2006BLKMegacab

I changed compressors in my 98 T800 in my sig, it was getting old and starting to leak so it was just time, however now after I got it changed out it builds air like it is supposed to, cuts out when it is supposed to, but when it looses a wee bit of pressure (down to 110-112 psi) it sounds like i have a good size air leak under the hood that last approx 2 or 3 seconds, then it stops making funny noises and then a couple seconds later the compressor cuts in and runs up to 120-125 psi where it cuts out again. I dont know whats causing the air leak sound im hearing or where its coming from because i cant get it to duplicate these issues when its sitting still..... I will try it later today at 1200 or 1300 rpm to see if it will do it again for me, I didnt change the Governor or pressure relief valve when i did the compressor.... unsure what to try over the weekend but i will try to diagnose and fix on tuesday..........

Any suggestions?

Thanks guys

Pirate

any chance it could be an automatic blow off to help exhaust moisture from the tank?

2006BLKMegacab

at this point in time I dont think its an air dryer issue but i will have a look, there is a check valve in the dryer that may or may not have anything to do with it haha

Hvytrkmech

Could be the governor, they are less than $30.00 here. It could also be a lazy discharge on the air dryer. Let us know when you check it out later.

2006BLKMegacab

So how do I properly diagnose a lazy discharge? just listen to see if it keeps hissing longer than it should?

Hvytrkmech

Yes, with the engine running wait by the air dryer. When it spits or discharges see how long it takes to shut off. If it does not shut off immediately after discharging push up into the center of the discharge hole with you finger to reset the valve. If that works you can remove the lower valve assembly dismantle it on a bench the clean and lube it. Do you have a scew on filter on your air dryer? If so you should replace that as well.

2006BLKMegacab

It was hard to find because it was very faint at 8-900 rpm but at 1400 the lazy discharge became very noticeable...... im thinking it might just be an easier fix to just go get a reman air dryer because trying to push the valve up to reset it didnt help for some reason, and it is definitely the dryer that is discharging when it isnt supposed to be that drops the pressure and is causing the compressor to cut in early

2006BLKMegacab

Ok, I installed a new Reman Bendix Air dryer and governor (for the $18 i wasnt going to not do it anyway) and it still has a lazy discharge, when i push up on the valve to reset the old fashioned way it will stop but it seems to have the same discharge at approxametly 115 psi that the old dryer-governor combo had although this one is a lot shorter of an event and doesnt seem to cause the compressor to cut back in......going for a drive later tonight to see what happens at speed and will advise