Last post on Nov 27, 2013 at 12:52 PM
You are in the Chevrolet Metro/Geo Metro
What is this discussion about?
Geo Metro, Chevrolet Metro, Hatchback
#1797 of 1867 Re: '91 geo metro ignition timing [jacmicwag]
Apr 03, 2011 (9:30 pm)
Thanks for the follow up. It is information like that which makes it easier for me to sort out such problems. Regarding the engine specialist's suggestion that the valves need adjustment; either he is trying to rip you off; or is looking in the wrong book, or the people who wrote the book he is using are operating on the totally false assumption that the Geo Metro engine is the same as the Chevy Sprint engine. Some companies who ought to know better have been making that same mistake ever since the Geo Metro first came out, in 1989.
The Chevy Sprint was sold from 1985-1988, had a 3 cylinder, 1000cc Suzuki built motor, and was sold by Chevrolet dealers. The Geo Metro was sold from 1989-2000, had a 3 cylinder, 1000cc Suzuki built motor, and was sold by Chevrolet dealers. So the people who only used this information to decide, incorrectly assumed that the Sprint and the Metro had the same motor.
The truth is that the Chevy Sprint engine had hemispherical combustion chambers and a single overhead camshaft; which operated two rows of adjustable rocker arms through solid lifters. That motor had a recommended valve adjustment interval of 30,000 miles. But the Sprint had a bad cylinder head design, and developed a reputation for blowing head gaskets.
Suzuki either couldn't, or wouldn't, fix the head gasket problem; so GM got their engineers to redesign the head. The head design was changed from a hemi head with two rows of adjustable rocker arms and mechanical valve lifters; to a wedge head with a single row of non-adjustable rocker arms and automatically adjusting hydraulic valve lifters. The new head design was introduced on the 1989 Geo Metro, and has continued on the 3 cyl and 4 cyl Metro engines through the rest of their production run. The result is that; although the Chevy Sprint engine needed 30,000 mile valve adjustments; the Geo Metro engine never needs valve adjustments (and there is no way the valves on the Metro engine could be adjusted, anyway). But those people who just guessed that both vehicles used the same motor never came to realize these differences.
So your engine specialist is flat out wrong in his recommendation. Please show him this post, and tell him that if he is going to give people advice about Geo Metro engines; he needs to catch up with the changes that were made to these motors 22 years ago.
Since this guy is apparently poorly informed about these motors; I wouldn't be surprised if he is also misinformed about the correct compression figures. The Geo Metro has a much higher normal compression pressure than most other motors. The NORMAL compression pressure on a 3 cylinder Geo Metro motor is 195 psi. The LOWEST acceptable compression pressure on this motor is 165 psi. If the person who checked your compression was unaware of the unusually high compression standard in this motor; and got 150 psi in all cylinders; the usual outcome would be that he would say the motor had passed the compression check with "flying colors." 150 psi would be flying colors on many other motors; but 150 psi is an UNACCEPTABLY LOW TEST RESULT on a 3 cylinder Metro. I have seen this kind of mistake made again and again on Metro engines; because complacent mechanics think they no longer have to look up specifications in the book (since they "are all the same.")
You need to know the actual pressure readings for EACH INDIVIDUAL CYLINDER that were produced during the compression test of your motor. If ANY cylinder had less than 165 psi; the engine would idle roughly, and could not be adjusted to run properly. If the mechanic cannot clearly remember or find the actual pressure readings he measured; make him run the test again!!!
If the compression is low; either the cylinder head or the complete motor will need to be overhauled or replaced.
If the compression is within the specs I listed above; then I would replace the spark plug cables (assuming they have not been replaced) and check the PCV valve for clogging. If that doesn't smooth out the idle; I would have the throttle body air bypass screw adjusted by someone who has the car connected to an exhaust emission analyzer; and adjusts that screw to give the lowest hydrocarbon readings with the motor fully warmed up, and the idle speed at 800-900RPM.
#1798 of 1867 zaken1 is the metro man!
Apr 06, 2011 (2:46 pm)
Wow - am I ever glad I found this forum! Sure wished you lived in Houston and worked on Metros in your spare time (if you have any). I'd fire all three of my mechanics immediately. Thanks for sharing and I will do exactly what you recommend, in the order listed. Thanks again for your help.
#1799 of 1867 Re: zaken1 is the metro man! [jacmicwag]
Apr 06, 2011 (3:28 pm)
Thank you for the kind words. I once lived in San Antonio for three months during the summer of 1959 (at Lackland AFB). One day at about 4PM, I looked at a thermometer that was in the shade; which read 118 degrees F. In August, I took a bus back to San Jose, CA. When I stepped off the bus into a typical balmy California autumn day, I started shivering. It took me some time to re-acclimatize to California weather. That was my Texas experience; and once was enough for this lifetime.
I hope it doesn't turn out that you need a new motor (like all too many people who have posted in this forum; after buying a used Metro without first checking the compression). That motor will run endlessly; if given proper driving and maintenance; but all too many people lug them, or use the wrong spark plugs; or don't change the fuel filter, or don't watch the temperature gauge and inevitably overheat the motor. These are the people who are not fit to drive a Metro; and we all inherit the results of their incompetence and carelessness.
#1800 of 1867 Little Metro History
Apr 06, 2011 (4:07 pm)
Well to be honest I was one of those people you are referring to. I've been looking for a 3 cylinder for some time. This one turned up on Craig's list and I flew over to New Orleans and bought it for 1k even though it idled rough and the air wasn't working at the time. The previous owner had beat this poor car half to death and on the ride home I promised her I'd bring her back to life if she just got me home safely - which she did at 54 mpg.
I've since had the dents pulled out, repainted her yellow, and totally cleaned up the interior including a new headliner. I'm hoping to get more out of this engine but if it needs a rebuilt, that's just one more step in the right direction as I intend to drive her forever and then some.
Also own a 98" Swift that I bought 3 years ago but it has an automatic and 1.3 engine. My son drives it now and loves it. I'll let you know how things turn out - I owe you a beer or a coke for saving me $120.
#1801 of 1867 Re: Little Metro History [jacmicwag]
Apr 06, 2011 (10:28 pm)
The 54 mpg sounds encouraging. It is unlikely that you could get that kind of mileage with a low compression motor. My 1990 Metro 3 cyl 5 speed got that sort of mileage when I bought it; in 1992 (with 58,000 original one owner miles on it) but it idled so roughly that the gear lever shook violently from side to side. I had checked the compression prior to putting any money down; so I knew the motor was sound. Turned out that the previous owner was using Bosch single platinum spark plugs (which have a center electrode that projects too deeply into the combustion chamber to run properly in a Metro that is in good condition). I had to trash those plugs and install a set of Autolite #63s and then adjust the throttle position sensor and the air bypass screw to match the plugs; in order to get it to idle smoothly.
Unfortunately, I don't drink alcoholic beverages or consume soft drinks; but I appreciate the comradely spirit of your offer.
#1802 of 1867 Re: 1989 Geo Metro Won't Start [timber605]
May 02, 2011 (2:21 pm)
YOUR PROBLEM IS MOST LIKELY YOUR CYLINDER HEAD.I BET YOU THAT THE VALVES ARE ALL SCREWED UP I JUST TOOK MY CYLINDER HEAD OFF(I HAVE NO MECHANIC EXPERIENCE BESIDES TUNEUP)UPON LOOKING AT THE VALVES WHERE THEY MEET THE CROWN OF THE PISTON YOU CAN TELL THAT THEY WILL BE DAMAGED OR EXTREMLY DIRTY THESE CARS ARE KNOWN FOR THIS.TAKE YOUR HEAD TO A MACHINE SHOP AND FOR AROUND 200 BUCKS GET IT REBUILD AND GET NEW GASKETS PUT BACK ON AND PUT HEAD ON. THEN FIND SOMEONE TO HELP YOU SET YOUR TIMING AND BAM YOUR ENGINE WILL PURR LIKE NEW.IF THE VALVES DO NOT GET AN AIR TIGHT SEAL THEY WILL NOT WORK CORRECTLY MINE HAD HUGE PIECES MISSING OUT OF THEM AND IT STILL DROVE.TRY CRANKING YOUR CAR AND TAKE SPARK PLUG WIRE OUT EACH CYLINDER REPLACE CRANK AND TRY NEXT CYLINDER IF ANY OF THEM BEING REMOVED MAKES THE CAR GO DEAD I KNOW THAT THOSE VALVES ARE DESTROYED
#1803 of 1867 Re: zaken1 is the metro man! [jacmicwag]
May 27, 2011 (7:26 am)
I will have to say many many thanks as well, my 1997 geo metro is doing the same thing... but. my tail pipe is completely gone...just bought the car, sight unseen, was told it had a crack in exhaust..thankfully i have a great mechanic whom is working on it for me, several minor things wrong...thanks for the GREAT info.....
#1804 of 1867 Re: zaken1 is the metro man! [1sally]
May 27, 2011 (2:37 pm)
Well, I must admit that it is refreshing to encounter people who both believe what I say, and also take effective action to address the issues that I have advised them on. I spend most of my time on the Edmunds generic "answers" forum, which is open to all brands of vehicles; and where I have answered over 2,800 questions in the last 3 or 4 years. But on that forum; people all too often take offense when my answer is insightful enough to contradict a preconception that they hold; which is keeping them from recognizing or fixing their problem. As a consequence, they do not apply the information which I gave them. So they protect their illusions at the cost of not fixing the problem they wrote in about.
I come here because I have owned a 1990 Metro for the last 19 years and 250,000 miles, and I cannot resist the opportunity to share useful information about those magnificent vehicles. And my perception is that people on this particular forum are nicer, more open minded and generally more realistic than the people on the public forum. But there just ain't enough Metros out there to keep me busy.
I appreciate the thanks!! You folks make my days worthwhile!
#1805 of 1867 sputter-sputter
Jun 09, 2011 (4:13 pm)
2001 Metro just turned 100,000. Recently started missing while driving. No particular drive time or tempture noted. Put in netural, race engine and miss clears. However, 'service engine' comes on. By checking and tightening gas cap the SE light oges off in due time. I have replaced gas cap but problem persist. Purchased with about 50K and have not done any maintenance other that fluids and filters. What tune-up can I do other than plugs?
Have enjoyed reading other blogs. Hope someone can give me an idea. Thanks.... margeo
#1806 of 1867 Re: sputter-sputter [margeo]
Jun 09, 2011 (9:02 pm)
The spark plugs on that motor should usually be replaced at 30,000 mile intervals (regardless of what the manufacturer recommends). Use only double platinum or iridium plugs. Iridium are slightly more expensive; but they will run better and last longer. You may be able to get 50-60,000 miles on a set of these plugs; but that depends on your driving style, the mechanical condition of the motor, and the type of fuel and oil you use. If you can go that far on a set of plugs; more power to you. The best performing plugs for that motor are Champion Iridium #9201. They should come pre-gapped at .044"(1.1 mm). Some parts stores may not have them in stock; but any real parts store that sells Champions can order them. Some of the discount parts stores may only be able to order a limited range of plugs; but NAPA or Car Quest or similar stores that cater to professional mechanics certainly can; and they won't jack the price up like certain unmentionable "discount" stores do on special orders.
There's not much else you can do on a tune up. If you really wanted to do it up; you could remove and scrape the carbon out of the EGR valve and its passages; and use Valvoline SynPower throttle body cleaner spray to clean the inside of the throttle body (particularly the upper and lower surface of the butterfly, and the surface of the bore where the butterfly edges touch. A toothbrush or bottle brush saturated with throttle body cleaner would be handy to reach the underside of the butterfly (while the throttle is held open by someone sitting in the car with their foot on the accelerator; or by moving and holding the throttle cable to keep the butterfly open; BUT BE SURE THAT THE THROTTLE CABLE IS PROPERLY SEATED IN ITS TRACK, BEFORE STARTING THE MOTOR. You may initially get some rough running for the first few minutes; until the cleaner burns off. Replace or thoroughly clean the PCV valve; and make sure the rubber PCV hoses are not clogged or leaking. Also check the vacuum hoses from the back of the motor to the MAP sensor on the firewall for damage or leaks.
The spark plug cables (only 2 cables on this motor) may eventually need replacement, if they develop more than 1,000 ohms resistance per inch of length, or if they become damaged; but that might not happen for some time longer. You could also replace the filter element in the vapor storage cannister, but that would outdo 98% of the owners out there. It would also be appreciated by the car if you flushed and replaced the brake fluid every 3 years; and changed the coolant at the interval listed on the brand of bottle you use. I use Prestone long life coolant (in the silver bottle), and mix it with equal quantities of distilled (not de-ionized) water before installing it in the motor.
And any motor will last longer and run better if you use only one brand and grade of motor oil for the life of the vehicle (people who care about their engine carry a spare quart of the brand and type of oil they use in the car; so they won't have to mix some other oil in the motor if it needs oil added between changes). And don't assume that the shop which changes your oil (if you have it done by a shop) knows what oil type and weight you use. Make sure they have the oil type you need in stock BEFORE they drain the oil; and don't be shy about telling them the brand and weight you want. If you have a choice of oil filters; I highly recommend the Fram "Tough Guard" oil filter; which has a "TG" prefix in the part number. It is reasonably priced, and keeps the oil noticeably cleaner. But don't use the other optional types of oil filters Fram makes: Some of them have chemical additives in them which I don't recommend.