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Engine sounds like a diesel; Engine sounds like a diesel
Topic Started: Apr 29 2011, 05:49 PM (2,255 Views)
drwausau
Fresh Fish
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I have a 1996 Geo Metro 1.0L that when under load sounds like a diesel. I currently use 93 octane fuel as I have since purchase. Timing is set correctly. New plugs,wire, cap. Egr port through head is clear. Compression check shows some disturbing results. #1 112psi #2 132psi #3 122psi. Still gives me 37 city and 42 city/hwy at 125k miles. I dropped the oil pan and no piston ring or piston chunks. This motor does not burn oil between oil changes. Starts and idles fine. Rev it up in neutral and engine sounds normal. Put it in gear and drive it sounds just like my high miles vw diesel. Clanging sounds. No ticking. Does anybody have an idea what my be causing this? I am thinking burnt valves but would this cause a diesel sound? I already have a rebuilt motor waiting to be swapped in but I would like to get the most miles I can out of the original without being stranded on the highway.
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snowfish
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Basic GearHead

Sounds like you best swap engines more sooner than later! :O She be getting tired. :shake

Welcome to the party, BTW. :cheers
Edited by snowfish, Apr 29 2011, 06:49 PM.
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Johnny Mullet
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Fear the Mullet

Ignition timing is too far advanced or you are off a tooth on the cam timing.
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Memphis metro


Better not run it long that way. Is the check engine light on? Is the engine overheating? Does it keep running for a bit when turn the switch off? Welcome to the forum.

A recording of the sound would be :thumb .


.
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bogs
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Duct tape heals all wounds

Drop the advance as Jm mentioned and drop the octane to regular.
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GeoRating
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Yep, I was putting 92+ in my car when I got it too, for about 2 months, and then I dropped to 87 due to low resources and I actually gained a tiny bit of power, same exact fuel efficiency. It took a couple tanks for it to level out on my power, but I definitely gained something from dropping down (I didn't have my gauges when I switched)

As you've probably seen elsewhere, the engine will run all the way down to 95ish, but oh man those are some LOW numbers, I'd switch her out quickly before you do end up on the side of the road :(
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drwausau
Fresh Fish
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Thanks for the welcome and all the replies. No check engine light, temperature gets up to dead center of normal. I have switched to 87 octane with not change to the noise. I think its time to swap motors...
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Bad Bent
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Facetious Educated Donkey

Welcome to your new forum, drwausau! :coffee

Yeah, compression numbers should be at least 150-155.

Well, you think it is loud now, the test for a catalytic converter is to remove the front O2 sensor and see if it runs better for a few blocks. Or loosen the Cat. tube/exhaust manifold bolts and test drive it a few blocks. Also the smell of rotten eggs and the Cat. may make noise as it cools down.

Might want to closely inspect your entire undercarriage and exhaust system for a leak. The "donut" gasket at the manifold/tube may be broken or just history. ANOTHER test is to Seafoam your engine :thumb You can get a $8(?) can of Seafoam and dribble a little in the brake booster vacuum hose and it will make a lot of smoke that will come out of any leak in the exhaust system while cleaning the valves/pistons a little. Click on http://www.youtube.com/watch?v=Y4XUS-F578Q

If you suspect the valves are going you might want to also test the vacuum at the MAP sensor and Throttle Body but "Ting" a vacuum gauge at that vacuum hose connection. You should have 19" of vacuum with no needle flutter.
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starscream5000
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Got 70 MPG?

Set timing to 8 degree BTDC, switch to 87 octane, and see if that helps any.
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cgem
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You didn't mention how long you have had the Metro. But that dieseling sound could be due to carbon buildup . To eliminate this reason, warm it up and start out at the bottom of a hill. If it noise gets louder or adjusts to the throttle position vicesa versa, ...could be that. I had a tick in mine similiar, but I narrowed it down to a sticking valve lifter.
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