How can I tell which cylinder isn't firing?

[doswacko]

I really think my tractor isn't running on all cylinders.. in the literal sense!

As many here know, I have a 336D I recently restored. Well, I'm convinced one cylinder isn't firing (or getting fuel, not sure which). How can I find out which cylinder, if any, isn't firing and if it is fuel related or compression related?

I'm a bit scared of toying with a diesel engine while it is running, given the pressures involved and could use some sage advice from the experts here.

Once the temps here improve a bit, I'll try and get a video of the engine running, so you can all hear what I'm hearing when it is running. It just sounds like it is running on 2/3 cylinders, and the constant stream of wet smoke out the tailpipe only hardens my distrust of this engine.

Thanks a bunch!

I use a temp gun on the exhaust manafold.

 

[Neat 1500]

the best way to check for flow is crack it @ the injector, it does come out but it doesnt gush. it will be noticeable on a good cylinder but not on the bad. it will also give you and indication of fuel flow and pressure from the pump so it can be ruled out or in. could be as simple as a crappy injector.

 

[Jimbrown]

The manifold does not come off you just mark the thing anyplace that you cansee it. It gets hot enought to burn the marker off real fast.

 

[Car Doc]

I am going with the others and say crack the injector lines and I would go ahead and loosen and re tighten them before hand with it off so you are familiar with the amount of force needed.

And it doesn't matter at the pump or the injectors use what is the handiest just dont bend any lines or dent them in the process.

The fuel will be only a tiny dribble you wont believe the engine can even run its such a small amount that leaks out not dangerous at all just messy. Once you determine which it is then its a matter of finding out if its not getting fuel into the cyl and why or the cylinder itself is deficient in compression. hth

 

[jonyyuma]

Cracking injector lines at the injector point hasn't ever hurt any of the engines i have worked on. It is required to get the air out of fuel lines after running the fuel supply dry. You will need ear muffs and a suitable wrench. back it off till it dribbles....I also use a heat gun, but the crayon spot on the side of the exhaust manifold works too for detection of bad cylinders?.

 

[MichKubota]

After the engine is cold, start engine and begin touching each injector. You will begin to feel the injectors warming. If injector is not warming up like other injectors, cylinder is not firing.

If you don't want to touch injector while engine is running, just let engine run for a few minutes, stop the engine and feel for warm injectors.

Probably don't need to say this, but don't try this after engine has gotten up to temperature.