8 months ago my Granddaughter got an "00 Ranger 3.0 for her first vehicle. It now has 160K. 6 weeks ago the truck started bucking/stumbling on her so bad she was afraid to drive it. I sent her to a small shop with a good mechanic for diagnosis. They said it needed a valve job but couldn't do the work. To help out, I decided to pull the heads and send them out. I haven't done any engine work of note since the early 90's but previously done several major rebuilds with good success.
When I drove the truck to my place about 25 miles away, I noticed the stumbling occurred while maintaining a steady cruise. I found out that loading the engine smoothed it out as did coasting, so I would accelerate to 65ish and coast to about 45, then repeat.
At my shop, I pulled the heads, and they were promptly pronounced DOA at the machine shop due to numerous cracks and said the engine had probably been badly overheated. The relatively new water pump backs that possibility up. The machine shop located a used reman set with no repairs and I installed them. I also carefully and accurately installed a reman CMP and synchronizer. Now the vehicle won't start.
#1 cyl. has great spark and great compression (others not checked). Fuel at the Schrader valve is under very high pressure. My scanner gives me cranking rpms of 250ish to 400+ which I believe indicates the CKP is working. The scanners temp indication matched OAT.
I am not sure about timing chain condition. One way I tested it indicated a potential 12* to 15* slop. Without the benefit of a helper I tried to check it again by marking the CMP flag location at TDC, then hand turning the motor further, then backing it up to TDC. I thought that would leave the flag at a different point where I could then determine the degrees of slop. But, nay nay, the flag was exactly where it had been previously.http://www.ranger-forums.com/rf/foru...:irked::irked: