Precombustion chambers

The most common failure of the precombustion chamber is rusting thru from the water jacket side. The chambers are surrounded by the cooling system. It becomes most noticeable when water begins to enter the combustion chamber and bubbles are seen in the radiator.


Matt

With proper cooling system maintenance......mainly correct anti-freeze with anti cavitation additive.....combustion chambers will last a very long time. Where things go bad is when there are cooling system leaks left unrepaired and tap water or (ditch water) is substituted for proper coolant. Corrosion and pitting of the pre-com chambers then becomes severe to the point where pin holes through the chamber can result.

I'd be a little suspect of an engine advertised with "new pre-combustion chambers" unless it was part of a major overhaul. New chambers alone would indicate to me that there were recent or maybe ongoing problems with the cooling system.

If a pre-combustion chamber was leaking and water was used for coolant, could it cause the engine to backfire/pop???

I'd say not very likely.....I would expect to see combustion gases in the coolant/radiator or the risk of liquid lock if water leaked back into the cylinder when setting. Also possibly steam/water vapor in the exhaust when fired up.

Where would the best place to buy Pre Combustion Chambers and seals? Im in the process of replacing one due to it leaking coolant. I figure I would replace all of them while Im at it. Would it be better to go with official Cat parts or would it be fine to buy aftermarket? This is for a Cat 951C with the 3304 engine.

That's kind of a personal choice. In todays global sourcing it's hard to tell where stuff is coming from, even Cat. Every once in awhile I hear about a chamber coming apart but can't tell whose it is. The aftermarket versions have worked for me but I don't buy very often. Regal, Costex or Heavyquip would be typical sources.

There are three reasons a PC chamber leaks, 1, the engine has been overheated and the seals burnt, 2, the seals have failed due to old age, 3, the chamber has corroded away. The most common reason is the first one, when the chamber is out, look closely at its bottom seat in the head with a flashlight, if the chamber was loose, you will very likely find cracks across its seat where it screws into the cylinder head.

Well I got all 4 chambers out without any problems. One of the chambers was rusted through. I went ahead and ordered all 4 chambers and seals from Florin Tractor. This should fix this problem anyway.

What are you doing for sealing washers. I am pretty sure you have glow plugs in those pre-cups. You will need to time those pre-cups so that the glow plug holes terminate in the same location which means you will use washers with different thicknesses to obtain this result.