Motor all apart, 225k, should I replace my injectors?

[73Elsinore]

Hi guys. '91 XLT 4x4 manual. I have my top end all apart to install new heads because both of the old ones were cracked. One was cracked through all three exh valve seats and the other head was cracked through two. Nice. Truck has 225,000 miles on it.

As a part of the rebuild, I was thinking about changing out the injectors but they *look* OK. The tips look OK, no damage or deposits. How do I tell if they are OK or worn out? Are they a wear item? The truck was running normally with no codes prior to my teraing it down.

New injectors are $160 each from F*rd... yikes...

Thanks guys!!!
Pete

 

[Creager]

If it was running fine prior to the rebuild, then you probably dont need to replace them. New o-rings should be all you need.

 

[73Elsinore]

Just to bring closure to this and to add a data point to the archives, here is what I did. I am a nerd about this sort of thing, so, bear with me.

I decided I would gamble the $20 per injector and have them inspected forst before springing for new or rebuilt injectors.

I took the injectors to a local diesel FI shop. They are a factory-authorized Bosch, Stanadyne, Delphi etc. shop. Anyway they also have a machine that does gas injectors: cleaning and flow testing. The machine is a Lucas. These are Ford injectors of course but I don't know who makes them for Ford; Delphi I think, but, not sure.

They first tested the injectors for pop, flowrate, and spray pattern. The tech said the injectors as-received were actually pretty clean, considering their age and mileage. All flowed 42-44 (I don't know the units but I bet they are cc/min - I forgot to ask) and the spray patterns were OK by visual inspection except for one which was kind of angling off toward the Joneses. Pressure in the fuel rail is 2.5 barg. The machine cycles the injectors from idle (simulated) up to 4000 rpm.

The injectors were then cleaned ultrasonically and flow-tested again, at which time the rates for all injectors went up 2 to 3 units, to 44-46. The spray pattern on the one funky injector was restored to normal after the cleaning.

They changed the o-rings and filters but not the plastic pintle cap because they couldn't get them. The tech said the caps were OK and didn't need to be replaced anyway.

All this for $169. The tech said the injectors were fine and were good to go, even though they are 16 years old and have 225k miles on them. Fuel used was reg unleaded, about 50-50 between Chevron and AM-PM rot-gut.