2013 CX5 2.2D Loosing Coolant - Cause?
 

Hi all,

My cx5 2.2 diesel with 100,000km on the clock seems to be using/loosing coolant as I'm having to top up the reservoir. There's no visible leaks and I've had the radiator system pressure tested by a local mazda service centre and they could not find any leaks either. They suggested it could be the EGR cooler. I priced up a new cooler and they are around $1000 NZD for the cooler only! So I took a gamble and brought a second hand one, and had it pressure tested by a radiator specialist before changing it out. There was no visible leak @ 15psi. Although they did mentioned, pressure testing at cold is not 100% accurate as thermal expansion etc can mean a crack is closed when cold and opens when hot....

Anyhow I changed it out and 2 weeks later - no difference, still loosing coolant at about the same rate!

So I'm fairly, although not 100% sure, it's not the EGR cooler. Any other suggestions? Or anyone who's had similar issues?

I'm struggling to believe it's the head gasket. As there appears to be no cross contamination in either the oil or coolant. However I am wondering if there could be a small leak in head gasket between coolant gallery and a cylinder. That means coolant is leaking straight into cylinder and being burnt. Hence no contamination nor visible sign of leaking. But I'm unsure of the block configuration therefore this is speculation...

Suggestions would be greatly appreciated.

Thanks.

Just to clarify the condition, a few questions.
From a normal state (Radiator topped off and bottle at "max-fill" level) cold, you drive around getting up to temperature and how long does it take to notice the following:
A) With the engine now shut and allowed to cool off, coolant level in the bottle drops? If no, coolant level in the radiator drops and bottle level remains the same?
B) With the engine at temperature for say 15 to 20 mins. minimum, does the coolant level in the bottle increase?
C) With the engine at temperature and running; does your exhaust contain any vapor (white clouding) or emit a residue that you can feel on your hand after letting the exhaust run against your palm and fingers and then rubbing them together? Does it feel wet or greasy? Does it have an odor that might be described as slightly sweet?
Report back and someone in here will give you a pretty good Idea of what to check next. Sorry for your trouble. I like mysteries but not one's that involve my car!

Hi many thanks for your questions, and no trouble at all, I really appreciate your help.
Here are my answers hopefully I interpreted your questions correctly.
A) From topping coolant up to the full level in the bottle on the weekend when the engine is stone cold, my partner will then drive it to work and back each day. She only works 3km up the road. But during the course of the week perhaps does 50-70km. I'll then check it the next weekend, again when engines cold, and the coolant will have dropped 10-15mm down in the bottle from full mark.
B) Yes when engine at normal running temp, radiator fluid level rises/increases by ~10mm in the bottle.
C) No white clouding or unusual smells from what I can tell, but I do feel there is a vapour being emitted as I can feel moisture when I hold my palm over tail pipe. I did look into this a week or two back and wondered if it was normal? Do diesel engines normally emit a bit of vapour as part of the combustion process?

I look foward to people's suggestions!

These engines are known for weak head gaskets, allowing compression gasses into the cooling system. --- Never coolant into the oil, or oil into the coolant. ---

Also I've seen many radiator caps fail on these too.

I would recommend getting the radiator cap pressure tested, and a TK test on the cooling system ( tests for compression gasses in the coolant)

Hi G.R, I have changed out the radiator cap for a new one few weeks ago. So it's not that. I'm not familiar with the TK test. Can I buy a test kit for that or should I get Mazda to do it?

In your experience do you think it's possible the head gasket is leaking coolant straight into cylinder?

Appreciate your time!

Any mechanical workshop can carry out the TK test. It's probably not worth you buying the tester yourself.

https://www.google.com/search?rlz=1C...4dUDCAc&uact=5

RE: "C) No white clouding or unusual smells from what I can tell, but I do feel there is a vapour being emitted as I can feel moisture when I hold my palm over tail pipe. I did look into this a week or two back and wondered if it was normal? Do diesel engines normally emit a bit of vapour as part of the combustion process?"
I must have been having a senior moment suggesting this as a useful troubleshooting tool on a modern vehicle. The catalytic converter would burn up most of the evidence I was interested in here. But yes, vapor is normal in the exhaust stream of any engine, As air is drawn in and compressed, it condenses and can be seen in the exhaust, especially before the engine warms up completely (the old "tail-pipe drip").
Per @grim_reaper, here is a YouTube video of the Tee Kay tester in use. A link to the device itself: https://www.google.com/search?q=tee+...L_enAU861AU861
Here is another fairly comprehensive video of tests to turn up the cause of the symptom you are having. If I were you, I would look into the possibility of there being a TSB from Mazda on this issue and see if there is anything a dealer can do for you before this starts getting expensive.

Many thanks for your response. One more question what do you mean by “TSB from Mazda on the issues...” what does TSB stand for?

Oh I think you mean Technical Service Bulletin.

Yes. I found this. Recall - Diesel Engine Concerns - Mazda CX-5 Forums