D315 pre-combustion chamber

I'm new to ACMOC and diesel mechanics. I bought 7U10608 last November. Pre-combustion chambers were old (possibly original) and badly pitted. I'll pass along here what I discovered in my search for replacement pre-combustion chambers for the CAT D315 engine. Old hands won't want or need the following information but newbies like me might appreciate the shortcut to "pre-cup heaven". First, the original chamber assembly, 4F8517, is no longer available except possibly as a used part (I never found one). Second, the CAT replacement for 4F8517 is 2S1273. Don't be fooled that 2S1273 is of a different design than 4F8517. 2S1273 looks different but it is the proper replacement. CTP sells 2S1273 under their part number 1S1970 (Does CTP manufacture 2S1273/1S1970? I don't know but what they sell is brand, spanking new, not new/old stock. Can someone clarify---Who makes the new 2S1273/1S1970?). Heavydutypros.com offers CTP 1S1970/2S1273 for sale, as do other aftermarket vendors. Agkits.com has it in stock for a most reasonable price. The required copper seal and o-ring are still available under the original CAT part numbers.

I have some D315 pre-combustion chambers nice condition

I replaced all intake and exhaust valve parts, machined head, and installed new pre-combustion chambers in my D315. I installed the old (maybe original) fuel nozzle assemblies. Am now starting the engine but mostly getting white smoke out the stack---apparently getting too little fuel to cylinders 2, 3, and 4. Fuel lines have been bled at injector pump and at cylinder head. I'm thinking to replace the old fuel nozzles with new. I need an expert's opinion: Will new fuel nozzles solve my start-up problem?

Thirty years ago new nozzles were not that expensive. I would say replace. But times change, are OEM"s still available? Not being an expert I will not say that is the fix to make it start.

How did you bleed the pumps? With the ovel bleeder screw that takes a special tool, or just crack the line. And from the site finding not the pumps even had the bleeders on the backside. I have had 2 occasions I spent hours bleeding D318 ( the next bigger engine with 6 as to your 4 cylinders), started as soon as I bleed the bleeder screws on the back side of pump. All other times just cracking the lines worked.

Take your injectors out and reattach them to the lines so you can see how they are spraying. You can unscrew the injector tips and clean them as well.

Thanks to Ray54 and Clayton for their useful suggestions. I found replacement nozzles (that don't appear to be a scam) on eBay and ordered them. To answer Ray54, I bled by cracking the lines. I'll clean out and blow out fuel lines again and re-attach. For those like me who are new to vintage diesel engines, I found a useful video entitled "Cat 3306 Fuel Nozzle and Precumbustion Chamber removal" put up by TextDirt 101 two years ago. It seems TextDirt 101 is no longer active but I'll send them a thank you here and hope it reaches them in west Texas.

Maybe not needed but none-the less - keep body parts away from those line joints and nozzle tips! You do not want to endure the results of high pressure hydrocarbon injections. - cts

As stated before, generally cracking the lines is enough. But I had twice I spend hours bleeding. Even went and got air to pressurize the fuel tank to get good flow out top of the filter tower.

So look behind the injection pump. As similar as D 315 and D318 engines are, there should bleeder screws. Flat on 2 sides oval on the ends, so it takes a special tool. Cat supplied and L shaped tool, with the oval opens 90 degrees off. I think you can get a 1/4 inch drive socket from Cat. Most find a cheap socket close to size and smash until it works.

I found a pice of 1/4 rod with a nut welded on at 90, with the nut gently persuaded with hammer to make the oval shape, I did wonder at first what is was for (obviously required in tool box) so I found out from changing filters in tower