Porpoising on rough road

[Gary Wolfer]

I am new to air suspension and am experiencing a lot of what I call porpoising. The lower needle on my air gage moves back and forth from 100# to 110# and the higher gage moves back and forth from 110# to 120# at the same time. Could I have a leak and if so how do I check it? Is it normal for the air pressure gage to move back and forth like that? and can that cause the porpoising?

[Keith Moffett]

Spray bottle with warm water and a few drops of Dawn dish soap.  Slowly spray all lines.
Took me two years to find our leak.  All the little ones like around the air tanks by the air filter canister and so on were simple.  The tough one was the control valve for the slide floor (step cover).  This was under the hood below the windshields on the passanger side.  There was a small electric selenoid attached t air 'T'.  The inside corner of the 'T' had cracked.  I bought a new one from Larry in parts at BCS.  
Air leaks mean slower recovery time to the suspension when driving and makes porpoising more of a problem.
Keith

[Gerald Farris]

Gary,
If your air gauges are moving when you are not using air from brake applications or a similar activity, you have a leak that needs to be fixed. However, the problem of porpoising is usually caused by weak or defective shocks, because the response time for the air suspension is to slow to cause or correct the condition. Also, short coaches seem to be more effected by this problem than the 40 to 45 foot models.  

Gerald

[Gary Wolfer]

Thank you both. Keith when you mentioned the sliding floor over the steps it rang a bell. The sliding floor seems to be sticking sometimes it will not come out the last week or two. I will look under the hood for the T I appreciate it. Gerald I noticed when the air pressure is at its highest and I hit a roller coaster in the road it is not  as bad as when it is down 10 pounds. I will use the dish detergent and water but am kinda afraid to get under fortunately I do have a couple 30 ton jacks and the box tube under the shocks is a good place to set the jacks. I have been working on lots of problems with this coach this week I took the coach into ITR in Vancouver and let Kevin check it out. First the fan in the hurricane had a bad bearing then the water pump that moves the water thru the coach was not pushing water fast enough and the fuel nozzle was replaced because it was stamped 1998. After we got it back together the hoses were not geting warm enough and the flame in the burner was weak. He put a pressure tester in line and it was only holding 2 psi and it needed to be 5 or 6 so we opted to tear it all out and install a new recon unit at the cost of 2,200. plus a water pump and upgraded the circuit board in the service panel. Total was almost 2800.00 but it is all new now. I had to replace all the 3 way valves in the water bay already but still trying to put the wall back in as the new valves are longer than the original ones and will not line up with the holes in the panel.At least it is not leaking anymore, It has been a challenge but I am getting there.