor says this has to be to much fuel . Has a stock 94 on it.
bought this carb many many years ago . Rebuild from western auto, still in the box. Got a kit and rebuilt it. Car starts good and runs real well. Have pressure regulator set at 3 lbs.

Ready to get it out and start driving it. But hate to change the oil again 700 miles on it.

Thanks
 
In my short experience of owning my 34’, I’ve had vacuum leaks at the carb and misfiring which lead to the oil being “black” (smelt like gas). Was burning pretty rich at idle to compensate for the loss of vacuum air. I haven’t had a chance to change it out since the misfiring/vacuum leak issue was resolved to see if it would maintain the normal oil pink color.

But I think it’s more common than you think to have a relatively “black” colored oil. The model A group I’m part of said it’s fairly normal just as long as it’s not burned out the exhaust (blue tint smoke) or like sludge on the dip stick. I’ve been curious myself now that my car runs well to but I had changed the oil out before the misfiring/vacuum leak.
 
Hi Everyone. Black oil means that it is holding contaminants in suspension. It's what they are formulated to do. Think of it as a good-ish thing.

Has this engine had the intake off of it? You might find some ghastly stuff in there which would explain things.

I second the oil analysis. It costs less than a meal out, in these times.
 
I have roughly 1000 miles on my oil in my AV8, 52 Merc, full flow oil filter, but running open frogs mouth air scoops with only screens to keep out the big stuff.
And yes it is black and time for an oil change, definitely fine contaminants in the oil.
 
Hey. Some of you are not old enough to remember these "old, poorly machined engines of yore", the oii got real dark in a hurry. Not to worry all that much. Age 88.
 
I do not run in a dirty enviroment, It has a nice sized air filter.
starts getting black almost immediatly. Has done it right from the start up.
To make a long story short ,I had the pan off since rebuild and it had a lot of black residue in it.

I thought to begin with maybe the rebuilder had not gotten it clean enough.
 
What do you mean by “a lot of black residue in it”?......was it like black peanut butter?....there’s no way the inside of the pan should be that dirty with 2000 on a rebuild. Did you clean out completely?.....Pull the intake and see if the valley is clean.....it may be time for a conversation with the builder......Mark
 
What temp are you running the engine at? Low operating temperatures and/or short runs that do not get the engine up to operating temperature can result in sludge build up. Still think an oil analysis is you best bet.
 
If you don't change the oil filter or clean the filter canister when installing new oil, any residual oil left in the canister will start turning the oil black in a short period of time.
 
I know this sounds silly but, did the rebuilder clean all the old sludge out of the engine?
Are you using detergent oil?
 
This is normal for a Multi grade oil. It has cleaning agents in it and it tens to remove the carbon from the cast iron. Or so I'm told??
 
There aren't generally computer controlled EFI fuel systems on old flatties. Carbureted engines are Not efficient like modern EFI systems. 2000-miles is about the normal oil change interval for the average early Ford V8 and it will always be dark colored.
 
I find different engines have different "oil colouring". My 52 Merc engine oil gets dark not too many miles after a change but is does have a lot of short runs and maybe not up to normal temp. But I've got an old Massey tractor with Perkins diesel that I use to handle bales through winter. That one keeps it's oil clean all through the winter. Cold starting and running but I can still see the colour of the dipstick through the oil when I check it. Can't explain that one. I don't worry about it. I'll change the engine oil in my Merc once a year even if it only has a few hundred miles on the oil.
 
RalphG said:
I find different engines have different "oil colouring". My 52 Merc engine oil gets dark not too many miles after a change but is does have a lot of short runs and maybe not up to normal temp. But I've got an old Massey tractor with Perkins diesel that I use to handle bales through winter. That one keeps it's oil clean all through the winter. Cold starting and running but I can still see the colour of the dipstick through the oil when I check it. Can't explain that one. I don't worry about it. I'll change the engine oil in my Merc once a year even if it only has a few hundred miles on the oil.
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Same: My fresh build 37 Flathead [with 90% fliter] 20/50wt oil looks a little dirty
56 fairlane same oil type ; a little less dirty
74 Cuda same oil type; Clean as, like Ive just poured it.
More modern cars I have are using 10 /30 or 10/ 40wt oils are dirty and they have that weird staining dark honey colour in it.
 
philipswanson said:
Read the opening post. He said the engine was just rebuilt 2K miles ago.
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I once had some one tell me the engine was rebuilt because the starter and gen had new brushes and carb was rebuilt? Rebuilt to him may be some thing different to you.
 
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