Diesel running rough after head gasket change - help!!

[Chancer]

Hi,

A while ago I overheated and seized the engine in a Ford Cargo rigid I use for carting my horses around in. After messing around and changing the head gasket I have managed to get her running, but roughly. There are two problems that are immediately apparent that I have to get sorted - the engine sounds like there's piston slap or knocking (I don't know the difference) going on, and the injectors are all leaking at the pipe join.

Could the two problems be connected?
What's the best way to stop the injectors leaking - is it a case of torquing them up more, or using ptfe tape or similar to plug the leak?
If the injectors aren't causing the knocking, what's the best way to diagnose the cause to the problem?

TIA.

 

[CRASH]

The two things occuring simultaneously leads me to believe you ahve an air leak in the injection system. This leads to air being mixed into the injection pulse, which can mess up the timing prety badly, leading to pre-detonation, and a piston slapping sound.

Make sense?

 

[Chancer]

I think you're quite right - I spoke to a guy yesterday about this. It's likely that the O-rings on the injectors perished and fell off without me noticing during the gasket change.

Thanks!

 

[19CHEROKEE89]

The two things occuring simultaneously leads me to believe you ahve an air leak in the injection system. This leads to air being mixed into the injection pulse, which can mess up the timing prety badly, leading to pre-detonation, and a piston slapping sound.

Make sense?

this is exactly what i would say.

also how did u seize the motor?

 

[Chancer]

Jubilee clip fell off the bottom radiator hose - I drove for 5 miles with no coolant! I suppose it was just wear and tear considering the thing's 22 years old!

 

[Matthew Currie]

I don't think PTFE tape is the stuff. The pressure is wicked high. Try torquing them better, and if that doesn't work you may need new lines.

Added note on diesel knock: they knock when cold, because of insufficient combustion. Some combustion occurs at the right time, perhaps in another cylinder, and the piston starts down, then combustion occurs, but the flame front is slower than the piston movement, so instead of work it makes noise like a firecracker in an empty drum. That's why diesel knock is harmless. If it were preignition it would break rings or cause other damage, which is what happens sometimes when people use too much ether to start a cold engine.

 

[Chancer]

I found out that there are O-rings on the injectors - they probably fell off and/or were perished. For all the price that's going to be to fix, I'll make sure those are renewed before panicking about forking out for a new engine. D'oh!