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Pete
Pete, Car Enthusiast
Category: UK Car
Satisfied Customers: 25288
Experience:  Over 17 years experience diagnosing and repairing automobiles.
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I have an '04 X5, 3.0i - the coolant requires topping up

Customer Question

I have an '04 X5, 3.0i - the coolant requires topping up frequently and there is no sign on leakage (I've had my independent pressure test the system and seems all good) - when I open the water filler cap, there's pressure when cold - the car has also started to misfire on cold start ups which clears after a minute or so - could this be a coolant leak into a cylinder through a faulty head gasket? The car hasn't overheated that I'm aware of. Thank,s
JA: How old are the hoses? And have you tested the actual mix of your coolant?
Customer: The hoses are probably original - I've had the car since May this year and it has 143,000m on it - the mix of coolant is correct as per BMW's requirements - there doesn't appear to be any oil in the water and there's no 'mayonnaise' under the oil filler cap
JA: Are you fixing your X5 yourself? What have you tried so far?
Customer: Nothing yet and if it's fairly straightforward, yes, I'd do it myself. As I've had the system pressure tested with no apparent leaks, I can only assume it's leaking internally.
JA: Anything else you want the mechanic to know before I connect you?
Customer: It had the heater valve replaced when I bought it and it takes a while for the cabin to warm up, though I'm told this is common for these cars.
Submitted: 1 month ago.
Category: UK Car
Expert:  Pete replied 1 month ago.

Hi my name is ***** ***** I will be happy to assist with this today.In some cases I may need more info to assist better.I apologize for any delay.

With what you have described here with system pressure even when cold and a loss of coolant but no external leaks,no fluids mixing, this does sound like a cylinder head gasket leak here.One of the head gaskets can cause coolant to leak into a cylinder or even the exhaust system.This can cause a misfire in some cases as well on start up.

If you have not removed any of the spark plugs this can be done and check for any white tips on them.If any have any white tips this can indicate coolant in that cylinder due to a head gasket leak.You can also plug in a scan tool to your model that can read engine data to observe engine misfire data to locate which cylinder is misfiring on start up and this can indicate the cylinder with the leak here.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service,your 5 star rating is appreciated.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete