ClassicIDI
Member
The truck in question is an Early 99 7.3 (build 01/99). It only has 93,xxx miles on it but is making a knock or clang noise that has me stumped. The truck idles smooth, has no codes, passes a Cylinder contribution and buzz test. It does have an edge tuner on it with EGT probe but that is currently set to stock. It is otherwise bone stock. It has plenty of power and does not smoke at all. It is an automatic transmission which appears original.
My diagnostic so far has included pulling both Valve covers and inspecting the valve train which appears fine. I unplugged each injector and when #5 is unplugged the noise is reduced by %70. I installed another known good injector into #5 but that did not change the noise. Warm compression on #5 is 390 which at my altitude (Denver, CO) is in my opinion very good. glow plug was not damaged in any way. both rock arms look fine and the Push rods are straight, (rolled them on a mirror). The oil is extremely clean. I drained it anyways and It might have a slight amount of metal in it but almost untraceable.
I pulled the trans inspection cover and don't see any damage to the flywheel and the torque converter bolts are tight. I have heard trucks with broken flex plates and this one does not sound like that. it is a very specific ping, ping, ping, ect. I have also heard the early 99 Torque converter noise and this is not that. The noise almost seems louder when cold. You can hear it at idle. If you get on the truck hard the engine noise drowns out the knock but once coasting you can hear it again.
Now the back story This truck was bought from a dealer that sent it out to another local shop. They replaced the #8 injector because they said it had a standard AD injector and not an AE. However they did not mention any such noise. They supposedly put in a OE Ford Injector. When the truck got to me I did notice the glow plug relay had been replaced with a starter solenoid so I disconnected it for the time being during my troubleshooting. I've seen this relay mixup before and actually had one truck fry the glow plug control circuit in the pcm because of it, hence why i disconnected it.
The one thing I find odd is that by the build date (01/99) it is an early 99 and it does have the small track bar bolts and steering box but the engine is not an early 99. It has an air intake heater, the bigger turbo, 3" plenums and AD injectors. The valve cover states the engine was built in Jan 21, 1999 and I verified it is a forged rod engine. It shows no signs of recently being out but it's just odd.
Also Unfortunately I have a strict time deadline. My customer has 24hrs to return the truck to the dealer for a refund. He would like to keep it since it took 3 mouths to find it but not if it needs an engine.
I guess my question is where else should I look before I condemn this engine? Rod knock? (doesn't sound that loud). Wrist pin? Broken piston skirt?
My diagnostic so far has included pulling both Valve covers and inspecting the valve train which appears fine. I unplugged each injector and when #5 is unplugged the noise is reduced by %70. I installed another known good injector into #5 but that did not change the noise. Warm compression on #5 is 390 which at my altitude (Denver, CO) is in my opinion very good. glow plug was not damaged in any way. both rock arms look fine and the Push rods are straight, (rolled them on a mirror). The oil is extremely clean. I drained it anyways and It might have a slight amount of metal in it but almost untraceable.
I pulled the trans inspection cover and don't see any damage to the flywheel and the torque converter bolts are tight. I have heard trucks with broken flex plates and this one does not sound like that. it is a very specific ping, ping, ping, ect. I have also heard the early 99 Torque converter noise and this is not that. The noise almost seems louder when cold. You can hear it at idle. If you get on the truck hard the engine noise drowns out the knock but once coasting you can hear it again.
Now the back story This truck was bought from a dealer that sent it out to another local shop. They replaced the #8 injector because they said it had a standard AD injector and not an AE. However they did not mention any such noise. They supposedly put in a OE Ford Injector. When the truck got to me I did notice the glow plug relay had been replaced with a starter solenoid so I disconnected it for the time being during my troubleshooting. I've seen this relay mixup before and actually had one truck fry the glow plug control circuit in the pcm because of it, hence why i disconnected it.
The one thing I find odd is that by the build date (01/99) it is an early 99 and it does have the small track bar bolts and steering box but the engine is not an early 99. It has an air intake heater, the bigger turbo, 3" plenums and AD injectors. The valve cover states the engine was built in Jan 21, 1999 and I verified it is a forged rod engine. It shows no signs of recently being out but it's just odd.
Also Unfortunately I have a strict time deadline. My customer has 24hrs to return the truck to the dealer for a refund. He would like to keep it since it took 3 mouths to find it but not if it needs an engine.
I guess my question is where else should I look before I condemn this engine? Rod knock? (doesn't sound that loud). Wrist pin? Broken piston skirt?
