M35a3 questions

[Loganwood]

Well, I've searched the forum and tms, can't seem to find the answers I am looking for, so here we go. I recently went to check out the a3 I bought as a pre retrieval inspection. The truck is in great shape and has been completely serviced as far as fluids and filters, etc. There were only a few issues that I could find that I need advice on:
1) as soon as power is turned on and before starting, the oil pressure gauge pegs
2) no air comes out of the inboard tank on opening of drain valve
3) how frequently should the air dryer vent and how warm should it feel

Reading the trouble shooting tm in the 24 manual for the oil gauge, I see how to do that. Problem is I'm 190 miles away from the truck now. So on retrieval, is the sending unit most likely culprit or the gauge? Or should I just take and install a mechanical gauge? I would like to keep the original cluster appearance.

On to the inboard tank. It was cold the day we went to inspect. If the check valve was frozen, would that keep air from being in inboard tank? I can't tell from the diagrams.
Or could it just be plugged petcock? I had everything with me i could think to bring, except a piece of wire to shove in there.

Now the air dryer. It vented every 5-10 minutes while idling with no air being used by us. Also, the dryer felt luke warm (about the same as my hand). Is that about right, or if too cool, could that be contributing to the no air in the inboard tank? There was no water expelled from the outer tank on draining it.

Any ideas or suggestions would be appreciated.

 

[mktopside]

Well, I've searched the forum and tms, can't seem to find the answers I am looking for, so here we go. I recently went to check out the a3 I bought as a pre retrieval inspection. The truck is in great shape and has been completely serviced as far as fluids and filters, etc. There were only a few issues that I could find that I need advice on:
1) as soon as power is turned on and before starting, the oil pressure gauge pegs
2) no air comes out of the inboard tank on opening of drain valve
3) how frequently should the air dryer vent and how warm should it feel

Reading the trouble shooting tm in the 24 manual for the oil gauge, I see how to do that. Problem is I'm 190 miles away from the truck now. So on retrieval, is the sending unit most likely culprit or the gauge? Or should I just take and install a mechanical gauge? I would like to keep the original cluster appearance.

On to the inboard tank. It was cold the day we went to inspect. If the check valve was frozen, would that keep air from being in inboard tank? I can't tell from the diagrams.
Or could it just be plugged petcock? I had everything with me i could think to bring, except a piece of wire to shove in there.

Now the air dryer. It vented every 5-10 minutes while idling with no air being used by us. Also, the dryer felt luke warm (about the same as my hand). Is that about right, or if too cool, could that be contributing to the no air in the inboard tank? There was no water expelled from the outer tank on draining it.

Any ideas or suggestions would be appreciated.

Can't help with the oil pressure gauge, but good luck!

My inboard tank petcock had a bunch of crud in it as well, I stuck a piece of wire through it to break up the mud that was caked inside. I think part of it was mud, and part of it is that my inboard tank is rusted through. I have new tanks on order. The other two drain cocks are reachable without crawling under the truck, the inboard is not. All I can guess is that people are lazy and didn't want to crawl under to drain it. If you are going to crawl under there to mess with it, you much as well just replace them with the chain pull types.

5-10 min is about how often mine vents as well. We had a discussion about this a few weeks ago and no agreement was reached on what is normal. Replacement dessicant and filters are available from Ericks.

Air Dryer Filter & Small Parts Set For M35A3, Pure Air Plus, DQ6036 (RN60Y/DQ6026)

 

[Loganwood]

Yeah, mk, I saw that thread. If I remember correctly, no agreement was reached on whether or when to replace to replace the filter and desiccant. The manual says every 2 years. If it's hand warm, is it functioning? And if its functioning I guess there's just crud in the petcock from prior laziness. And if that's not warm enough, then I guess I need to replace that stuff. Would that be correct?

 

[mktopside]

I really don't know, I don't know enough about that unit (or air dryers in general) to really tell if it's working or not. I know there is a heater inside of it, but I've never crawled under to feel if it was warm. I can only assume mine has been working as since I've been driving the truck barely any water builds up in the tanks. I plan on replacing my filter and desicant, but it's a few steps down on the list....... and got pushed even further down this morning after the cold finally took a toll on the crap batteries I had in the truck

I'd worry more about if the current tanks are rusty (like mine) than I would about the air dryer at this point.

 

[wsucougarx]

Can't speak for an A3, however on my A2. When I first got her home I opened the air tank valve....nothing. Then I removed the valve and all kinds of crap came out. I turned the truck on and allowed the tank to vent as much as she could. I then made up a mixture of rubbing alcohol and Mystery Oil and fed the air compressor some of this mixture. I allowed the air pressure to build up and opened the air tank. Even more crap came out. I repeated this cycle about 4 times until it was somewhat clean.

 

[Loganwood]

Ok, thanks for the advice. Mine look new from the outside, although I obviously can't tell about the inside. Could you see any signs of deterioration from the outside? I think the dryer is functioning properly, as there was no water or crud in outboard tank and I hope the check valve was just frozen. Which brings up another question: where do I add alcohol to the air system?

 

[wsucougarx]

I fed my mine directly into the air compressor intake. I just cupped by hand just under the intake and poured some into my hand. The air compressor lapped it right up

 

[Loganwood]

Alright. Got that understood. I'm taking new valves with me on pickup. Already got the oil and alcohol. Now, anybody got any thoughts about the oil gauge? Thank you guys for the help so far.

 

[mktopside]

Alright. Got that understood. I'm taking new valves with me on pickup. Already got the oil and alcohol. Now, anybody got any thoughts about the oil gauge? Thank you guys for the help so far.

The A2 air system is different than the A3. You can't just pour stuff into the compressor intake and have it distribute throughout the system. IIRC, anything out of the compressor will get caught by the air dryer filter, including oil. Also, the compressor intake draws from the charge pipe from the turbo to the top of the intercooler, not that it would run funny at idle (it wouldn't run well at all if you tried to drive it with that off) if you took that off, but it is a very heavy duty rigid hose that looks like it would break before you got it off. I wouldn't mess with that hose until you get it home.

Try clearing out the valve with some coat hanger wire before you try to remove it. If you can't clean it out be very careful removing it. If it's crudded up with rust, it might be rusted in place, if it breaks off in place while on your recovery you'll have a problem on your hands.

I knew my inboard tank was rusted when I had a pinhole rust thorough. I drilled it until I saw shiny metal, filled it with an entire tube of epoxy, then put a pop rivet in the hole. I banged around with a hammer and no other holes developed, but I ordered new tanks because it's not worth the risk.

 

[Loganwood]

Ok scratch that idea. Guess I'll do the coat hanger thing and see if that works. If not, then wait till I get home to try the drain valve change? Where did you find your tanks just in case?

 

[mktopside]

Ok scratch that idea. Guess I'll do the coat hanger thing and see if that works. If not, then wait till I get home to try the drain valve change? Where did you find your tanks just in case?

That's what I would suggest, though I can't see you not being able to un-clog the drain valve, you should be able to just push through any crud in there. Personally I think it would suck a whole lot more to have a gaping hole in the tank with some stripped out threads, than it would to have a little bit of water in the tank. FWIW, the valves on my truck leaked when closed until I squirted a bit on WD40 into them while turning them around. They don't leak now.

Eastern Surplus has them in stock. They are $55 each + shipping, if you buy two they come on the rack. They are A2 tanks, I couldn't find A3 tanks, so I have no idea how they are going to match up fitting wise.

 

[Loganwood]

Yep, a hole would be a major suck. Thanks for pointing it out as I would have tried it there on the lot before the trip home. Now I've got that potential issue addressed for now, anybody with any thoughts on the oil pressure gauge pegging please feel free to offer any suggestions. I really don't want to drive it home without a functional gauge. Maybe I'll buy a cheap mechanical gauge, then troubleshoot the original when I get it home. Assuming my euc ever clears of course

 

[glcaines]

I have no experience with the air tanks on my A3. However, when I first picked up my A2, both valves were plugged solid with crud. I used the coat hangar also, and got them both the drain after repeatedly using the coat hangar. It looked like grey mud mixed with small chunks of rust. Both tanks were about half full of water. I then decided that I couldn't do any real damage putting water back in the tanks to wash them out. I took some tubing and placed it on the petcock with the other end on a two gallon can of hot water. I put about 1-1/2 gallons of hot water into each tank and then recharged the tanks with air and let it blow out, repeatedly cleaning the petcock with the coat hangar. I repeated this several times until the water came out looking relatively clean. Since performing this procedure, I have never had any problems with a plugged up petcock. I routinely purge all air from both tanks after each use.

 

[mktopside]

Oil Pressure Sending Unit, 120 PSI, MS24539-1

I think this is the Oil pressure sender. Unless one of the wires is grounded out, sender or gauge is where your problem most likely is.

Someone who knows a lot more about Diesel engines than I do will have to answer this for sure, but I don't think a CAT 3116 will run without oil pressure, as oil pressure is needed to make the injectors work.

 

[renovate7]

A2 and A3 tanks are not interchangeable! The A3 tank has 2 sections with a solid divider in between. It has 4 air line connection points plus the drains. I almost blew up my air system when I put an A3 tank on an A2 truck. I ended up getting a very long bit and drilling a hole thru the divider to connect the two halves, then putting plugs in the extra holes...I have an A3 truck now. I believe, but am not certain, that an A3 has one 2 section tank and 1 one section tank, like an A2. Make sure you match the tanks exactly to what you have now on your A3. The A3 has the dual brakes, completely different than an A2.

 

[mktopside]

A2 and A3 tanks are not interchangeable! The A3 tank has 2 sections with a solid divider in between. It has 4 air line connection points plus the drains. I almost blew up my air system when I put an A3 tank on an A2 truck. I ended up getting a very long bit and drilling a hole thru the divider to connect the two halves, then putting plugs in the extra holes...I have an A3 truck now. I believe, but am not certain, that an A3 has one 2 section tank and 1 one section tank, like an A2. Make sure you match the tanks exactly to what you have now on your A3. The A3 has the dual brakes, completely different than an A2.

Interesting. Well, maybe I'm in for more work than I thought! Maybe I'll end up with 3 tanks when all is said and done.

 

[Floridianson]

I will have to look again but the A2 check valve is between the two tanks is oneway valve from the inboard tank to the outboard tank. If the outboard gets a hole it won't drain the inboard. You check this valve by compleatly draining the outboard tank and the inboard should hold air. Now like I said I don't rember shipt but what check valve are you talking about.
As far as the gage goes I would check to be shure with a mechanical. I doubt the oil pump went bad but that a risk some would not take.
As stated never let the compressor drink anything. When working the dryer should be enough and it cycles so sounds like your fine.
The dessicant cartrige I would not worry about yet as what realy kills them is when the compressor oils the heck out of them.

 

[Loganwood]

Man, I got busy at work. Dang boss (me!). Anyway, I think I'll just take a cheapo manual gauge with me and trouble shoot it best I can there. If I can't fix it there I'll just plug in the manual gauge. This is of course assuming any old gauge from napa will work. Anybody know if thats the case? Good to know about the air tanks not being compatible between a2 and a3. Guess I better fix this one!

Mk, that's the one I was looking at, but I think I'll try to see what the problem is first. Not sure how they are about returning merchandise if that's not the problem.

Gl, thanks. I'll try that if it's too crudded up

Thanks guys. Help is greatly appreciated!

 

[Loganwood]

Floridianson, I was talking about the check valve between the 2 tanks. Like I said, the outboard tank purged fine with no water or crud. So if that's the case the inboard tank should be full and still pressurized. Sounds like I might not want to be in the way of the thing when it does free up. Oh yeah, ctis does seem rather sucky as many have said. Only had 3 flats when I got there

 

[mktopside]

Floridianson, I was talking about the check valve between the 2 tanks. Like I said, the outboard tank purged fine with no water or crud. So if that's the case the inboard tank should be full and still pressurized. Sounds like I might not want to be in the way of the thing when it does free up. Oh yeah, ctis does seem rather sucky as many have said. Only had 3 flats when I got there

"You'll shoot yer eye out kid!!"