Replaced Cylinder head ... not firing.

Hey folks. I have been working on this project and I thought I was nearing the end. My 2003 Mazda 6i (2.3L Auto) had a warped head b/c it was driven while overheating. I took it off and paid to have the head re-worked back into spec. After reinstalling everything I went to start it up and it just sits there and turns over without starting up. The camshafts and timing chain were reinstalled exactly how they came out, so that shouldn't be the problem. The thing is, the car was running before the teardown, just poorly, which makes me think the fuel pump is not the issue. I did notice when it I was trying to start it it would turn over 3-4 times normally, then on the next turn it would "bog" down, turning more slowly, then would go back to normal. Would this make you think starter? I had charged the battery overnight and while it didn't have a full charge, it was turning the engine over just fine. I am missing the o-ring that sits on the fuel injector for the #4 cylinder, so I was wondering if the fuel rail wasn't pressurizing properly, but I am not even smelling fuel out of that cylinder. I am going to pick up this o-ring tonight. But for now, any thoughts??

I'd double-check the timing and make sure it isn't 180 degrees out of phase.  (Remember these are 4-stroke engines, so the pistons reach TDC twice for a single compression cycle.)  If you're off by 180 degrees, it will try to spark at the same time the fuel/air mixture is trying to get into the cylinder rather than during the actual combustion stroke (intake, compression, expansion, exhaust)  Spark should come between compression and expansion, not between exhaust and intake.

Hmmm ... Makes sense. I'll double check the timing and let you know what I figure out. Thanks!

My friend and I marked the placement of the camshafts and made sure not to move the crank, so wouldn't the reinstall be right if we lined everything up correctly?

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ORIGINAL: mazda6guy7

 I did notice when it I was trying to start it it would turn over 3-4 times normally, then on the next turn it would "bog" down, turning more slowly, then would go back to normal. Would this make you think starter?

 
Do you think the bog could be the engine just be hitting a harder compression stroke? I was wondering if it was the starter because once and a while when it "bogs" down I hear a noise, kindof like a grinding noise that is made when a starter starts to go out. The starter before the beginning of this project was fine, but it has been getting a lot of use trying to get this engine to start. I know this can't actually be anything inside the engine because I was very carefull in re-installing everything. I torqued the caps and head bolts using the proper sequence and torque, installing the timing chain, etc... One idea my friend had was the crank pulley.  Is there a certain way that is supposed to be aligned, because there are no indicator marks on the pulley or crankshaft to align it. So maybe this is making some  kind of noise? Who knows.
 
On the agenda for tonight: I am going to double check the injectors and fuel pump are working and also check for spark.

Not necessarily.
 
Your crank would go around twice to the camshafts single revolution...valves only open/close once during the compressions cycle, but the piston moves up/down twice.
 
Intake open/Exhaust closed - air/fuel are pulled into the engine by piston moving down in cylinder
Intake closed/Exhaust closed - piston raises is cylinder compressing air/fuel mixture,
Intake closed/Exhaust closed - spark occurs igniting mixture, forcing piston back down in cylinder
Intake closed/Exhaust open - piston moves back up cylinder expelling burnt gasses
 

Hmmm ...ok. Any ideas on what could be causing the momentary "bogging" and "grinding" ?

Ok ... after I charged the battery I tried starting again to see what was going on. While it still didn't fire, it didn't make the "bogging" and "grinding" noises it was before. My conclusion there is that there wasn't enough juice from the battery for the start to turn the engine over, thus making the grinding noise.
 
I also pulled the fuel injectors after trying to start the car and I did smell fuel, so that must not be the problem.
 
The bad thing is I think I burned up my starter while figuring all this out!
 
The only thing I can think of is the timing. Even though I marked both camshafts of their exact position and didn't move the crank, the Mazda tech that I talked to yesterday at the dealership said that even that wouldn't guarentee that the timing was correct. What do you guys think? Do you think it is a timing issue? Does anyone have the procedure to set the timing correctly? Thanks!

Top Dead center of the #1 cylinder is where everything needs to get aligned to.
 
I'd say get the crank to TDC #1 (piston at the top of the cylinder), then remove your valve cover and set the cams to TDC #1...you should be properly timed at that point.
 
Have you done a compression check on your motor to verify that everything sealed up properly after the rebuild? 
 
What kind of pressure do you have in the fuel line?  It should be between 55-65 psi.  Looking in the manual it doesn't look like there is an easy way to check that other than hooking in an in-line gauge through your fuel lines at the filter. 
 
I think the start-start-start-bog thing is your cylinder getting flooded with fuel.
 
Are you getting spark?  You can take one of the wires off of the spark plug and let the arc jump to the engine block (or anything else metal) while you are cranking, check all (4) cylinders.

My friend who put the timing chain back on said he aligned the marks he made and the chain went on perfectly, so he still thinks the timing is right.
 
I have not yet done a compression check yet. Let me ask this: If the engine was running before the rebuild, just poorly due to the warped head, then the block should be ok to go don't you think? Other than the possibility of not sealing everything up perfectly during the rebuild do you think the block is ok?
 
Dont know on the fuel line pressure. I don't have an inline guage and since the fuel supply has always been ok I will leave this as a last resort to test.
 
Still need to check spark ... I have been home alone without any extra hands for the past few days so I have to wait for someone to help me on that.
 
One more question ... what will exactly happen if the timing is just off a little bit? Say like one tooth? Because when I was trying to start it would crank and crank and crank, then act for a fraction  of a second like something wanted to happen, but then go back to crank crank crank. If the timing is just barely off should it start and run, only run poorly? Will there be any noises while trying to start? Or will it just sit there and crank without firing?
 
 

I would think the block should be OK so long as your oil supply was never restricted.
 
Is your friend who put the timing chain on helping you out with this?  A single tooth results in quite a few degrees of timing difference.  It may start with being only 1 tooth off, it may not.
 
You can borrow compression gauges from most Auto parts stores, just remove the coil wire and take out 1 spark plug and screw the gauge into the hole (if you can pinch off your fuel supply, that's even better so you aren't flooding the cylinders with fuel.  Crank the car over with the starter and get the highest reading off of the gauge.  Measure each cylinder this way and record the readings
 
Min pressure is around 175 psi, should be around 250psi if everything is new and sealed up properly. 
Max difference cylinder to cylinder should be no more than 28 psi variance.
 
That will tell you real quick if you've got a good seal on the motor.  Low compression means either the heads didn't get sealed up properly when you put them on the motor or you've got piston rings that need to be replaced.

My friend has been helping me with this project, yes. He is very knowledgable so I brought him into the project to help out. We will be testing out the compression and fuel pressure mid-week, so I will keep you posted. One question though ... the car was running before we took the engine apart. Since that is the case, do you still think it could be the piston rings? If there wasn't any compression due to the piston rings being bad the car wouldn't have run before we started the project right? I hope that the rings aren't the issue because that would be a huge kick in the nutz! Also, is this an interference engine? I am curious if the engine can be damaged if we try to start it with the timing being slightly off, if the timing is the cause of the problems. Thanks!
 
Kyle

If your car wasn't smoking blue out of the tailpipe, your piston rings are probably fine.

Ok. My friend and I ran some diagnostics on the engine last night. First thing we checked was the fuel pump. We heard it turn on so all is good with that. Then, we went to test for spark. Nothing. We took the spark plugs out one by one because we were going to test compression, and when we got to the # 4 cylinder we took the spark plug out. Here is where the problem is. The side electrode is completely smashed and resting against the center electrode! Holy crap! These were new plugs, so we thought maybe it was a defect, so we threw a different one in that cylinder and it did the same thing. I called autozone and they verified they were the correct plugs. So, what is causing this? First, I was thinking that the cylinder head repair shop milled too much of the surface off and the plug was actually sitting down too low in the cylinder, causing contact with the piston. We ruled this out however because if the head was milled incorrectly, the plugs in the 1-3 cylinders should have sustained some kind of damage. They however, were completely fine, even the #3 cylinder plug. So we started thinking. Hmmmm. We looked down into the cylinder (as best as we could through the plug hole), and noticed something. Yes, something is in the damn cylinder! We must have not noticed when it fell in before we put it all back together. While we can't see what it is, my friend who noticed it says it is too big to come out through the plug hole. And it is apparently not magnetic, as we tried with a magnet to no avail. So, you know what that means ... head has to come back off! Damn!

We can't figure out, however, why we aren't getting a spark from any of the plugs. Do you think that this issue with the smashed plug could have caused some kind of short in the system frying the coil or something? We checked all the connections we could fine and all seemed good. Anything dumb we might be forgetting about? Is there a way to test the distributor or at least to narrow down what could be causing the lack of spark?

Kyle

Any thoughts are appreciated.

Sorry to hear that, but at least you're making progress.
 
You have an ignition module that fires off the various pulses to the cylinders. (Not a distributor, in the exact sense of the word)  It should be a pretty easy swap to put in a new one, it's what all the spark plugs wires are coming off of.  Keep the new part clean and if it makes a difference, then you're good.  If not, return the part to the autoparts store....That's probably the easiest way to check it out.

How many miles on your mazda 6i? I wonder it need a lot of work to do it.

The car only has 85xxx miles or so on it. This is what happens when someone drives it who doesn't know what it means when the temp gauge goes into the red!
 
Anyway, this weekend I suffered a painful observation. Very painful. Evidently, the timing wasn't correct. Since this engine is an interference engine, you can probably guess the rest. Both of the intake valves on the #4 cylinder broke off and were just resting on the piston. However, when we were trying to start it, it caused a considerable amount of damage. It put some cuts and gouges in the top surface of the piston, and also the bottom surface of the cylinder head. The piston was resting at TDC so I could not inspect the cylinder walls at all, but I will try to hand crank the engine so I can inspect the wall sometime this week. This whole thing is just a huge blow to a project I thought I was near the end of. I don't know if I now need a new head, if it needs to be repaired, or even if the piston needs to be replaced. The intake valves put indentations on the other pistons, however they are not broken, and they don't look like they are bent. I just don't know where to go from here. I guess I should take the head back in the shop and see what they think? What about the piston ... can it have a few scrapes and still operate ok (as long as they aren't too deep) ?? Thanks for hanging in here with me!

Some dings in the tops of the pistons won't do much as far as performance, just make sure you get any loose particles out and that there isn't any damage around the perimeter of the cylinders near where the rings seat.  It would be better to replace those pistons, but not necessarily critical. (The dings could cause a little turbulence inside the combustion chamber and reduce performance, probably a negligible amount.)  Any damage on the perimeter and you are talking new pistons.
 
Hopefully the cylinder walls aren't damaged.  If they are, you might be able to get them honed out (but that would require getting slightly larger pistons...the upside is more displacement for your engine, the downside is more cost and slightly thinner cylinder walls which could cause it to run a little hotter than normal.)
 
I'd tear your heads down completely and make sure that all valves slide real easily up/down on the guide sleeves, if they do, they aren't bent.  If you encounter any resistance, they are bent.
 
When you get everything re-assembled, hand crank the motor to make sure everything is clear and not interfering anywhere.

After further inspection of the engine ... I tried to hand crank the engine so I could inspect the cylinder walls, and it was way too difficult to crank. I was able to move the piston about 2 inches. I then went up to look at the piston. It is not sitting perfectly straight up and down. It is nearly "resting" on on side of the wall. Also, there is one small scratch on the cylinder wall, not really deep, but visible. I am guessing something is bent in the engine that is causing the piston to sit like this. I have only one word: "Damn." I guess I should now consider having a new engine put it. My question now is ... I know it is possible to find used engines (usedmazdaengines.com), but this isn't something I want to tackle. Do repair shops only deal with "new" parts? Or will they find a used engine to throw in to drastically cut cost? I am asking because one repair shop specifically that I have used many times in the past won't put in a part you bring in because they then cannot gaurentee their work.

That sucks...sorry to hear that.  Bolting in a used engine isn't that difficult as long as you can find one with the same tranny combo that you have. (wiring & some of the controls are different between Manual/Auto.  It's a lot easier than rebuilding/assembling an engine.
 
Sounds like you may have bent a connecting rod to me.  At this point, either take your losses and get a different motor, or tear that thing down completely and go through it. 
 
You'd be amazed at what an engine can go through and still be repaired.  One of my friends has a V8 pushing 1000 hp (no exaggeration) that's he's blown up 3 times (I'm talking connecting rods destroyed, cylinders cracked, etc.).  Some sleeves in the cylinders (actually stronger than just a cast block), inspection of the heads and new bearings and it's good to go.
 
If you find a cheap price on an engine, get in writing whether or not it's a new motor.