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Need a bit more info. By broken, do you mean bent or completely broken. Does the car run? Does it make any noise?

I can tell you from fist hand experience, if even 1 exhaust valve is bent or not closing properly the car won't idle and will run like crap.
 

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No it runs but im not driving it right now. don't want to blow the motor.

When i start it there is a normal idle down and then when it gets to the aproximate 750 rpm idle, it sounds different. it sounds like it is missing a silinder when it idles. i can drive it but then when i get down from around 60 mph to idle it wants to die then it automatically ramps up the rpm and starts running by it self seems like with throttle control.

I have an aftremarket Turbo (Garret GT34 Family) watercooled and i have 680 RC injectors with a Emannage Blue controlling the fuel curve and timming. External waistegate set at 9PSI
 

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A stuck open valve won't give you pressure in the crankcase. It'll either push out the exaust, or push back through the intake, depending on which valve is not closing.

Excess pressure in the crankcase is caused by blowby...which is caused by a worn or broken piston ring. This loss of compression can cause bad running.
 

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QUOTE (Bluemikecheck @ Apr 8 2009, 11:26 AM) index.php?act=findpost&pid=1544633
No it runs but im not driving it right now. don't want to blow the motor.

When i start it there is a normal idle down and then when it gets to the aproximate 750 rpm idle, it sounds different. it sounds like it is missing a silinder when it idles. i can drive it but then when i get down from around 60 mph to idle it wants to die then it automatically ramps up the rpm and starts running by it self seems like with throttle control.

I have an aftremarket Turbo (Garret GT34 Family) watercooled and i have 680 RC injectors with a Emannage Blue controlling the fuel curve and timming. External waistegate set at 9PSI[/b]
these issues don't really sound like valves, especially when you factor in the issue at idle and the ramping of RPM's on it's own. i'd hunt for a vacuum leak first, as it's very likely (check the hose under the intake manifold since you are boosted) then i'd look at the MAP sensor.

what are you atributing the blow by to? are you seeing something, hearing it, feeling it?
 

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QUOTE (MrTea @ Apr 8 2009, 04:00 PM) index.php?act=findpost&pid=1544709
these issues don't really sound like valves, especially when you factor in the issue at idle and the ramping of RPM's on it's own. i'd hunt for a vacuum leak first, as it's very likely (check the hose under the intake manifold since you are boosted) then i'd look at the MAP sensor.

what are you atributing the blow by to? are you seeing something, hearing it, feeling it?[/b]
When i open the oil cap while at idle i can see the air puching out of the oil cap whole. when i put my hand over it i can feel a constant pulsing push of aiir comming out. kind of like when you put your hand in front of your exhuast out. i really hope it aint now pistin ring. to mee it seems like one of the exhaust valves is stuck open or the intake valves are stuck open. i took off the valve cover and i did notice that the B and B exhaust valves does have some burning discolleration by the roker arms and on the case side wall. when i pulled the spark plugs out, the piston closest to the intake throttle body is wet on top. maybee fuel and not making combustion. that is why i fear it might be a piston ring. i have my topend built but not yet the bottom end. this whould be a great time for it i quess. do you know a company that makes stainless steel valves, forged piston, rods, etc for the 03 mazda 6 4i?
 

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QUOTE (Bluemikecheck @ Apr 8 2009, 06:32 PM) index.php?act=findpost&pid=1544779
When i open the oil cap while at idle i can see the air puching out of the oil cap whole. when i put my hand over it i can feel a constant pulsing push of aiir comming out. kind of like when you put your hand in front of your exhuast out. i really hope it aint now pistin ring. to mee it seems like one of the exhaust valves is stuck open or the intake valves are stuck open. i took off the valve cover and i did notice that the B and B exhaust valves does have some burning discolleration by the roker arms and on the case side wall. when i pulled the spark plugs out, the piston closest to the intake throttle body is wet on top. maybee fuel and not making combustion. that is why i fear it might be a piston ring. i have my topend built but not yet the bottom end. this whould be a great time for it i quess. do you know a company that makes stainless steel valves, forged piston, rods, etc for the 03 mazda 6 4i?[/b]
Air coming out of the oil filler cap is nothing abnormal, if you leave it open it will spray a fabulous oil mist all over your engine bay too, I've seen that on a couple of other cars that were in perfect condition. There is naturally going to be air pressure in the engine, that includes the head and the block. Do a compression test, if it reads normal, try a leakdown test. That should tell you what you need to know. If you have idle issues, it may be a vacuum concern as someone posted earlier, but if you suspect engine, those two tests are really the main things you can do outside of a teardown and inspection.
 

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QUOTE (-Six- @ Apr 12 2009, 10:30 AM) index.php?act=findpost&pid=1546348
Air coming out of the oil filler cap is nothing abnormal, if you leave it open it will spray a fabulous oil mist all over your engine bay too, I've seen that on a couple of other cars that were in perfect condition. There is naturally going to be air pressure in the engine, that includes the head and the block. Do a compression test, if it reads normal, try a leakdown test. That should tell you what you need to know. If you have idle issues, it may be a vacuum concern as someone posted earlier, but if you suspect engine, those two tests are really the main things you can do outside of a teardown and inspection.[/b]
What is normal for the compression per cylinder. i am not sure. and what whould be normal for a leakdown test. Never done a leakdown before. not sure about it.
 

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QUOTE (Bluemikecheck @ Apr 22 2009, 05:31 AM) index.php?act=findpost&pid=1551013
What is normal for the compression per cylinder. i am not sure. and what whould be normal for a leakdown test. Never done a leakdown before. not sure about it.[/b]
You will have to get those numbers from the service manual to know for sure. I would guess compression should test somewhere around 140psi for normal, but that is only a guess. As far as a leakdown test goes, it has been a while since I learned about/done it, so I can't remember the details from the top of my head, might take some extra research.
 

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manual says 145-207 @ 290rpm (cranking), variance of no more than 28psi between cylinders

as fare as the leak down, we just applied air into the spark plug hole and listened for leaks. i can't remember if it is BTC on the compression stroke though? quick google search can tell you though. KVC6 has done it i'm sure, so he might have more input for you.
 

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I would start diagnosis with a compression test, make sure you remove all spark plugs to save your starter and allow each cylinder to perform without fighting the compression
caused in other cylinders when you have the spark plugs in. Make sure you disable fuel and spark. As you perform your compression test, do your first test dry, and second test wet. Just squirt a few drops of oil into the cylinder through the spark plug hole. Depending on the difference between your wet and dry test will let you know the condition of
your piston rings. The oil will help seal any excessive clearances caused by worn rings. If your piston rings check out ok, you can move onto a leak down test starting with the
cylinder with the lowest compression. Make sure you rotate your engine so the cylinder you are testing is at BDC of the compression stroke, this will ensure your intake
and exhaust valves are closed. Hope this helps :)

Oh yeah another good thing would be to have a battery charger handy, your battery could effect your results as it looses charge.
 

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Discussion Starter #13

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Boostin 2003 Mazda 6

After a TON of money Spent, i got the issue fixed at Secret Services Auto (SSA) in houston. Pretty uch had some heat damage in my bottom end in the cylinder pockets. Got the bottom end rebuilt, competition valve job, Stand alone Haltech engine management and a great tune....

SSA done a great Job. Car is now a Beast

Pics are here
https://picasaweb.google.com/108426811918498663202/TheLife02?authkey=Gv1sRgCIKyyJ_kvraMGw
 

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Those rods and pistons look yummy! Yeah, you spent some cash alright!
 

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Those rods and pistons look yummy! Yeah, you spent some cash alright!
Yes they are. Next steps are to build the tranny. the motor dyno'ed at 410 with the stock tranny but is started smoking and overheating on the transition and slipping in redline. So, unitill i get the tranny done, i am limmited to about 290 HP. that is only to be on the safe side until i have enought foe a new tranny build. BUT, a Big BUT, the potential of this motor build is much greater than what it seems. will keep yall up to date when i get the Tranny done and i will put up the dyno sheets.:D

Secret Services Auto did the work thus far.
 

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Yes they are. Next steps are to build the tranny. the motor dyno'ed at 410 with the stock tranny but is started smoking and overheating on the transition and slipping in redline. So, unitill i get the tranny done, i am limmited to about 290 HP. that is only to be on the safe side until i have enought foe a new tranny build. BUT, a Big BUT, the potential of this motor build is much greater than what it seems. will keep yall up to date when i get the Tranny done and i will put up the dyno sheets.:D

Secret Services Auto did the work thus far.
Hi mate,

Sorry for bumping up and old thread. I am just wondering, which haltech are you using and did you wire this up as a biggyback only to control the fuel/ignition?
 

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A stuck open valve won't give you pressure in the crankcase. It'll either push out the exaust, or push back through the intake, depending on which valve is not closing.

Excess pressure in the crankcase is caused by blowby...which is caused by a worn or broken piston ring. This loss of compression can cause bad running.
In your opinion what do you think the cheapest easiest way to fix this is?
  • Repair head? ( with this a chance of bottom end failure in future?)
  • Engine replacement?
Or does anyone have any other suggestions?
 
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