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58 MPG, 150mi/quart of 5w-30; 1990 Geo Metro 4dr 3cyl 5sp
Topic Started: Sep 3 2017, 12:27 PM (240 Views)
BenRiegel
Fresh Fish
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So, I'm a little confused. I bought a 1990 Geo Metro 4 door 3cyl 5spd for cheap, knowing that it was burning oil. I've wanted a metro for a while, liked the idea of a four door, and thought it'd be a good engine to try a rebuild on. I was expecting fairly low gas mileage because it's burning oil, yet I've consistently gotten 57-59mpg without even trying; approximately 90% highway at 65-75mph. I noticed that the PCV hose had been plugged with a bolt where the PCV valve connects. From what I've read, it seems that oil consumption generally results in lower gas mileage, does the fact that I'm not only getting great gas mileage, but significantly better than it's rated for indicate anything in particular that I should check out before embarking on a rebuild? Perhaps it would be better suited to a different topic, but as far as a rebuild goes, should I invest in tools to measure tolerances, or should I pay a machine shop to measure them? and should I wait until after it's been measured to buy a rebuild kit? I had seen this kit linked to in another topic: http://www.ebay.com/itm/260738323023?rmvSB=true, anyone have experience with it, or recommend a different one?

Thanks in advance for your time and any help,
Ben Riegel
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MR1 Kingsbury
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Exp. builder/rebuilder

If you are getting good mileage, do a compression test... That will tell you if the engine should be rebuilt. if it's burning LOTS of oil then it will kill the cat and burn valves in the head, but if it's burning only a little and leaking the rest, then fix the leaks and drive on.
The pcv should be corrected/replaced/installed and hosed into the intake.
Edited by MR1 Kingsbury, Sep 3 2017, 12:50 PM.
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PTA2PTB
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I'm totally awesome! I swear.

The first thing I would do is a compression test on it, to see just how strong or weak the engine is, and determine if it's the rings or valves that are the cause of your oil consumption problems.

Congrats on the great gas mileage, though. :thumb
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freegeo
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Is the car stock as far as trans and tire size?
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Dystopiate666
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Tree Banger

The PCV is probably plugged because it was blowing oil into the air intake maybe causing oil farts. With no crank case vent, its probably leaking in a few other places (cam and crank seals and distributor o ring the most likely), you didn't mention if it is a leaker or not, but when I sealed up my engine when I first bought a geo (cam, crank, valve cover, oil pan, dist o-ring, oil pressure sender etc...), my oil consumption was brought down to a manageable level.

Another thing to consider is that once the tops of the pistons get carboned up, compression can actually go way, way up. I am not sure if you would see better performance from this or not though?
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cwatkin


My first engine was a MAJOR oil burner! The PCV was plugged with sludge and the engine had overall seen some pretty bad neglect but ran exceptionally if you could ignore having to add a quart of oil on a daily basis and the plumes of smoke coming out the back. You might think those coal rolling trucks are something until you saw my GEO!

The car ran great with plenty of power and got great mileage. I had to change plugs pretty often but it ran great besides that. I got well over 50MPG although I got about 100 miles to the quart, or less, on the oil.

I never had any other issues but knew the engine wasn't going to last so located a good replacement. One I had the replacement on hand I would just floor the car and watch all the smoke come pouring out the back.

Yes, apparently these engines can still run decently even in pretty poor condition. Fix the leaks, replace the PCV, and go from there. Sometimes an oil burner will improve greatly with some TLC.

Conor

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