Oil...maybe. In Radiator...but no other signs of head gasket failure.

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Deathacus

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Hello everycreature! So, I think I've asked this kinda before, but not in its own dedicated thread. I've been noticing light brown sludge in my coolant. Looks like oil, from what I understand. It's not like, frothy or bubbly or anything, but it does have that gross chocolate milkshake look to it. I've been reading on this forum that head gasket problems are pretty uncommon on the 3.0, and She seems to run just fine.
I've done a combustion leak test, cylinder leak down test, compression test, I've looked for bubbles all looks good, great even. I haven't sent any oil samples off to Blackstone or whoever, but a visual inspection shows oil is good. The only other thing I notice is excess oil in one of my cylinders.

Now, I've only put about ~15k miles on her since I bout her, and I can't remember when the first time I changed the coolant, but it was super low and pretty nasty. Like, half a gallon of sludge, it seemed. I haven't had that much since, ran a couple chemical flushes, but it's hard to say if there even is an ongoing problem, or if its old contamination breaking free.

I just hate to do a head gasket if I don't have to, nor do I want to put my new rad in until I know it's running clean.
 

shaldaya

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If you forgot to put antifreeze, it could just be rust buildup
I'd recommend doing a coolant flush because who knows how long it's been and what sort of stuff might have built up over the years

Also, i really don't recommend you use politically correct talk here, most of us here prefer vulgar "**** you" talk, and we tend to take people less seriously when they talk with political corectness

Sent from my SM-G991U1 using Tapatalk
 

Irish Pride

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More than likely it's just sludge buildup from improper service over it's lifetime. I would do a couple flushes and see how it turns out.

What I do, drain the coolant in the system and leave the draincock out and use a hose in the top to completely flush the radiator. After you have the rad flushed replace the draincock and add one gallon of white vinegar and then top off with water. Drive it like that for about a week and then drain the system again. If it's still looking a little brown then repeat with another gallon of vinegar. Once you've completed your flushes then refill the system with 50/50 mix of green coolant and distilled water. Run it like that for another week and then drain and refill again with the 50/50 distilled mix. At that point you should be go to go.

-Chad
 

zoomlater

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I wish I knew about this vinegar trick. My 94MTX with 69K developed the same issue (not really driven but sitting). Brown junk in the coolant tank and top of the radiator. I flushed the radiator probably 10 to 15 times until I no longer saw brown water coming out. Full fills and ran up to temperature until draining and replacing. Not knowing the history prior to my purchase, I suspected radiator stop leak and there was a small leak at the bottom of the radiator. Anyway, wanted to flush anything out so I knew it was clean after that. Haven't had an issue since then.
 
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Irish Pride

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Forgot to add that when I do a flush on one of my cars with the vinegar I always remove the thermostat so that the cooling system is free flowing. When finished I always add a new thermostat.

-Chad
 

rubydist

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But, it is possible for the head gasket to fail in a way that allows oil into the coolant without compromising compression or having any leakdown issues, so do not rule that out.
 

Tbird6

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Check coolant for combustion gases? Kit is about $45 and will quickly tell you if head gasket's are the problem. Or find a shop that can do it.

Check for Combustion Gases Kit

For flushing I have found nothing better than Thermocure. Made by the Evaporust people if your familiar with that product. Works great and is NOT an acid so no worry about leaving it too long in the engine. Interesting as I did NOT know Evaporust was purchased by CRC in 2021 either! I usually run it for a week or more as multiple heat cool cycles make it work better,

Thermocure
.
.
.
 

Greg Corcoran

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... I've been noticing light brown sludge in my coolant. Looks like oil, from what I understand. It's not like, frothy or bubbly or anything, but it does have that gross chocolate milkshake look to it. ....
Well, I have an alternate explanation that occurred with my '92 when I lived in Chicago area. OEM thermostat failed open during the winter (or maybe in the fall, don't know precisely when, since it failed open). Chocolate milkshake describes exactly what I saw in the overflow bottle and in the radiator when I started to investigate why my heater output was pathetic and the temperature gauge barely moved on a sub zero day. Apparently some type(s) of bacteria likes to munch on ethylene glycol as their carbon source. The only mystery is how they got into the cooling system in the first place. Since the cooling system never got to sterilizing temperature with a failed thermostat, they were warm and comfy and multiply like crazy making that milkshake looking sludge.
A thorough chemical flush (twice I think?), fresh thermostat, and fresh coolant solved my problem and the milkshake never returned.
 

SHOdded

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coolant flush and combustion gas testing are the least labor intensive approaches to try. you may have to replace the water pump as well if it worn badly enough or is due as a part of regular maintenance.
 

Deathacus

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Long shot but what can yall tell me from this? This came from under the rad cap. Doesn't feel gritty, doesn't feel quite as sticky as antifreeze but not super oily, and it appears to rinse off the q-tip and my fingers with running water.
 

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Deathacus

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Finally doing the Thermocure now that it is above freezing. Found the front block drain plug too and wow, what a mess but got so much more out. The coolant actually looks pretty good despite my 12 hour trip to Milwaukee last fall for Ciderfest. So it probably is old residue.

That does bring me to something I found, all my sources say the stock thermostat should be 192 or 195 degrees, but reading the service manual for '94, it says it opens between 180-220 deg. Arn't thermostats usually marked by the temp they start opening at? Wouldn't that make a 180 the correct OEM 'stat? My envelope of records show the last guy put in a Gates 33339S, a 195 'stat. The gauge does point to "M" while driving. (as long as I don't get stuck in the drive thru)
 

Deathacus

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Okay, now what?
 

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rubydist

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that looks normal for startup on a cooler, humid day. What was the weather like?
 

Deathacus

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54F and 78% humidity, according to google. Funny thing is, I have been running the car on and off all day. I started this flush at 9:30am, it is now 10:23pm. Because of course it is. I didn't notice anything until just now, and after the engine was warm. I've never seen it smoke like that.
Shall I try again when it's dry this weekend?
 

shaldaya

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the look of your drain pan looks like oil and coolant, and that would suggest head gasket failure
But if that sludge is after a flush or after sitting then it could just be buildup or the flush doing its job

Also if your draining then filling the engine without letting it sufficiently cool down, you might have warped the heads
 

Deathacus

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Well, ran her again today, drove her nice and fast for 15 min, no more visible smoke. Felt a little humid putting my hand up to the tailpipe. Is that normal? Kia doesn't put out enough at idle to compare it to. Also tasted the wet gravel beneath and it tasted like plain water.
 

rubydist

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Water is one of the byproducts of combustion, so yes it is normal for the exhaust to be wet/humid
 

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