So I installed the Harland Sharp 1.7 RR's in my 5.2 97 Dakota and did the plenum reinforcement as well. Got it all put together and she ran like a champ. Drove it about 20 miles and really babied it being careful not to get the RPMs up to high. Stopped at a Taco Bell to go through the drive thru and it stalled at idle. Started it back up and she has a loud knock. Limped it back home and pulled both valve covers. Everything looked fine until I pulled the rockers and found a bent push rod on number 7 cylinder (I think it was the exhaust PR). Bought 2 new PR's and replaced both in that cylinder. Put it all back together again and it still knocked. Pulled the left side VC again and inspected the PR's and they are straight. I'm thinking its a stuck lifter. I was careful not to let any junk fall into the lifter valley, but you never know. Poured some Marvel Mystery Oil in and she still knocks bad. Sounds like its still coming from #7. Sounds like a machine gun when I rev it above idle. Am I safe driving it for a week hoping the MM oil does its magic? I hate the thought of pulling the intake again to get to that lifter, especially since I'd have to buy new TTY bolts, but I'd rather do that than cause any damage. Any suggestions?

 

Dr. B, I'll be doing this soon to my '97 also and really hope I don't have this issue. Are these the adjustable or non-adjustable RR's? Are you using the stock guides or did you remove them?

If I came across this problem I'd pull both VC's again, pull the coil wire and have somebody crank over the engine and watch each RR to see which ones are moving and which ones are not. It could be a sticky lifter or a dead lifter. Worst case a flat lobe on the cam but I don't think that's it.

And I definitely wouldn't drive it like that. Keep us posted with what you find.

 

Non-adjustable and yes, I removed the stock guides. I am planning on doing exactly as you suggested to see which RR isn't moving, although I can almost guarentee its number 7. I'll keep you posted on what I discover.

 

Well, I found the culprit. Bent exhaust valve, # 7 cylinder. Heads are off getting re-built. FYI: talked to a very knowledgable ederly employee at Autozone who used to work for a lifter company. He said a stuck lifter will NOT bend a push rod. Usually a push rod gets bent when the piston hits a valve while it is open. No sure why this happened to my truck, but apparently there was a brief moment of mis-timing.