39 Dodge Gearbox oil very foamy?

[Rata Road]

Just drained my 39 Dodge stock gearbox as it crunches when going into 2nd both ways when cold, its better when it heats up so I thought I would look at the oil first and then add an additive to see if it helps.

I ran the car on blocks for 5 or more minutes then drained. The oil came out very foamy, 30 minutes later the bucket of oil is still very foamy? Oil looks clean.

I was going to reuse the oil but the foaming is something I've never experienced so maybe I should use new oil.

What would you do?

[Bloo]

Use new oil. The foamy oil is probably contaminated with something. Maybe water.

 

If I had synchronizers not working I would change the oil anyway, and see if it helps. Otherwise you would be tearing the transmission down to replace the synchronizers. Use some synchronizer friendly oil, NOT hypoid oil for a rear axle. I don't know what might be available to you in NZ. I am using Redline synthetic 75W140*NS* in my 1936 Pontiac transmission, works good. 

 

In a synchronized transmission something closer to plain oil is preferable to the super-slippery type used in a rear axle. If cheaper and more common is what you want, maybe GL-1 gear oil or some tractor oil would be good.

 

Before putting too much thought into the oil as a cause of the grinding, make sure your clutch isn't dragging.

 

[Rata Road]

Sorry for the delay in responding Bloo I have just found your response.

Thanks for your feedback.

I have replaced with new oil with an additive with no benefit. Next time I will use plain gear oil and see how that goes.

I am just living with it in the meantime, double clutch gets it smooth most the time.

[Mark Gregush]

There were some 600W years back that foamed real bad. Don't know if that is what you are using so just a thought. Don't know the layout on the 39 transmission, but it is possible that the vent is plugged. 

[nat]

     A worn/seized pilot pilot bearing, (in the flywheel), can and will cause the input shaft to rotate with the clutch disengaged.  Some amount of grinding when shifting gears while the vehicle is stopped suggests that the pilot bearing is misbehaving or that the clutch isn't fully disengaging.

     If it willingly goes into gear at a standstill but grinds during gear changes, a little practice will cure your woes.  

     The clutch and syncros are optional equipment once the vehicle is moving.

[Rata Road]

Goes in fine when not moving and every now and then it goes back down into 2nd with no crunch (like it should) but mostly it does so I'm now just double clutching. Sometimes I get it right lol.