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CAT 310 rebuild.

lighthousecarwash

lighthousecarwash

Active member
I've been paying someone to rebuild my pumps when they have began to pulsate. I ordered a video from CAT and hope to start servicing them myself. I see that there are a couple special tools that are required, but I wanted to know how I determine what seal kits I will be needing. Should I just do a full kit on the head when I tear it apart, or can you just do partial kits? The only time I have had the guy fix mine is when they first start to pulsate and he pulled the plugs and found that a couple of the o-rings were missing. He found some old ones in his toolbox and installed them. Seemed to fix the issue, but I was wanting to start putting a kit in them once a year as more of a preventive measure. Would this be a good idea or just a waste of time and money? Any comments or suggestions would be appreciated.


Thanks,
Lighthouse.
 
IMO, a seal kit every year is a waste of money. A 310 will usually run several years before it starts pulsating unless you have another issue causing problems, namely cavitation. As soon as you feel the slightest pulsation you need to get on it or the head may be ruined.

You should keep on hand a seal kit, complete set of valve o-rings (they really should be with the kit, but they aren't), and a couple of extra valves. The valves seldom give trouble, but they also pop apart sometimes and you may lose a part out of one.

Regarding special tools, all I ever needed was the seal case removal tool. I think MEP said he made one out of a piece of flat bar, which probably wouldn't be too hard. Anyone that has ever removed valves has had one come apart and leave the bottom stuck in the head. I always just clamped a nail in a pair of Vise-Grips and used the head under the valve lip to yank it out.

These pumps are not complicated to work on. Don't be intimidated, you can do it. Most operators have a spare pump, you should too. If you get into trouble you can swap out the pump and come here and we will bail you out.
 
If it’s not broke don’t fix it. I haven’t replaced a seal kit on my pumps in over 5 years and God only knows when the last time I replaced a valve. The only special tool I have is the Seal Case Socket Kleen-Rite #PU33004. Always use a complete seal kit when you change seals, the seal kit is #PU30623. I have an old gentleman who will replace one seal at a time or valve, toss the new unused seals into a can of old seals so they all get mixed together. His pumps are terrible, low pressure, pulse etc. The biggest thing you want to watch for is “Head washout” When the pump begins to pulse you want to get on it right away so you don’t damage the head. Get yourself a Seal case socket and keep a spare seal kit and a valve kit #PU30821 on hand.
 
Yes, I still use a flat pry bar (aka "Wonderbar") on the 310 seal case. The seal case socket gets worn quickly and after a while will round off a perfectly good seal case. I've never damaged one with the Wonderbar that wasn't already so bad it needed to be replaced. I also keep a large screw extractor on hand to remove them if they're stuck so badly the brass just breaks, but that shouldn't usually be a problem if they aren't overtightened. The valves themselves don't need to be replaced, but the o-rings and backup rings should get replaced at least as often as the seals. At the first sign of pulsation or loss of pressure, change the valve seals, then if it's not smooth pull the manifold.
 
Well, today was the big day. I took the PC to the car wash and watched the CAT video before pulling the plugs on the pump. I found all 3 of the o-rings on the top valves were cracked and had some chunks missing. The lower valves looked like they were not far behind so I replaced all 6 valves. I think the next time I put in an order, I will skip the valves and just get the o-rings and backup rings as that seems to be the biggest issue. I did not pull the head, but was wandering if I should have. What problems would I be looking for to pull the head and replace the seals? The valves cleared the pulsation up so I decided it was good to go. Also, when the valves were out, I was looking at the brass seats in the head. Some of them seemed to not have as much bevel on them as the others. Is this what you mean by washed out? Is there any way to fix this or just replace the head?


I was surprised at how easy it was and how few parts there are to work with on the valves. Glad I decided to tackle it myself. Thanks for everyone's help.


Lighthouse.
 
You really need to pull the valves back out and check the bores. There may very likely be a groove eaten in the mating surface adjacent to that broken o-ring. Go check out the "sticky" thread about 310 manifolds. I think it is in the "general" section.
 
I.B. is right - if it's been pulsating for long there could be some erosion in the valve seat area. You'll know for sure if the new valves' o-rings fail in a few weeks.
 
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