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Ron
Ron, ASE Certified Technician
Category: Ford
Satisfied Customers: 35033
Experience:  23 years with Ford specializing in drivability and electrical and AC. Ford certs and ASE Certs
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Ford focus running rough with low compression on the number

Resolved Question:

Ford focus running rough with low compression on the number one cylinder. Pressure tested the cylinder and couldn't find a leak
Submitted: 7 years ago.
Category: Ford
Expert:  Ron replied 7 years ago.

HiCustomer

 

Thank you for asking your question on JustAnswer.

 

What are you compression reading on all cylinders?

 

Customer: replied 7 years ago.

1 115. 2 195. 3 195. 4 195
Expert:  Ron replied 7 years ago.

HiCustomer

 

Thank you for asking your question on JustAnswer.

 

The most common cause for the issue you are having , is in most cases caused by a valve guide concern. With the engine shut off you will pass a leak down test but with the valve moving on a compression test it will not seat like it should. As we both know, the cylinder will not fire with such a difference in compression from the rest of the cylinders. The head is going to have to come off and valve work done to correct this issue.

 

Customer: replied 7 years ago.

I had head work done to it replacing the valves springs retainers and guides
Expert:  Ron replied 7 years ago.

HiCustomer

 

Thank you for asking your question on JustAnswer.

 

There are only a couple of thing that can effect compression, poor seating rings and or poor seating valve. If you have had head work done, then they need to recheck there work. They missed something here.

 

Customer: replied 7 years ago.

They told me that they vacuum tested the head after the work was completed and it came up fine
Expert:  Ron replied 7 years ago.

HiCustomer

 

Thank you for asking your question on JustAnswer.

 

Im sorry, but if it was fine why do you only have 115 lbs of compression. There are only a couple of reasons for low compression, worn rings or bad valves.

 

Customer: replied 7 years ago.

I don't think its the rings cause I replaced the rods pistons and rings
Expert:  Ron replied 7 years ago.

HiCustomer

 

Thank you for asking your question on JustAnswer.

 

I dont think it is eaither if it passed the leak down test. I would roll the car back to the machine shop that did the head and have them run compression and then explain why you only have 115 on #1... Would love to hear there story.

 

 

Customer: replied 7 years ago.

I will let u know what it ends up being
Expert:  Ron replied 7 years ago.
Ok, Im here every day. Good luck.
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