Coolant in Oil, Oil in coolant, internal leak?
 

So, I was working on the car Saturday afternoon, mainly playing around with the idle and checking for vacuum leaks. I had finally got the idle dialed in pretty good, and decided to take her for a spin. During this time, I did a small pull which, to put a long story short, blew off the hose from the turbo to TMIC. I fixed this (the hose clamp was damaged), and drove back home conservatively. On my short drive home I noticed the car's coolant temp gauge slowly creeped to the half way point. I got home and shut the car off immediately just about when it reached the half way point.

Next day: I check the coolant, fan, belts, and oil (mind you, I was driving the car throughout spring without this issue, and regularly check the coolant and oil.) The oil level was extremely high, and was chocolate milk colored. I checked the coolant at the water pump fill, and it was a bit low, but nothing crazy, the coolant was also pretty close to the same color as the oil, and with a consistency halfway between coolant and oil, not good. I open the oil fill neck, and it's whip cream consistency!

The car is originally a 1986 GXL, but I've swapped in an entire S4 T2 drivetrain into it.

Anyways, my car doesn't smoke, and has good compression both rotors over 90, no previous signs of low coolant or polluted oil or coolant? I NEVER use straight water, and I don't mix coolants. What could have caused this?

Would a Freezeplug allow both, coolant and oil to be mixed with eachother like this? Dowell? Coolant jacket?

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Either way, the engine will be pulled, and rebuilt as needed.

A freeze plug's job is to Pop like a cork (sort of thing,not literally) when the coolant freezes inside.
It is supposed to save the engine from well,internal damage..

there is a freeze plug on the front iron and its really rare, but if it were to leak it would go right into the oil. it is basically the only place that water can get into the oil on one of these.

How does the Oil get into the water though? that's what really has me stumped. I have to put some time aside and I'll have her out and figure out what the issue is. In the mean-time, I have my vert to enjoy.

Well, I guess if the oil pan had enough coolant and oil mixed it could eventually reach into the coolant system too.

This sucks, im having a similar issue,coolants been dissapearing and i found out its been finding its wat in my oil. Added some dye to the coolant.Checked everywhere with a uv light and nothing,even checked the exahasut,pulled dipstick and it was glowing,could also see the dye running through my OMP Lines to the oil injectors. Assumingill need a rebuild aswell but im also going to check my turbo seals first and the lower intake manifold for any leaks.


Update: I was trying to figure out how the dye couldve got into the oil pan but why there was no sign of moisture on my dipstick or the filler cap,i decided to take a clean paper towel and wipe the stick off a few times then double checked it with the UV light and got nothing,so it looks like i may have had false readings the other night due to the dipstick material. Now i need to figure out why my overflow tanks filling up and the exhaust smells sweet on cold start up.
Also thought the coolant issue might be related to my crappy idle issue if its getting into the housings.

sounds like OP has a bad coolant seal

Well, engine is out. If I find time, I can try to post what the drained fluids looked like. I'd say peanut butter chocolate swirl mocha, or one of those stupid Starbucks drinks.

I'm HOPING it is a coolant seal, that would be super simple as the engine was making decent power still.

Here it is, what your coolant should never look like. The oil looked the same pretty much.
https://cimg7.ibsrv.net/gimg/www.rx7...5ef83e63dd.jpg

Freeze plug on the front iron or outer coolant seal letting go above the oil pan would get coolant in the oil. Both are pretty rare. When you rebuild it make sure to flush the oil coolers, radiator, and heater core.

Is there any really best practice to flush them? Just hose at full blast? I tried to do this to my radiator last night, and it seems like some of the oil doesn't want to leave. I'm hoping it's a coolant seal. This is what I get for using a used 50k mile engine, without taking it apart first. Live and learn.

My thoughts as well. Not a freeze plug issue.

The other potential is a cracked CHRA allowing oil and coolant in the turbo to mix.

Actually, another rotorhead I know suggested this too. This would not be that bad either, I wonder how I could notice this without disecting the turbo.

had same issue and it was cracked front iron

best way to find the source of leak is remove oil pan and front cover and then fill up engine with coolant/water and pressurise it...

If you have 2 systems working side by side and something "lets go",you got your answer.
Oil system is at a higher pressure than the Coolant system..so Oil would be introduced to the Coolant..(then maybe,when the car is off and the cooling system is still pressurized the coolant may find it's way into the oil.)

That's a common myth. A freeze plug is installed to cap a port that was used during casting for gas relief, pouring, expansion, etc. The "freeze" refers to when the metal solidifies.

It just so happens that freeze plugs can pop out when the coolant freezes. However of all the frozen engines I have seen, I've never actually seen the popped out plug protect from damage. Generally this happens:

https://www.rx7club.com/attachment.p...1&d=1500132852

That engine had a lot of coolant in the oil, but no oil in the coolant.

I've seen a cracked turbo CHRA that mixed coolant and oil.

Could be, I know a bit about manufacturing and a lot of the time there are hole left the casting from the fixturing of sand cores. Previously molded sand cores have to be supported in proper position in the mold. This leaves holes in the casting they later machine and plug with what is called a "freeze plug". Everything that is space in an iron was done with a suspended premolded core, most likely, more than one. One for each separation of elements (air, oil, water, they can't be connected cores).

I also believe it's a myth about freeze protection and was more of an observation from when engines froze and they popped out.

The verdict is in!

Before disassembling the engine, I checked the turbo, checked out fine, took oil pan off, looked for any metal residue, checked out fine, then I felt in the front cover for any missing freeze plugs, nope.

Took the engine apart without seeing this, almost certain it was a bad coolant seal. All seals were in good shape surprisingly, dug a bit deeper and found this. I feel like I didn't have to do a complete disassembly, but wanted to check the rotor bearings regardless to see if any bearing damage was done.


https://cimg3.ibsrv.net/gimg/www.rx7...5ed9d1cee0.jpg

https://cimg5.ibsrv.net/gimg/www.rx7...53f3e4f1eb.jpg


How does this happen? Also, how in the world do I get this out? I might as well replace the other plug also, even though it looks fine.

Flaw in the sheet stock they stamped the plug from that caused the corrosion. Very rare except in questionable manufactures.

Pretty wild that this could even happen. I had taken the engine apart and found both stationary gears were worn quite a bit, the coolant-oil mix was literally everywhere in this thing. Everything has been flushed, what a mess. Time to replace the plug, and put her back together...

uhh, it's not corrosion from the side you are seeing, once you pop the plug out you will see just how bad it was on the other side of the plug inside the coolant gallery. check all the other plugs for similar damage on the inside before bothering to reassemble your engine. some other core plugs are likely about to let go as well.

Wow! You can pop them out with a hammer and drift. New ones are available at the auto parts store. Reinstall with green Loctite retaining compound and an appropriately sized socket to pound them in.

That sucks but at least it isn't massive damage.

luckily its not a really common problem, but if the rust is scaled and beginning to flake off id replace any other suspect bad plugs.