3A 152 Injector Nozzle Pressure Setting

Information on setting the injector nozzle pressure settings for a Perkins 3A.152 3 cylinder engine as fitted to a Massey Ferguson 35 tractor.  This discussion follows the story of Ryan’s tractor.

When trying to get good starting performance there may be more than one issue that needs attention.  Ryan began by reconditioning the injectors, but also had to undertake a little maintenance on the starter motor…

1. Ryan Jackson
   

   Hi all,

   I’m struggling at the moment, I’ve just reconditioned the engine on my MF 35 and while as was at it I tested the Injectors too see what the spray pattern, yes it was terrible – dripping out – not spraying.

   Therefore there was no choice to exchange the Tips – the question is what pressure should I set the Nozzle tips to break off at?

   I’ve heard they should be 2060 psi = 142 Bar and somebody else said they should be 185 Bar.

   I don’t know were to be at! And I don’t want to set them at a wrong pressure and fit them – and then they will wash the liners etc.. After investing many hours reconditioning the Engine.

   Guys do you know what pressure I should set them at? your help would be very much appreciated.

   Ryan Jackson

2. Ryan Jackson
   

   Hi Guys,

   I did some rooting today. I reckon I’ve got the right setting now 2500 PSI = 174 Bar. Anyway I’m going to set them to this.

   Just want to keep you men up to date – in case anybody else needs this values.

   Hopefully we will get some smoke this weekend – here’s hoping!

   J

3. admin
   

   Hi Ryan,

   For the 3 cylinder Perkins it is 120 atmospheres (about 121.6 bar).

   For the 4 cylinder Standard engine is it 130 atmospheres (about 131.7 bar).

   Have you done your own injectors? What process and equipment have you used to do this? I’m sure everyone would be very interested to learn the technique if you have a moment to teach us.

   Regards,

   Steve.

4. Ryan Jackson
   

   Morning Steve,

   Thanks for the feedback. Shxt I have set the injectors to 174 bar. No worries I can adjust them again. Steve it seems a little too low on the pressure. But if you say so.

   Yeah did not get any smoke yet.

   Last night I was turning the motor over to check if I was getting oil pressure / delivery to the rocker shaft.
   Got the oil up there, so that is good. But I did notice it was very hard to turn over even with the injectors out.
   When I re-worked the engine the crankshaft was turning over freely. But that problem you always get on those motors- the rear main brg oil seal “rope seal” is always leaking. So when i fitted the new one I made sure it was tight on the crankshaft – this made the engine hard to turn over – but I never thought it would be so hard with the starter on it. She is tight. You could cook eggs on the starter motor after turning over. And I had a big ass 135 AH Forager battery on there.

   Tonight I will check the starter to see if it is “Lazy” measuring the voltage drop when turning over and will clean the brushes too. In the worst case, we will just have to tow her to get her started and bed that rope seal in. I think the voltage should not drop below 10V when cranking from the power supply into the Starter motor and the ground/earth.

   What I did with the Injectors, got a replacement set of Nozzles – as that is the only thing which “Normally” goes wrong “they drip, spray unevenly etc.”. So you just have to fit the Nozzles and then simply adjust the the tensioning spring holding the needle down. How you set them is by using a injector test gauge see link – http://www.bosch.co.za/content/language1/html/3315.htm

   You do not need to send them away to be reconditioned – if you have the tools handy you can DIY it.

   Thanks for the info Steve

   BR
   Ryan

5. Ian@vte
   

   Hi Ryan
   Re injector pressures.The info in my factory manual concures with Steves figures,however it has been said that a small increase to the pressure for the 23c engine does help with starting.Add approx 10 to 15 atmos.??Ian

6. Ryan Jackson
   

   Well men,

   Thats me loving life now!

   We got smoke tonight – Beautiful!

   The rat was not the back-end seal. It was the starter motor, I turned the coil down where the brushes run on and squared the brushes up too. The power is coming on there good and strong. When I was setting the solenoid fork up, I did notice the IMPORTANCE of setting is right. Just a little turn too far and the pinion gear rides into the housing and the motor turn slower. After a little “screwing” about we got her sweet. Riding to the end “housing” but no slowing the rotation speed down.

   After modifying the fuel in-line to run out of a 5L (in stead of the normal tank) and then and blead her. First turn of the key or better to say BiG screwdriver to bridge the starter she brust into life.

   It was a long time coming but was sweet, until I smoked the workshop out. That is a great training excersie for the Fire Department – Blue smoke and eye lids for Chinaman on me – but it was worth it.

   So we are away with a mixer now.

   Just back to pressures on the Nozzles – I set them to 130 Bar. Even though our Steve and WSM says it should be 120Bar. I did notice at 120Bar the nozzles did not spray as nice as at 170+Bar. The question was – what can the Fuel pump deliver too – pressure. So she got the 130Bar set on the injectors – until yet no problems incruded. Fingers crossed!

   be good

   Jackson

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