Perkins 4108 Injectors - refitting

[neil1967]

My Perkins 4108 used to vibrate worryingly at idle, but was fine above about 1200-1400 RPM. I decided to have the injectors tested and found that 2 were down on pressure and 2 only dribbled fuel, so I had them refurbished. Unfortunately I have now come to refit them and I have a problem. When I removed the injectors I noticed that 4 of the bolts were longer than the other 4 (34mm and 27mm respectively). The long bolts now appear too long - they become tight to turn before the injector is properly tightened. When I removed the injectors they were tightly fitted (even without the bolts), so I did not notice a problem. I would welcome any advice - should I just fit shorter bolts, or am I doing something wrong?

Thanks

Neil

 

[essexboy]

The problem is that they should be. Studs not bolts ! One and a half long x five sixteenths NF ( short end into head)

 

[rich]

+1

 

[neil1967]

Ah! That would explain it. Some of the previous owners maintenance is a bit suspect, so I am not entirely surprised. Many thanks for both your prompt replies.

Neil

 

[AndrewB]

It should be OK though to substitute them with bolts ... but not too long of course. Maybe there was a washer on top you've forgotten?

PS make sure the seating is nice and clean before replacing, and use new olives. The collar on each injector will only fit one way round, be careful about this as they might appear to fit both ways, but one way the collar will not tighten the injector down properly as it fouls on the head studs.