Hi.

Hoping for some help, but already not boding well as I'm no longer sure the vehicle is a CX-5 or 7, but it's a 2017, 2.5L with 97,000 Km (58,000 mi), looks well maintained, clean oil, claims to be driven gently. Just doing my research before going down any particular rabbit hole Monday.

Boss's wife brought it in with intermittent starting and a 'ticking' sound. No codes stored or pending, MIL is off.

The former just a battery, the tick sounds suspiciously old school valve train but I only had a few minutes to look Friday.

What I did notice is an incredible !!! amount of blow by from the oil filler cap. Enough to lift the cap when unscrewed. There's no fluid cross contamination that I noticed, and no tail pipe smoke .. My first thought was head gasket combustion to oil gallery failure.

Never worked on a 2.5. (then again, LOL .. never worked on the old 1.6 either - even though I owned three and put on a million miles between them. Could they even break?)

Just checking to see if these 2.5's had known head gasket issues or revised gasket calls and figured here might be the place to ask.

I appreciate any help or the knowin' from anyone 'still in the game'.

Jim.

 

How does coolant look? How does it behave in reservoir when running?

Check the PCV

As easy as it is, I'd pull the plugs. Even take a look in the chambers if you have a scope

 

That is normal ... Old school engine pre 2000 that would be a point of concern.
That is why there are so many vendors that offer catch cans.

I might suggest in a friendly way that you all get up on new engine technology and all the sounds they make. With balance shafts, variable cam timing add a few other engine operating parts and system it is a noisy world under the hood.

Here is a short sound video of a 2.5 Skyactiv engine in textbook perfect health.
Sorry I am not going to take one removing the oil cap and making a mess of my engine.....LOL

 

Lol .. friendly is appreciated. I'm no neophyte .. but things are moving faster than i get old. I'm not even a mechanic anymore and don't want to be .. but somehow last week got talked into a 5.4 Triton cam phaser, VVT solenoid, and chain tensioner refresh, then this.

I thought about PCV .. but with the filler cap off to atmo .. wouldn't see pressure.

.

 

Oh no. Same car just came back DOA. crank, no start. Still no codes.

Sounds like it wants to start first few revolutions .. then no longer does.

First impression was no fuel. Now I don't know if it works on modern plants (say 2018 +) - or why it wouldn't, Mazda particular? But I did the fresh gas dribble (beer can with a pin hole) down the throttle body side of the PCV. To date I've never seen anything that wouldn't at worst start fart and bark if it had proper ignition, at best I've made the next off ramp limping along the shoulder with a Molson carburetor and an '07 Crown Victoria. I know it sounds hillbilly, then again I do have a bus on my lawn.

Nothing.

So digging deeper. Sniff of ether .. nothing.

Nice fat sparks, plugs 1 and 2 a bit rich sooty - but not gas fouled, 3 and 4 look textbook good. Cam down the bores .. looks like a good running engine.

Fuel mist from the plug holes when cranking.

So kind of dismissing fuel ..

Nothing awesomely stupid like an air box full of water, the cams are turning, no open fuses, etc.

Kind of stumped why I can't get a fart, if not a start. A place to just begin looking.

In turn pulled the crank and cam position sensor harness plugs, and each both sounded different while cranking and stored the appropriate code in turn - so I call them both good. Once again hillbilly . but an effective way to test them, and whether or not the ECU sees them.

Spidey senses still say this is fuel .. so tomorrow I'll go through the system properly and in order .. But i should have had an ether fart.

Anyone with a hail Mary here .. my next hound will have your name.

Thanks, Jim.

 

Vehicles manufactured from 1995 and newer use OBDII or CANbus ECU's. Your Mazda with a no start should be showing several DTC's. At least 1....???? With not finding any DTC the first thing using your scanner connected to the OBDII diagnostic connector should be is it can communicate with your ECU?

 

No point in mentioning anything based on what you wrote so far, because it would be nothing but a pure guess, with lots of them to choose from. And I'm sure that one of your first diagnostic steps will be to check for spark, which will tell you more than you know now. All I can say is that I've not seen any hint of a systemic issue reported on these first gen engines, related to the symptoms you're seeing. Good luck with it, and it will be interesting to read what you ultimately find to be the culprit.

 

No guess on my part the first thing based on what he posted would be to check that the ECU has not failed or is not getting good continuity (the connectors). It is a process not a guess to determine a no start situation. The fact that he gets a spark no start and no codes is a direction to first check the ECU!

ASE

 

m5xguy,. Yes, first thing I did was a scan .. oddly no codes. I actually wondered for a moment if Mazda had locked out the generics (or my rig was obsolete), but then was able to generate several intentionally by unplugging the crank, then cam position sensors..

Yes I am 'guessing' - but with a whole lot of old school smarts. For all the internet was 20 years ago for info, it sucks now, and the dealers certainly aren't going to send me bits of the shop manual. Darts at the board here, thinking someone may say "ah yeah .. that danged thing - seen it fifty times." Yes I'm obsolete .. and it took some time to even figure out what some of the gizmos are in the fuel system.

All moot now. Got it running and it's toast .. clear bottom end knock. A bit surprising for what appears to be a well maintained low mileage car with virtually no noticeable cam wear. Just bad luck?

I would have liked to do some exploratory surgery .. may only need a crocus cloth polish and bearing(s) .. but the boss man bought a "new" (lol) engine today .. so guess what I'm doing this weekend.

Going to assume nothing new in the transverse-four swap play-pen in 2017 .. same as it ever was from K cars, to Fireflies to 323's.

 

wait until the forums are flooded with owners of Tesla's what d to do with problems.. That will start I suspect in a year maybe 2 from now. LOL