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Cat 340 line vibration

Rtharlan

Member
Had a pump fall to 200 psi a month ago. Put on a rebuilt head that was on the shelf. I however did not rebuild it. All seemed good. This morning half way through a bay wash it dropped to sbout 600 thrn started pulsing an vibrating the trough. I shut it off then back on. 1200psi but still vibrating.

checked all the valves. Swapped regulators and accumulators. Still vibrates but now its at 1000psi. Going to check the inlet check valve later. Does on all functions.

what is the priming procedure for a cat pump? I could not find anything when i swapped heads a month ago so i waited for it to pump itself up. Running it dry like that was probably not a good idea.
 
Hold the trigger and turn it on to a high pressure function, then turn it off and hold the trigger until flow completely stops. After 3 or 4 times it should be primed.

Bad regulators don't cause pulsation. Accumulators only smooth the normal "hum" through the lines of a properly working pump.

What does the thread title mean?
 
Hold the trigger and turn it on to a high pressure function, then turn it off and hold the trigger until flow completely stops. After 3 or 4 times it should be primed.

Bad regulators don't cause pulsation. Accumulators only smooth the normal "hum" through the lines of a properly working pump.

What does the thread title mean?

there basically the same pump.sorry for the confusion.
 
FWIW I've had a lot more trouble getting the 340 to prime than the 310, probably because of the shorter stroke. I used to take the valve cap off closest to the outlet used by the main outgoing flow and pulsing the pump on a few times. The trick I mentioned above works just as well.
 
Probably not, even if it wasn't fully primed it would still have some water in it to cool and lubricate the seals.
 
Im gonna go out on a limb an say it wiped the hp seals. Also found the crank case seals were wet with oil. I put a freshened up crank case on with new seals o-rings and copper washers and new wicks. Rebuilt head. And a rebuilt wand in the bay got rid of my vibration in the trough above. Sits at 1100psi with out the trigger pulled.
 

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Right but its a month old rebuild. I did not do the seal install. And this person is known for using used seals some times. Or it wasnt lubricated very well.
 
Water lubricates the seals, except for putting the head back on the pump. That seal has seen several years of use. That's normal wear. Unless you ran it for 10-15 minutes with NO water in it at all, you didn't do that.
 
Water lubricates the seals, except for putting the head back on the pump. That seal has seen several years of use. That's normal wear. Unless you ran it for 10-15 minutes with NO water in it at all, you didn't do that.
Interesting. Well maybe it was not a fresh rebuild when i installed it. Thanks for the tips. Greatly appreciated!!
 
Found that the failed head had a deep grove dug underneeth where the hp seal sits. Its still seems a little noisy at times. It comes an goes. Still a a light vibration in the line too. I also noticed the crank case i put on seems to generate a bit more heat than the others. Everything seemed great as far as the rods an plungers go.
 
The groove in the head is called "Wash Out" and needs to be either replaced with a new head or sent off to get repaired. A new seal will not seat correctly and fix wash out. There used to be a sticky thread on washed out heads, but can't find it now.
 
I have actually found it through google. I have emailed a place on getting sleeves done. In fact i have 3 other heads that need done now that i know what im looking for.
 
Here it is, in case anyone else wants to see it.

 
Is this normal? Theres a slight burble or “misfire” if you will. If you cant hear it. You can see it on the guage. Its done this since i installed the new crank case and head. It was worse,it seemed to have an air leak at the soap inlet nipple, installed new check valve an tightened the hose on the nipple.

 
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It's not normal, it's most likely air. Does the system have city-pressure water to the pump on rinse? If it does and it still has that loss of pressure, it's probably something floating around in one of the pump's valves.
 
It's not normal, it's most likely air. Does the system have city-pressure water to the pump on rinse? If it does and it still has that loss of pressure, it's probably something floating around in one of the pump's valves.

Forgive me here im learning. It has hot and cold going in to a tank on back of pump stand from city water press. So i assume its gravity fed. So i guess ill pull the valves and inspect.
 
It's more likely to be an air leak. It can pull air through the low pressure seals - did they look new on the head you installed, or did you replace them? Is there any water dripping from between the head and crankcase?
 
It's more likely to be an air leak. It can pull air through the low pressure seals - did they look new on the head you installed, or did you replace them? Is there any water dripping from between the head and crankcase?

they were brand new. No water dripping.
 
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