Bulldozers caterpillar d7f piston injection pump

[medkab33]

Hello friends....

Let me introduce myself, a caterpillar enthusiast since my childhood, I bought a 1974 D7F (with the new, more reliable reduction system!!!). To terrace and level a wooded area.
my problem and the following: the engine runs on 5 cylinders vergicles remain stopped for a long time (acceleration and normal engine shutdown), I dismantled the injector lines and I noticed that piston n°3 of the injection pump does not provide fuel.
My question is the following: is it possible that the piston remains blocked at the top and how can I unblock it? or how to change the piston of the injection pump without dismantling it, with specific tools in particular the grooved socket to remove the upper nut and therefore change the piston?

How to stall the injection pump at maximum acceleration by dismantling a minimum of parts to be able to insert the new piston without having a timing problem?

I would be really grateful for advice and a procedure (especially after reading several posts from Nigeria) with plans or other photos.

Waiting for a response, a big hello to all caterpillar enthusiasts

 

[Nige]

I bought a 1974 D7F (with the new, more reliable reduction system

Do you mean the newer style of transmission.?

the engine runs on 5 cylinders vergicles remain stopped for a long time (acceleration and normal engine shutdown), I dismantled the injector lines and I noticed that piston n°3 of the injection pump does not provide fuel.

To obtain detailed information regarding the fuel injection pump on your engine will require the engine Serial Number. I imagine it will be 3Nxxxxx.

There were a lot of changes made to fuel injection system design during the production of the D7F. It is important to know which generation of fuel injection system you have. Some photos of the fuel injection pump and governor would also be useful.

Question: Does the engine run on all 6 cylinders at any time or under certain specific conditions.?

Disclaimer: I am not a fuel injection specialist but when they see this they will require answers to the questions above plus photos in order to offer you advice or suggestions.

 

[medkab33]

Good morning

thank you for your answer indeed the engine does not run on 6 cylinders but on 5 cylinders since by dismantling output number 3 (engine on the road no fuel came out)
The engine number is 3N71762 it is a 3306PC.
What do you think, can I unseize piston number 3 by dismantling the upper part (discharge valve) and tapping lightly with a mallet and a 5mm thick rod on the piston head to bring it back down?
Do you think this would be possible without damaging the assembly by placing the camshaft of the injection pump in the low position on cylinder 3?

Thanks

 

[Nige]

Thank you for the information above.
Can you supply 1 or 2 photos of the fuel injection pump please.?

 

[medkab33]

My bad attached the photo of the injection pump

 

[Nige]

That should be enough information. Now you have to wait for the fuel injection specialists to offer opinions/suggestions.

 

[medkab33]

Thank you Nigeria I look forward to the reviews

 

[Welder Dave]

LoL

 

[thepumpguysc]

It’s possible to replace it on the engine..BUT.. you’ll have to get eyes on the problem..which means cleaning the heck outta the big flat panel where the filter is..
When u pull it off, pay attention to an overflow valve and spring in one of the corners..
So go getcha a pressure washer and a case of brake cleaner and a scraper..
There’s several different problems it could be, so get eyes on it..

 

[medkab33]

Good morning



Thank you for your response, I will actually remove the protective sheet and see what is stuck behind it.

As the bulldozer was stationary for a long time, I think it was condensation in the fuel tank which would have put a little rust in the circuit.

I will try to lower the piston if it is stuck, and then do a global overhaul of the injection system (taring the injector etc.)



thanks again

 

[thepumpguysc]

U can buy a “Bonnet” removal tool online or at your local Cat house for about 30-35.00..

 

[medkab33]

thank you the pump guy

for information I will try to dismantle the upper splined nut and separate the valve from the piston to exert light pressure on the piston head (by spraying copiously with brake fluid) and force it to go back down into its housing (of course by putting the piston cam in neutral on piston number
3)

I will try to go slowly so as not to remove the whole thing so as not to miss a timing tooth on the rack since the pump is still on the engine

Do you think this operation is feasible?

 

[thepumpguysc]

Stop guessing at it.. u won’t know what you’ll need UNTIL u get the cover off..AFTER ITS OFF, post a picture and we can go from there..

 

[terex herder]

If it sat for a long time and only 1 hole isn't pumping fuel consider yourself lucky. The size hammer required to free the piston in the bore may scare you.

 

[Old Magnet]

3N1762 Engine should have a compact scroll injection pump but your picture shows a sleeve metering pump?????

 

[medkab33]

old magnet

that's the engine number I'll post a photo of the plate

 

[Welder Dave]

It looks like 3N71762.

 

[medkab33]

old magnet

the injection pump looks like a 3306 Di?

 

[Coaldust]

Is that a mango worm borrowed into your arm?

I’d wash that engine before taking anything apart.

 

[Old Magnet]

3N71762 would have the sleeve metering pump. Can't find anything on a 7N1533 arrangement.
Odd that it would be a PC engine