rangerenthiusiast
New Member
- Joined
- Aug 26, 2016
- Messages
- 553
- Reaction score
- 2
- Points
- 0
- Location
- Hudson Valley, NY
- Vehicle Year
- 1992
- Make / Model
- Ford
- Engine Size
- 4.0
- Transmission
- Automatic
Hey, guys.
Just did my first compression test and I hope I got it right, because if so, it may mean that I didn’t fork over 1500 bucks for a 1992 Ranger Custom with a junk 4.0 engine. I performed this test because I’m having a terrible problem with vibration out on the road and when I pulled off one of the wires on the coil pack (corresponding to plug #5, located on the driver’s side), I noticed that it made no discernible change in the idle, while the others all did. I took the spark plug out of cylinder #5 and switched it with one of the others, but there was no change.
Following the instructions that I found elsewhere on the site, I disconnected the coil pack, removed all the wires, pulled the fuel pump relay fuse and started taking out the plugs. Unfortunately, the ones on the passenger’s side are a b@tch to get to and the one in the back on that side is almost impossible (due to the AC box). So I ended up leaving the plugs in on the passenger’s side and just removed the ones on the driver’s side (since that’s where the aforementioned plug is located).
With all 3 of the plugs out on the driver’s side, I screwed in the test gauge and cranked the engine over a couple of times on cylinder #5 and got about 165 lbs of compression. I then re-read the instructions and cranked it over for about 10 seconds (which seemed excessive, but it’s what the instructions called for). This time it read around 180 lbs and so did the other two. I was thrilled.
So I’m just wondering if having the passenger’s side plugs still in when I did the test could have somehow thrown the test off? Also, the instructions called for the engine to be run for a while, then shut off for 10 minutes before the test. I drove the truck around on the road a while before conducting the test, but it was cooling down for more like a half hour or so before I actually got to cranking her over and reading the gauge. Just wondering if either of these things could have led me to have a higher compression reading than I otherwise would have. Also wondering if cranking her over for close to 10 seconds could have led to a false high compression reading. I don’t think so, but would love to hear it from someone else.
Thanks so much and sorry for the long thread.
Just did my first compression test and I hope I got it right, because if so, it may mean that I didn’t fork over 1500 bucks for a 1992 Ranger Custom with a junk 4.0 engine. I performed this test because I’m having a terrible problem with vibration out on the road and when I pulled off one of the wires on the coil pack (corresponding to plug #5, located on the driver’s side), I noticed that it made no discernible change in the idle, while the others all did. I took the spark plug out of cylinder #5 and switched it with one of the others, but there was no change.
Following the instructions that I found elsewhere on the site, I disconnected the coil pack, removed all the wires, pulled the fuel pump relay fuse and started taking out the plugs. Unfortunately, the ones on the passenger’s side are a b@tch to get to and the one in the back on that side is almost impossible (due to the AC box). So I ended up leaving the plugs in on the passenger’s side and just removed the ones on the driver’s side (since that’s where the aforementioned plug is located).
With all 3 of the plugs out on the driver’s side, I screwed in the test gauge and cranked the engine over a couple of times on cylinder #5 and got about 165 lbs of compression. I then re-read the instructions and cranked it over for about 10 seconds (which seemed excessive, but it’s what the instructions called for). This time it read around 180 lbs and so did the other two. I was thrilled.
So I’m just wondering if having the passenger’s side plugs still in when I did the test could have somehow thrown the test off? Also, the instructions called for the engine to be run for a while, then shut off for 10 minutes before the test. I drove the truck around on the road a while before conducting the test, but it was cooling down for more like a half hour or so before I actually got to cranking her over and reading the gauge. Just wondering if either of these things could have led me to have a higher compression reading than I otherwise would have. Also wondering if cranking her over for close to 10 seconds could have led to a false high compression reading. I don’t think so, but would love to hear it from someone else.
Thanks so much and sorry for the long thread.