ASCII.jp Maintenance of U.S. military vehicle Humvee, oil was not the only leak

I will continue to disassemble around the engine

Humvee was found to have an oil leak when he found a stain on the ground. She rushed to Sky Auto in Saitama, which is always indebted for maintenance, and as a result of having the bonnet hood removed and checked, not only engine oil but also coolant (cooling water) and fuel for cooling the engine are leaking. I found out.

Humvee's engine is offset backwards enough to dig into the cabin in the second half, with a big radiator in front of him. This radiator is a super obstacle when I try to maintain the engine.

I removed various things for engine maintenance, and now I can see the water pump.

So, last time (282nd "U.S. military vehicle Humvee, docked for the largest heavy maintenance ever"), I removed the radiator, power steering oil cooler, shroud that sends the wind to the cooling fan, etc. I removed the fan and the coupling and pulley that fix the fan from the engine that I could see.

This time it's a continuation. Remove the water pump behind the fan.

Hose that bypasses the coolant

The water pump is a pump that circulates coolant and is an important part to prevent overheating. There are two hoses connected to the top, so first remove them.

The water pump is in the center.Above the pump, the thermostat bypass hose is connected to the right and the heater hose is connected to the left.

The hose on the right is the thermostat bypass hose, which allows the coolant to pass through when the thermostat is closed.

The thermostat is a valve that opens and closes depending on the temperature, and closes when the water temperature of the coolant is low. The coolant that has taken the heat of the engine and has risen in temperature is cooled by the radiator and heads for the engine again, but when the thermostat is closed, the water channel to this radiator is blocked.

So what happens to the lost coolant is that it returns to the engine through this thermostat bypass hose. In other words, the coolant circulates at a high temperature.

The reason why it works is that the engine is not something that should be cooled anyway, but it does not operate normally even if it is too cold.

The coolant has a proper temperature, 190-230 ° F (88-110 degrees) for Humvee. When the engine is cold = the coolant is cold, it is necessary to raise it to that temperature as soon as possible, so the radiator is not used.

The Humvee thermostat is designed to open when the engine warms up and the coolant reaches 190 ° F (88 ° C) and fully opens when it reaches 212 ° F (100 ° C).

Also remove the hose that connects to the heater

The other one, on the left, is the heater hose. A hose through which the coolant returning from the heater core of the heating passes.

A heater core is a device like a small radiator. Coolant heated by the engine passes through the inside, and the wind of a fan called a blower fan hits here, and warm air is sent to the inside of the car. It's the same as hot air coming out from behind the radiator while the engine is running.

It is a smart system that reuses the heat that is originally wasted. The air conditioner of a general car also uses a heater core for heating, and is combined with a cooling device to make an air conditioner.

The coolant cooled by passing through the heater core joins the coolant from the radiator and returns to the water pump.

Remove both hoses

The thermostat bypass hose and heater hose will get in the way in the subsequent work, so loosen and remove the fixing band.

When you remove the cover, the gear will come out.

Next is the engine oil filler port. The black pipe above the water pump is the lubrication port, which is also an obstacle, so remove it.

Remove the engine oil filler above the water pump

There was a hole in the place where the lubrication port was attached. This part is a part called an adapter plate, which is a cover for the fuel injection pump gear that drives the fuel pump. Since the water pump is attached to this plate, remove the adapter plate together with the water pump.

When you remove the adapter plate, the gear of the fuel injection pump and the pump drive gear will come out from inside.Both are for driving fuel injection pumps.

You can see the two gears by removing the adapter plate. Above is the fuel injection pump gear, and below is the gear to rotate it. It is called a pump drive gear.

Behind the pump drive gear, there is a gear called a timing gear, and the two are fitted together on the camshaft. Furthermore, since the timing gear is connected to the crankshaft with a chain, the fuel injection pump, camshaft, and crankshaft move in tandem.

The camshaft is a cam for opening and closing the intake and exhaust valves, and the crankshaft changes the vertical movement of the piston into rotational movement. In other words, fuel injection, opening and closing of the valve, and vertical movement of the piston are operating at the same timing, and it is this part that transmits them.

Was leaking from here

The case containing the gear is called the timing gear cover. If the operation timing of each gear is off, abnormal combustion may occur, but this repair is not there. The problem is not the inside but the outside. The adapter plate and timing gear cover.

When I removed the adapter plate, the bottom of the timing gear cover was discolored. The one that seems to be particularly dangerous is the lower left. You can see that the discoloration spreads toward the lower right of the hole.

The large holes at the bottom left and right of the timing gear cover are the coolant path.The discoloration of the surroundings is evidence that the coolant and oil were leaking.

This is a trace of coolant and oil flowing. It means that it was leaking from here. The seal between the adapter plate and the timing gear cover is not a special product but a liquid gasket, but it seems that the cause is that a gap has been created due to aging. Fortunately, the adapter plate and timing gear cover did not seem to be distorted or chipped.

Clean the adapter plate and reuse it

Clean the removed adapter plate by removing the old liquid gasket that has stuck. After that, I applied a liquid gasket to the seams and reassembled it as before, but since it was disassembled so far, I asked him to check the points that can not be confirmed unless it is in this state.

I also want to get rid of the fuel tank, which is not leaking flashy, but the fuel is seeping out. Next time around that!

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