Brakes and Charging system

[theonlyman]

I finally got my 89 Magnum 8X8 out for a major run and had a great time. It pulled a very heavy trailer with no trouble and ran like a dream. What it did not do, at times, is stop! In my mind when the brakes got hot I would lose all braking power on my left handle. If I let it sit for a few minutes the braking power would return?!?!. This fade in and fade out situation would happen every couple of miles. What's with this? Are there seals in the master cylinders that may need changing?

Also, my battery died on the way in. It is charging on my bench as I type and will be tested later. How can I test the charging system on the Argo? The machine ran despite the dead battery (pulled it to start) and ran very well. None of the accessories ran (lights, cigarette lighter, sump) and I assume this is because there was no battery power and too little engine power. Are the charging system and the power system to run the engine separate systems?

If the charging system proves to be bad, do I have to do anything other than install an alternator to keep the battery charged? Do I have to disable anything with the stock charging system?

Thanks for the help!

[racerone3]

do you have a brake fan on your machine? mine will only fade like that if i forget to turn on the brake fan... i'd say if it comes back when you let the machine cool off they the master cylinders are ok.
what engine does your machine have. some (most) use a magneto to fire the ignition and therefore don't need battery power to run the engine. all of your accessories not working is a result of the dead battery. once you have it charged, haul it to the auto parts store and have them test it. could just be a bad battery

[Rock Doctor]

I've been told that Brake Fluid should be changed every 2 yrs (3 at the most), as the heat causes it to break down. I never bothered to do it myself, but this yr my brakes started to act up, just as you describe. I changed my fluid, and it seems to have corrected the problem. I think what you are experienceing is the heat causing the brake fluid to "flash" into a vapor (similar to an "air lock" in the brake line), then when you sit and let it cool down it condences back to a liquid. A buddy of mine had a Magnum, yrs ago, and it was notorious for running HOT, especially when pulling a load. Does your machine have the 18hp Kohler?

As for the charging system, if you run the machine without a battery hooked up, you should ba able to put a Volt Meter on the battery cables. If the volt meter read over 12 volts, it should be working. Did you do lots of winching by any chance? Charging systems are VERY slow on machines without an alternator. I have killed my battery numerous times due to winching. Even running the lights for extended periods can have an effect on your battery.

RD

[Planter Bob]

These brakes run hot, especially in the summer months. Rock Doctor is right, the fluid, even this synthetic Dot 5, can boil. In addition to changing your fluid, you have to find the source of the excessive heat.

As was already mentioned, you need to make sure that your 3" duct from the fan to the firewall plenum is connected and hole-free, and that the fan is on ALWAYS. Napa sells the 3" hose as "cold air duct". If you buy it from there, don't use those plastic clamps they sell with it. In a vibrating, off-road Argo, they're worthless.

If your blower and duct is working properly, there's a good chance you have a dragging caliper. This can be hard to notice, and can be caused by the piston in the caliper sticking, a master cylinder not releasing, or even a damaged hose.

I had the exact same fading you describe, and got sick and tired losing my brakes and having to stop and let them cool.

Rather than chasing down all the different things that could cause the problems, I just rebuilt both master cylinders and both brake cylinders. I also replaced both hoses and my brake pads. The parts for the whole job were under $200. I can't remember the exact amount I spent, but the job was dirt simple, and documented well in the service manual (which you should have).

I haven't had a lick of brake problems since. I recommend the entire job to anyone who buys an older used Argo. It's cheap insurance, and failed brakes should not be taken lightly. Where I ride, it could be fatal.

Now, on to your battery:

Install your batter after it's fully charged and the electrolyte levels in the cell are topped off with distilled water. Only hook up one side of the battery, and put your DVM set to DC amps in series with the battery. With the key off, you should see no current flowing. If you see current flowing, you have a short to ground somewhere in the system, and need to track that down.

If that goes well, hook up the other side of the battery and set your DVM to 25 VDC. Check the voltage across the terminals. You should read 12VDC +/- .5 volts. Take your DVM off the terminals, and fire it up.

With the motor running at idle, check the battery again for VDC, and you should see a higher reading than you did with the engine off. It should be around 13.7 VDC, but it could be higher or slightly lower depending on the idle speed setting on your engine. Now rev your engine to full throttle and you should see something over 14 VDC. If it's much higher than that, you may have a damaged regulator. Depending on your engine, the regulator may be set higher. If you see no change in voltage with the engine running, your charging system is inoperable.

Without knowing the engine you have, I can't give you the particulars of what you would need to replace. Regarding an external alternator, the charging system of nearly every engine Argo has used is capable of driving a 2500 pound winch if wired properly and operated within reason. One upgrade I do recommend is installing the largest battery that will fit within your engine compartment. Most stock batteries were grossly undersized, and well below the capacity of the engines used.

Hope that helps...

Planter Bob

[theonlyman]

Ailing Magnum

Thanks for the informative replies. The Magnum has an 18hp Kohler. I am going to assume that because the battery died the fan was not working to blow cool air to the brakes - this lead to the overheating. Is it normal for NOTHING to work with a dead battery? Should the engine not produce enough power to run the accessories, dead battery or not? I will change the fluid to be sure and will also change the lines - cheap insurance for sure.

My concern is the charging system - I am sure I am going to install an alternator. Do I have to do anything to the existing charging system, working or not, before I install and hook up an alternator?

thanks again!!

[evil8x8]

I have a 1985 Argo 8x8 with a 18hp Kohler Magnum. I have had to replace a blown rectifier(easy job). If you find out your rectifier is bad, I can give you the part number. Also on another occasion, I have blown the fuse after the rectifier. If your charging system is working properly, you probably won't need an alternator( I don’t have one) I have heard of many people getting bad rectifiers on older Kohler Magnums. The new replacement rectifiers are supposedly better.

If your battery is bad, it may read 12 volts with no load, but as soon as you put a load on it, it would drop drastically. Take a volt reading of the battery as you start the engine, if the voltage drops drastically, your battery may be the problem.

[glen1971]

Load test

I would get the battery load tested.. that will tell you if you have a bad cell(s)... Most places will do it for free (that I have found)..

Once you have eliminated the battery, and checked the charging system as described above, I would HIGHLY recommend a battery tender. I just put one on my machine and on my quad, and love them.. They keep the battery charge up, without overcharging it. This is especially handy since I don't run my argo for a couple of months at a time..

As for the brakes.. Check the fluid.. If in doubt, change it.. That is all the insight I can think of for the brakes..