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Crankshaft Gear Noise
Topic Started: Dec 6 2016, 04:21 PM (862 Views)
David Bonazzoli
New Member
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1992 base Metro automatic. 162k A lot of noise is coming from the area of the crankshaft gear.
I found the crankshaft gear bolt to be loose. Tightened it, the noise is not as bad but it continues.
Also when revving the engine, I can see the Belt pulley move in and out a little. Rev the engine, the pulley moves in, let off the gas the pulley moves out.
Is there another bearing further in that might have been damaged by driving the car with a loose Crankshaft Gear Bolt?
Otherwise the car runs and drives wonderfully.
Many thanks to all. I just got this car. Not fond of automatics, but trying to save this one as its a rust free, dent free Florida car.
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suzukitom
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Tom

The crankshaft also uses a Woodruf key that keeps the pulley in position when the bolt is tightened.
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suzukitom
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Tom

The bolt has to be tightened to a torque of 81 ft. lbs.

But the key must not be damaged before you do this.

This is a picture of a damaged key.
Posted Image

Edited by suzukitom, Dec 6 2016, 05:42 PM.
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David Bonazzoli
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My key looks a bit different from yours but it is not damaged. it is as tight as I can get it. Yet the loud noise continues.
Is there a bearing further in? or am I hearing the sounds of a bad engine?
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suzukitom
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Tom

Lots of things can make noise down there. Having a loose crank pulley condition for a while may have accelerated wear at the oil pump, crank bearings, or thrust washers. Wear of these items can be responsible for noises, based on the back and forth movement you reported seeing in the pulley as you rev the engine.

Have a read of these three postings:

http://geometroforum.com/topic/5953486/1/

http://geometroforum.com/topic/5755128/1/

http://geometroforum.com/topic/5346175/1/
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Car Nut
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With the engine turned off, (shouldn't even have to say that) grab the front crank pulley and try to push it in, and pull it back out. If you hear a clunk when doing this, and the play seems excessive, your thrust washers are probably worn out. I've seen cars that you could push in the clutch while it was running, and the engine would start knocking because the thrust washers were so worn.
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ptcapboy


I learned something today by reading this topic-never even heard of thurst washers-thanks
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freegeo
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ptcapboy
Dec 8 2016, 12:28 AM
I learned something today by reading this topic-never even heard of thurst washers-thanks
Do you know what they are and what they do?
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ptcapboy


no-can you elaborate?
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freegeo
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ptcapboy
Dec 8 2016, 03:50 PM
no-can you elaborate?
As soon as I get off work.
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ironman752
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http://5xracing.com/i-13483427-king-crankshaft-thrust-bearing-for-mazda-miata.html
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MarkZ28


Tore apart a chevy 305 once that had thrust bearings so worn out that they had dissappeared completely and the crank and even the block had deep wear grooves in them, lol. Thing ran quietly with normal oil pressure. Obviously it was junked but shows youll have a hard time killing a small block chevy. About the only way thrust washers ever went bad was because of a ballooning torque convertor that when swelling up, pushed the crank forward all the time wearing the bearings out quickly. I suppose thats a possible cause in your racing Metro. Long live the manuals!
Edited by MarkZ28, Dec 8 2016, 06:19 PM.
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freegeo
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Ironman752 posted a link to a good picture of a thrust washer or bearing as the FSM calls it. There are 2 thrust bearings , 1 each side of the main bearing between the # 2 and 3 pistons. The thickness of the thrust bearings is what sets the crankshaft end play. Below is a picture of how the thrust bearings are installed.


Posted Image
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ptcapboy


thanks guys, I was just semi- familiar with rod bearings and main bearings-rod bearings were the only thing I have replaced in my car-appreciate it-
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David Bonazzoli
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Thanks for everyone's advice. Indeed, I can grab the pulley and move it back and forth. Its very loose, tho the bolts are tight. When moving it, it hits the block, that's the cause of the noise I hear when the engine is running. It does not move in and out much, but is very loose going back and forth. Does this info help determine exactly whats wrong? Again, thanks. I'd likke to save this car, but not if it needs an engine rebuild. The past owner replaced the front oil seal and did not tighten the bolt properly, thus the problem I'm now having.
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