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  • 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-

Compression test. How bad is it?

  • Thread starter Thread starter Road_Runna
  • Start date Start date Mar 21, 2019
R

Road_Runna

20+ Year Stangneter
Dec 23, 2002
594
6
39
Ogden, UT
Mar 21, 2019
#1
  • Mar 21, 2019
  • #1
I've completed 3 compression test on my 90k mile engine. I wanted to find out where my motor was for future upgrades,but i am so unsure of my numbers. Dry test numbers arent exactly matching to each other. Wet test looks better than both dry test.

Cyl- 1st dry/ 2nd dry/ 3rd wet (oil)
1-115. / 111. / 115
2-109. / 105. / 120
3-117. / 105. / 120
4-111. / 114. / 118
5-111. / 106. / 115
6-108. / 115. / 117
7-115. / 112. / 116
8-121. / 121. / 125

I was thinking about doing a gt40p head swap and turbo kit, now? I've got a haunting engine overhaul worry (not what i wanted).

Throttle was held opened on 2nd and 3rd test, and started from cylinder #1 all the way up to #8.

(edited): upon further reading on compression tests, the engine has to draw the same ammount of voltage by the battery on every cylinder. I might have a parasitic draw somewhere, my car doesn't start up immidiatlly in the mornings, but will fire up quick inside of a 10 hour-non use.

2 of my spark plugs (5&6) had fouled black sutt, no oil. Plugs 1 through 4 are not applicable because i changed those out last week and have had 5-8 plugs on for about 12 months (started cleaning 1-4 and i decided to buy 4 new ones for the ones i pulled. I basically have 4 very old plugs on the drivers cylinder.

Any ideas or opinions will be welcomed.
 
Last edited: Mar 21, 2019

CarMichael Angelo

my rearend will smell so minty fresh,
15 Year Member
Nov 29, 1999
10,641
8,909
234
Birmingham, al
Mar 21, 2019
#2
  • Mar 21, 2019
  • #2
Road_Runna said:
I've completed 3 compression test on my 90k mile engine. I wanted to find out where my motor was for future upgrades,but i am so unsure of my numbers. Dry test numbers arent exactly matching to each other. Wet test looks better than both dry test.

Cyl- 1st dry/ 2nd dry/ 3rd wet (oil)
1-115. / 111. / 115
2-109. / 105. / 120
3-117. / 105. / 120
4-111. / 114. / 118
5-111. / 106. / 115
6-108. / 115. / 117
7-115. / 112. / 116
8-121. / 121. / 125

I was thinking about doing a gt40p head swap and turbo kit, now? I've got a haunting engine overhaul worry (not what i wanted).

Throttle was held opened on 2nd and 3rd test, and started from cylinder #1 all the way up to #8.

(edited): upon further reading on compression tests, the engine has to draw the same ammount of voltage by the battery on every cylinder. I might have a parasitic draw somewhere, my car doesn't start up immidiatlly in the mornings, but will fire up quick inside of a 10 hour-non use.

2 of my spark plugs (5&6) had fouled black sutt, no oil. Plugs 1 through 4 are not applicable because i changed those out last week and have had 5-8 plugs on for about 12 months (started cleaning 1-4 and i decided to buy 4 new ones for the ones i pulled, so i have 4 very old plugs on the drivers cylinder.

Any ideas or opinions will be welcomed.
Click to expand...
There's nothing wrong with your engine. Most compression tests are deemed acceptable if the differences between cylinders is Limited to 10%. Yours look to be within that spec.

And what is " sutt"?
 
R

Road_Runna

20+ Year Stangneter
Dec 23, 2002
594
6
39
Ogden, UT
Mar 21, 2019
#3
  • Mar 21, 2019
  • #3
CarMichael Angelo said:
There's nothing wrong with your engine. Most compression tests are deemed acceptable if the differences between cylinders is Limited to 10%. Yours look to be within that spec.

And what is " sutt"?
Click to expand...
That black powder coating covering the electrode on the plug. Sorry, its known as fouled carbon.
 

CarMichael Angelo

my rearend will smell so minty fresh,
15 Year Member
Nov 29, 1999
10,641
8,909
234
Birmingham, al
Mar 21, 2019
#4
  • Mar 21, 2019
  • #4
Road_Runna said:
That black powder coating covering the electrode on the plug. Sorry, its known as fouled carbon.
Click to expand...
Or.......”soot” maybe?
 
R

Road_Runna

20+ Year Stangneter
Dec 23, 2002
594
6
39
Ogden, UT
Mar 21, 2019
#5
  • Mar 21, 2019
  • #5
CarMichael Angelo said:
Or.......”soot” maybe?
Click to expand...
. Made my day, lol at my spelling mistakes.
 
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