Guys, i have a 1986 terex 72-31BA wheel loader. 471 detroit with a bendix tuflow 500 compressor. Ive been having a problem where it will not build air at idle. Only once the engine is warmed up you have to floor it for a minute and hold in the maxi, and then only will it build air. Ive leak tested the system, replaced the governor, heated the machine in the shop and drained air tanks etc and i CANNOT get this machine to build air from the get go. Any ideas fellas??
I think you have issues with the compressor, most like the head removed at 1000 hrs. for carbon deposits and restriction by carbon deposits. Then at 3000 hrs. a full tare down to check wear and worn parts. This is something most will never do and we wait until it quits and or a engine rebuild and replace it at that time. I would think that discharge valve , inlet valve, unloader plunger, has some issues and more than likely will need a reman unit, it's hard to find these parts and most of the time the unit is about worn out. You could also have a discharge hose that the liner is bad, a check valve that is sticking not letting air go to the tank. By putting pressure on the air system with the engine not running it may not show a leak after the check to the compressor and with the engine running you may not hear it.
I'll agree with the above, my personal guess would be one of the inlet or outlet valves is broke. However I do have one question: Does it hold air with motor off once it does build up to the cut-out pressure? A samll air leak can make it very hard for a marginal compressor to keep up.
Carbon build up in the outlet hose will cause that, as will a sticking unloader plunger. Take off the air inlet, and see if both unloaders pistons are free to move, and that they are UP. #13 on page 5 here http://photo.mecaniqueindustrielle....gue_pieces_compresseurs_bendix_tu-flo_500.pdf They have a tendency to stick down on seasoned compressors. They should be up until, well, the compressor needs unloaded (cutoff pressure is achieved)
One thing i forgot to mention. the compressor was replaced with a reman unit about 500 hrs ago. I will take it completely off after this next storm to check it over for the things mentioned above.
One thing i forgot to mention. the compressor was replaced with a reman unit about 500 hrs ago. I will take it completely off after this next storm to check it over for the things mentioned above. It does hold air for about two days once the engine is off, so its pretty tight for a piece of equipment.
Before going any farther, remove the ENTIRE discharge hose assembly (first hose off the compressor, usually 5/8", but can be larger depending on application), and run a rod through it, or verify that it isn't plugged by any other means. That first hose out is a wear item, and should be changed EVERY time the compressor is replaced. Verify it or replace it. To further diagnose, with the discharge hose off the compressor, and the engine running (with the tank pressure below cutoff pressure), the compressor should make air. If not, remove the governor signal line (furthest from the adjustment cover). Now, it should make air without the ability to "govern". If that makes a difference, then the governor hoses are reversed.
As for the unloaders, they can be checked with just the air inlet cover off. No need to remove the whole compressor.
if it were me I`d be only pulling the compressor head off and replacing the flaps and seats and if it is holding air in the tanks my bet would be that there is a one way valve between the compressor and tanks
Bringing her in the shop today, let you know what i find!
Make your self an air fitting to hook shop air to compressor discharge hose and find air leak. Bob
Bingo Found it! When airing the tank up via the compressor discharge hose, i could hear air rushing on the other side of the machine. This only occurs with the maxi popped out. It is the power booster for the brakes bypassing and leaking the air out. None of this could be heard with the engine running, esp with a detroit under the hood. Parts are ordered and will finish her up next week!