1991 Injectors

[TeeRoy]

Hello All... New to site and owning a diesel.



My 1991 W350 has 216,000 miles on it and after reviewing threads on this site and computing fuel mileage (15-16mpg, . 307, 35in tires, 747) it seems it might be time for new injectors.

1. As with everyone else I do enjoy extra hp/torque, however longevity it also a concern. Should I use stock injectors or what is the make/part number of an injector that works nicely with this year of engine without sacrificing durability and drivability?



2. What is the B50 life of this engine?



Thank you and great site…. Troy

 

[BushWakr - RIP]

Hey there... welcome to the group... the only dumb question is the one you DON'T ask... so have at 'er. .



The answer to your question will depend on whether you have a 91 or a 91. 5 model... the latter is an intercooled engine/truck... . if that is your truck then you can go with a nice upgrade injector like the "190" injector.

If you have an early 91 (89-91. 5) then you already have a near equivalent injector to the 190's... in fact they are what has/is known as the 185 hp injector.

If you are going to have your injectors re&re'd then have them flowed/balanced and have the pop-off pressure raised to about 165 bar.



The average life of an engine in our application will depend on how far and hard you push these things... if you stay relatively stock or near it then you can figure an average life of 300K-500K miles... . assuming you use a good service schedule and good quality fluids/belts/hoses.

Always try to run an additive with your fuel as well. The injection pumps on our trucks are lubed and cooled by fuel only so even thought the "engine" doesn't "need" an additive the pump will thank you over the long haul.



Look for an additive that gives you some cetane improvers, lubricity and, detergent properties. These will pretty much address all the basic needs with the only exception being winter time... if you have cold weather then you'll need something to compensate for the cold weather.



pb... . Our Lady Of Acceleration Church ...

 

[TeeRoy]

Pastor Bob: Your knowledge on the subject of Dodge/Cummins becomes obvious when reviewing threads throughout the site and I GREATLY appreciated you sharing it... My truck is an early '91... . perhaps my wife will purchase the injectors for my B-Day. Thanks again.

 

[BushWakr - RIP]

Hey TeeRoy,,,,... . this is a team sport and you're now on the list to help the next guy out when/were you can bud. .



pb...

 

[JLEONARD]

TeeRoy,

Just do yourself a favor and do NOT buy regular stock replacements. They will have the 9mm dia body. The newer ones and all the upgrades are 7mm body and they will fit with the use of the special adapters that are a combination of a sealing washer and a bushing to make up the dia difference (they look like a "top hat").

Then if you ever have to replace your (engine's) head with a modern one thathas the 7mm holes, the injectors will be usable.

Jay

 

[RWWinslow]

When I replaced my injectors on my early 91, I could not purchase the 9mm - only the 7mm were available. Worked fine - no problem. As far as engine longevity, the first 6B5. 9T's were backfitted into Fords, Dodges, and Chevrolets in the mid-80's by several Cummins shops in the West. Specifically, the Gillette, WY shop performed hundreds of these backfits. There B50's for this region of the country were typically:

1) 500K for the fuel injector pump.

2) 1 Million for the engine.

Alternators were non specific - variable life spans. Water pumps and most other auxiliaries typically lasted one million miles.



Remember that this service was typically in the Western US and involved a lot of long distance highway driving. Plugging in the engine heater at temperatures below 32F will typically add a lot of life. Pre-lubing the engine (spinning the engine over with the starter with the fuel injector pump solenoid disconnected until oil pressure shows on the gauges) if the engine has not run for longer than 72 hours will also significantly reduce engine wear and promote longer life. (Engine pre-lubing was recommended by Cummins Service engineers in the 1980's)



It is interesting that this Cummins backfit effort was done to show the feasibility of the Cummins 6BT5. 9 in the heavy pickup truck application. It was very popular with ranchers and mine owners in this section of the country.

 

[BushWakr - RIP]

If you adapt the 185's or the 190's in an early truck, you'll end up with what is, in essence, a set of injectors that perform almost identically to the original ones... .



pb,

 

[TKingsbury]

If you are worried about fuel mileage, try to go down a tire size. I had the 35s on my truck and got about 16. I put the stockers back on (same diameter as a 33") and my mileage is 18. I noticed the truck cruises easier with lower boost and EGTs, this tells me the truck isn't working as hard with the shorter tires. Just thought I'd pass this info on. I've talked to others who have had the same experience.

Travis. .

 

[RWWinslow]

Bushwkr is correct - I did not notice any difference in performance with the injectors and fuel economy did not change - 20 mpg average.