Changing Valve Springs for PacBrake

[dremelts]

Just ordered my PacBrake this afternoon from Truck Parts East. I also ordered the valve springs.



Can anyone recommend a tool for compressing the valve springs? The Snap-On site has one that has a knob on the top for compressing the spring, or is the lever style better. Either way it has to be able to function in the confined space under the cowl on the rear cylinders.



One post that I found in the archives recommended changing the intake springs also - I guess just so that they are all the same age? Any recommendations on that? (I have just over 100k on the truck, bought it used so don't know exactly what has been done in the past)



Also, with that many miles on it should the valve stem seals be changed while I've got the springs off?



Thanks for any input - I don't know what I'd do without the TDR.

 

[Don M]

The valve seals seem to last a long time. I would not change them if they are not leaking.



I would do all the springs together. Get ready to cuss and spit. It aint easy to do. KD makes a little tool that is ok for doing them.

It has the lever and a bolt to replace the lever for use under the cowl or tight spots. The 60 lb springs are longer than the 30's and are more difficult to get in the compressor.



Im sure you know this, but adjust the lash after you are done. The valve cover gaskets seem to be able to continue longer as well. They are a good grade of rubber/silicon? and can usually be reused.



Good luck and get ready to spend a few hours cussin.



Don~

 

[BFaoro]

change

I changed mine out. I used the spring compressor from NAPA. It cost like $35 . It was the one with the knob on top. I didn't have any trouble changing the springs on 4,5, and 6. was fun but doable. A good word or two seemed to help :-{}

 

[LarryB]

If you are only adding a brake then doing just the exhaust should be fine. Stronger exhaust springs allow you to run a higher back pressure for more braking without danger of blowing the exhaust valve open. That would be a bad thing if the valve collided with the piston.



The only reason to do the intakes is for the govorner spring kit that allows higher revs. Stronger springs on both help prevent any chance of valve float. Valve float is when the valves do not have enough time to snap closed before the cam lobe comes around again.

 

[MLee]

Re; valve springs

When i done mine i went to checker auto and got the KD tool they rent them ---FREE. unless they have changed policy, there is room for the tool on 5&6. get a good screw driver with a 90* on the shaft for the 5&6, blade large enough to fit SNUG in the slot for the adjustment, i used the twin 90* and the blade is thin, hard to hold. these are the time consuming adjustments. my pennys worth.

Marv.

 

[QRTRHRS]

Once you get your valve spring tool, do this. Take one of your 60 lb springs and compress it. Being larger, your going to need to just about squeeze it shut. If it pops out of the tool, don't even go there, find a tool that works.



Get yourself set up to spend a lot of time laying across the top of the motor. So have something to lay on handy.



Noting you have 100k, it may not hurt to pick up a set of six valve cover gaskets and o-rings for the bolts. The valve cover gaskets, like Don M said last but those little o-rings and I forget the size will be shot.



Enjoy your brake, I use mine constantly.

 

[dremelts]

Thanks for the replies everyone. I'll probably leave the intake springs alone, unless it's necessary to replace the valve seals. How would I know if they are leaking?



I've never been inside the valve cover of the Cummins so I don't even know what kind of valve seals they use. On the gassers that I've done in the past they usually had a little umbrella type thing that fit tight on the valve stem and then pressed over the valve guide boss. If they felt hard and brittle I'd replace them. Are we talking the same kind of seals on the Cummins?

 

[Big John]

Dremelts, I did the same job a few months ago and wrote several posts on it. Try a search on Big John and see what was said. The collets you are talking of are like you described. They come in two halves. Keep the engine covered with a rag to keep from loosing one down the push rod holes.



The new gaskets and o-rings are a good idea, since you are there already.



Good luck

 

[LarryB]

Does it use a lot of oil. Usually bad valve seals allow oil to pass the guide and enter the cumbustion chamber or exhaust and the oil is lost. If you are not adding oil between changes then most likely the seals are fine. If you are adding oil, it doesn't nessasarily mean it's the seals. I've seen more problems with improperly installed seals than worn seals. I would leave them alone unless you know there is a problem with them.



Free advise is worth every penny!