Supersonic Six a bit too hot - what happened?

[51Deluxe]

As I mentioned in a response on another thread, on the way home from Jackson I took the interstate and the '51 Deluxe didn't do well. I did 65-70 for about 50 miles, all seemed OK, but then oil pressure dropped to almost nothing and temperature got in the danger zone. I immediately pulled into the first gas station and checked the engine. First time I've ever seen oil smoke coming from the breather with the engine shut off, with a distinct burning oil smell. I added a quart and barely saw anything on the stick, so added another. Much of the oil was up in the engine, making it difficult to judge what should be in the crankcase. Tried to take off the radiator cap but it wanted to spew, so left it on.

Long story short, I got the car home safely. After a mile or so of spitting and sputtering (car does this anytime it gets hot), it cooled down and ran happily home on the backroads at it's favorite speed of 40mph.

Checked the oil the next day and it was 1/2" past the full mark. Assuming the crankcase holds 5 quarts, it still had over 3 quarts in it when it overheated. My question: Did the car get hot just from the excess RPM of running 70?  Or would being two quarts low on oil contribute?

One other factor I almost forgot to mention: Just before getting on the interstate, I had filled the car with it's first tankful of ethanol gas in months. Been using non ethanol constantly but none available this time.

[joefrazer]

My thoughts...
- The oil issue may be due to a blocked gallery. Oil is getting trapped high in the engine and it isn't draining as it should. It won't be due to the oil filter as its partial flow and isn't really a factor. When the engine is cool (fresh start) if the pressure is good, keep an eye on it as the engine warms. It will drop but shouldn't fall to near zero at idle. A worn oil pump or loose bearing clearances will cause low pressure.

- The burning oil smell is probably due to a leaky seal. The downside is the leak, the upside is your car is getting undercoated.

Run the car around town locally and keep tabs on how things act and sound. Let us know what you find!

[Fid]

I've run ethanol in my Js and in the '51 Kaiser I had. No problems. Ethanol may cause problems over time such as rubber seals/gaskets corroding.  The engine will run hotter but I've never seen it run hot enough to cause problems.  I normally run non-oxygenated fuel but as you point out, there times when you can't get it, and I have had to run ethanol. It never caused any problems, I drove my '51 Kaiser Special all the way to Chicago and back running ethanol.  Also drove it to a meet in Souix City (750 miles round trip) no problems. Doing it once in a while is not likely to hurt it. Doing it all the time will but it takes more than one tank.

[51Deluxe]

- The oil issue may be due to a blocked gallery. Oil is getting trapped high in the engine and it isn't draining as it should. It won't be due to the oil filter as its partial flow and isn't really a factor. When the engine is cool (fresh start) if the pressure is good, keep an eye on it as the engine warms. It will drop but shouldn't fall to near zero at idle. A worn oil pump or loose bearing clearances will cause low pressure.

Interesting theory - when I checked the oil when hot it seemed like almost nothing on the stick, later when cold, over the full mark. Oil pressure has always seemed low but I assumed the gauge was incorrect. It reads 15- 20 at speed and under 10 at idle. Engine is supposed to be completely rebuilt, but has a main seal leak.



- The burning oil smell is probably due to a leaky seal. The downside is the leak, the upside is your car is getting undercoated.


Good call there. Not sure why smoke was coming out of the breather though.


Run the car around town locally and keep tabs on how things act and sound. Let us know what you find!

[dusty]

ONE OF THE SIMPLEST THINGS THAT ARE MOST OFTEN OVERLOOKED IS THE FAN BELT !! EVEN WHEN TIGHT ENOUGH, WHEN THEY GET WORN AND SHINEY THEY WILL SLIP AND WITH SOMETHING OVER 55 MPH WILL CAUSE THE PUMP NOT TO BE CAPABLE OF MOVING THE FLUID TO COOL THE ENGINE.

[51Deluxe]

Interesting - the fan belt is new like everything else - but I replaced the fan with a modern flex fan. It works great at idle, and in general the car runs 10 degrees cooler,  but I wonder if the multi blade fan takes more force to turn at speed and makes the belt more likely to slip?

[JoeKeys2010]

Mine runs a little warm at idle but cools off when I get moving. Is that normal. It does not boil over.

[51Deluxe]

That's absolutely normal. The stock 4 blade fan doesn't pull a ton of air so it heats up at idle. When the car is moving, a lot more air is drawn through and it cools off some. One of the Jackson attendees told me he closed off the two holes in the sheet metal in front of the radiator in his car, forcing it to draw all the air through the grill and said it improved the cooling.

[dusty]

For 1954 the factory blocked the 2 triangular holes to aid cooling.

[84RabbitGTI]

My 51 smokes just a bit from the breather tube after a warm run.  Nothing excessive, mind you.  Make sure you don't rely on the dash gauge to determine your oil pressure.  Put a mechanical gauge on it to check for sure how it is running.  Mine shows 50lbs cold at idle, and it drops a bit as it warms up, also stays at around 50 when cruising.  Also I've found that as your oil ages, your oil pressure drops a little.  My car leaks (seemingly from everywhere: from the higher pressure?) but still has good oil pressure.  I used straight 30 weight Valvolene Raging oil VR1 and it seemed to be good, but I can't find it anywhere anymore.  I had started using non-ethanol gas, to control driveability problems and vapor lock (the gas probably doesn't have anything to do with what you experienced, though).  Works for my car, but others have different experience with it.

[51Deluxe]

Where is the best place to tap in the oil pressure gauge?

[joefrazer]

Install the gauge in place of the existing electrical sending unit. It's located under the exhaust manifold at the back of the engine.