I've got an old (1960) 495 cummins in a road grader. I'm wondering if the pt pump will run a "Thermostart" that Massey ferguson used on perkins engines.
Thermostart is a fuel injector/glowplug that blows hot (flaming!) fuel directly into the intake manifold. I have one on a perkins in my pickup, truck will start when it has absolutely no right to. The cummins should be plugged in when it gets much below freezing.
I think the pt pump on the cummins probably only puts up maybe 200 lbs, and the CAV pump on the perkins probably puts up a lot more, not sure how much goes to the thermostart. Wouldn't be tought to screw the thermostart into the cummins manifold.......
The thermostart is normally fed by gravity from the return line or from the transfer pump, it doesn't require much pressure. Some older perkins engines just had a small reservoir located high on the engine that the return line passed through, and kept full, on its way back to the tank. The thermostart line was tapped into the bottom of this reservoir. Later engines fed the thermostart from the mechanical transfer pump (likely 5-10psi). I've never seen one plumbed into the high pressure supply or the injection pump, and I would advise against it. The PT system pressure is variable depending on the position of your foot, but is always far too high for the thermostart.
I would rout the return line up to the top of the engine near the manifold and tap into it there for the thermostart, There should be enough residual pressure in the return line to feed it. If this doesn't provide enough fuel you may have to install a dedicated pump to feed it, since the cummins PT system doesn't use an external transfer pump.
Thanks! I thought about it for a while after I posted, and realized tthe one in my truck is hooked to the return at the fuel filter. Explains why I have to turn the engine over a little to feed some fuel to it!
The fuel tank on my grader is higher than the pump, might be high enough to be higher than the thermostart too. Have to take a look, maybe I can just feed it with the feed line, gravity? At least I know what I'm looking at now. Grader actually starts fairly well, but sometimes I need to plug it in, don't want to wait for it. Get home at 4:00 and want to clean the lane/yard before dark! :lol:
I seem to have problems getting into the board lately. Half the time it says I'm not logged in, so I can't post. Won't let me log in, but the next time I go back I'm alredy logged in. Problems on the board??
I would imagine a gravity feed from the tank would work, if you can tap into a source downstream of the filter. You don't want to fill your thermostart unit with gunk.
I've seen dual thermostarts used on 8.3 cummins engines, maybe that would be the "hot ticket" (pun intended
).
I would imagine a gravity feed from the tank would work, if you can tap into a source downstream of the filter. You don't want to fill your thermostart unit with gunk.
I've seen dual thermostarts used on 8.3 cummins engines, maybe that would be the "hot ticket" (pun intended ).
You could also use a cheap electric pump just to feed the preheater.
I'm using a cheap ($45) Facet fuel pump designed for carbureated gasoline engines on my truck on the main fuel line (since it doesn't have a lift pump at all, but I don't want to starve the injection pump if my filter starts clogging running biodiesel -- a few people have destroyed injector pumps on the 5.9 liter cummins when the lift pump failed and they didn't have a fuel pressure guage to detect it). I don't how well these hold up to biodiesel or diesel, but I'll see I guess.
Thanks guys, looks like a gravity feed from the tank would work if the tank was full, but not at 1/2 full. Think I'll get a buddy of mine to fabricate a little (4oz?) tank with 2 lines on the bottom, one on the top. Returns from the injectors and pump to the bottom, feed to the thermostart at the bottom, return to the tank at the top.
I knew the fuel pressure varied with throttle position, just picked 200 pounds as a maximum. I remember that a truck I once had was set at 180 lbs. This pump is a littel different than the truck pump, throttle shaft is off the back side of the pump, not the middle. Load governed as opposed to speed?
Also like the picture of an 8.3 with two. We have one at work (92 model grader) but starting is never an issue because it's parked in a heated shop. Had problems with coolant in the oil lately, after changing the head (gasket leak) and still finding coolant in the oil, thay elected to exchange the whole engine. New engine doesn't have the same grunt, but burns less fuel in a day. Hoping it will get better with some hours! Okay for grading, severely lacking pushing snow.