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Low compression on all five cylinders

Tiny
FOCUS ST
  • MEMBER
  • 2008 FORD FOCUS
  • 2.5L
  • 5 CYL
  • TURBO
  • 2WD
  • MANUAL
  • 170,000 MILES
Came from work parked car next day went to start engine just swings. Removed battery terminal rest computer box started one shot switch off do not start. Drove the car to mechanic at his place switch off an now it just swings. Checked spark, fuel pressure, changed all sensors, checked compression all five cylinders. It has low compression 90 psi on all cylinders. Checked timing, checked belt, checked cams. Took out plugs put in some oil, put plugs back in to built compression engine just swings. Does not start please I can really do wit lots off help. Will 90psi not start the car?
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Friday, October 26th, 2018 AT 9:58 PM

9 Replies

Tiny
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  • MECHANIC
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That is more like 83 psi.
It appears to me as though you need all new piston rings.
I do not understand though what you mean by "swings".
I assume you mean the engine cranks over but will not start.
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Saturday, October 27th, 2018 AT 8:01 AM
Tiny
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That is more like 83 psi.
It appears to me as though you need all new piston rings.
I don't understand though what you mean by "swings".
I assume you mean the engine cranks over but won't start.
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Saturday, October 27th, 2018 AT 8:01 AM
Tiny
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Yes, it cranks but does not start. Will it start will that amount of compression?
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Saturday, October 27th, 2018 AT 1:05 PM
Tiny
STEVE W.
  • MECHANIC
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If the car was running fine and did this after being shut off I would do a leak down test on the engine to see if it is cam timing related. Loss of compression on all cylinders could be from worn rings but they would not instantly fail. However a timing issue from an advanced camshaft could cause this and happen if a belt or chain is worn or a tension-er failed and let it slip.
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Saturday, October 27th, 2018 AT 1:47 PM
Tiny
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Do the wet compression test first. Squirt a little motor oil into the cylinder and if the compression rises, then it is the rings.
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Saturday, October 27th, 2018 AT 3:01 PM
Tiny
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Did the wet compression test compression remain the same. Checked cam belt, checked tension-er, checked the cams, checked the timing. All is okay.
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Saturday, October 27th, 2018 AT 4:52 PM
Tiny
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It is not even giving an error code.
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Saturday, October 27th, 2018 AT 4:54 PM
Tiny
STEVE W.
  • MECHANIC
  • 13,590 POSTS
The compression has to be going somewhere. I would still do the leak down test. I have seen more than once where the timing seemed to be perfect but the cam(s) or part of the drive system was bad and allowed the cam(s) to move. In this case I would suspect that as it is about the only thing that would cause low compression in all of the cylinders after it was shut down. Check the VVT system, if one was to lock out it may be enough to cause an issue. That engine has a lower compression ratio than many others but it should still have over 100 psi.
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Saturday, October 27th, 2018 AT 9:11 PM
Tiny
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Be sure to keep a battery charger on while doing the compression test and open the throttle wide open so it gets all the air in needs.
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Sunday, October 28th, 2018 AT 8:13 AM

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