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Running on Three Cylinders


seb fontana
 

As the title states my 47 CC is running on three cylinders..This happened while going down the road at 40 mph, no hint at anything being wrong prior..No pinging, no over heating, no extra noise..Cyl #4 Just stopped running..Plenty of spark; the plug looked fine but replaced it and still no fire.Valve clearance is at spec of .004/.006.Checked compression and found #30 lbs, all others are at #120..Put air adapter in spark plug hole and hooked air supply up and air was exiting the exhaust pipe..So bad exh valve or seat..Am I missing some thing? There was no clue to something being wrong; I didn't think a valve could go bad in an instant..Any input? 


Barry Smedley
 

Did you check and see if the spring is broke.

 

   Barry Smedley

 

From: Crosley-Gang@groups.io [mailto:Crosley-Gang@groups.io] On Behalf Of seb fontana via Groups.Io
Sent: Thursday, October 31, 2019 8:31 PM
To: Crosley-Gang@groups.io
Subject: [Crosley-Gang] Running on Three Cylinders

 

As the title states my 47 CC is running on three cylinders..This happened while going down the road at 40 mph, no hint at anything being wrong prior..No pinging, no over heating, no extra noise..Cyl #4 Just stopped running..Plenty of spark; the plug looked fine but replaced it and still no fire.Valve clearance is at spec of .004/.006.Checked compression and found #30 lbs, all others are at #120..Put air adapter in spark plug hole and hooked air supply up and air was exiting the exhaust pipe..So bad exh valve or seat..Am I missing some thing? There was no clue to something being wrong; I didn't think a valve could go bad in an instant..Any input? 

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Butch
 

Seb,

Although I doubt that the spring broke (this would have shown up when checking clearances), it's quite possible that some carbon has dislodged and caught between the valve and the seat.

With the cam cover off, the follower located at the center of the cam base circle (lobe pointed straight up), take a hammer and a punch (preferably a soft punch, even a hardwood dowel) and smack it forcefully, several times.

If this can be done, with the air hose attached to the spark plug hole, it will be more effective.

Exhaust valves and seats, do burn occasionally, but not real often on Crosleys, and it's not an all at once thing. The exhaust valves were made of good material. Numbers on and four, exhaust seats, are prone to recession and burning, due to poor coolant circulation and cooling.

I hope that this helps, it's my best long distance, diagnosis for now.

Butch

On 11/1/2019 6:32 AM, Barry Smedley wrote:

Did you check and see if the spring is broke.

??

???? Barry Smedley

??

From: Crosley-Gang@groups.io [mailto:Crosley-Gang@groups.io] On Behalf Of seb fontana via Groups.Io
Sent: Thursday, October 31, 2019 8:31 PM
To: Crosley-Gang@groups.io
Subject: [Crosley-Gang] Running on Three Cylinders

??

As the title states my 47 CC is running on three cylinders..This happened while going down the road at 40 mph, no hint at anything being wrong prior..No pinging, no over heating, no extra noise..Cyl #4 Just stopped running..Plenty of spark; the plug looked fine but replaced it and still no fire.Valve clearance is at spec of .004/.006.Checked compression and found #30 lbs, all others are at #120..Put air adapter in spark plug hole and hooked air supply up and air was exiting the exhaust pipe..So bad exh valve or seat..Am I missing some thing? There was no clue to something being wrong; I didn't think a valve could go bad in an instant..Any input???



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seb fontana
 

Up date is I bought a bore scope and found a pretty carboned up combustion chamber although the piston top had very little as I could see aluminum of the piston..What i could see of the exhaust valve was a lot of carbon but no burn. with cyl #4 at tdc and trans in gear I removed the cam and lifter, retainer/keepers and spring and let the valve rest on head of piston. With bore scope in place and rotating the valve the bad spot came up, it was a slot of missing material right across the valve seat. About 3/16 wide x 3/16 from edge in towards stem..I may fix that one valve but then there 3 more that may got that route. I'll have to check for who can do the seat down the hole. Seb.  


nobadrivers
 

I'm going through the same exact thing only my bad cylinder is #3 cylinder.  But I think you may have answered a question I have been wondering.  With the piston at TDC and valve spring removed the valve will sit on top of the piston ok without dropping down into the cylinder?  You can still grab onto the valve and rotate it? 


Butch
 

Yes, at TDC, the valve stem will still be in the bucket well.

ButcH

On 1/28/2020 8:16 AM, nobadrivers wrote:
I'm going through the same exact thing only my bad cylinder is #3 cylinder.?? But I think you may have answered a question I have been wondering.?? With the piston at TDC and valve spring removed the valve will sit on top of the piston ok without dropping down into the cylinder??? You can still grab onto the valve and rotate it???
_._,_._,_


dale@servicemotors.net
 

Service motors has the the correct tooling and the ability to install hardened seats also.  Give them a call.


On Jan 28, 2020, at 5:16 AM, nobadrivers <scanner2@...> wrote:

I'm going through the same exact thing only my bad cylinder is #3 cylinder.  But I think you may have answered a question I have been wondering.  With the piston at TDC and valve spring removed the valve will sit on top of the piston ok without dropping down into the cylinder?  You can still grab onto the valve and rotate it? 


seb fontana
 

Initially I used a piece of 1/2 vynol hose stuck in through the spark plug hole for the valve to sit on..Testing the waters so to speak..Seb.


Butch
 

One good way is, with the piston down in the cylinder, stuff the cylinder full of rope (about 1/4 to 5/16" diameter) then rotatge the crankshaft until it stops.

Then proceed as normal.

Butch

On 1/29/2020 2:25 PM, seb fontana via Groups.Io wrote:
Initially I used a piece of 1/2 vynol hose stuck in through the spark plug hole for the valve to sit on..Testing the waters so to speak..Seb.