smaring
Member
I'm having trouble with valves not fully seating in a couple cylinders on my 2001 4.6L Expedition. I believe I've narrowed the problem down to the lifters, which are all new. I came to this conclusion because if I leave the rockers off there is no leak while doing a water test. As soon as I add the lifters and rockers back in it leaks. If I compress the lifters all the way to the bottom in a bench vise and immediately install them, the valves will seal. If I "prime" them by soaking them in oil, which is what I thought you were supposed to do after compressing them, I have the same problem again. The valves leak because the lifters won't sink down enough. Am I doing something wrong? What happens if you don't prime the lifters? Do I have bad lifters? Are my new springs too weak?
I obviously don't want to put these heads back on unless I'm pretty damn certain I will get good compression this time.
-Steve
Titusville, FL
Here's the backstory ...
Last year I was driving along and heard a huge bang followed by smoke rolling out the exhaust and a significant loss of power. I felt lucky to make it the 1/2 mile home and into the driveway. I started stripping it down and found that a timing chain guide had broken and the camshaft sprocket looked to have jumped a few teeth, which I presumed accounted for the lack of power and smoke rolling. I figured as long as I was that far into it that I might as well pull the heads and do a valve job as it seemed to lack the power it used to have before even before the chain guide broke. As I suspected, the piston tops and heads were caked with 20+ years of carbon. I did a water test and more than half of the valves were leaking pretty bad. I cleaned everything up, lapped the valves until I was sure they were seating well, put in all new springs and lifters, and replaced a couple rockers I thought a bit loose. I also replaced a bunch of other stuff while I was there. When I was done, it ran terrible. No power. While I was reviewing some video I took I happened to see a big "R" behind the oil pump, meaning it was a Romeo. I then cursed the Wikipedia gods I had consulted to erroneously determine it to be a Windsor and proceeded to correct the timing. It didn't help much. It still didn't have much power. I then did a compression test on all the cylinders. I got about 152 psi on average on (6) cylinders and zero compression on (2) cylinders. I stuck an endoscope camera in them. One of them I was convinced looked like a piston top had been crushed in. The other looked fine. I reasoned that the bad timing probably destroyed the one piston and perhaps broken piston rings accounted for the other. I checked the spark and the fuel injector. All good. This go around I pulled the engine. When I took the heads off I was surprised to see that the piston top I thought was damaged was in good condition. All of the piston tops were. There was no sign of damage from the difference in timing from a Windsor to a Romeo, thankfully. I pulled all the pistons thinking I was going to find broken piston rings. I didn't. I replaced all the rings while I was there and the rod bearings. I then decided to focus my attention back on the heads. I decided to do a water test on my "flawless" valve job. In one of the cylinders with no compression an exhaust port leaked like crazy. In the other cylinder with no compression an intake port was leaking like crazy. Both ports on the (6) cylinders with good compression held the water fine.
I obviously don't want to put these heads back on unless I'm pretty damn certain I will get good compression this time.
-Steve
Titusville, FL
Here's the backstory ...
Last year I was driving along and heard a huge bang followed by smoke rolling out the exhaust and a significant loss of power. I felt lucky to make it the 1/2 mile home and into the driveway. I started stripping it down and found that a timing chain guide had broken and the camshaft sprocket looked to have jumped a few teeth, which I presumed accounted for the lack of power and smoke rolling. I figured as long as I was that far into it that I might as well pull the heads and do a valve job as it seemed to lack the power it used to have before even before the chain guide broke. As I suspected, the piston tops and heads were caked with 20+ years of carbon. I did a water test and more than half of the valves were leaking pretty bad. I cleaned everything up, lapped the valves until I was sure they were seating well, put in all new springs and lifters, and replaced a couple rockers I thought a bit loose. I also replaced a bunch of other stuff while I was there. When I was done, it ran terrible. No power. While I was reviewing some video I took I happened to see a big "R" behind the oil pump, meaning it was a Romeo. I then cursed the Wikipedia gods I had consulted to erroneously determine it to be a Windsor and proceeded to correct the timing. It didn't help much. It still didn't have much power. I then did a compression test on all the cylinders. I got about 152 psi on average on (6) cylinders and zero compression on (2) cylinders. I stuck an endoscope camera in them. One of them I was convinced looked like a piston top had been crushed in. The other looked fine. I reasoned that the bad timing probably destroyed the one piston and perhaps broken piston rings accounted for the other. I checked the spark and the fuel injector. All good. This go around I pulled the engine. When I took the heads off I was surprised to see that the piston top I thought was damaged was in good condition. All of the piston tops were. There was no sign of damage from the difference in timing from a Windsor to a Romeo, thankfully. I pulled all the pistons thinking I was going to find broken piston rings. I didn't. I replaced all the rings while I was there and the rod bearings. I then decided to focus my attention back on the heads. I decided to do a water test on my "flawless" valve job. In one of the cylinders with no compression an exhaust port leaked like crazy. In the other cylinder with no compression an intake port was leaking like crazy. Both ports on the (6) cylinders with good compression held the water fine.
