Compression values
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Joined: Mar 2004
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Compression values
Does anyone know what the compression should be in a 4.9l straight 6 (300)
My truck has 357000 kms on it, and i tested the compression, and it comes out as follows:
1- 125 psi
2- 120
3- 120
4- 115
5- 120
6 -125
so they are all pretty much the same, i am trynig to decided whether or not to replace the engine, since it runs rough
thanks .. .MIke
My truck has 357000 kms on it, and i tested the compression, and it comes out as follows:
1- 125 psi
2- 120
3- 120
4- 115
5- 120
6 -125
so they are all pretty much the same, i am trynig to decided whether or not to replace the engine, since it runs rough
thanks .. .MIke
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Joined: Feb 2004
Posts: 116
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From: Northwest
When you did the check....... did you have all the spark plugs out at the same time so the engine could turn over real easy ? Also, did you have the throttle in the wide open position so the intake could suck in air ?
Your numbers are fairly even..... perhaps it's something else that is making it run rough ?
Your numbers are fairly even..... perhaps it's something else that is making it run rough ?
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Joined: Mar 2004
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i called Ford of Canada, and got referred to a dealship, they said the values for an 1983 4.9l should be around 130, so he said my compression is fine, however, he said to take a vacumm test instead, my engine has a 'puffing' sound at idle, and he seems to think that one of the valves is not opening, causing raw fuel to be discharged, so thats my next step.
He asid that if the vacumm shows the needle beuing erratic, then the problem is a valve (or more), but if it stays constant, theres something else wrong
He asid that if the vacumm shows the needle beuing erratic, then the problem is a valve (or more), but if it stays constant, theres something else wrong
