I have a problem for the last few months with my scania r620. Somehow there is oil leaking into the water system. I have changed oil cooler and all that goes with it and around it, plates front and back, new radiator and all new water jackets. Radiator and retarded are ok. Checked and pressure tested. No oil in the pipes on the retarder. I have the pipes joined together, bypassing the heater because it keeps getting clogged. Can anyone tell me if it's possible for it to get in through the compressor in any way???

  • Welcome to Motor Vehicle Maintenance & Repair! Sep 4, 2018 at 22:29

2 Answers 2


There are a few common issues with the R620

Here's the ones I can think of that you haven't mentioned:

The compressor:

Too rule out:

Remove the two coolant pipes going to the compressor and join them together.

You could then either:

Run the engine and watch for oil coming out of either coolant port on the compressor

and / or

Flush and clean the coolant system run up to temp and leave for a while or drive and monitor the coolant.

Oil Filter Housing Seals

Oil Seals behind Water Pump


Oil leaking into the cooling system is a sign of head gasket failure. You'd need to replace the head gasket to fix.

  • Oil in the cooling systems could be a number of issues. It COULD be a head gasket but on a truck engine with air compressor, piston liners, water cooled fuel pumps, oil cooler and loads of other items that share oil and water it could be a number of things. Dec 4, 2018 at 21:48

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