Tort1llaboy

#1

Hello.
Sorry for my bad english

My 7afe have been smoking blue smoke for some time now.. and the smell of oil is present almost all time (USE ALOT OF OIL!)... It smokes never when idle, only when i give it some trotle.
i have been thinking it may be the Valve seals, but it might be the piston rings aswell...
what is your opinion?

Special_Edy

#2

Piston rings most likely. You can try to do a piston ring soak on it with Seafoam or Marvel Mystery Oil to see if maybe its a stuck ring, but most likely they are shot.

Tort1llaboy

#3

i have done a compresion test and all the sylinders are the same..
160 psi on nr1
160 psi on nr2
165 psi on nr3
166 psi on nr4

any sugestions.?

lagos

#4

A good way to tell if its your valve stem seals is to drive down a very steep hill. Keep your foot off the gas to generate vacuum for a few seconds, and then get back on the throttle. If it smokes as soon as you are back on the throttle, then you are seeing the oil that was pulled past the valve steam seal getting burned. Mine has started doing this recently and i have perfect compression and less than 5% difference on a leak down test.

It also helps to do this test when the engine is not fully warmed up. Once I am at operating temp, the symptom is less noticeable.

This post has been edited by lagos: Jul 4, 2014 - 12:13 PM

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15PSI - 30MPG - Megasquirt Tuned

enderswift

#5

compression rings might be alright, oil scraper rings might be sludged up

Tort1llaboy

#6

Looks like a long weekend for me any one knows the piston rings specs? sizes and diameters?

VavAlephVav

#7

engine/transmission stickys
http://www.6gc.net/forums/index.php?showtopic=73956

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Bust a Deal; Face the Wheel.

Tort1llaboy

#8

dint find the size. but i got them the hard way found the spare pistons whit rings and measured them
1 Ring 1.20mm
2 Ring 1.50mm
3 Ring (oil) 3.00mm

Tort1llaboy

#9

The order list is put in then
New piston rings,
New valve seals
New head gasket
New Main rod bearings
New Crank bearings
ect.

Box

#10

The 7A is NOTORIOUS for burning oil due to stuck rings. Piston soak it and run a flush to free them up as much as possible and then start using 20W-50. Burning oil doesn't hurt anything, and if you can get it to where it doesn't have visible smoke and you only have to replace a quart every 1,000 miles then who cares.

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2001 Miata LS 5-speed

Special_Edy

#11

O2 sensors and catalytic converters dont like oil

Box

#12

If he can get it to where there's no visible smoke it'll be fine, burning a quart every 1,000 miles is within factory tolerances. There's no point in spending a small fortune and the hassle of rebuilding the 7A to stop it from burning a little oil. Run the engine into the ground, then replace it.

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2001 Miata LS 5-speed

Box

#13

>

QUOTE (Special_Edy @ Jul 4, 2014 - 8:39 PM)

>O2 sensors and catalytic converters dont like oil

Also anti-fouler and test pipe, problems solved.

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2001 Miata LS 5-speed

Bitter

#14

>

QUOTE (Box @ Jul 4, 2014 - 9:06 PM)

>>

QUOTE (Special_Edy @ Jul 4, 2014 - 8:39 PM)

>O2 sensors and catalytic converters dont like oil

Also anti-fouler and test pipe, problems solved.

not for the upstream sensor that sets the adaptive air/fuel ratio....

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2000 Celica GTS 'slowest gts evar'1998 Mazda 626 FS-DE/CD4-E

Box

#15

Take it out and clean it once a month if it still smokes badly. That or yank the anchor out and throw in a 20 valve.

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2001 Miata LS 5-speed

VavAlephVav

#16

is burning a Quart per 1000 miles really within tolerance? that's like 3 quarts per oil change. I lose 2 quarts per oil change, a little into the coolant, a little down the back of the head, not bad enough to leave spots in the driveway and doesn't smoke.

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Bust a Deal; Face the Wheel.

Special_Edy

#17

Its burning it in the combustion chamber which will mess stuff up, on the backside of the motor it is only going to coat you undercarriage and act as a rust inhibitor

Box

#18

>

QUOTE (VavAlephVav @ Jul 5, 2014 - 2:50 PM)

>is burning a Quart per 1000 miles really within tolerance? that's like 3 quarts per oil change. I lose 2 quarts per oil change, a little into the coolant, a little down the back of the head, not bad enough to leave spots in the driveway and doesn't smoke.

Yep, actually up to a quart every 1,500 miles is. Pretty much anything they can do to minimize warranty work. Then you have Wankels that burn by design.

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2001 Miata LS 5-speed

Tort1llaboy

#19

>

QUOTE (Box @ Jul 4, 2014 - 5:02 PM)

>The 7A is NOTORIOUS for burning oil due to stuck rings. Piston soak it and run a flush to free them up as much as possible and then start using 20W-50. Burning oil doesn't hurt anything, and if you can get it to where it doesn't have visible smoke and you only have to replace a quart every 1,000 miles then who cares.

i dint pass my MOT whit the smoking.

Box

#20

Ahh, see where I live they don't have emissions or even visual inspections. So I tend to forget others aren't as fortunate. Still, I stand by what I said earlier with doing the piston soak and flush then changing out to 20W-50. You can even throw in some stop burn if that kind of thing is even sold over there just to pass inspection. It really won't cost anything and it should make it to where it can be lived with easily, just have to check your oil every 1,000 miles.

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2001 Miata LS 5-speed

Tort1llaboy

#21

>

QUOTE (Box @ Jul 7, 2014 - 7:38 AM)

>Ahh, see where I live they don't have emissions or even visual inspections. So I tend to forget others aren't as fortunate. Still, I stand by what I said earlier with doing the piston soak and flush then changing out to 20W-50. You can even throw in some stop burn if that kind of thing is even sold over there just to pass inspection. It really won't cost anything and it should make it to where it can be lived with easily, just have to check your oil every 1,000 miles.

dont think we got that stop burn.. but why not just rebuild a head when i allredy have a spare one .
But when i take the head of, do i have to use new bolts to fit it back or can i use the old ones? i know its strech bolts.


Anyways tnx for lots of awnsers you guys are awsome

This post has been edited by Tort1llaboy: Jul 7, 2014 - 4:46 PM

VavAlephVav

#22

always use new bolts. at least that is the manufacturer recommendation they say the old bolts stretch and that could have been the first part of your problem.

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Bust a Deal; Face the Wheel.

Box

#23

If it's valve stem seals anyway and not rings. Probably won't hurt to piston soak anyway. Go ahead and do new head bolts, might as well do timing and water pump if you haven't in awhile.

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2001 Miata LS 5-speed

Tort1llaboy

#24

I have a new timing belt for it aswell
was cheking on Auto data and it said No to change the head bolts... just tighen to 21 nm and then tighten 90° and then tighten 90° again...
Then i called the local toyota dealer and they sayd the same thing.. but i need to check if thay are damaged or stretched.
if thay are not its okey to use them again

Special_Edy

#25

If your valve stem seals were leaking it would puff out a cloud of smoke when you first start it, after it's been sitting for several hours or more. Piston rings leak while the engine is running.

Perform a cylinder leakdown test, all you need is a compression tester, disconnect the gauge from the hose and attach the hose to an air compressor hose.

Tort1llaboy

#26

yeah i have tools to do that just need the time... its so hot outside ist not funn working :S
but it will get done... i am curently working on rebuilding a head for that car

Box

#27

Valve stem seals can leak severely while running too, a la Mitsubishi 6G72. Leak down and compression test like Edy mentioned would be a good starting point though.

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2001 Miata LS 5-speed

Tort1llaboy

#28

the problem is that it have been doing this for over a period of time... (10 month ish). so i think the rings are done. the previos owner dint know what he was doing, he just drove it like it was... i shuld have walked away from that deal whit that car, dint notice the smoke untill i was driving the car home after we signed a contract, Sold as it is. the car in it self looks strait and good.

Box

#29

What happens with the rings is that the oil control rings end up stuck to the piston and let oil into the combustion chamber. Piston soaking and running an oil flush usually frees them up enough to where the burn is very little if at all. More or less ALL 7A's do this, it's just a matter of the severity of the burning. So that means they've been running and driving for years this way, so it's not going to hurt anything outside of spark plugs and the emissions equipment. Trust me, do the soak and flush and change it out to 20W-50 and that should help significantly.

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2001 Miata LS 5-speed

Tort1llaboy

#30

>

QUOTE (Box @ Jul 8, 2014 - 3:44 PM)

>What happens with the rings is that the oil control rings end up stuck to the piston and let oil into the combustion chamber. Piston soaking and running an oil flush usually frees them up enough to where the burn is very little if at all. More or less ALL 7A's do this, it's just a matter of the severity of the burning. So that means they've been running and driving for years this way, so it's not going to hurt anything outside of spark plugs and the emissions equipment. Trust me, do the soak and flush and change it out to 20W-50 and that should help significantly.

okey i might give that a try. how do i procead?
btw the engine has run 260000 km... just for some info