 Valve problem, This time I think I'm screwed |
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| fitzm1 |
 Apr 23 2009, 11:57 AM
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#1
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Member  Group: Members Posts: 74 Joined: 21-April 08 From: Ballston lake,ny Member No.: 8,947 Region Association: None  |
Just finished all the work I had planned for this spring. Bump steer kit, CB fuel pump and cleaned (rebuilt ) the carb that has been giving me problems. Seemed to be running great. As I am going up a hill near home I hear a pop and the engine sounds like a sewing machine. First I thought I had lost a gear in the tranny but that seems fine. I checked the compression and all cylinders are 120. Car starts fine but sounds like one or more of the valves are real loud. Any explanation besides the one I fear (trashed motor).
Joe I think I broke your motor. Mike |
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| r_towle |
Apr 24 2009, 09:51 PM
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#2
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Custom Member Group: Members Posts: 24,705 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States 
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Take the valve covers off, jack up the passenger side of the car so that wheel is off the ground and the drivers side rear wheel is on the ground.
Put the car in 5th gear. While laying on the ground and watching the rockers, turn the passenger wheel backwards...as if you were in reverse. This turns the motor forwards. You have have a broken spring, or you may have not seated a push rod correctly and once it finally did seat, that valve no longer opens (thus you loose power) Or, you dropped a valve seat. Either way. stop running the motor..just turn it by hand until you figure it out. You should be able to turn the motor through all four compression strokes by hand and not feel and resistance. RIch |
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| fitzm1 |
Apr 25 2009, 09:16 AM
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#3
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Member Group: Members Posts: 74 Joined: 21-April 08 From: Ballston lake,ny Member No.: 8,947 Region Association: None |
I have the car up on stands. I have checked the valve clearances using Cap'n Krusty's valve adjustment technique. I have .008Ex & .006In. I don't see how I could have a pushrod problem.
I'll do another compression check. Is it possible that a valve could drop but snap back into place to give good compression readings? That would explain why it goes through all the cycles via the wheel turning. Could I be hearing a valve seat not quite out but slapping in and out a few mils? That could also be the reason the car kept running. Possible? QUOTE(r_towle @ Apr 24 2009, 07:51 PM)  Take the valve covers off, jack up the passenger side of the car so that wheel is off the ground and the drivers side rear wheel is on the ground. Put the car in 5th gear. While laying on the ground and watching the rockers, turn the passenger wheel backwards...as if you were in reverse. This turns the motor forwards. You have have a broken spring, or you may have not seated a push rod correctly and once it finally did seat, that valve no longer opens (thus you loose power) Or, you dropped a valve seat. Either way. stop running the motor..just turn it by hand until you figure it out. You should be able to turn the motor through all four compression strokes by hand and not feel and resistance. RIch |
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| Bartlett 914 |
Apr 26 2009, 10:13 AM
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#4
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Advanced Member Group: Members Posts: 2,218 Joined: 30-August 05 From: South Elgin IL Member No.: 4,707 Region Association: Upper MidWest |
QUOTE(fitzm1 @ Apr 25 2009, 09:16 AM) Is it possible that a valve could drop but snap back into place to give good compression readings? That would explain why it goes through all the cycles via the wheel turning. Could I be hearing a valve seat not quite out but slapping in and out a few mils? That could also be the reason the car kept running. Possible? Yes it can. I had this happen on a 2.0. I was so surprised to see how loose the seat was when I took the head off. My car ran for a long time this way until finally I lost compression all together on that cylinder. |
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