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+--- Thread: 300SD help needed (/showthread.php?tid=1386)
300SD help needed - btrapr - 05-23-2010
I have a 84 300SD________around 260K on it...The chain looks like it has been replaced.
I have been driving the car to the tune of around 1100 miles since I got it going. Cleaned the soot out of the intake. eliminate egr and added a cold air intake.
My question is__I pulled the injectors today to put some Monarks in ONLY to discover that my homemade pop tester has two pin holes and won't pump up...
SO I thought what the heck I have done this before without popping on my wagon__________
I polished the surfaces and put them back together, adjusted the valves, changed the oil, AND pulled the fuel pressure spring out and measured it and it was 21mm______SO I pull it out to 26mm and put it back togther!
*started it up and got a knocking noise that sounds bad almost like a rod knock/rattle!
ANY IDEAS?
I am going to pull the valve cover back off tomorrow and double check underneath/valves etc>>> then I am going to put the spring back to 21mm____IN case I got to much fuel pressure NOW!
THE only other thing that I can think of____Is I put something upside down in one of the injectors! PERHAPS that little piece that goes under the spring towards the nozzle (it has a stud on both sides one short & one long with a taper)....then there is the flat piece and the nozzle!
RE: 300SD help needed - ForcedInduction - 05-23-2010
(05-23-2010, 07:05 AM)btrapr ANY IDEAS?
Fix your injectors.
ANY change to the injectors will significantly change their pop pressure. Even simply opening and reassembling them can change it. Lapping the surfaces is more than enough to alter them a few bar.
Quote:then I am going to put the spring back to 21mm____IN case I got to much fuel pressure NOW!No such thing. You can even block off the return flow entirely without ill effects (other than no automatic air bleeding). The absolute limiting factor of fuel pressure is the lift pump's spring. Once it reaches a maximum pressure it will simply stop pumping until the pressure is reduced. In other words its a variable flow pump.
RE: 300SD help needed - btrapr - 05-23-2010
So do not worry about the spring? Could this pop change make a noise that almost sounds like a rod/piston pin?
Just wished that i had a working pop tester! $200 seems crazy...tried to make one but it won't pump up...leaking!
Guess I will rob the injectors out of the 82 SD for now and run mine by a shop and get them set...
THANKS
Fix your injectors.
ANY change to the injectors will significantly change their pop pressure. Even simply opening and reassembling them can change it. Lapping the surfaces is more than enough to alter them a few bar.
Quote:then I am going to put the spring back to 21mm____IN case I got to much fuel pressure NOW!No such thing. You can even block off the return flow entirely without ill effects (other than no automatic air bleeding). The absolute limiting factor of fuel pressure is the lift pump's spring. Once it reaches a maximum pressure it will simply stop pumping until the pressure is reduced. In other words its a variable flow pump.
[/quote]
going to stick in a set out of a running 300SD for now...until I get the pop tester fixed OR take them by a shop to balance...
The lift pump spring is on the back side of the PUMP where the fuel line comes off, right? If so I stretched it to 26mm from 21mm_______
RE: 300SD help needed - ForcedInduction - 05-23-2010
(05-23-2010, 07:52 AM)btrapr The lift pump spring is on the back side of the PUMP where the fuel line comes off, right?
Yes. Thats what regulates pressure. The spring inside the lift pump is what does the actual pumping. Some flow is needed for air bleeding and cooling of the pump, otherwise the lift pump alone would be plenty.
RE: 300SD help needed - btrapr - 05-23-2010
Thanks! FI
I switched the injectors out! and viola! NOISE ELIMINATION!
I tried to re-weld the leaks in the tester, but they still have a few pin holes!
I hooked one of the monark nozzles in it anyways________needle barely moving under 100 and DRIZZLING FUEL was the injectors repsonse!
***So much for saving money and skimping on a tester_____I will be taking the monark injectors by a shop and pay the $80? to have them set them up at 135bar....Then back in they will go!
THANKS AGAIN
RE: 300SD help needed - Rudolf_Diesel - 05-23-2010
The best thing to do for a DIY pop tester is to use a porta-power style pump - no welding OR JB weld required. A nasty leak at high pressure is going to ruin your day if it gets injected into your skin at 135 bar.
With out the pop tester it would be tough to set then up. I used 4000 grit cloth on a piece of glass to polish the surfaces with some oil as a lubricant.
The injectors will make a little noise when they are new and may require a few hundred miles to "break in"