'99 dt466e with air brakes, has constant low pressure alarm and slow pressure build.

[laegion]

Originally Posted by Brad_SwiftFur

Air systems are pretty durable and reliable. Air pressure gauges rarely fail, since even on the IH buses, they are mechanical, not electronic (at least all the ones I've seen are.)
If you're showing over 60-80 PSI and getting a low air alarm, I would check/replace the pressure sensor which turns the alarm on/off at the 60 PSI range.

That's what I'm thinking too. I wouldn't have driven it the rest of the way home otherwise. I actually stopped at a rest stop shortly after the alarm went constant and did the airbrake test as in the video I posed earlier and it passed everything except of course the constant alarm and the recharge time. Maybe he's off on that part?
However judging from the gauge and when I would see it recharge while driving (any time it dropped below 100psi) when it purged (around 115-120psi) and when the emergency brake engaged during the test (about 30psi) the gauge seems to be mostly working. My only concern is that the two needles don't ever seem to change their distance from each other.

I think you're right and the sender is bad or even leaking itself.

The funny thing is that the tone of the alarm changes as if the resistance is changing in the sender; but not quite enough to turn off the alarm. When the gauge gets over 60, sometimes it almost goes off...but not quite, and then gets louder again.

[laegion]

Originally Posted by Simplicity

Welcome. Where in Washington are you? I'm in Auburn.



Here's a good video:

I'm in South Eastern Washington. I drove this thing from Spokane to about 170miles south of there.

I'm watching this video and it literally looks identical to my bus. So my Wet Tank, Primary, and Secondary are all in that one large tank...hmmm...great video except the upload quality is awful.

[cadillackid]

on international the low air alarm device is connected at the compressor and senses wet-tank pressure.. the dashboard gauges show the primary and secondary tank pressures..



the air comes from the compressor to the air dryer and from the dryer into the wet tank, from the wet tank it feeds into the primary and secondary tanks..



if the check-valve in the air dryer is failing then when the governer kicks off and the purge occurs the wet tank pressure drains down quickly.. sometimes triggering the low air alarm before the compressor and get kicked back in again.. a symptom of this is the dash gauges staying at or near 120 all the time and seemingly frequent air purges (SSSHH sound).



the low air buzzer sensor is a single wire sensor .. if the wire gets grounded then it will go off so a chaffed wire or burning against exhaust pipe or the sensor itself damaged that can cause the wire to intermittently shirt will trigger the low air alarm sound on the dashboard.



if the unloader in the comoressor fails to cut back in when the governer calls for it the wet tank air typically backs out into the compressor and may trigger the low air alarm before it gets going again.



wet tank pressure triggers the low air alarm, wet tank pressure is not shown on the dash gauges..



-Christopher

[laegion]

Originally Posted by cadillackid

on international the low air alarm device is connected at the compressor and senses wet-tank pressure.. the dashboard gauges show the primary and secondary tank pressures..



the air comes from the compressor to the air dryer and from the dryer into the wet tank, from the wet tank it feeds into the primary and secondary tanks..



if the check-valve in the air dryer is failing then when the governer kicks off and the purge occurs the wet tank pressure drains down quickly.. sometimes triggering the low air alarm before the compressor and get kicked back in again.. a symptom of this is the dash gauges staying at or near 120 all the time and seemingly frequent air purges (SSSHH sound).



the low air buzzer sensor is a single wire sensor .. if the wire gets grounded then it will go off so a chaffed wire or burning against exhaust pipe or the sensor itself damaged that can cause the wire to intermittently shirt will trigger the low air alarm sound on the dashboard.



if the unloader in the comoressor fails to cut back in when the governer calls for it the wet tank air typically backs out into the compressor and may trigger the low air alarm before it gets going again.



wet tank pressure triggers the low air alarm, wet tank pressure is not shown on the dash gauges..



-Christopher

Judging from your description, I'd say it's either a faulty air pressure alarm sender or a short in the sender's circuit. I didn't hear frequent purges, and the alarm is absolutely constant, however I do hear a little variation in tone which leads me to believe the resistance in the circuit is changing slightly ( I assume it's an on/off sender that grounds the circuit when there's low pressure, like the low oil pressure sender on most cars). Granted I'm not used to air brakes but the only time I heard anything was when my tanks dropped below 100 and the compressor recharged the tanks to 120, or when I actually used the brakes.

It seems it should be easy to tell. If I disconnect the wire from the sender and the alarm continues when pressure is good...then it's a short. lol If not, then replace the sender and see if that fixes it. If not then I need to take apart my air dryer and figure out what needs replacing.

Thanks for the insight into the logic of the system, it helps me a lot. I probably should take the air dryer off and service and clean it anyway it seems.

What's your opinion on recharge time? is 5 or so minutes from 20psi to 120psi while holding 1500rpms too slow?

[Mountain Gnome]

I just replaced my compressor. Reading your post makes me think the cylinder ring in yours is wearing out. That makes it pump oil. Mine get's its oil from a dedicated supply line. That is why you have oil on your wet tank. The instructions for installation said if you are pumping oil, you should think about replacing the air line from the compressor - the oil hardens to carbon-gunk with time/heat/pressure and can clog lines.


The clogs can reduce you pressure build-up time, as well as the compressor itself being worn out. I think it is the charge time (several minutes) that is the tell-tail evidence of a worn compressor.



What caddilackid said about the check valve may also be caused by the oil-gunk??? I think checking the condition of the filter/drier for oil will help tell you.


And yes, I think your alarm needs to be replaced, or the circuitry for it fixed.


Perhaps the circuitry for the gauges is a just a bit corroded giving a difference in reading, or maybe you need new gauges. That is confusing me a bit. I have a "digital" gauge set on my dash; it shows "bars", not exact pressure, but they can be 1 bar apart, until they are both full, then the bars become equal.

[cadillackid]

Recharge time varies on each bus. Like my dev bus has a single large tank with interior dividers . Plus an aux tank. When the system drains to 20 psi chances are all of the aux circuits are empty . Air springs flat, door circuit , seat circuit ... so the system has all of that to air up and depending on your compressor model and such it can take a while . I have mine pretty tight now where overnight I’ll still have close to 90 psi so it airs quick when I start up

[laegion]

Originally Posted by Mountain Gnome

I just replaced my compressor. Reading your post makes me think the cylinder ring in yours is wearing out. That makes it pump oil. Mine get's its oil from a dedicated supply line. That is why you have oil on your wet tank. The instructions for installation said if you are pumping oil, you should think about replacing the air line from the compressor - the oil hardens to carbon-gunk with time/heat/pressure and can clog lines.


The clogs can reduce you pressure build-up time, as well as the compressor itself being worn out. I think it is the charge time (several minutes) that is the tell-tail evidence of a worn compressor.



What caddilackid said about the check valve may also be caused by the oil-gunk??? I think checking the condition of the filter/drier for oil will help tell you.


And yes, I think your alarm needs to be replaced, or the circuitry for it fixed.


Perhaps the circuitry for the gauges is a just a bit corroded giving a difference in reading, or maybe you need new gauges. That is confusing me a bit. I have a "digital" gauge set on my dash; it shows "bars", not exact pressure, but they can be 1 bar apart, until they are both full, then the bars become equal.

What engine does your bus have? Did you have to remove your front cover to remove the compressor?

[laegion]

Originally Posted by cadillackid

Recharge time varies on each bus. Like my dev bus has a single large tank with interior dividers . Plus an aux tank. When the system drains to 20 psi chances are all of the aux circuits are empty . Air springs flat, door circuit , seat circuit ... so the system has all of that to air up and depending on your compressor model and such it can take a while . I have mine pretty tight now where overnight I’ll still have close to 90 psi so it airs quick when I start up

Mine definitely does not hold pressure overnight. I'm not sure if that's because there is an issue or if it auto empties the tanks after a time? I've read some tanks auto empty.

[Mountain Gnome]

Originally Posted by laegion

What engine does your bus have? Did you have to remove your front cover to remove the compressor?

Cummins 5.9L 24V ISB


No, I got to it from underneath and above, but I have a flat-nose front-motor bus, not like yours.

[laegion]

Originally Posted by Mountain Gnome

Cummins 5.9L 24V ISB


No, I got to it from underneath and above, but I have a flat-nose front-motor bus, not like yours.

I must be blind...since it's right in your profile, haha...

I was actually thinking about the front timing cover...but I'll have to look at my engine and see how that's attached on mine.

[Truthseeker4449]

Originally Posted by laegion

I'm thinking WIX filters? As I've heard they are the ones to go with on diesels? Any recommendations or ones to watch out for?

I've worked for 3 companies now that favor Baldwin filters. When they don't have a filter in stock, they turn to Napa. The filters on your bus look like Napa filters. I own two buses with the Caterpillar 3126, so I run CAT filters where possible. I do this largely for asethics but also because Cat filters are often regarded as good filters. Fleetguard is another good choice, being the OEM line for Cummins. Donaldson is another good choice and in addition to filters, they are an OEM supplier for a lot of trucks. WIX has a good enough of a reputation that I wouldn't be scared of it either.

Any of those brands should offer plenty of adequate protection.

I wonder if any of these lines and components would be damaged by Engine degreaser??? I really want to get this stuff cleaned off so I can see better what's what and not get covered in grime just from looking around...

I don't believe it will, I've used straight up floor degreaser for degreasing engines. A pressure washer of a few thousand PSI or less will do fine, just don't hold it over any computers.

Yes, I'd noticed my transmission seems to have a deeper pan/sump than the short sump I've seen. I've looked up the transmission a bit more now, enough to know what it is and what the gear ratios are. Too bad it's not an MD3560 (being on the mountainous side of the country), but I can't really complain about an MD3060...

I've seen 2" and 4" sumps, yours looks even larger than those so I reason it must be 6" or even 8". An MD3060 should serve you fine, both of my buses have them and I was just recently in the mountains of Southwest Virginia. The steepest grades will slow me to about 30 mph. Overall, including out on the Interstate, I can go faster than most semis going up grades. Granted that bus has a staggering 6.25 ratio in the rear end. Even with 6th gear, 70 mph is almost on the rev limiter.

I don't see what I would call a "nut" on the top of the reservoir but there is a round knob that says "oil level" on it. I figured it was a dipstick; but I haven't tried pulling it out yet.

That's fine if you don't have a power steering filter, I would wager you have a dipstick on the knob. You will likely have to turn the knob to release tension on a rubber plug and allow the dipstick to be removed.

If that's the governor for the compressor and that is the low pressure sender than that seems even more likely to me that it could be my issue. Since it doesn't seem to effect anything other than charge time I suspect it's not in the brake system itself.
I'm not sure how the sender is constructed but I've run into other senders that sometimes when they go bad will leak whatever fluid/gas they are supposed to be monitoring. Or one of the fittings there could be loose, etc.

My wager would be that the electrical internals of it have failed but it's still sealed. If it's a two wire switch, it should be receiving a 12v supply with the key on and when the air pressure drops below the specification, the switch closes to turn on the light and warning buzzer. You can simply take a multmeter to the pins of the switch with the air pressure above 100 psi. If you have continuity across the switch then it has failed.

A three wire sensor is not as easy to troubleshoot.

[laegion]

Originally Posted by Truthseeker4449

I've worked for 3 companies now that favor Baldwin filters. When they don't have a filter in stock, they turn to Napa. The filters on your bus look like Napa filters. I own two buses with the Caterpillar 3126, so I run CAT filters where possible. I do this largely for asethics but also because Cat filters are often regarded as good filters. Fleetguard is another good choice, being the OEM line for Cummins. Donaldson is another good choice and in addition to filters, they are an OEM supplier for a lot of trucks. WIX has a good enough of a reputation that I wouldn't be scared of it either.

Any of those brands should offer plenty of adequate protection.


I don't believe it will, I've used straight up floor degreaser for degreasing engines. A pressure washer of a few thousand PSI or less will do fine, just don't hold it over any computers.


I've seen 2" and 4" sumps, yours looks even larger than those so I reason it must be 6" or even 8". An MD3060 should serve you fine, both of my buses have them and I was just recently in the mountains of Southwest Virginia. The steepest grades will slow me to about 30 mph. Overall, including out on the Interstate, I can go faster than most semis going up grades. Granted that bus has a staggering 6.25 ratio in the rear end. Even with 6th gear, 70 mph is almost on the rev limiter.


That's fine if you don't have a power steering filter, I would wager you have a dipstick on the knob. You will likely have to turn the knob to release tension on a rubber plug and allow the dipstick to be removed.


My wager would be that the electrical internals of it have failed but it's still sealed. If it's a two wire switch, it should be receiving a 12v supply with the key on and when the air pressure drops below the specification, the switch closes to turn on the light and warning buzzer. You can simply take a multmeter to the pins of the switch with the air pressure above 100 psi. If you have continuity across the switch then it has failed.

A three wire sensor is not as easy to troubleshoot.

If I'm not mistaken, WIX is who makes the napa filters. However if International has an OEM available I may go with that...I would assume they would know what works best with their engines?

I figured engine degreaser should be fine...but there's always a possibility that something would be different on a bus.

I'm glad I ended up with a 3060 rather than a 1000 or 2000 series; but the super low 1-3 gears on the 3560 would have been really nice especially since I'd like to pull a trailer behind the bus and I'll probably be driving down more than a few gravel roads out in the areas around here to find good parking spots in the summer.
I imagine if I found a used MD3560 at some point it would be very easy to swap in since the gear ratios and assumably the TCU shift points would be the only differences.
Final Drive ratio is one of the next things I need to find out.

If this sender in the picture is the low pressure sender then it's a single wire; which it would have to be a grounding type. Which should also be easy to test.

Thank you for the info. I will have to look into the filter brands you mentioned.




Does anyone recall the name of the company that people always refer to that does oil sample analysis? I've looked them up before but I don't recall who it was.

[o1marc]

Originally Posted by laegion

If I'm not mistaken, WIX is who makes the napa filters.




Does anyone recall the name of the company that people always refer to that does oil sample analysis? I've looked them up before but I don't recall who it was.

I've used these people in the past for oil analysis.
https://www.blackstone-labs.com/

What has really surprised me is for years I quit shopping at NAPA because you paid a premium for the name. I could find equla quality parts much cheaper in area part stores. But then NAPA made changes and they are often much cheaper than the others. NAPA's oil filter for a DT466 is the 1799 for $25.67. The equivalent filter at O'Reilly's is a 51799 for $48.99, a 95% increase.

[Truthseeker4449]

Originally Posted by laegion

If this sender in the picture is the low pressure sender then it's a single wire; which it would have to be a grounding type. Which should also be easy to test.

Thank you for the info. I will have to look into the filter brands you mentioned.

Does anyone recall the name of the company that people always refer to that does oil sample analysis? I've looked them up before but I don't recall who it was.

Ah yes, I should've picked up on that in the picture. Yup, Either take a meter to the pin and to any decent ground on the engine, or a test light connected to battery positive to the pin.

Blackstone is the well known one, however there's a couple companies that do it now.

I'm happy to provide any help I can.

[laegion]

Originally Posted by o1marc

I've used these people in the past for oil analysis.
https://www.blackstone-labs.com/

What has really surprised me is for years I quit shopping at NAPA because you paid a premium for the name. I could find equla quality parts much cheaper in area part stores. But then NAPA made changes and they are often much cheaper than the others. NAPA's oil filter for a DT466 is the 1799 for $25.67. The equivalent filter at O'Reilly's is a 51799 for $48.99, a 95% increase.

Awesome, I ordered two kits, now that I think of it I should have ordered 3 or 4...but I'll start off with analyzing the oil in my car and the bus. lol. I'm a big fan of data...haha

I tend to go to Napa more than other parts stores. However, being in the middle of wheat fields here we have a few tractor and truck supply stores, I'll have to see what they stock.

[laegion]

Originally Posted by Truthseeker4449

Ah yes, I should've picked up on that in the picture. Yup, Either take a meter to the pin and to any decent ground on the engine, or a test light connected to battery positive to the pin.

Blackstone is the well known one, however there's a couple companies that do it now.

I'm happy to provide any help I can.

Thankfully I have a couple meters that do continuity testing so I'm set there. I kinda want to change the oil before I run it much more though...I have no idea when it was last changed, and also we've had a lot of temp changes over-night (being in a scrub grass desert essentially) I'd hate to cause a problem from condensation in the block.

[laegion]

In case anyone is still wondering....I figured out what that white bulb looking thing with the drain valve is. It's a catch can system for crank case ventilation.

[laegion]

I've also identified the mystery filter. It looks to be a filter for the air brakes with a water collector bowl on the bottom. I still can't and won't be able to see the part# without removing it (the mounting plate is blocking it), but I was able to get a picture of the instructions and the hose info coming out of it.

[Truthseeker4449]

Originally Posted by laegion

I've also identified the mystery filter. It looks to be a filter for the air brakes with a water collector bowl on the bottom. I still can't and won't be able to see the part# without removing it (the mounting plate is blocking it), but I was able to get a picture of the instructions and the hose info coming out of it.

That's actually your fuel/water separator (note step 6 on the filter which is fill with clean diesel fuel). Though that's pretty odd it's plumbed in with air line and mounted on the opposite side of the engine compared to normal. That filter should feed the fuel filter on the other side of the engine. I guess someone thought it would be too crowded over there or something, and while unusual, I can't really find much fault with using air line as fuel line. I don't believe the diesel fuel would break down the line nor does it operate with hardly any pressure.

[laegion]

Originally Posted by Truthseeker4449

That's actually your fuel/water separator (note step 6 on the filter which is fill with clean diesel fuel). Though that's pretty odd it's plumbed in with air line and mounted on the opposite side of the engine compared to normal. That filter should feed the fuel filter on the other side of the engine. I guess someone thought it would be too crowded over there or something, and while unusual, I can't really find much fault with using air line as fuel line. I don't believe the diesel fuel would break down the line nor does it operate with hardly any pressure.

Hahaha, oh boy that is embarassing. I wasn't reading very closely this morning.

At least I wasn't wrong about the other mystery item...