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Old 02-10-2008, 07:45 PM   #1
dennybam
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Oil Consumption: Answer this and you値l be the man!

A 1993 GEO Metro: 3 cyl, 5 spd. With 117, K miles. I just bought it. It is giving 58 MPG smoking out the exhaust bad when holding the idle up, also when winding out the gears. At 60 MPH, it uses 2 quarts/ Hr. With average compression is around 175 PSI in all 3 cylinders, I pulled the head and installed new valve seals that where bad; I put it back together; It still smokes! While inside the engine: I had no tool to measure the bore accurately. The pistons are standard and are the correct ones, and in there proper order for that engine. Measurement of ring gap at top of Cyl., is at its ware limit of .027 Bottom is at .017 .
Moving the pistons side to side with my hand, it appeared that they had excessive side play movement. The walls had no ridge on them. Near the top, I measured between the piston and the Cyl. wall, on one side with a feeler gage; My best guess is of .014 I could not find the specs any ware for piston to wall clearance on that engine.
It looked like some one had been in this engine before me. Because it had a new head gasket and oil pan gasket on it. I checked the oil clearance on the rod bearings .004
Any ideas why this engine is still smoking? Where is the oil coming from? The head is straight. No oil in air breather, no blow by out dipstick or any signs of blow by internaly; only out the exhaust pipe.
Thank you!
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Old 02-10-2008, 08:19 PM   #2
G.A.S.
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Re: Oil Consumption: Answer this and you値l be the man!

you did all the above, I didnt see anything about valves, just seals.
what kind of shape were they in?
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Old 02-11-2008, 06:55 AM   #3
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Re: Oil Consumption: Answer this and you値l be the man!

The stems of the valves and guides seem to be in good shape. I am use to rebuilding large V-8s not a small 3 cyl eng. There was little movement of the valve, when wiggling it while raising it off of it seat; maybe .020
When I removed the valves they had a lot of carbon on them; the intake valves had a thick build up of soft black carbon on them in the ports. I cleaned all re lapped them and replaced two of the exhaust valves that where getting ready to burn. I checked the head for cracks the best I could.
All cylinders are burning oil, you can see it on the plugs
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Old 02-11-2008, 07:55 AM   #4
G.A.S.
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Re: Oil Consumption: Answer this and you値l be the man!

I am woundering if the .020 movement is the culpret. even with new valve seals oil could bypass these. expecially if there is a moderate volume of pressure within the crankcase. I know it is not blowing out the dipstick but if you have a carbon buildup within the intake chamber that tells me oil is getting in that area somehow and the most logical place would be the intake valve/exhaust guides. I mean, how else is any build up of carbon going to get into that intake chamber arround the seat of the valve?
just a thought.
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Old 02-11-2008, 07:49 PM   #5
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Re: Oil Consumption: Answer this and you値l be the man!

Quote:
Originally Posted by G.A.S.
I am woundering if the .020 movement is the culpret. even with new valve seals oil could bypass these. expecially if there is a moderate volume of pressure within the crankcase. I know it is not blowing out the dipstick but if you have a carbon buildup within the intake chamber that tells me oil is getting in that area somehow and the most logical place would be the intake valve/exhaust guides. I mean, how else is any build up of carbon going to get into that intake chamber arround the seat of the valve?
just a thought.
You may be right, I dont know enough about the nature of a small eng. like this,on a large V8 that would be nothing I keep thinking that it could be that .020 I am not sure so dont know what to do yet.
The oil build on the intake valves was an indacator of what the problum was, so this is why I replaced the oil seals and decarbonized all parts. But after starting it back up the smoke was still as bad. So I figured that it was oil build up in the exost systom left over from before. So I drove the car and ran it hard. It will not stop smoking, it is not a build up in the exost causing it. Have checked well for blow by; I removed the PVC hose where it enters the valve cover, and there is nothing at all coming out, No blow by at all!!
Thank you for your time!
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