Built motor, can't keep injectors sealed?

05MonsterDmax

05MonsterDmax

New member
Well over this past winter I built my block. Added dual pumps, had my tips cut, charger etc etc. all the valve covers were powder coated. All mating surfaces were sanded down to ensure the injectors were sitting down in the bore far enough. Swapped the oem injector hold down bolts out to a harder grade and are getting torqued at 35ftlb vs the stock 22lb or whatever it was. When u really beat down on it the injectors still seep fuel out from the bore like their lifting. This is only on my 600hp tune, not any of my big ones which would really pour prolly. Idk wat else could be the issue unless the oem hold Down retainers are flexing and letting the injector raise under high pressure? Are most of u guys with built motors/dual fuelers etc running billet tie downs or the existing oem ones? I've done everything I can think of and still to no avail..
 
Your OEM hold downs will work fine. Did you put new coper washers on the injectors when you installed them? I would also recheck all your injector feed and return lines.
 
Yes they was installed with new coppers and orings. Done pulled them several times and thru new coppers/rings on them and still leak some under a high load. It's not coming out of any of the lines. Coming up from the bore itself just as if they are lifting and letting fuel past the copper.
 
Fuel doesn't come out of the cylinder unless you have bigger issues. If you have fuel, it is leaking from the body of the injector or the lines.
 
I've had these injectors balanced And tested. Supposedly they say their perfect. Heads was just Gone thru and refreshed with new valves/seals, Hamilton springs etc. how could the lines be leaking? Doesn't leak anything unless under a load. When they leak it leaves a trace on the valve cover like its coming out of the bore from under the retainers. How else can u test it?
 
05MonsterDmax said:
I've had these injectors balanced And tested. Supposedly they say their perfect. Heads was just Gone thru and refreshed with new valves/seals, Hamilton springs etc. how could the lines be leaking? Doesn't leak anything unless under a load. When they leak it leaves a trace on the valve cover like its coming out of the bore from under the retainers. How else can u test it?
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If you don't have EFILive you could unplug your CP3 to raise your rail pressure and then check for leaks.
 
I'd triple check those lines. I know their has been a few times i've chased a leak only to find that a line needed some TLC to seal up right.

Unplug the FPR and get more rail pressure behind the injectors, you may be able to spot the leak at idle then.
 
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Will do. Not all of the injectors are leaking. Just a select few. Ill prolly command it with Efi vs unplugging as its a pita to get to my valley pump, top pump is easy though but both would have to be disconnected correct? And are y'all using any type if sealant on the compression line threads or just letting the compression seal by itself? I also didn't tq the lines, I righted them with a wrench but they are pretty dam tight. Ill pick up some end wrench adapters for my tq wrench and tq them, see wat happens
 
no sealant on the lines. You just gotta inspect the sealing surface on the lines and on the injector. Sometimes some crud will get in there and prevent it from sealing good.
 
Gotcha. Ill fool with tomorrow or possibly tonight after work and see if I can find anything cause I'm sure lost on it. I've never had a problem before when I studded that stock block a while back etc. but it wasn't dual pumped and all back then.
 
Sounds good, I'd just pull those lines off and clean the hell outta them. If you notice that they were dirty be sure to check the injector connection for a bunch of crap and make sure none went into the injector. Let us know what happens
 
When I installed them, I cleaned them with just a rag and cleaner. But I didn't polish the compression fitting or anything. Ill see what it does when I ramp the fuel pressure up at idle. Hopefully it'll tell me something.
 
Haven't had time to ramp rail pressure up at idle to see whats going on but I've been scratching my head all day. And here's wat over. When I first seal them injectors, their sealed. Once beat on of course they will seep fuel past them (what I'm assuming is past them) and after that every time I start it I hear compression blow by on start up. When I pulled them injectors I had a bunch of carbon buildup on the tip up the body? Seems to always be the back 2 on drivers side. Rest dnt leak any
 
you can just unhook the ground from your twin cp3 controller and it will run full rail with out unplugging the pump control wires.

are you sure you put the copper washers under the injectors? with out that washer the hold down bolt might get tight by bottoming out in the threads and the injector might not be sealing to the head. that could be why you hear a leak when you crank it over at start up, but when its running u probably dont hear it.
 
100% positive it's diesel. Bolt holes are clean and yes the copper is under it. Like I said I've resealed them prolly 4-5 different times and they won't stay down after beating on it. I'm off today so ima start messing with it in a minute. See what the deal is here cause its driving me nuts.
 
Make sure the hold down "pucks" on still there. These are the small flat pieces that are on the opposite side of the hold down on the valve cover. Without these the hold downs will not torque properly. We use studs or replace hold down bolts anytime we install injectors.
 
Platforms are there. After going to all new harder grade bolts every injector is holding besides 4 and 8. So its getting better considering the other day I was pissed off and gave it hell trying to get which ever ones was going to leak to leak. Ima reseal these 2 and see what happens.
 
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