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Discussion Starter · #1 · (Edited)
Hi, a quite sad thing happened today. When checking the oil level I saw that the coolant overspilled from the reservoir cap and was covered in a brownish stain. When I took the cap off, I saw this (pic 1) and same muddy deposites in the reservoir.
I had to get home and after the 15 km drive it looked like this (pic 2, 3).
Is that oil in the coolant? The car wasn't overheating, no smoke from exhaust, oil is clean.
GT 2004 2.0 JTS
Thanks for any suggestions
 

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Oil cooler failed? Not sure what type of cooler these engines have. Otherwise have the compression checked in the engine to get a better idea on the head gaskets condition. If the car did not overheat then the head gasket will hopefully be ok. Once you know the fault the cooling system will need a good flush!
 

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JTS is a TS but with slightly higher compression, single plug ignition direct injection. It uses same coolers etc but it does seem to have more chance of failing cylinder head gasket, I have noted and experienced.

As for test equipment, this eBay link is for a cheap type of tester; Combustion Leak Tester Kit Detector Head Gasket Block 30ml Fluid Petrol/Diesel | eBay
The oily coolant is the same as I experienced. I did always have an over-pressurised cooling system though so eventual gasket failure was completely expected.

Cylinder head gasket failure is awkward enough but the JTS really benefits from improved Goetze piston rings, drilling in pistons (in valleys of oil control rings), injectors cleaned and a new coolant expansion tank after flushing it through thoroughly. It would be expensive to have to pay someone to do that.
 

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Discussion Starter · #4 ·
I changed my expansion tank like two months ago since it was leaking so I think an over-pressuirsed system isn't the case here. I also recently had my clutch and timing belt done so another costly repair is unfortunately a no go for me.. So I guess I'll get my compression tests done and then decide wheter to sell it for parts/repair or not :/ . Earlier this morning I tried running the engine with the tank cap off to look for bubbles in the coolant and I didn't see any. The coolant also looks quite clean but I noticed some smoke comming out of the filling hole after a drive to work. New video by Adam Fačevic
 

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When the heat exchanger on the TS started leaking 2.5 years ago, I removed it and just used a rubber hose to connect up the coolant pipes until a replacement exchanger arrived.

If it is a cylinder head gasket, on another car, I previously used the Steel Seal liquid to seal it up. It took a couple of weeks of local running to seal completely. I used it for 6 months and it culminated in a 1000 mile drive across Europe to return so I could fix it properly. It would be a way of delaying the cost but despite claims, I still prefer to fix properly.
 

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I did always have an over-pressurised cooling system though so eventual gasket failure was completely expected.
Excessive cooling system pressure does tend to imply that the gasket has probably already failed, more than likely the cause of the raised system pressure...?

Or, the other explanation could be the existence of a hot spot(s) inside the cylinder head, i.e. metal that forms part of the combustion chamber roof(s) is getting so hot that it is causing localised coolant boiling in one or more locations in the water jacket. This can occur inside the cylinder head, always the hottest parts of the cooling system even when it is operating correctly, because temperature is never equal within the water jacket. Some parts are always quite a bit hotter than others, with the hottest coolant being directly adjacent to the metal forming the combustion chamber in the head, and the coolant surrounding the exhaust ports.

When liquid turns to gas its' volume increases by around 600X, so it doesn't take much localised boiling to add significantly to the cooling system pressure, even if it may not add all that much to the general system temperature. The average temperature may not rise by much, and the temperature gauge sender may still be detecting an acceptable temperature, yet a small hot spot(s) where a relatively small volume of hyper heated coolant can still exist.

The gauge can read a lower temperature (than the highest temperature in the system) because by the time the coolant comes into contact with the gauge sender the the hottest coolant has mixed with cooler coolant. Even in a properly functioning system the temperature at the location of the gauge sender is never as as high as the highest coolant temperature in the system, which is always hottest directly adjacent to the metal forming the chamber roofs and exhaust ports.

This sort of problem (localised coolant boiling) is more likely in systems that have poor coolant flow, either a bad coolant pump and / or if coolant low is impeded due to general crap accumulated in the system.

Regards,
John.
 

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Hi, a quite sad thing happened today. When checking the oil level I saw that the coolant overspilled from the reservoir cap and was covered in a brownish stain. When I took the cap off, I saw this (pic 1) and same muddy deposites in the reservoir.
I had to get home and after the 15 km drive it looked like this (pic 2, 3).
Is that oil in the coolant? The car wasn't overheating, no smoke from exhaust, oil is clean.
GT 2004 2.0 JTS
Thanks for any suggestions
What's the texture like? grainy? smooth? it might be you have an airlock in your cooling system somewhere that's belched up some old rust from the radiator guts. Alternatively someone tried to plug a leak with some rad repair stuff that's turned to gunk.
get a tester to make sure your head gasket is good then Flush your system and replace your coolant making sure you evacuate all the air.
 
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