Signs of a Blown Head Gasket

[murdoc_47]

Thanks for the info. I'll tuck it in the back of my head for a later date. I'm okay if it weeps a little like it did before this job. I'm certainly not interested in undoing my progress at this point.

 

[murdoc_47]

Well, it was a fun run, but I might be at the end of this project. I got everything buttoned up today and started her up for the first time. Well, I cranked it a while with the fuel pump disabled first to build some oil pressure. Then I started it up. After a bunch of initial racket and rough running, the engine smoothed out and settled down. Happy to say I have no leaks, VERY unhappy to say that I do have errors. First I got a P0031, but found that I hadn't fully seated the O2 sensor, so I plugged it in fully. But my heart really dropped when I saw I also have a P0017 error which indicates timing is off, and I still show a P0304, which is what started me down this path.

I REALLY don't want to pull the front cover off again! I swear I checked the timing chain MULTIPLE times and all of the marks were lined up right with the case, and the marked links in the chain. I even took pictures to prove it to myself. I wonder if the VVT isn't working right. Anyone know how to test the VVT?

I'm also not sure if the P0304 was left in the ECU from before I started this project? (fingers crossed) The only thing left that could cause the miss-fires is just a worn out cylinder and rings. And I just don't think I have it in me to pull this engine and do the whole thing top to bottom. For what it would cost, I'd be better off getting a used engine with a warranty for around $2000.

If I could get the timing sorted,

Feeling pretty defeated...

 

[ruthrj]

Im far from an expert on anything like this (so don’t fire her back up on my advice alone), but I found a report on timing being off being thrown due to low oil 2016.5 CX-5 2.5L Timing chain skipped a tooth?

Anybody think the first start after rebuild and without fuel pump on could’ve caused the code? Like, clear the codes and give it another whirl now that oil has circulated in the system and there’s now fuel pressure? VVT wasn’t happy on first start?

 

[AL Cx5]

I'm sure you cleared the codes and tried it again by now. I wouldn't be overly concerned on the initial start up and maybe you didn't clear the codes before you started the project.

To build oil pressure on new engines we prime the oil pump before spinning the motor. We remove the spark plugs as well. I've removed an engine plug and used a garden type sprayer to force oil into the oil pump. Some guys pack the oil pump with assembly oil to prime the pump. After the time and expense to build an engine, we want it to make oil pressure as quickly as possible.

IF it throws a code on the next, brief, start up, then be concerned.

Good LUCK!!

 

[yrwei52]

Well, it was a fun run, but I might be at the end of this project. I got everything buttoned up today and started her up for the first time. Well, I cranked it a while with the fuel pump disabled first to build some oil pressure. Then I started it up. After a bunch of initial racket and rough running, the engine smoothed out and settled down. Happy to say I have no leaks, VERY unhappy to say that I do have errors. First I got a P0031, but found that I hadn't fully seated the O2 sensor, so I plugged it in fully. But my heart really dropped when I saw I also have a P0017 error which indicates timing is off, and I still show a P0304, which is what started me down this path.

I REALLY don't want to pull the front cover off again! I swear I checked the timing chain MULTIPLE times and all of the marks were lined up right with the case, and the marked links in the chain. I even took pictures to prove it to myself. I wonder if the VVT isn't working right. Anyone know how to test the VVT?

I'm also not sure if the P0304 was left in the ECU from before I started this project? (fingers crossed) The only thing left that could cause the miss-fires is just a worn out cylinder and rings. And I just don't think I have it in me to pull this engine and do the whole thing top to bottom. For what it would cost, I'd be better off getting a used engine with a warranty for around $2000.

If I could get the timing sorted,

Feeling pretty defeated...

I’m lazy and just Googled “P0017 code Mazda CX-5” and here’s the result from its “AI Overview”:

”The P0017 code on a Mazda CX-5 means the crankshaft and exhaust camshaft (Bank 1 Sensor B) aren't synchronized, often due to low/dirty oil, a faulty oil control valve (OCV) solenoid, a stretched timing chain, or bad VVT components, causing poor performance, rattling noises, and potential engine damage, requiring checks of oil level/quality first, then VVT parts or sensors, and potentially timing chain inspection.”

So if you’re sure you’ve lined up everything correctly while installing the timing chain, your leaky OCV could be the culprit?