Diagnosing Coolant in Oil - North American Motoring

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Diagnosing Coolant in Oil

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Old 01-11-2019, 06:48 PM
Racingguy04
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Diagnosing Coolant in Oil

I recently noticed milkshake looking sludge on my oil fill cap, but It's been cold and I'd been doing a lot of short trips so I thought/hoped/prayed that it was just condensation build up. I changed the oil, and the oil looked fine, so I thought my problem was solved. but less than a week later, after doing much longer trips (at least 30 mins each time) the buidlup has returned. So what's my next step? I'm hoping that it's the oil cooler that is causing the mix but I don't want to just change it and see. The car has never overheated, and it starts, runs, and drives perfectly. Should I try and borrow a compression tester and do that? should I find a garage that can do a sniffer test on the coolant? (the coolant looks pretty good, I've changed it every 2-3 years since I've owned the car, most recently this summer) Is there something else I can do so that I know what the problem is?

 
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Old 01-11-2019, 07:26 PM
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Originally Posted by Racingguy04 View Post
I recently noticed milkshake looking sludge on my oil fill cap... I'm hoping that it's the oil cooler that is causing the mix but I don't want to just change it and see.
Unfortunately, coolant in the oil is likely due to a head gasket failure...

When the oil cooler fails, you'll have oil seepage into the coolant, as the oil pressure is greater than the coolant system pressure, thus you'll find the milkshake mixture in your coolant reservoir. See my thread HERE that outlines my experience with a failed oil cooler.

Originally Posted by Racingguy04 View Post
...should I find a garage that can do a sniffer test on the coolant? (the coolant looks pretty good, I've changed it every 2-3 years since I've owned the car, most recently this summer).
No need to go to a garage who will charge you a service fee when you can go to your local Autozone or similar and rent (for free) a block tester that you'll place over the coolant reservoir to test for the presence of exhaust gases in your coolant -- again an indicator of a possible head gasket failure.
 

Last edited by AoxoMoxoA; 01-11-2019 at 07:38 PM. Reason: Clarification
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Old 01-11-2019, 07:26 PM
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30 minutes is not long. Drive long enough to heat up everything and see if the condensation burns off. If the oil looks totally fine then you probably don’t have a coolant leak.
 
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Old 01-11-2019, 07:49 PM
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Ugh, AoxoMoxoa, I'm worried you're right, but I'm hoping you're wrong. thanks for the tip on the block tester though. I had no idea that such a thing existed, nor that I could borrow it at autozone. I'll do that tomorrow and see where things stand.
 
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Old 01-11-2019, 07:51 PM
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Originally Posted by Tgriffithjr View Post
30 minutes is not long. Drive long enough to heat up everything and see if the condensation burns off. If the oil looks totally fine then you probably donít have a coolant leak.
How long is long enough? Right now, my commute is 22 miles and it takes me between 30 minutes and an hour depending on traffic. I'd say everything seems up to operating temp by the time I get home, but I'm willing to drive farther if you think that'll help.
 
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Old 01-11-2019, 07:57 PM
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Originally Posted by Racingguy04 View Post
I recently noticed milkshake looking sludge on my oil fill cap, but It's been cold and I'd been doing a lot of short trips so I thought/hoped/prayed that it was just condensation build up. I changed the oil, and the oil looked fine, so I thought my problem was solved. but less than a week later, after doing much longer trips (at least 30 mins each time) the buidlup has returned. So what's my next step? I'm hoping that it's the oil cooler that is causing the mix but I don't want to just change it and see. The car has never overheated, and it starts, runs, and drives perfectly. Should I try and borrow a compression tester and do that? should I find a garage that can do a sniffer test on the coolant? (the coolant looks pretty good, I've changed it every 2-3 years since I've owned the car, most recently this summer) Is there something else I can do so that I know what the problem is?
An oil drain with the engine up to temperature then letting the oil sit then carefully pouring the oil into another pan can find some water/coolant on the bottom of the 1st pan. The oil will float on even just a few puddles of water.

Or an oil analysis will check for anti-freeze compounds in the oil. You want to collect an oil sample while draining the oil hot and from mid stream. You don't want an oil sample from the initial gush of oil nor from the dregs that dribble out towards the end of the drain interval.

If the engine doesn't overheat, if the coolant shows no signs of oil in it -- there will be drops of oil floating on the coolant -- if the coolant level doesn't drop nor the oil level go up, there is no check engine light, the odds are better what you are seeing is just water moisture condensing around the oil fill cap. That's about the the coldest spot in the engine and it is common for vehicles driven in cold damp weather -- aka winter -- for some milkshake like goop to collect. I saw it once in a while in my Boxster which had what seemed like a several foot long oil filler tube.
 
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Old 01-11-2019, 08:02 PM
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Out of curiosity, if you're losing coolant into your oil, you would most certainly notice some incremental loss of coolant in your reservoir. Have you noticed your coolant level going down?
 
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Old 01-11-2019, 08:26 PM
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go for the oil cooler first as it is the cheapest fix, and we've seen several of them fail
https://www.waymotorworks.com/oil-co...s-r52-r53.html

After that it's usually in the head. but make sure you have a machine shop check the entire head as we have seen cracks in the front of it that don't effect the cylinders or head gasket they just leak coolant into the oil.
 
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Old 01-11-2019, 09:08 PM
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Originally Posted by AoxoMoxoA View Post
Out of curiosity, if you're losing coolant into your oil, you would most certainly notice some incremental loss of coolant in your reservoir. Have you noticed your coolant level going down?
I've been keeping an eye on it, and I haven't noticed any lower level, but I do have a black aluminum coolant tank, so it's harder to read than the OEM plastic tank.
 
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Old 01-11-2019, 09:18 PM
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Rock C, thanks for the pointers. I drained the oil a week ago and it looked good and felt good to me, but I have it in a jug, so I may pour it out and see if I can see a bit of coolant/water on the bottom.
 
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Old 01-11-2019, 09:26 PM
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This is what my oil cap looked like tonight.
 
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Old 01-12-2019, 06:46 AM
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I say just condensation. If you had any coolant in the oil you would notice a difference in the appearance from typical oil appearance. The crank shaft is constantly whipping the oil in the pan, hence the milkshake effect. I’ve seen the condensation line n the cap also during winter. Short trips will warm the engine but the winter helps keep the top of the engine cooler than other times if the year. Try wiping out the sludge before your next trip. Then check the cap afterwards.
 
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Old 01-12-2019, 08:43 AM
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I really hope you're right, but I wiped it away 6 days ago, and haven't had any drives less than 30 mins since then. I may start checking it after every trip. I checked it once earlier this week and there was a small drop of sludge. My coolant temp, once it gets up to operating temp, is usually around 199 - 203 Fahrenheit in the winter and more like 205-210 i the summer.
 
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Old 01-12-2019, 09:29 AM
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Originally Posted by WayMotorWorks View Post
go for the oil cooler first as it is the cheapest fix, and we've seen several of them fail
An interesting response, especially since itís generally understood that when the oil cooler fails, it results in oil flowing into the coolant due to the higher pressures of the oiling system.

Have you seen the opposite, with failure of the cooler resulting in the flow of fluids in the opposite direction (coolant flowing into oil)?
 
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Old 01-13-2019, 10:44 AM
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I'm also curious about Way's response, mostly because I'm hoping that it is the oil cooler, but I'm trying to avoid just throwing parts at it to diagnose it. $150 isn't the end of the world, but I'd rather not spend it if it's not going to help.

I ran the block tester today and it came back negative for exhaust gasses in the coolant. I'll probably run it again just to be sure, but I'm kind of encouraged that it might not be the head gasket after all.

nice and blue.
 
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Old 01-13-2019, 11:09 AM
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Do you park your car outside at night & is it a humid environment where you live? If so, It may just be humidity being drawn in as the engine cools down.

If you could park it in a dry environment for a few days, you might see it disappear (I would wipe it off after every drive during this test).
 
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Old 01-13-2019, 11:34 AM
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Originally Posted by Racingguy04 View Post
I'm also curious about Way's response, mostly because I'm hoping that it is the oil cooler, but I'm trying to avoid just throwing parts at it to diagnose it. $150 isn't the end of the world, but I'd rather not spend it if it's not going to help.
Those were my thoughts exactly when I posted.

Iím crossing my fingers that itís as simple as failure of the oil cooler. One would welcome the possibility that an oil cooler can fail in the opposite way, i.e., coolant getting into the oil. Iíve just never heard of it working out that way.

That development would save many from the expense of what might be an unnecessary head gasket job.

Glad the block test yielded positive results.
 
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Old 01-13-2019, 12:03 PM
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Here’s a great pic illustrating the different locations of possible head gasket leaks and the resulting effect on symptoms.
 
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Old 01-13-2019, 12:38 PM
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Tip to check coolant level in an opaque reservoir: Just get yourself a short, unpainted wooden dowel and mark it with a ballpoint pen where the level is currently but do it when the car is stone cold and check it again only when the car is stone cold.
 
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Old 01-13-2019, 02:17 PM
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Originally Posted by Minidogger View Post
Do you park your car outside at night & is it a humid environment where you live? If so, It may just be humidity being drawn in as the engine cools down.

If you could park it in a dry environment for a few days, you might see it disappear (I would wipe it off after every drive during this test).
I live in Baltimore at the moment so definitely not what I would call a dry environment, especially since I moved here from Colorado. I park in a parking garage, which is kind of damp, I think, but it is open to the air on one side.

Do do you mean wipe off the car? Or wipe off the oil cap?
 
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Old 01-13-2019, 03:01 PM
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Sorry, meant cap. Then you would know if you are making any progress.

Another idea is to wipe the bottom of the cap clean when you get home, then check it the next morning. If it is just atmosphere moisture, it might show up then. Good luck,
 

Last edited by Minidogger; 01-13-2019 at 03:07 PM. Reason: better message
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Old 01-13-2019, 06:19 PM
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If you park a warm car in a humid environment, which Baltimore is cause it’s by the ocean, you will have condensation form under the cap.
 
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Old 01-14-2019, 08:13 AM
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Are you running an oil catch can?
 
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Old 01-14-2019, 12:46 PM
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Out of curiosity I checked mine & have same white goo. I typically just go to stores a few miles away & then put away in dry garage.

I need to drive it longer & more often!

 
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Old 01-14-2019, 01:47 PM
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Originally Posted by MINI33342 View Post
Are you running an oil catch can?
Yes, I'm running a catch can, The M7 can plumbed according to M7's recommendations (and I'm aware of M7's reputation).

Out of curiosity, I checked the cap on my wife's 4runner today. It's a completely different car and engine (V6) but driven and stored in basically the same conditions. Her car also has a bit of sludge on the oil cap. So I think between that and the negative block tester test, it's most likely condensation. For now I think I'll just keep an eye on it, and reevaluate once the temps warm up (since I can't plan on the humidity dropping, this is Maryland after all....)
 

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