- Joined
- Jun 13, 2016
- Messages
- 134
- Reaction score
- 40
- Points
- 28
- Location
- Connecticut
- Vehicle Year
- 1989
- Make / Model
- Bronco ii
- Engine Type
- 2.9 V6
- Engine Size
- 2.9L
- Transmission
- Manual
- 2WD / 4WD
- 4WD
- Total Lift
- 6
Alright, guys, I'm back with a new problem.
some of you might remember that over the summer I rebuilt my 2.9 and have been dealing with issues ever since. since my last post, I have replaced my entire wiring harness, all engine sensors, and swapped around a few ECMs which resulted in a "running" "driving" truck. Sadly the more money I threw at this thing the worst it got, so this past weekend I figured I would do a compression test on the engine (yes I should have done this a LONG time ago). I cranked the engine 3 times per cyl and got 155psi in each with a max of 180 after 5 cranks. Now I was very happy with the results until I got to cyl 1...I got 3-5 psi. I figured maybe I needed to crank it more or maybe there was debris in the spark plug hole which created a leak. no such luck, I cleaned and re-tested with the same results. so long story short I got a little carried away and tore the engine back down in the truck, both heads and intake off etc. I expected to see a damaged valve or piston...nope! both valves were fine and sealed correctly, the piston was fine and the bore was fine. THE ONLY THING I saw was scratching on the surface of the piston. they were spread over the surface and not nessesarilly where the valves are. and like i said the valves are perfectly fine, no damage. the scratches were very shallow and around the center of the piston. I used a feeler and made sure the piston ring was intact, it was, the valves were fine, and the piston wall is looking mint. please for the love of god someone help me understand how I can have 3 psi when seemingly everything is fine. Also, I should mention that cyl 1 is the only one affected by this strange issue.
any help would be much appreciated-Jon
some of you might remember that over the summer I rebuilt my 2.9 and have been dealing with issues ever since. since my last post, I have replaced my entire wiring harness, all engine sensors, and swapped around a few ECMs which resulted in a "running" "driving" truck. Sadly the more money I threw at this thing the worst it got, so this past weekend I figured I would do a compression test on the engine (yes I should have done this a LONG time ago). I cranked the engine 3 times per cyl and got 155psi in each with a max of 180 after 5 cranks. Now I was very happy with the results until I got to cyl 1...I got 3-5 psi. I figured maybe I needed to crank it more or maybe there was debris in the spark plug hole which created a leak. no such luck, I cleaned and re-tested with the same results. so long story short I got a little carried away and tore the engine back down in the truck, both heads and intake off etc. I expected to see a damaged valve or piston...nope! both valves were fine and sealed correctly, the piston was fine and the bore was fine. THE ONLY THING I saw was scratching on the surface of the piston. they were spread over the surface and not nessesarilly where the valves are. and like i said the valves are perfectly fine, no damage. the scratches were very shallow and around the center of the piston. I used a feeler and made sure the piston ring was intact, it was, the valves were fine, and the piston wall is looking mint. please for the love of god someone help me understand how I can have 3 psi when seemingly everything is fine. Also, I should mention that cyl 1 is the only one affected by this strange issue.
any help would be much appreciated-Jon