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Tech Tips 2020 no. 1

Steve Turchet dives into what is ailing your military vehicle
Tech tips Jeep


I bought a Kaiser M715. Can you tell me something about the engine? — Craig Larsen

I’m not sure what you want to know, but here’s some data:

The Tornado 230 cid in-line 6 cylinder engine uses a cast-iron block and cylinder head with overhead valves and an overhead cam. The Tornado is the only Kaiser-built engine to be used in Jeeps. (The four-cylinder L-head and F-head engines, and the 6 cylinder L-head were Willys’ designs.)

The Tornado was used in Jeep pickups, Jeep stationwagons, J-series pickups, Wagoneers, and M715s and their variants. The Tornado was used in Jeep pickups (Gladiator) from 1963 until 1965.

Tornado 230

Bore x Stroke: 3.34” x 4.38”

Displacement: 230 (3.76L)

Compression Ratio: 8.5:1

Horsepower (net): 140@4000rpm

Torque (net): 210@1750

Main Bearings: 4

Valve Configuration: SOHC

Carburetor: 1bbl or 2bbl

A low-compression version of the 230, using flat instead of dome-top pistons, was available in Jeep pickups, Jeep wagons in 1964. It was also available in Jeep pickups and Jeep wagons in 1965, and was used in the M715 and variants.

Tornado 230

Bore x Stroke: 3.34” x 4.38”

Displacement: 230 (3.76L)

Compression Ratio: 7.5:1

Horsepower (net): 133@4000rpm

Torque (net): 199@2400

Main Bearings: 4

Valve Configuration: SOHC

Carburetor: 1bbl or 2bbl

When It Sucks

It can be very aggravating having an HMV with an engine that won’t idle correctly and/or stumbles and hesitates on acceleration. These are sometimes symptoms of a vacuum leak.

Vacuum leaks are also called false air, or air that enters an engine where it’s not supposed to. Cracked, loose, or broken vacuum lines, leaking intake manifold or carburetor gaskets, open or missing carburetor fittings, and loose or missing carburetor screws are just a few of the sources of vacuum leaks.

Vacuum leaks can be difficult to detect, especially those that affect the intake-manifold gaskets. Other than listening for an obvious hissing sound, one of the basic ways to determine if your engine has a vacuum leak is to remove the air cleaner and cup your hand over the carburetor intake while the engine is idling. This artificial choke will create a richer mixture. If the idle speed increases and/or a ragged idle smooths out, there’s a probably vacuum leak somewhere.

Test It Right

Before testing the condition of a battery with a hydrometer, check the level of electrolyte. Add distilled water as needed. Then start the vehicle’s engine and let it run at a fast idle for at least 20 minutes, or attach a charger for 20-30 minutes.

Charging mixes the water and electrolyte. Make sure you do this. If they don’t mix, you’ll end up only testing water. This mixing also helps keep plain water from freezing, preventing cracked battery cases. It’s best to test the electrolyte right after shutting off the engine.

Staying Normal

No matter how cold it may be outside, your vehicle’s cooling system should be able to reach and maintain 160-180°F. If it doesn’t, check the thermostat: it may need replacing. A vintage vehicle engine that always runs at more than 200°F also probably needs attention.

A broken thermostat, a clogged radiator, a bad radiator cap or dirty coolant may be the culprit. Or, the engine’s air flow may be blocked.

To speed up heating in freezing weather, you can partially cover radiator’s the air intake grille with canvas when starting the vehicle. But remember to remove the cover after the engine reaches operating temperature.

Also inspect the radiator cap. It should be the type your service manual calls for. Just any cap that fits won’t do. The pressure rating of the cap is vital. Too low a rating lowers the boiling point of the coolant. Too high a rating builds up pressure that can crack radiator seams or blow out hoses.

Early Or Late?

I have a chance to buy an M38A1. It has been stored for many years and seems to be in very good condition.

This will be my first military vehicle and I want to restore it correctly. The seller says it is an early model. I don’t know much about these vehicles yet, but I thought most jeeps were the same except for the style, like the MB, M38, etc. Is there a way to tell if this is really an early model? — Steve Brown

Most military vehicles that were in production for a fairly long time had modifications or updates. Some of these changes are subtle and not easily spotted except by experienced eyes... such as the style of transmission/transfer case skid plates on WWII jeeps. Other production changes are obvious, such as the front fender differences between M151s and M151A2s.

In the case of the M38A1, early production models generally had hinges on the bottom of the grille so the grille could be folded forward for engine replacement. Many early models also had the cowl battery box cover secured by thumb-screws. Later production models did not have a hinged grille, and had metal straps to hold the battery cover in place.

There were a few other differences, such as the seams on the front fenders and radiator brace rods, but if your potential purchase has a hinged grill it’s a pretty safe bet it’s an early model. 

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