NAA Milky Oil

Hiney

Member
I can usually find the answers to my questions by searching through the numerous post that are on this site, but this time I need some assistance that I couldn't find by searching. I have a NAA that has milky colored oil after only a few hours after an oil change.

I noticed the milky colored oil prior to the oil change and the coolant level was low, so I thought that I probably had a head gasket leak. So I started checking things in an effort to pin point the issue, prior to digging into a head gasket change. I checked the radiator for bubbles while the tractor was running with the thermostat open, but didn't see any. I didn't notice any oily residue floating on the top of the coolant either. I conducted a block test using a combustion leak test kit, but the test didn’t indicate any leaks. I did however notice that the radiator cap was rusted enough that the spring was not able to be compressed, so I thought that might be my problem, as it would allow too much pressure to build in the coolant system. So I installed a new radiator cap and changed the oil, but after only a few hours the milky oil has returned. I don’t know if this is an indication that I still have an issue somewhere or if the milky oil is just a byproduct of water that is still in the oil system from the radiator cap issue.

I also conducted a hot compression check on the engine. The results are 80psi, 70psi, 80psi, & 95psi.

I am using Rotella 15W40 oil, if that makes any difference at all.

So right now, I don't know what to check next, but don’t like the look of the milky oil and hoping that someone might be able to help me out. Anyone have any suggestions or encountered a similar condition before?
 
Does the oil smell like gasoline? Too much gas in the oil can cause it to look milky as well.

With the low coolant level I would lean toward a head gasket leak.
Head gaskets have multiple failure areas and the failure doesn't always allow coolant/oil to enter the combustion chamber.
You may have breach from a coolant jacket into an oil drain gallery where oil draining back down into the block it not under pressure.

Could also have a cracked head or block (The crack being between a pressurized coolant area and a drain or un-pressurized oil area), but a failed head gasket seems much more likely.
 

Motor oil transmission oil and hydraulic oil all get milky from condensation about 500 times more frequently than by an engine problem. The most frequent cause of the condensation is frequent cold starts with short run times.
 
Yep, oil that is contaminated by water will be a murky-brown/milky-whitish color. Engine oil, especially just after an oil change turning milky white, may indicate you have a cracked block and/or head leak, a bad gasket or worse. The only way to be sure is to do a tear down. You may get lucky and spot the problem just by removing the head. Then, since your half way there for a complete tear down, pulling the engine and taking it to a reliable engine shop who will boil the block, Magna-Flux it for any cracks, and then if any cracks are detected, the next decision can be made -is the crack repairable or should the engine be replaced?

Tim Daley(MI)
 
Years ago, many years ago, I had a cracked head on an early 4 cyl Ford....forget just which one, I think it was on a 4000 SOS I bought as what I say
below caught my eye on the tranny. I went to Alexander's Ford restoration over in E. Texas for some parts and had a look at what all was available in
that business.

They had a machine shop where they did Ford engines, heads, SOS transmission - geared replacement kits and lots of Ford parts among other things.

I struck up a conversation with a mechanist/mechanic/repair person......and he was fixing the problem I had with my Head.....a longitudonal crack down
the center of it, a couple of inches long. His method of repair was to drill a continuous succession of small holes along the crack and drive in lead
plugs. He said that it was a common problem and they had them in there to fix all the time.

I bought one of those heads (had the valve work done too as part of their repair process) and installed it and to this day best I know it's still
running...."was last time I saw it". Wink!

You may have a cracked head similar to what I had.
 
Thanks for the replies. It sounds like a teardown is in store to be able to locate the issue.
 

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