compression issue

6 replies to this topic
  • 67imp

Posted March 10, 2014 - 03:39 PM


2002 wr426 , something is a wrong, I can turn over the motor without using the decompression lever. what is the chance that it is a stuck valve and if so solutions?

  • Krannie McKranface

Posted March 10, 2014 - 05:18 PM


It's one of:

Stuck valve

Leaky valve seat

Broken decomp << most likely

  • 67imp

Posted March 10, 2014 - 05:41 PM


how does one tell if the decomp is broken? I am able to pull in the lever and see the switch move under tension.

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  • flyandride

Posted March 10, 2014 - 07:02 PM


At least one of the valves has zeroed out.  Meaning no clearance and loss of compression.  Time for a head rebuild.  

  • Krannie McKranface

Posted March 10, 2014 - 08:00 PM


Actually, a zeroing valve usually does not mean no compression, just no start. 

  • grayracer513

Posted March 11, 2014 - 01:30 PM


A valve at zero generally does cause a loss of compression.  Usually, by the time they get in that condition, they go beyond zero, and you find them off the seat when the engine cools down.

  • Krannie McKranface

Posted March 11, 2014 - 04:31 PM


You are right


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