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Was checking the coolant level in my '03, and this whitish/creme colored deposit was on the underside of the radiator cap. a small amount was on the inside of the filler neck, but coolant looked clean. Radiator cap is barely a few weeks old. Do I have something to worry about here?
 

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Was checking the coolant level in my '03, and this whitish/creme colored deposit was on the underside of the radiator cap. a small amount was on the inside of the filler neck, but coolant looked clean. Radiator cap is barely a few weeks old. Do I have something to worry about here?


Someone could have added something to the cooling system (stop leak)?

Short trips in cold weather without a fully warmed engine can cause deposits like this to form as shown.
 

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I see no evidence of any stop leak, radiator and coolant tank levels have stayed at normal levels since I have had the car. When I take it out , it's always driven till the car is up to operating temp. I guess I'll just wipe it off and just keep an eye on it
 

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To me, it looks like it could be oil in the condensate on the radiator cap. If so, you can flush a bit of it out of the COOL radiator by filling the neck with hose water and float it out. My guess there is a gooey, aw ****, residue needing wiped out.

Does the underside of the engine oil fill cap or even the dipstick have any of that milky goo? Peek in the coolant overflow tank while shining a light into it and what does it look like? Oil in your coolant isn't to be ignored.



The only other thing I can think of is Dex-Cool going over to the dark side or maybe some green coolant got topped off into the orange. Good radiator caps are essential with Dex-Cool too. Either way, don't let this thing get ahead of you. Es no bueno.
 

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Only one real way to find out what's going on...drain, flush, and refill that bad boy and see if the gunk comes back. I've seen similar build up in other cars caused simply by being old fluid that was way overdue for a change. Also I've seen it from people that didn't know they are supposed to use distilled water if they used the concentrate antifreeze. Using tap water all that white chalky mineral deposit stuff that builds up around the faucet now turns into a glob in the car
 

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Was checking the coolant level in my '03, and this whitish/creme colored deposit was on the underside of the radiator cap. a small amount was on the inside of the filler neck, but coolant looked clean. Radiator cap is barely a few weeks old. Do I have something to worry about here?
How many miles do you have and how long have you owned the car?
It could be all that you need is a thorough system flush.
 

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Discussion Starter #7
How many miles do you have and how long have you owned the car?
It could be all that you need is a thorough system flush.

Sorry for the delay in responding. Car has 190k on it now. Bought it in July 2019 with 184k on it. I used my coolant tester and it's good to -35, coolant still had a good orange color to it. I wiped that white gunk from the radiator cap a couple weeks ago, and checked it today, was more of it on the bottom of the cap, and on inside of filler neck. Did not see any in the coolant. I've not had to add any to it since I've owned it, and up until now this white gunk was not there. Should I be concerned? I still owe 2850 on this thing, should I dump it before it gets worse?
 

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I agree with Wz7u

To me it looks like oil vapours mixed with coolant that have collected on the highest point in the cooling system.

I know that's not something that you would like to hear, but that is what it looks like to me.

Where is it coming from ??? Don't know.

You can have one way leaks, ie: oil into coolant but not have coolant in the oil, and vice versa kind of thing.

I assume you have no overheating issues, and that the underside of the oil filler cap does not have any similar schmoo on it .
 

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Discussion Starter #9
To me it looks like oil vapours mixed with coolant that have collected on the highest point in the cooling system.

I know that's not something that you would like to hear, but that is what it looks like to me.

Where is it coming from ??? Don't know.

You can have one way leaks, ie: oil into coolant but not have coolant in the oil, and vice versa kind of thing.

I assume you have no overheating issues, and that the underside of the oil filler cap does not have a similar glob of schmoo on it .

No sign of the same white stuff on the underside of the oil fill cap. Does not overheat, I took it for a good drive this morning, and checked the radiator after it cooled down, no sign of that white substance,whatever it is must take a week or more to show
 

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Discussion Starter #11
This is what the temp gauge reads when driving at highway speeds. when driving in town, or stop and go driving it will move to the center mark on the gauge and stay there
 

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