Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 15, 2025 ...

UPDATE: Got a call back from James today. He apologized for not calling back he was out doing a delivery and the message to call me fell thru the cracks. He helped me with my issue (air dryer continuously popping off) and at the end of the call ribbed me about no shocks on the active air statement I made above. Per James there are no Foretravels without shocks. I was basing my statement on a active air front end I'd seen during a factory tour. I also feel I had some obligation to call back when I didn't get a prompt response. I was juggling several projects and didn't get back to this issue till it was time to leave and since I was headed to FOT decided to just ask once I got here. So as far as I'm concerned all is forgiven. Apparently they are reading the forum since that was how he found out about my call.

see ya
ken

I have had an ongoing issue with the air dryer popping off about every 5 to 7 minutes while at idle... Is that what you are experiencing? What suggestions did James have for you?

Don,

Is the air compressor cycling along with the dryer?  Do you have a pressure gauge on your wet tank?  If yes, does the wet tank pressure go up and down in concert with the compressor operation?

Don,
There are a lot of Internet posts on this topic of rapid cycling. From what I can see it can be several different causes, need a dryer rebuild to a leak in the air control line from the governor.

I had my AD-4 dryer in for routine service and was told it is obsolete and parts hard to find. I upgraded to the AD-9. Cost was $800, new dryer $280, labor $520.

The Holset air compressor used in our coach (I think they went to a different compressor in 2000), requires what is called an isolation valve
 I put in a new one and it didn't make any difference.

Don,

Please clarify,  your coach should have came equipped with a Pure Air Plus, is this what you have now or has it been changed to an AD-9?  Even though they do  the same thing (drying air) they are made and operate differently.

Pamela & Mike

I would bet on the check valve at the air dryer.  The compress will come on, until it get the signal to cut off. Once it is cut off the air bleeds back thru the check valve, lowers pressure and it all starts again.  When I had this problem the pressure gauge at the dash stayed close to the full mark all the time.

@Don,

Already a lot of good suggestions here. James says there is a piston(?) involved in the pop off process at the dryer that can fail and cause fast pop offs. I asked if that part was replaced during a rebuild. He said no (don't know if this only applies to the Haldex). I had previously talked to Alton who thought it might be an air leak in the line to the dryer or wet tank. He said he pulls the line from the dryer, puts air pressure on the line with a compressor, and uses a gauge to check leak down. He must have a custom adaptor to do this. Would not be hard to make one....
EDIT: I did change out my D2. It didn't help.

see ya
ken

Don,
When you get back to this project look at the line on the isolation valve that should be tagged 60.  It is the 1/4" black nylon line that comes off the isolation valve and disappears up the frame rail.  This line terminates on the wet tank.  Drain the air from the wet tank and  remove this line from the fitting on the wet tank end.  Now remove the fitting itself.  This fitting should be a check valve/fitting combo.  Make sure the spring isn't broke or full of rust as this will cause the isolation valve to stay open.

Pamela & Mike

1. Are you referring to the main check valve on the wet tank (I thought there was just one)?
2.  Is there another one that is just on the isolator line? If so, that sounds like an excellent candidate to be the trouble maker!