Oil like residue in radiator cap

[MalindaG]

Hi All,

 

Can an expert tell me why there's oil like residue deposited under the radiator cap...??

I did a radiator flush in January...

Vehicle - Toyota Vios 2003

[AVANTE]

Although the pictures aren't clearly showing the problem, I think you mean an oily layer floating on top of the coolant under the cap?  Two cases as far as my experience goes:

1)There's alot of rust in your radiator

OR

2) You have a failed head gasket. 

Start the car with the radiator cap open (make sure no one is standing nearby) and take a peek and see if there are bubbles coming up. If so, you have a failed gasket. 

Edited March 9, 2020 by AVANTE

[tiv]

  On 3/9/2020 at 9:14 AM, MalindaG said:

Hi All,

 

Can an expert tell me why there's oil like residue deposited under the radiator cap...??

I did a radiator flush in January...

Vehicle - Toyota Vios 2003

Expand  

I dont really see  big issue here, newer coolants have a bit of an oily component, 

It is most certainly not diluted enough. 

Also if oil was mixing with coolant it will be like greyish or brownish. 

Also the bubbling, some cars, esp diesels have water pumps that can agitate the flow to mimick bubbling, so a trained mechanics eye may help than self diagnosis. 

 

[Hyaenidae]

It just looks like crusted coolant, maybe you didn't mix the coolant properly with water when doing the radiator flush

[AVANTE]

  On 3/9/2020 at 12:59 PM, tiv said:

Also the bubbling, some cars, esp diesels have water pumps that can agitate the flow to mimick bubbling, so a trained mechanics eye may help than self diagnosis. 

 

Expand  

Oops, I should have mentioned 'alot of of bubbles'.