gear box tempature.

[hotrodrupp]

hey guys! randy from Ithaca NY here. got my new road gears installed no problem! thanks to Mr. Stahl and Jim at Taber St Auto. Jim also hooked me up with some side pipes he had kicking around, he put them vertical and made a sweet y pipe. old dawg has a bark now. ANYWAY, my question. after driving my rig to work on average 3 to 4 days a week I have noticed the temperature of the gear boxes.. After a 11 mile trip to work at the crusing speed of 45 mph the trans is cool to the touch, BUT the transfer case is quite warm. I cant hold my hand on it for more than a second or two. the E- brake drum is warm so its not the band dragging. is one or the other something I should be worried bout??....is a cold trans a sign of a problem or a hot x-fer a sign of a problem? thanks, Randy

[Elwood]

Because of how the power is routed through the gears inside the NP200 in the M37, the transfer case will run hot, especially at higher speeds.

Are you using a gear lube in the transfer case? If so, try switching to a lighter synthetic oil (Charles at M Series Rebuild recommends Amsoil 50w Long Life Synthetic transmission oil), which will help the transfer run cooler.

This issue has been discussed at various times here. A search will find some good threads that discuss this temperature condition, and some solutions.

[w30bob]

Hotrod,

A couple things to consider....... If you can hold it for a second or two with your hand it's not that hot. I've always used 150F as rule of thumb for what you can touch and not get burned. If it's hotter than 150F it should burn your skin when you touch it.

As Elwood mentioned, the lube you're running is important. There are lots of high performance lubes out there now-a-days. I've heard of guys running ATF in the transfer case........I don't think that's a great idea. Heat is the enemy of ATF and it breaks down pretty quickly as it gets hot. The following is from an auto trans website........but you get the idea.

175 Degrees: 100,000+ miles (Normal is typically 179 to 195 degrees)
200 Degrees: 90,000 miles
225 Degrees: 55,000 miles (Pressure Drops)
250 Degrees: 25,000 miles (Valves Stick)
275 Degrees: 17,000 miles (Varnish Forms)
300 Degrees: 4,000 miles (Seals & Clutches Burn)
325 Degrees: TRANSMISSION FAILURE

regards,
bob

[Sal]

Here is a old Post on the subject that might be of some help.

http://www.g741.org/PHPBB/viewtopic.php ... ple#p26862

Sal

[hotrodrupp]

thank you all for the information!!..relieved its nothing major!.. that certainly makes sense. I have no real idea what gear oil is in there. wouldn't surprise me if it were the original oil.... I will swap over to a lighter syn 40 wt oil... cheers! Randy.

[MSeriesRebuild]

I hate popping your bubble; however assuming you have no issue is not a smart decision. Really it is nothing more than someone telling you what you want to hear when it comes down to it. The straight up truth is this, yes the case will run warmer than any other box on the truck; but there is no way to know whether the warmth you feel is too warm. Face it, our hands are not a temp gauge. Excessive heat can be caused by failing bearings and several other issues, I have seen more than one case with galled bearings, especially on the 2-speed shaft. As far as lubricant, we have been running Amsoil 50W long life synthetic transmission fluid in out rebuilt cases for several years now. Great track record thus far; but the biggest improvement is to incorporate an oil cooling system. The way we build our coolers, the case fluid capacity doubles, a very good advantage as the case only holds 2.5-qts. Increasing that to 5-qts. makes a big difference in several things, oil life, oil having more time out of the case to cool, etc. Our system also incorporates a 1 qt. size oil filter. The pump and cooler fan are both thermostatically controlled, so the system is ready and functions automatically as needed as oil temp rises. Pilot lights on the dash let you know what is running, when, and shows on-off function of each system component. There is also an oil temp gauge on the dash showing the actual oil temp inside the case; the difference the cooling system makes is easily monitored and I can tell you the temp lowering ability of the system is outstanding. Obviously it makes a tremendous difference in the oil life because of less heat break down of the oil's additive package. This spells big relief for bearings and seals. It is a huge life saver if you do sustained highway travel at higher speeds; the extended life of the case would certainly be several times over that of a non-cooled case.

[PoW]

When popping bubbles, I might as well mention this again;

A Dodge engineer that worked on the G741 project told me the target life of stock systems was only 15,000 miles before rebuild . (three sets of tires LOL)

You always wondered why the military had so many parts in warehouses....

DG

[MSeriesRebuild]

When popping bubbles, I might as well mention this again;

A Dodge engineer that worked on the G741 project told me the target life of stock systems was only 15,000 miles before rebuild . (three sets of tires LOL)

You always wondered why the military had so many parts in warehouses....

DG

Depot level rebuilds for M37's were scheduled every 12,000 miles. My truck has a depot rebuild tag on the dash with a mileage stamp of 11,999 miles. This is the military, if you have ever been involved as a part of serving your country; especially if you were involved with vehicle maintenance and rebuilding while you served; then you already know how hard it was to obtain parts at the actual ground level. I've often wondered with such a supply of spare parts, some of which still exist today, why we had to look for an unattended truck belonging to another unit that we could steal the parts from to fix ours. Anyway, the way we had to steal, patch, and a few other things I won't mention now, it was certainly no surprise to anyone that indeed it needed a major rebuild at 12,000 miles or before. As a vehicle maintenance person on the ground; let me just say this. Most of the vehicles of the day were very well built, however in a rather simple fashion, but great technology of the times. Tough trucks, I'd have a hard time getting most to believe things I saw them put through and survive to do it again and again. They do require lots of maintenance, some of which was highly neglected, enough said there. We had a POL yard, (petroleum, oil, and lubricants) in our Company, so a ready supply of these types of products was not a problem; just go and pick it up. Now if these products had been of high quality like some of the high end stuff today; it WOULD have made a huge difference in engine, gearbox, suspension, longevity; of course that is assuming the oil change maintenance had happened as it should; not very likely. Cleanliness of such service; well even if possible, not very likely. Yes there are many reasons why equipment required major rebuilds at such low mileage intervals; but in the vast majority of cases, it was not because engineers expected it was not capable of holding up longer IF cared for in a proper fashion. Maybe it was because they knew full well it would be abused to the MAX; and that the very best product they could turn out in that day would not stand up to long mileage intervals of service because of it. Look at the equipment being sold as surplus today; it has not seen nearly the service that M37's saw.

I get weekly email prompts from government planet showing equipment auctions that will be coming soon. Being in the grading business for 35 years, I take note of a lot of the heavy construction equipment that comes across the block. Last week I received a notice of 29 CAT 130G motor graders being auctioned on Sept 22. It is unusual to see this many machines rolled out for sale in a single lot, so I paid attention to that. Government planet does a pretty good job of offering pictures and fairly detailed info of the machines. I noticed only one of these 29 machines had over 1,000 hours on the meter. There was 1 that showed only 41 hours. Details did note that the meter on that machine was not working, so very likely actual hours was more than 41. Looking through over 100 pictures of the machine, several issues stood out. The interior area of the circle where the support shoes contact; the paint was not even worn away, a good indicator of extremely low hours. Anyway, my big question was why were these machines being sold off when the paint is barely burned off the exhaust system. Some one in the position of making these decisions is not too smart; but hey it's the military, surprise. G series CAT motor graders is still a highly sought after machine in the civilian contracting world; if I were still in the business, I'd be watching this sale hourly. My bigger point in making mention of all this is right here. I've wondered many times why certain decisions are made, stupidity is apparently in high demand as it is certainly displayed often. All the M Series equipment we have dealt with here is very good quality equipment with the exception of the M715. I don't understand why they ever accepted that junk from Kaiser Jeep, but that is another story and I'm sure the reason why its manufacture for military service was only 2 years. M37's lasted from 1951-1968; that says a lot. In the end, the thought of an M37's service life before rebuild being only 15,000 miles is really absurd; except under the deplorable conditions of the military, AND the extreme lack of discipline in seeing that equipment is properly cared for.

[PoW]

As a point of comparison, what was the factroy warranty period (miles/months) on the WDX to WM300 PW's and what did it cover?

DDG