Perkins 4.236

[aidank]

I changed a diesel filter in a perkins 4.236 yesterday. It proved itself to be v difficult to prime.

Engine arrangement: Rebuilt 4.236T engine, 1500hrs on the clock, going v well. Not using oil. Replacing diesel filter as had a weep from diesel filter seal, I think the weep finished off the starter which is underneath. Regular filter arrangement seen on Perkins. No Glass Bowl installed. Engine runs for 2hrs everyday, it had been running for 40mins before the filter change. New Starter, good battery.

Note: New Hand Pump fitted 3mths ago, ran out of diesel and old one wouldn't suck up the fuel from the tank, upon investigation found something had broken internally in the pump. Didn't open hand pump filter yesterday, whenever I have opened it in the past its always spotless. Haven't had a diesel filter issue in the last 15years, we keep good diesel.


Priming procedure

• Change filter and replace with new.
• Bump starter to bring Hand Pump into a position where it is pumping, it was initially at the top of stroke so wouldn't do anything. No matter how many times i bumped starter handpump seemed to only pump for 50% of travel. Is there a way of turning over to achieve full stroke.
• Opened banjo nut on filter housing where diesel enters pipe supplying the injector pump and operated handpump until filter was full of diesel. Close Banjo. In theory all air should have been gone when this step was completed. ?
• Opened bottom bleed screw on injector pump and pumped for a while 50pumps. No air whatsoever in the fuel here and plenty flow. Closed screw
• Opened Top Bleed Screw and gave another 50pump. No air whatsoever in the fuel here but poor flow.

Fired up and it ran for 5seconds and stopped.

Part 2

• Opened bottom bleed screw again and pumped, again plenty flow. Closed screw
• Opened top bleed screw again and pump. No air but poor flow.
• Cracked injectors and cranked. Fuel drip at injector but no start.

Eventually after repeating Part 2 must have done it 10 times, cranking noise began to change and sound like it was attempting to start. Closed 2 injectors and it started.


I was wondering what could the reason be for the Poor flow at the top bleed screw on the injector pump, I have done this job 10 times on the same engine over the last 15years and never had so much bother. Its a new Hand pump.


Current Problems

• As mentioned I loosened injectors for cranking purposes. There is a weep where the silver pipe from the injector pump fits onto the injector nozzle. I haven't oversqueezed, just gave it a regular squeeze with a 17mm spanner. Any ideas on how to correct it.

 

[Harry in Ky]

The top bleed screw is not important. Most pumps don't even have one. Just bleed at the lower one. As for the injector line weep. Back it off one flat. Jam it tight again. Back it off one flat and jam it tight again. It will go just a little farther every time. Do that three times. That usually works for me.

 

[WNM]

Experienced those Perkins in the industrial application over the years. They always were a bear to get running after changing fuel filters
Like you had to repeat the bleeding procedure several times . Just the nature of the beast I guess

 

[woodsplitter]

This is interesting, I changed fuel filters on a 180 with a 4-236 Perkins diesel, my hand pump only had pressure for the last 1/4 of lever stroke, is there a relation to the crank position for the hand pump to work better? we had a tough time getting mine running.

 

[Dieseltech]

This is interesting, I changed fuel filters on a 180 with a 4-236 Perkins diesel, my hand pump only had pressure for the last 1/4 of lever stroke, is there a relation to the crank position for the hand pump to work better? we had a tough time getting mine running.

Sometimes the engine needs turned a bit for the hand lever to have full stroke, depends if the engine cam lobe is holding UP the lever inside engine when it stopped. Turn the crank one turn and it helps hand lever work again as cam turns 1/2 engine speed. The hand lever will ALSO go out of stroke WHEN the fuel filters and pump are full of fuel. Most MF/PERKINS fuel systems have a constant bleed orifice fitting on top of a filter base to keep air OUT of the filter BEFORE air can get into injection pump inlet, which WILL cause shut down. Make sure the orifice is not plugged or you will see lots of stalling trouble. I've seen this a lot in years past as an OLD MF mechanic and then into diesel injection repair over forty years.

 

[woodsplitter]

Thanks Dieseltec, I will remember that for next time