Coolant in oil? (1 Viewer)

[Hollicasnooze]

First time poster here. I have an ‘86 FJ60 with 166K miles, strictly my weekend ride. At each oil change (which I limit to ~500 miles) I send a sample off to Blackstone Labs for testing, all of which have come back positive for coolant in oil. By appearance, the used oil does not appear milky. The underside of the oil filler cap shows some “milky cream” but what appears to be a normal amount.

I have performed the following diagnostic tests and maintenance procedures:

1) Cooling system leak down test-negative result.
2) Combustion test-negative result.
3) Compression test-numbers look great, all within range.
4) Replaced the oil cooler, positive for coolant in oil afterwards.



I have yet to pull the head, inspect it and replace the head gasket (not sure I want to tackle that project myself) but I understand that represents the proper path forward.

Could it be that one or more of the Welch plugs under the valve cover are the cause? If it is the head gasket, why do the above test results look good?

 

[ceylonfj40nut]

If your not seeing temp spikes when driving and exhaust does not smell sweet or white in color, drive it!

Creamy cap is likely due to you running short trips and not letting your engine heat up to boil out the combustion moisture. I would periodically run it for a longer trip to get this out. A 50 mile trip at > 50 mph should do it.

 

[Hollicasnooze]

If your not seeing temp spikes when driving and exhaust does not smell sweet or white in color, drive it!

Creamy cap is likely due to you running short trips and not letting your engine heat up to boil out the combustion moisture. I would periodically run it for a longer trip to get this out. A 50 mile trip at > 50 mph should do it.

Very helpful, thank you.

Engine temperature has been fine and the exhaust gas has only a very faint wisp of smoke during warmup.

I will try the 50 mile trip @ 50 mph technique as well.

I did fail to mention that my coolant overflow reservoir will regularly run dry (it actually will leak coolant on a hot day when the engine has not been started, is this a telling sign)?

 

[ceylonfj40nut]

So is the bottle leak tight and coolant leaving from somewhere else or bottle leaking?

 

[Hollicasnooze]

The bottle overflow hose drips when the engine has not been started on a hot day (90F). I have to frequently add coolant to the overflow bottle just to maintain a minimum level.

 

[ceylonfj40nut]

Is your radiator cap good? Gasket good? Pics of said bottle, overflow, and radiator cap?

 

[Hollicasnooze]

Radiator, radiator cap and overflow bottle are all new (~2 years old) as I changed them out myself.

I can send pics but everything looks fine.

 

[OSS]

When everything is working as its supposed to, the radiator expansion tank won’t lose any coolant in a year of daily driving or more (mine didn’t).
I also never saw milky residue on the inside of the oil fill cap in 30 years and 290,000 miles.

Blackstone sees coolant in your oil with every test, your oil cap is milky and you’re losing coolant…. How much evidence do you want???

The head gasket needs to be replaced. They are wear items and dont last forever. Have the head bolts ever been retorqued? Probably not and that’s a recommended procedure in the Toyota manual.

 

[ceylonfj40nut]

If your overflow tube is pushing coolant out of the bottle its getting pressurized somehow. I know on my 80, i accidentally switched the hose ports on the coolant bottle cap and had coolant spew out. Sharing.

If coolant bottle does not have a vent, it can pressurize, but not enough to empty it out. Only other source of pressure to your cooling bottle is the radiator/cap. Is cap OEM?

 

[ceylonfj40nut]

Just re read your original post. Why did you replace the oil cooler? With new unit? Is its integrity good?

 

[Hollicasnooze]

Thanks, I’ll see about getting the head gasket changed. Have not retorqued the head bolts so that will be taken care of by default.

The cap, although new, is not OEM as best as I can recall.

 

[Hollicasnooze]

I replaced the oil cooler with a new unit thinking that the old one might be the source of the leak (albeit a lesser probability) plus it was easy enough to do….it’s integrity is as new.

 

[Devils Paw 80]

I did fail to mention that my coolant overflow reservoir will regularly run dry (it actually will leak coolant on a hot day when the engine has not been started, is this a telling sign?

Reservoir might have a crack in it, in addition to a bad head gasket.

 

[OSS]

The cylinder head could be cracked too. Sometimes it happens. Make sure to have the cylinder head pressure tested (removed from block) and magnaflux to make sure there’s no cracks. Some cracks can be repaired at the machine shop.

 

[Spike Strip]

^^

Valve cover will have to come off and I would look for a hairline crack in the cylinder head, near the rear 5 and 6 rocker arm towers.

Sometimes these cracks can't be seen without magnafluxing, and only appear when engine is hot, but you may be able to see something.

This is a fixed one by @HemiAlex but it should give you an idea what to look for.

 

[Hollicasnooze]

This is very helpful, thank you. I will delve further!

 

[HemiAlex]

80,000 miles with the repaired head and a fel pro gasket and it’s going strong.

The engine is using a little more oil and doesn’t like to go 75-80 mph some times but, never the less it persists.