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Engine Specifications / Re: air leak 91 beaver Baronet
« Last post by David.e.atherton on July 16, 2018, 10:32:17 PM »
On the road again, agree with top post ( air dryer ). With age of motorhome the air
Compressor unloaded valves sticking and not allowing air pressure to recover very
fast. Dave Atherton Retired Cat Mechanic
Engine Specifications / Re: air leak 91 beaver Baronet
« Last post by antiqueclockservice on July 16, 2018, 06:24:48 PM »
It sounds like you might have an air dryer,purge valve assembly that failed.  Mine is a Haldex on my 05 Alfa.  It should be enough of a leak to hear it under the coach.  Good luck

Engine Specifications / air leak 91 beaver Baronet
« Last post by ontheroadagain on July 16, 2018, 09:25:29 AM »
I've got an air leak somewhere in the chassis.  air compressor is able to keep up for brakes and check valve keeps it from leaking from tank that holds air for brakes... 2nd tank is for air throttle and air shifter and horn and airbags if I have any... that one bleeds down as soon as I turn the engine off... have anought air pressure to operate throttle and shifter on the road..using the air horn twice or 3 times uses up all the air in the tank if engine isn't running...3 days ago I had nothing at all could not get enough pressure after an hour of running the engine to move it...finally got it near an air hose.. put 125lbs of air in tank 2x each time by the time I got back inside it was sounds of leaks...3rd time it must have blown some dirt out of a check valve or something as I had enough to move motorhome still has very low air pressure in tank maybe 20 lbs    any ideas where its going quietly??  also do I have an air ride chassis?  its a Gillig chassis
here is a picture of a balanced coil type gauge circuit.

If your fuel gauge only has 2 terminals on it, it is a bi-metal type.  The checking procedure is pretty much the same, except you will not have a ground terminal on the gauge, just a power terminal, and a terminal for the sending unit wire.
Most fuel gauge circuits of that vintage can be diagnosed by disconnecting the sender wire, with it disconnected the gauge should go to one extreme, with it grounded it should go to the other. If there is no change then the next thing to check is the wire from the sending unit to the gauge. If the wire is ok then the circuits to the gauge is the next step. There will probably be 2 more terminals in the gauge one will be a ground the other is a power supply. The power wire is usually a lower voltage some are around 8 volts this comes from a small voltage regulator for the gauge. A voltage regulator is used instead of battery voltage so that the gauge does not fluctuate as the battery voltage does when driving. Some gauge circuits share that voltage regulator with other gauge so other gauge would not be working if it was a problem.

Another problem that can cause gauge so to be inoperative or read incorrectly is if diesel fuel has leaked through the terminal or wires on the sending unit, diesel fuel becomes conductive as it absorbs the moisture in the air, cleaning with brake clean would only be a temporary fix.

Checking the sending unit, they should have a resistance of 20 to 120 ohms depending on the position of the float. Note: depending on the type of float used they can saturate with fuel and cause incorrect readings or read empty if they are sunk.

the sending unit may have 1,2,or 3 wires on it. A common ground, the fuel level wire and sometimes a power wire for an internal lift pump.
 If the resistance spec is known the accuracy of the gauge circuit can be checked by putting a resistor of the approximate values between the gauge wire and ground wire.

This is something that all Caterpillar owners with 3126 A, B, E and C-7 and C-9 engines should be aware of. If an engine problem is diagnosed as injector failure or sticky injectors and HEUI pump not getting correct high pressure but replacement doesn't cure low power problem, cause may be the oil rail. This is can be caused  due to extended over due engine service (break down of engine and sludge build up present). Problem will show up as low power and hard starting. Many service shops overlook the high pressure oil rail and the build up of oil sludge. This may trigger event codes of 42-11 and 164-11 (Injection Actuation Pressure fault). But by now, we are throwing parts at the engine.

To resolve this, the oil rail needs to be cleaned. There are 2 large plugs at front and rear of engine that a 3/4" breaker bar will fit. Remove both plugs. Use brake clean and air pressure to clean the rail. A person would be surprised how much oil sludge is present. Then reinstall the plugs and be sure to use locktite on the threads.  To summarize;  If both event codes present along with new injectors and Heui pump and you still have low power your engine oil rail needs to be cleaned of buildup of sludge.
Dave Atherton Retired Cat Mechanic
Excellent advice and thats just what i will do.

Thanks Rick
How to Guides / Re: Approval Requirements for New Posters to Forum
« Last post by David.e.atherton on July 07, 2018, 07:02:37 AM »
As part of the ongoing efforts to keep the forum security up-to-date, Steve Cook (our forum guru) implemented an approval requirement for first-time posters.  So if your post doesn't show up right away, don't worry.  It hasn't been lost; it's just in the queue to be approved.  This shouldn't take more than a few hours at most, and is often just a few minutes if one of us is active on the board.  Once you've posted a few times the post will automatically move from the queue to the chosen discussion board.
Hopefully, someone else with that vintage Beaver/Magnum chassis will have details.

BUT, before doing that you do need to diagnose the problem-- you want to insure that it is not a loose wire or sending unit problem before ordering and installing a new gauge or gauge cluster.

Said another way, do not ASSUME that is is the dash gauge at fault-- prove it first.
Thank you for your replys. Where can i purchase the gauge to replace it? Magnum chassis.

Thank you

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