Rotary injection pumps

[wmachovina]

anyone with opinions on the 250 cummins w the rotary fuel injection pump?? Got a lead and I'm getting some advice=like don't do it. Bill

[Harry Babb]

I don't think there is anything wrong with a rotary injection pump.....been in use for years and years.

Personally I do not know the particulars about why a manufacturer would use a rotary pump vs an inline pump......

I have a forklift, a tractor and a backhoe all with the rotary pumps.....no problem......I think Doug and Steve Z both run the rotary pumps on their Cummins boat engines.....may be they will chime in here.

Harry

[wmachovina]

guess my question relates to the 250 cummins- one of the mechs said in the low horsepower it was ok, but the 250 with that pump had problems producing the pressure and volume thats why they went to the nippo and bosch pumps.

[Bruce]

Stanadyne is a big manufacturer of rotary injection pumps and yes they have issues pushing high volumes of fuel needed for higher HP stuff. The design does not allow for cc volume.

They have hugh failure issues with water in the fuel and also the plungers sticking from lack of use.

When I've seen them fail, they fail big time as in not rebuildable.

I've got a 3 cylinder on order from Stanadyne right now for an Onan gen set that has to be built at a cost of 1400 bucks.

The shaft broke at the plungers due to water in the fuel.

[Capt. DQ]

There have been upgrade conversions for the Lucas injection pumps for the early 250's buy replacing them with the Bosch's, but very expensive to convert and get it right. But as Bruce said, totally correct. Being water in the fuel will destory the pump as fast as you can say rubber-baby -buggy-bumpers. But also have it calibrated for the correct CPL # or hp rating of your Cummins.

They usually worked very well for the 210hp Cummins, but as the saying goes ( A Bridge to Far) for hp of the early 250's, but did have some problems in volume if not calibrated right, but if its done right to begin with, no problems as long as you keep your filtration clean on your fuel clean, your ok. Thats why I used Tony Athens Multi-Stage Filtration 30m/10m filters before the engine fuel filter to make sure that doesn't happen, plus Algae-X units on each motor, which to some is considered voodo medcine.

But as far as the 89 model 250hp 6bta Cummins I have in my boat I would not change what I have for anything else, they are real workhorses like a timex watch which are very well proven and UV will back me up for that comment.


DQ

[bob lico]

honestly after all these years i have the algae-x in the boat i can say it is positively helping.those cummin start up in a quarter turn winter/summer with no smoke . a tiny white vapor at start in temperature 40 degrees or less.boat runs at 30mph at 2000 rpm with clean bottom.you tell me!!!

[Capt. DQ]

Bob,

I agree with you 100% about Algae-X units because I have hardly no smoke when I first start-em up and no smoke at all running after the temps come up to normal. So Voodo or not they work for me.

DQ

[In Memory of Vicroy]

My 6BTA 250s (CPL 1247) were built in November, 1989 and have been virtually trouble free for some 3,000 hours. I installed the Algae X units in 2000 and after about 50 hours of use began to notice a remarkable reduction in smoke, and a 7-10% increase in fuel economy. The more you use the boat and circulate the fuel, the better they will clean up the fuel system. I've put very few hours on mine since Katrina in 2005 and the fuel is pretty dirty again, so I get a good bit of blue smoke on cold start-up. I have engine heaters on a thermostat that kick on at about 55 degrees that help a lot in cold starts, but it has not been below about 65 here since last winter.

I had trouble with one injector pump that was probably due to my own neglect in not changing out the engine mounted spin on fuel filter when I should have, thus letting some crud get in the pump. A rebuilt on the pump was about $600. The 250s (and the later 270s) are very fine engines and just right for the B31. They have the added advantage of the fresh water cooled aftercooler that eliminates the high maintaince needed to keep up the sea water cooled coolers on the 300+ hp 6BTAs.

A very tight, air-leak free fuel system is essential to these engines performing well....any tiny suction leak will cause hard starting. with a tight fuel system they will start instantly no matter how long they have laid up.

Very fine engines, about as bullet proof as they get.

UV

[Harry Babb]

Algae X units.......do you guys install just one or is it necessary to put one on each engine.

Harry

[In Memory of Vicroy]

One on each engine. The best way to install them is to use the 500 series - fine for your hp - and hard-plumb them to the intake side of your Racors. The 500 has 1/2" FPT ports on each side and if you get the right fitting, i.e. 1/2 MPT on one end and the correct SAE on the other for the Racor you can screw it right into the Racor....then use a similar fitting on the hose and screw it into the other side of the Racor....I did mine using just two fittings per side and no cutting of hoses at all.

Just make sure you get the Algae X with the 1/2" ports so you have enough beef in the fittings to support it...and mount it with the curved side up......easy to do, and you never have to touch them again, no maintaince at all.....like most snake oil things....

Actually I had one of my patent atty. partners check out the technology of passing a fluid thru a magnetic field to see if it was for real and it is...the first patents were issued in the 1800s and used in hot water systems to reduce particulate fouling.

UV

[wmachovina]

Well ,bit the bullit and a pair of 700 hr. lake Erie 250 cummins are enroute to Seachele for a Jan date with the yard. I've got a couple questions ,like can I change out the gears in a 220a from 2to1 to a 11/2 to 1, or will the 2to1 work with a bigger prop. Also gonna put the gassers onsite soon, good running new manifolded 454 1200hr gassers.The 250s seem to be a good mix of fuel efficency and performance. By the way the post was locked Capt Pat, but on the way,Bill

[In Memory of Vicroy]

Because the 6BTAs are low speed engines, seems all of us have used 1.5 gears. I'm swinging 21 x 22 three blades and doubt you can swing anything bigger.....so if you keep the 2:1 gears you would have to go up in pitcdh to maybe 24 or 25 and I personally like to keep the props as "square" as possible. Because new 220As can be had for uncer $3k I wonder if changing rations and the associated labor and parts would be worth it. If it were me I'd make a call to Tony Athens and get his views - shoot, maybe changing ratios is not that big a deal.

You won't go wrong with the engines - prop them to turn 2650WOT with a full load on board, cruise them at 2400, keep rust off them, and they will be running when you go room temp.....I'd invest a few bucks in the S&B air filters that are permanant vs. the crappy stock paper ones & you can get them from Tony, as I recall they are about $75 each. When you get the engines look at the Sherwood raw water pumps and if they have not been rebuilt with Tony's aftermarket parts, do so at once. These pumps are probably the only weak link in the engines and Tony's stuff fixes that cheap and good.

Another weak point are the two small parallel tubes on the back of the ZF 220A gears - a couple of inches long and on the upper port side of the back of the gear that carry high pressure oil to the shifting mechanism...they are made from hi carbor steel and will rust & get pin holes in them if not cleaned and painted, and kept doused with Corrosion X. They are a bitch to get at and change too, something you don't want to try offshore. They are held in with a banjo type clamp and one allen head machine screw and have o-rings on the ends as I recall....they cost next to nothing and are easy to change if the gears on sitting on the floor....examine yours with a magnifying glass and if they have ANY rust on them, change them now and paint them with something good like hi zinc primer and a good coat of enamel, then use your HD CX on them. I wore the ZF people out at the FLL shows several years in a row about why the hell they didn't just make them out of stainless, bronze, etc like everything else on the gear but no, they insist on hi carbon steel to save a dime.....also, keep the shift lever on the gear shot good with CX to prevent rust and keep the detent ball under it from seizing up.

Overall a real good trouble-free engine/gear combo for the B31.

UV

[Capt. DQ]

UV is dead on with his comments, I have the same engines as UV and the 1:5.1 ratio is the best combo with the 250's.

As UV said the Sherwood pumps would be the first thing to change parts out with Tony's aftermarket parts. DO NOT WASTE your money on Sherwood parts like impellers and so on.

The next thing I would suggest, Tony recommends, would be to change out the banjo fitting from the turbo from 3/4" to 1" on the turbo and also the fitting on the back left hand side of the head to 1" and also on the front right upper side on the head to 1" down to the lower front right side also is a upgrade on fitting. Brass or bronze will work find. You should be able to see from this photo.

[img][img]http://i145.photobucket.com/albums/r210 ... G_0046.jpg[/img][/img]

Good Luck, as you will soon find out, this combo is a very nice set up. UV also mention the fresh water aftercooler is another great feature.

DQ

[Tony Meola]

UV is right on the props 21 inch is about as big as you can go. On the 270's I just installed we put on 20x23 with a slight cup and turn 2700. Will be tweeking them with a little more cup this winter to try and get them down closer to 2600.

On the transmissions, the shop I used changed the fittings on the hoses to bronze/brass, to eliminate the problems UV notes.