yellow / brown fluid in expansion tank

[lawser]

Just replaced the radiator on my 1995, 2.6 auto coupe, old one was leaking........the replacement is 2nd hand. After 10 or so minutes yellow frothy fluid filling my expansion tank.....First thought was head gasket but on checking my oil i have no coolant that i can see mixing with the oil, spark plugs are dry also. 2nd thoughts then are could it be that the oil pipes routed inside the radiator are duff & leaking into coolant ?
Any easy way to check ?

Cheers,

Paul

[Crasher]

Clamp off the pipes too and from the engine oil cooler and flush the system clean with a strong non foaming detergent, I use Flash. If the contamination stops, fit a new oil cooler. I cannot remember if that model has a trans fluid cooler in the radiator, were there any oil lines to the radiator?

[lawser]

Hi Crasher, yes there are indeed oil lines to & from the radiator.........Sorry wasn't very clear in my attempt at explaining my thoughts..........Always sounds right in your head !

[Crasher]

I suspect what you are seeing in the water is ATF and coolant emulsification. I think you should remove the radiator and get it pressure tested. A new radiator for your car is a rather painful £492.13 from Audi, their part number 8A0 121 251 C, but it is a much more reasonable £234 from GSF for their part number 173VG0490 and they are readily available.

[lawser]

Thanks Crasher, Eurocarparts appear to do one for £150.....Is it a case of more expensive, better quality ?

[Crasher]

It looks correct.

http://www.eurocarparts.com/ecp/c/Audi_Coupe_2.6_1995/p/car-parts/car-cooling-parts-and-car-heating/cooling/car-radiator/?203440421&1&2dc350af40fc9ac422e2ed76731deee5b8ade1cb&000261

[lawser]

Eurocarparts £150 radiator is cheaper for a reason, apparently manufactured in China...Went instead for a Nissens bought from Murrays for just over the £200 mark still a saving of well over a hundred quid for the equivalent from Eurocarparts !
Working fine now, thanks again for the pointers Crasher.