Keeping it cool in the desert is important.

Keeping it cool in the desert is important.

Overflow tank helps to keep your precious coolant in your radiator. Here’s how to use it.

Cursing, the driver shifted to a still lower gear. Those blistering, shifting sands were tougher to fight than the Nazis. He glanced at the heat indicator. It looked bad.

Realizing how little of his reserve water supply was left, he stopped the truck to cool it. He climbed down from the cab. Then it happened…first a rumbling, gurgling noise followed by water gushing out the overflow pipe. He looked under the truck just in time to see the irreplaceable liquid disappear into the parched sand…O.K.–you can relax now; it’s only a yarn. But for you fellows whose vehicles don’t have them, that’s why radiator overflow tanks have been installed on half-tracks, scout cars, and some Dodges, and (in the future) on GMC’s and 1/4-ton jeeps. Not all the Dodges, GMC’s and 1/4-tons are to be modified, but more on this later. After reading the Desert Cooling System Kit modification work orders for these vehicles, we couldn’t see why any mechanic should have trouble making the modification. In each case it means changing the fan assembly, radiator cap and fan belt, and installing an overflow tank which is hooked up to the radiator overflow pipe. On the Willys and Ford 1/4-tons the modification also requires installing a larger radiator core.

As anyone who has driven in hot climes knows, when coolant gets hot it expands. And if no place is provided to receive the expanded coolant – it will flow out the overflow pipe to the ground. If this happens in an area with a scarcity of water, somebody is going to be mighty thirsty. But on vehicles equipped with the overflow tank, this doesn’t happen. The cooling system is sealed by a positive seal cap on the radiator and by tubing running from the radiator overflow pipe to the overflow tank. The tank has a pressure cap.

When the coolant expands from heat, the water that would ordinarily run out the overflow pipe is conducted into the overflow tank. When the temperature of the coolant in the radiator decreases it forms a partial vacuum in the line between the radiator and overflow tank. This partial vacuum causes the coolant in the tank to flow back into the cooling system – if you have kept the cooling system good and tight.

Any air leaks in the cooling system, such as loose hose connections or a vented radiator cap, will break the vacuum and prevent the coolant in the tank from returning. If the coolant level in the radiator is found low, the overflow tank should be checked for trapped liquid before any additional water is added. If there is water in the tank, it should be drained into a container by using the valve and poured back into the radiator. But the presence of coolant in the tank after the radiator has cooled, is a sure indication that the system isn’t working right. In such cases, check for proper installation of the kit, check all hose connections for leaks, and check the radiator cap to make sure some one didn’t slip you a vented one. (A vented one will break the vacuum in the radiator to overflow line). But if the water in the radiator is low and isn’t in the overflow tank, you can start looking over your cooling system for a water leak.

Now if you follow these few simple rules your desert cooling system kit will work O. K.

‘Where and when do I requisition the desert cooling system kits for the GMC’s, 1/4 ton jeeps and 3/4-ton Dodges?’ The answer is you don’t requisition them. They will requisition you. When your destiny is decided — that is, when it is known you are going to a water-short area, you will be given the desert cooling system kits.

I don't like it too hot, neither does my jeep's engine.

I don’t like it too hot, neither does my jeep’s engine.

You can find out more interesting facts about WW2 jeeps and maintenance in my book: Military Maintenance for MB/GPW Jeeps 1941-45.

Answers can be found in TM 9-803, page 70 and 71.

You should know what your jeep’s safe operating temperature is.
I'm just waiting for the little ol' engine to warm up!

I’m just waiting for the little ol’ engine to warm up!

Warm-up.
Temperature Gage. Engine temperature should rise gradually during warm-up period to normal operating range, 160F to 185F.

Road test!

Road test!

Run-in Test.
Dash Instruments and Gages. Do not move vehicle until engine temperature reaches 135F. Maximum safe operating temperature is 200F.

You can also see info under the “Road Test” and “During Operation” section.

Basically, if your are not losing coolant either from the block or the radiator then don’t be overly concerned about the engine’s temperature. Some of it has to do with whether or not you are running a 165F or 180F thermostat. Ambient temperature and engine load (how hard the engine is working) all have impact on the temperature. Later models of MB/GPW were equipped with the 180F thermostat as the higher temperature helps to cook off contaminants in the oil supply.

You can find this out and more in TM 9-803 Willys Overland Model MB and Ford Model GPW ¼ Ton 4×4 Technical Manual. If you don’t have one and own a WW2 jeep then click the link and order your copy today.

Is you carb sad? Why not a new one?

You need to keep your gears lubricated.

From EM 1110-2-1424 28 Feb 99:

Gear Lubrication
a. Lubricant characteristics. Gear lubricant must possess the following characteristics:
(1) General. The following characteristics are applicable to all gear lubricants. The lubrication
requirements for specific gears follow this general discussion:

(a) Viscosity. Good viscosity is essential to ensure cushioning and quiet operation. An oil viscosity that is too high will result in excess friction and degradation of oil properties associated with high oil operating temperature.In cold climates gear lubricants should flow easily at low temperature. Gear oils should have a minimum pour point of 5C (9F) lower than the lowest expected temperature. The pour point for mineral gear oil is typically -7C (20 F). When lower pour points are required, synthetic gear oils with pour points of -40 C (-40 F) may be necessary. The following equation from the ASM Handbook provides a method for verifying the required viscosity for a specific gear based on the operating velocity:

equation01

where
equation02= lubricant kinematic viscosity at 40EC (105EF) (cSt)
V = pitch line velocity (ft/min) given by :
V = 0.262nd
where n is the pinion speed in rev/min and d is the pitch diameter (inches).
(b) Film strength. Good film strength helps prevent metal contact and scoring between the gear teeth.
(c) Lubricity (oiliness). Lubricity is necessary to reduce friction.
(d) Adhesion. Helps prevent loss of lubrication due to throw-off associated with gravity or centrifugal force especially at high speeds.
(e) Gear speed. The now superseded Industrial Gear Lubrication Standards, AGMA 250.04, used center distance as the primary criterion for gear lubricant selection. The new version of this standard, designated AGMA 9005-D94 Industrial Gear Lubrication, has adopted pitch line velocity as the primary selection criterion. As noted above, gear speed is a factor in the selection of proper oil viscosity. The pitch line velocity determines the contact time between gear teeth. High velocities are generally associated with light loads and very short contact times. For these applications, low-viscosity oils are usually adequate. In contrast, low speeds are associated with high loads and long contact times. These conditions require higher-viscosity oils. EP additives may be required if the loads are very high.

(f) Temperature. Ambient and operating temperatures also determine the selection of gear lubricants. Normal gear oil operating temperature ranges from 50 to 55 C (90 to 100 F) above. Oils operating at high temperature require good viscosity and high resistance to oxidation and foaming. Caution should be exercised whenever abnormally high temperatures are experienced. High operating temperatures are indicative of oils that are too viscous for the application, excess oil in the housing, or an overloaded condition. All of these conditions should be investigated to determine the cause and correct the condition. Oil for gears operating at low temperatures must be able to flow easily and provide adequate viscosity. Therefore these gear oils must possess high viscosity indices and low pour points.

Army Jill and the WW2 jeep.

Does all those numbers make your head hurt like mine? Simple truth? Use the right oil for your jeep engine…I use 10w30 to keep it simple.

 

 

So what is viscosity, anyway?

So what is viscosity, anyway?

As we saw in an earlier posting we need to be concerned about the viscosity of the lubes we employ in our WW2 jeeps (of course this is true in any vehicle). More from EM 1110-2-1424 28 Feb 99:

viscositypour

Effect of viscosity on flow of light and heavy oils.

Note–The spout in each container is of the same size, and each grade of oil has flowed for the same time. Graphic from TM 10-540, December 26, 1940

Viscosity. Technically, the viscosity of an oil is a measure of the oil’s resistance to shear. Viscosity is more commonly known as resistance to flow. If a lubricating oil is considered as a series of fluid layers superimposed on each other, the viscosity of the oil is a measure of the resistance to flow between the individual layers. A high viscosity implies a high resistance to flow while a low viscosity indicates a low resistance to flow. Viscosity varies inversely with temperature. Viscosity is also affected by pressure; higher pressure causes the viscosity to increase, and subsequently the load-carrying capacity of the oil also increases. This property enables use of thin oils to lubricate heavy machinery. The load-carrying capacity also increases as operating speed of the lubricated machinery is increased. Two methods for measuring viscosity are commonly employed: shear and time.

(1) Shear. When viscosity is determined by directly measuring shear stress and shear rate, it is
expressed in centipoise (cP) and is referred to as the absolute or dynamic viscosity. In the oil industry, it is more common to use kinematic viscosity, which is the absolute viscosity divided by the density of the oil being tested. Kinematic viscosity is expressed in centistokes (cSt). Viscosity in centistokes is conventionally given at two standard temperatures: 40 EC and 100 EC (104 EF and 212 EF ).

(2) Time. Another method used to determine oil viscosity measures the time required for an oil sample to flow through a standard orifice at a standard temperature. Viscosity is then expressed in SUS (Saybolt Universal Seconds). SUS viscosities are also conventionally given at two standard temperatures: 37 EC and 98 EC (100 EF and 210 EF). As previously noted, the units of viscosity can be expressed as centipoise (cP), centistokes (cST), or Saybolt Universal Seconds (SUS), depending on the actual test method used to measure the viscosity.

Say, you might be interested in Military Maintenance for MB/GPW Jeeps 1941-45 which is available from Amazon.com

How much does a jeep weigh?

How much does a jeep weigh?

Do you have the manuals? It’s in there. IF you don’t have them yet then look at this – General Stats.

 

What does a jeep weight?

What does a jeep weight?

Net weight – 2,453 lbs.

Do yourself a favor. If you haven’t already purchased the WW2 jeep manuals–do it! Amazon has a reprint of the complete set of maintenance manuals for the jeep –The Complete WW2 Military Jeep Manual (Brookland Military Vehicles).

Come home safe! Check your steering.

Come home safe! Check your steering.

You might want to look at an article from my book, Military Maintenance for the MB/GPW Jeeps 1941-45. The article Jeep Steering Gear was original from the WW2 Army Motors magazine. It basically suggests. “Before starting your adjustments on the ball thrust bearings on the cam you have to relieve the assembly of all load. Disconnect the steering gear connecting rod from the steering arm, loosen the instrument panel bracket and steering-gear frame bolts to allow the assembly to align itself.” And you really need the manuals, the cheapest way is $20 or less for the manuals on CDrom.

They have the added advantage that you aren’t mucking up your documentation on a single job. Just print and throw away when done.

Anyway if interested click on the link above. Good luck.

JillwBookNjeep

Among other things, you need the WW2 jeep manuals to work on your Willys MB or Ford GPW.

You need to get the manuals if you don’t already have them. Buy ‘The Military Jeep Complete’ technical manual it includes: TM 803, 1803A, 1803B. You might also consider the electronic version as well! It is so very important to own these manuals because they tell you the basics of what you need to know. What grade oil to use? How do you service the brakes?
Good bargain, print out the pages you need, take them to the garage, screw them up with grease and who cares ’cause you can print more. More advice can be found here.