Cat 3204 on 943 19z engine having problems FIRE

Pull injectors and have them checked
Adjust valves

You’re probably going to need an engine overhaul though. 3204 is not one of the longest lived engines made.

I would check the injection timing, could be late.

3204 doesn’t have cylinder sleeves unless it’s been bored out and dry sleeves installed in a machine shop during a previous overhaul.

It also doesn’t have side covers on the block like some of the older or larger Caterpillar engines have, so you have to drop oil pan and do everything from the bottom. Not sure what a 943 charger is, but if you are willing, there’s usually a way! Problem is your cylinders probably will need boring to an oversize and install pistons and rings to match if you want your repairs to last. This is done in machine shop, so engine out for that and do the assembly on an engine stand where you can stand up and work on it.

[quote="ccjersey"]3204 doesn’t have cylinder sleeves unless it’s been bored out and dry sleeves installed in a machine shop during a previous overhaul.

It also doesn’t have side covers on the block like some of the older or larger Caterpillar engines have, so you have to drop oil pan and do everything from the bottom. Not sure what a 943 charger is, but if you are willing, there’s usually a way! Problem is your cylinders probably will need boring to an oversize and install pistons and rings to match if you want your repairs to last. This is done in machine shop, so engine out for that and do the assembly on an engine stand where you can stand up and work on it.[/quote]

Hello .
I disassembled the head.
The seal was melted between pistons 2 and 3.
Pistons 2 and 3 have a melting angle, I think they need to be changed.
On cylinder number 3 the triangle (about 3mm) lost by the piston has melted in the cylinder itself.
For sure the bands are very damaged
That's why all that smoke from the oil drain.
Precautions to replace pistons?
Thanks so much
Simo

Either send the block to a shop to be bored for oversize pistons or AT LEAST....remove the ridge at the top of the cylinders and then hone them to allow the new rings to seat properly.

Failure to ream the cylinders to remove the ridge usually results in damage to the piston and new top ring when it contacts the ridge that has been left by the worn rings. Reaming the ridge also helps get the old pistons out without damage but it sounds like you need new ones anyway.

Replacement of ALL bearings on the crankshaft is probably a good idea. Or check clearances carefully and only reuse if the clearance is within the Caterpillar recommended range. I personally would not reuse a connecting rod bearing unless it was nearly new and showing minimal wear

Head should be resurfaced and checked for cracks as part of the reconditioning process and valve grind.

The most likely cause of the burned pistons is bad injectors, so do not fail to have them checked for proper spray pattern and pressure setting.

[quote="ccjersey"]Either send the block to a shop to be bored for oversize pistons or AT LEAST....remove the ridge at the top of the cylinders and then hone them to allow the new rings to seat properly.

Failure to ream the cylinders to remove the ridge usually results in damage to the piston and new top ring when it contacts the ridge that has been left by the worn rings. Reaming the ridge also helps get the old pistons out without damage but it sounds like you need new ones anyway.

Replacement of ALL bearings on the crankshaft is probably a good idea. Or check clearances carefully and only reuse if the clearance is within the Caterpillar recommended range. I personally would not reuse a connecting rod bearing unless it was nearly new and showing minimal wear

Head should be resurfaced and checked for cracks as part of the reconditioning process and valve grind.

The most likely cause of the burned pistons is bad injectors, so do not fail to have them checked for proper spray pattern and pressure setting.[/quote]

Hi I removed the pistons, one was quite damaged. It is striped on the upper side.
It seems that the detonation took place in the outermost part and melted a small portion of the piston.
I don't have much experience, but as you say it seems a problem of incorrect atomization of the injector.
The cylinders are completely mirror smooth.
The cylinder head is undamaged, the engine has 5100 hours.
Now do I have to remove the injector, do I have to change it completely or can I only change the sprayer?
Thanks for your help .
Simo