Brown Sludge - water in the oil?

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The backstory : Inherited a 1978 Stock FJ40 from my dad. Engine oil looked good. Took it for a spin and checked the oil again after about a 20 minute drive and noticed it was milky brown. Decided to pull the valve cover and this is what I was greeted to. I suspect this is a result of water getting into the oil. Failed head gasket I suspect or ??? Soliciting your expertise and opinions. I'm thinking to start I'll remove the head. Anything else that could be the culprit. Cracked block I suppose is also an option. Thanks

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pjohnson

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And maybe been there a while by the looks of it.
 
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Head gasket, hopefully not a cracked head. Been there and replaced both. Not hard just time consuming.
 
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Thanks for the replies - Since this contamination has been going on for a while do you think there may be some lower end issues with possible rust? It sat for several years and was not driven much. I think my dad would start it periodically but that was about the extent of it. It's got 158K miles on it. I guess I can pull the oil pan and find out.
 

middlecalf

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Might also do a compression test. A lot of bypass can cause that as combustion gas has a fair amount of water in it. Also, pull radiator cap (when cool) then run and see if you get constant bubbles in coolant.
 

3_puppies

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how long has it sat?
could water or moisture gotten into it thru the years and running it mixed everything up in the oil pan?
if you had changed the oil first before running it you would have seen it, if it was in the oil pan
 
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It's probably only been driven 1000 miles in the past 10 years. He took it in for an oil change every year regardless. I found several receipts for those changes in the glove box. Last one I found was 2021. I have not changed the oil myself yet. Just trailered it home a few weeks ago. So just started looking it over. I didn't think about changing the oil since it was done last year and not driven. Looked fine on the dipstick prior to the drive. But I think I will drain it now and see what it looks like.
 
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Since this contamination has been going on for a while do you think there may be some lower end issues with possible rust?

Maybe? If the mix had a more red color, I'd be more concerned.


Change the oil. Run it, get it warm. Change it again. Then make another assessment.
 

Skreddy

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I’m with the votes on water in oil due to bad head gasket or some cracked cast iron.
If you can, do a compression and a leakdown test before pulling it apart. You can also pressure test the cooling system while it’s all together too. Could help you narrow down the culprit pre teardown.
Sorry about your milkshake of sorrows.
 
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It's probably only been driven 1000 miles in the past 10 years.

Engines that are never driven 'good and hot' can develop moisture and crud like that in the valve cover. This is because the engine is never hot enough to drive off the water.

If you determine that the head gasket/block, etc. are fine, I would drive it hard on the highway more often, and change the oil regularly.

If there are head gasket issues, you might eventually pull a bearing cap and see if the bearings survived the antifreeze/oil mixture.
 

ceylonfj40nut

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Check your thermostat. If it is one that is set too low, moisture cannot evaporate from oil easily. Also if engine has not reached operating temp for a decent amount of time each time it is fired up, moisture can build up in oil. Do you have white smoke from the tail pipe?
 

pb4ugo

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I’m with the votes on water in oil due to bad head gasket or some cracked cast iron.
If you can, do a compression and a leakdown test before pulling it apart. You can also pressure test the cooling system while it’s all together too. Could help you narrow down the culprit pre teardown.
Sorry about your milkshake of sorrows.
/\/\/\This/\/\
Compression test, leakdown. Pressure test the cooling system. It's easier to test and diagnose when it's all together. Then you can know where to look, upon disassembly. I think its too much water for condensation from sitting for a year.
 
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Thanks for the input. Next steps will be compression/leak down test. Cooling system pressure test may be a problem because I think the radiator is leaking. Noticed some antifreeze on the support and some wet spots on the fins after my initial drive. I think i’ve inherited another project here. Guess I’ll add it to the queue.
 
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All the advice regarding leakdown tests, head/block cracked, etc is fine and dandy and likely worst case only, the more obvious and easy thing to check (which is often the culprit) is whether the small freeze plugs in the head or on side of the block behind the pushrod cover have pinholes and have rusted through from all the standing.

Before pulling anything, drain the oil/water mix, wipe the concoction off of the rocker arms and the freeze plugs in the head, pull the side cover also, wipe the freeze plugs behind the side cover, fill water and you will see if water flows out of them. This has been the culprit on a few of my Cruisers which have stood for long.

Compression and leakdown figures will likely not be good until it has run more
 

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