300 tdi oil in coolant

Took my newly converted 300 tdi lightweight for its first mot today and it passed

Ran well no smoke but coolant pipes seemed hard although no signs of overheating ,i waited for it to cool down and checked coolant and its black with oil

Oil level has dropped from full mark on dipstick to bottom mark so has used a few litres ,no signs of water in the oil

Engine was always good before conversion ,i fitted a new radiator so im hoping its the oil cooler

Is it possible the oil pressure caused the coolant hoses to go hard ?

chrisstdt said:

Took my newly converted 300 tdi lightweight for its first mot today and it passed

Ran well no smoke but coolant pipes seemed hard although no signs of overheating ,i waited for it to cool down and checked coolant and its black with oil

Oil level has dropped from full mark on dipstick to bottom mark so has used a few litres ,no signs of water in the oil

Engine was always good before conversion ,i fitted a new radiator so im hoping its the oil cooler

Is it possible the oil pressure caused the coolant hoses to go hard ?

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Could be, coolant works at about 15psi max while oil pressure can be 55 psi so could be forcing its way in to the coolant system. That said the coolant cap should relieve pressure above 15psi (or thereabouts) so if the oil was pressurising the coolant system (and being transferred to it) there should have been a corresponding coolant loss. Are you positive there is a couple of litres of oil in the coolant?
You will need to flush the coolant system so it may be worth draining if off into a container and let it separate just to make sure there is a lot of oil in there, there may have been some residual oil in the coolant galleries from the conversion which is making it look black but you may actually have an oil leak instead (but you should have spot that).
Worth trying to get the radiator oil cooler pressure tested just to eliminate (or condem) it.

Drained it this morning and there is alot of oil in there and the oil level has dropped alot

Its been run a fair bit up and down a private road and been up to temp but this is its first proper run ,there was no sign of oil before yesterday

Il cobble a pipe up at work today so i can join the oil cooler pipes together and once its been flushed il run it without the cooler and see what it does

Worth bearing in mind that if the oil cooler does have a leak and you bypass it then you may end up with a coolant leak going the other way i.e. coming out of the open oil cooler connections.........just keep an eye on coolant levels.

Thats a good point ,il keep an eye on that but if it does that would confirm the faulty cooler and would be better than lifting the head !

chrisstdt said:

Thats a good point ,il keep an eye on that but if it does that would confirm the faulty cooler and would be better than lifting the head !

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If it does then leak that does confirm you have a faulty cooler / rad, however if it doesn't that doesn't necessarily mean that it is ok, it may be able to hold 15psi (water pressure) but 55+psi oil pressure may be able force its way through a small defect. If it doesn't leak it is still worth pressure testing the oil cooler just to make sure.

I was going to take it for a run after ive flushed it and if the water level doesnt rise and the oil level doesnt drop then that should rule out a fault with the engine

Id like to be able to put the airline onto the oil cooler and get it up to 60 psi but i think id struggle to get the right fittings