Jump to content

Oil in Coolant

Recommended Posts

I have recently bought a 5 year old XK5.0 from a private trader with less than 20,000 miles on the clock. I found Oil mixed/floating in the header tank. The local J dealer  did some tests and said they could find nothing wrong so they removed the header tank and cleaned it out and flushed the coolant.  All semed well for 100 miles so concluded someone had put Oil in  the header by mistake. Now after a few  hundred miles of motorway driving, the first signs of Oil are reappearing, some emulsification and maybe  a teaspoonful floating in the surface of the water.



What is the next step in getting to the bottom of the problem?


Any help much appreciated.



Link to comment
Share on other sites

Hi Jo, and welcome to the club.


I have seen this before in a Rover Sterling, about 20 years ago which was eventually diagnosed as a failing cylinder head gasket.


There could well be another reason, and hopefully it will not be an expensive one.





Link to comment
Share on other sites

Hi joe,

Iwould say Peter is correct in his diagnosis. There is an Oil gallery seal in all engines on the cylinder head and it sounds like yours has failed between the Oil gallery and the water jacket.

Hope its not too expensive to fix.



Link to comment
Share on other sites

Thanks for your responses guys, I also wondered if it could be this but I understand that both the engine Oil and the gearbox Oil pass through the radiator to be cooled so it could be a leak in the radiator somewhere. I wondered if anyone had experienced the problem specifically with the XK with its complex cooling system.


I would like to know if it is common and how the cause of the problem was diagnosed. 


Thanks again,



Link to comment
Share on other sites

  • 5 years later...

Just a tip to help.

Check if you have water or coolant in the Oil, since Oil systems work at higher pressure oil will be going from a higher pressurized side into the coolant which is at lower pressure, the top pressure for cooling system is  15 or 16 psi, Oil runs at a higher pressure, this will indicate oil getting into the coolant at heat exchanger, the xkr has one under the supercharger in the v of the block, on the other hand the head gasket side will be different way since oil is just dripping from valve train down to the sump, water or coolant will be in the oil if head gasket is blown and coolant excaping (usually this happen with compression blowing from the pressurized cylinder 150 psi into the cooling 15 psi or oil drain back under atmospheric pressure at idle due to pcv vacum), when the engine is shut off hot pressure will remain in  the coolant side and will try to go in the oil heat exchanger side with minimal possibilities because the oil in the galleries does not drain back and has minimal space to accept the coolant and if a little coolant gets in it will evaporate and be discarded by the pcv system when the engine gets hot again, base on the pressures explained here I would check the engine oil and if there is no emulsified traces of oil and coolant in the oil, then for sure I would look into the heat exchanger or engine oil coolers, check the one in the v of the block for a bad seals, on the other hand if a head gasket would be blown, when the hot engine is shot off, high pressure will not be in the cylinders anymore, this will permit low of coolant to the cylinder and could cause hydrolock when trying to crank it the next day after cool down, and definitely will get a burnt coolant smell in the exhaust. my 2 cents

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Join The Club

    Join the Jaguar Owners Club and be part of the Community. It's FREE!

  • Our picks

    • Simply Jaguar - Beaulieu Motor Museum - 26th June 2022
      Jaguar Owners Club have a stand at this years Simply Jaguar event at the National Motor Museum at Beaulieu, Hampshire on Sunday 26th June 2022.

      Anyone wishing to be on the stand will need to arrive by 10.30am and if members have not arrived by then club spaces will be allocated to general participant parking.

      We will need a final update on numbers two weeks prior to the event following which club labels will be sent out to you via email for you to then 

      Club members then need to print and display these in their windscreen on arrival. This helps Beaulieu then park you all in the club area together.

      Tickets are available online here: https://www.beaulieu.co.uk/events/simply-jaguar/

      Club Members will need to purchase their tickets in advance as this will speed up arrival on the day.

      Please Note:  Tickets are per person, so please ensure that all persons arriving are covered by a ticket.


      We do ask for a final update on numbers 2 weeks prior to the event following which we will send out club labels to you via email for you to then distribute out to club members. Club members then need to print and display these in their windscreen on arrival. This helps us then park you all in your club area together.

      1. Wrinkly (John)
      2. Aubrey (Julie)
      3. Trevor (admin)
      • 5 replies
    • Jaguar F-PACE now with six-cylinder 300 and 400 Sport models and Amazon Alexa across the range
      The Jaguar F-PACE now offers more choice and technology than ever, with the addition of the dynamic new 400 SPORT and 300 SPORT models – and the introduction of Alexa voice control across the range
      • 0 replies
    • Simply Jaguar - Beaulieu Motor Museum
      JOIN THE Jaguar OWNERS CLUB STAND HERE .....click below to attend


      Participant prices are only valid if arriving in a Jaguar and taking part in the rally. They are not valid for those arriving on foot.

      Children under 5 require a ticket, this can be booked online free of charge.

      Participant and visitor tickets will include entrance to the rest of the Beaulieu attraction, including the National Motor Museum, Palace House, Little Beaulieu, World of Top Gear, Beaulieu Abbey and its grounds and gardens.

      The best time for viewing the Simply rally is between 10am and 2pm.








      Normal admission applies.

      Normal admission applies.

      More information: https://www.beaulieu.co.uk/events/simply-jaguar/


      Entry with your Jaguar is from 9.30am – 2pm. Please make sure you have your ticket printed, ready to be scanned on arrival.

      Please do not arrive early for our Simply rallies as no facilities will be open prior to 9:30am.

      Cars cannot leave and re-enter the grounds for the Simply rallies.

      • 0 replies
    • Jaguar Land Rover gives second life to I-PACE batteries
      Jaguar Land Rover has partnered with Pramac, a global leader in the energy sector, to develop a portable zero-emission energy storage unit powered by second-life Jaguar I-PACE batteries.

      • 0 replies
    • Jaguar I-PACE now with new Premium Black Pack option
      New Premium Black Pack: Enhances I-PACE’s visual impact and presence with combination of the Black Pack, new Gloss Black 22-inch wheels, rear spoiler and air suspension. Ostuni White metallic paint is also now available
      • 0 replies
  • Create New...