Compression fluctuation on #5 280CE
 

I have a 1980 280CE chassis # WDV 1230531209364 that is not firing on #5 I have changed wires, plugs and blown out the gas lines. While doing compression test it hit 150 then the engine started and the compression dropped between 30 to 60. I checked the others and they all stay at or around 150 while running. What could be doing this?

Thanks for all of your input!!

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valve sticking on that cylinder??

screwed up the value?
 

Not sure what bump is, but thanks for the reply.
Is there a way to tell if the value is sticking on that cylinder without taking the head off?
We found a vacuum line between 5 and 6 that was broke. Fixed it, but the problem is still there. Could that have screwed up the value?

Any other suggestions would be great.

Thanks again for the help

It's "bumping" the thread to the top of the list so that someone that did not see it previously might now. Also "to the top."

bump..
 

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Need to figure this out
 

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My son is coming home from school and I wanted to send him back in the 280. Will it hurt to run it without the #5. I really do not have the funds to rebuild this motor now. The mechanics here are talking about removing the heads. :confused:

Bad injector or seal on #5

Vacuum leak on manfold gasket around #5

Fuel distributor not "distributing" to #5 - crack fitting at injector slightly and see if it is getting fuel

Valves out of adjustment?

Here's a post on the Vintage Forum that may be of help:

http://www.peachparts.com/shopforum/showthread.php?t=106616