Engines UMZ-4178, -4179, -4218 or ZMZ-4021, -4104 are installed on the car. All of them have basically a similar design

The engine is carburetor, four—cylinder, inline, four-stroke, with two valves per cylinder.

 Особенность и неисправности двигателя автомобиля УАЗ-3151, -31512, -31514, -31519

The order of operation of the cylinders: 1-2-4-3.

The cylinder block is cast from aluminum alloy. Cylinder liners cast iron, removable (wet type) or filled into the block on the engine UMZ-4218

Engine Characteristics

 Особенность и неисправности двигателя автомобиля УАЗ-3151, -31512, -31514, -31519

The sealing of the "wet" sleeves along the lower joint is provided by copper gaskets or rubber rings.

An aluminum clutch housing is bolted to the rear end of the block. The pistons are cast from aluminum alloy.

Two compression rings and one oil removal ring are installed on each of them.

Compression rings — cast iron, upper — chrome, lower — tinned.

The piston pins are of a floating type, they are held from axial movement by locking spring rings.

Connecting rods are steel, forged, I-section with a detachable lower head, the cover of which is fastened with two bolts with nuts.

A bronze bushing is pressed into the upper (piston head) of the connecting rod.

The crankshaft is cast iron, cast, full-bearing, with counterweights, dynamically balanced assembled with a flywheel and mounted in the cylinder block on five detachable main sliding bearings.

The main and connecting rod bearings are made in the form of inserts made of steel tape with an anti-friction aluminum-tin alloy applied to it.

The shaft is held from axial displacement by two thrust rings, which are mounted on both sides of the front main bearing.

The ends of the crankshaft are sealed with rubber cuffs. On the ZMZ-4021 and ZMZ-4104 engines, the rear end of the crankshaft was sealed with an asbestos cord gasket.

A hub is pressed on the front toe of the crankshaft, to which a damper pulley is bolted.

The cylinder head is cast from aluminum alloy. Cast-iron seats and metal-ceramic valve bushings are pressed into it.

The head is attached to the block by ten studs with nuts through a metal-asbestos gasket.

On the right side, the exhaust manifold and intake pipe are attached to the head.

The camshaft is cast iron, installed in the bored holes of the lower part of the cylinder block.

On engines manufactured before 1996, the camshaft was mounted on antifriction bushings pressed into the cylinder block.

At its front end, a textolite or polyamide bevel gear drive is mounted on the key.

Camshaft cams, when it rotates, act on cylindrical pushers that are installed in the holes of the block.

Aluminum push rods with steel spherical tips actuate the rocker arms of the valves mounted on a common fixed steel axis. There is a screw with a lock nut on the short arm of the rocker arm to adjust the gap in the valve actuator.

Thin-walled bronze bushings are pressed into the holes of the rocker arms.

The valves are made of heat-resistant steel. Each valve is equipped with two springs with right and left winding and is installed in a metal-ceramic guide sleeve made of sintered copper-iron graphite powder with molybdenum disulfide.

The valve rods are sealed with rubber oil-reflecting caps, which prevent the penetration of oil into the combustion chambers. The top of the block head is closed with a stamped steel lid.

The lubrication system is combined - under pressure and spraying.

The main and connecting rod bearings of the crankshaft, camshaft bearings, rocker arm bushings, upper tips of push rods are lubricated under pressure.

The gears of the camshaft drive and the drive of auxiliary units are lubricated with a jet of oil, and the remaining parts are sprayed.

The cylinder walls are additionally lubricated with a jet of oil, which is ejected from the hole in the lower connecting rod head. The gear oil pump is driven in conjunction with the ignition distributor sensor by a helical transmission from the camshaft.

The pump body is aluminum, and its working straight-tooth gears are made of cermet.

The oil is taken by a pump from a steel stamped sump pan through a mesh oil intake, then it passes the pump, a full-flow filter and is fed into the oil line.

The oil pressure in the system is limited by a pressure reducing valve. On ZMZ engines, the oil filter is collapsible, with a replaceable filter element.

A non-removable oil filter is used on UMZ engines. There are bypass and anti-drainage valves in the filter housing.

The sensor of the emergency oil pressure warning lamp (triggered when the pressure drops to 0.4–0.8 kgf/cm3) and the sensor of the oil pressure indicator are connected to the oil line. An oil cooler with a tap is also integrated into the lubrication system.

The radiator is connected parallel to the main oil flow and is installed in front of the radiator of the cooling system. When the faucet is open, part of the oil passes through the radiator, cools and drains into the pan.

The radiator faucet should be opened at an air temperature above 20 ° C and (regardless of temperature) when driving in severe road conditions.

The crankcase ventilation system is closed, forced with the discharge of crankcase gases into the intake system through an oil separator with a vacuum regulator.

The power unit (engine assembly with clutch, gearbox and transfer case) is attached to the car frame on four supports, two of which are placed on the sides of the cylinder block. The other two are supported by a plate mounted between the gearbox and the transfer case.

Possible engine malfunctions and methods of elimination

The engine does not start, but the crankshaft is turned by the starter

- No fuel supply or insufficient fuel supply:

The strainers of the fuel intake, carburetor, fuel pump or fuel fine filter are clogged, the fuel filter sump is clogged

Rinse the filters in solvent, blow with compressed air

- The fuel line is clogged

Blow the fuel line with compressed air, after opening the fuel tank plugs

- Air ingress through fuel line connections

Tighten fuel line connections

- The fuel pump valves are leaky, the diaphragm is damaged, the diaphragm spring is weakened, the drive lever is worn out

Check the fuel pump, repair it or replace it

- The float jams in the carburetor when the valve of the float mechanism is closed

Eliminate jamming, rinse and blow the valve with compressed air

- Frozen water trapped in fuel filters, carburetor or fuel lines

Place the car in a warm room. Warm up the pipelines and remove water from the fuel system by purging with compressed air

- The air flap does not close completely (when starting a cold engine)

Adjust the damper drive

- The fuel jets are clogged

Clean and blow the jets with compressed air

- The carburetor float chamber is overflowing:

- The float jams when the valve of the float mechanism is open

Eliminate jamming, replace worn parts

- The tightness of the float is broken

Replace the float

- The tightness of the valve of the float mechanism is broken due to disconnection or absence of a sealing washer on the valve

Install a new sealing washer

- The carburetor float chamber unbalance valve does not work

Check the operation of the valve and eliminate the malfunction

- Ingress of coolant into the cylinders:

- the cylinder head gasket is damaged;

Replace the gasket

- crack or sink in the cylinder head;

Replace the cylinder head

- the tightening of the nuts of the pins of the block head attachment has weakened

Replace the cylinder head gasket, check the flatness of the block head

- Ignition system malfunctions

Check the ignition system See. "Ignition system"

The engine is running erratically in idle mode

- Incorrect adjustment of the idle crankshaft speed

Adjust the low speed of the crankshaft

- Air suction through the intake pipeline gasket

Replace the gasket. Check the condition of the ends of the pipes and in case of non-flatness exceeding 0.2 mm, replace the pipeline

- The location of the high voltage wires on the distributor cover does not correspond to the order of operation of the cylinders

Connect the wires correctly

- Ignition system malfunctions

Check the ignition system See. "Ignition system"

The engine stalls when the throttle is abruptly opened

- The accelerator pump does not work (the diaphragm is damaged, the pump drive is faulty, the check valve is leaky)

Eliminate the malfunction of the accelerator pump or check valve, replace the pump

- The discharge valve of the accelerator pump sprayer turned out

Wrap the discharge valve

- The accelerator pump sprayer is clogged

Clean and blow the sprayer with compressed air

- Jamming of the discharge valve of the accelerator pump in its socket due to wear of its cone part

Replace the valve

The engine does not develop full power

- The engine is not warmed up

Warm up the engine

- Incomplete opening of the throttle valve when the accelerator pedal is pressed all the way down

Adjust the throttle actuator

- The air filter is dirty

Rinse the filter element

- Reduction of compression in cylinders:

- Looseness of the valves to the seats

To grind the valves to the seats, adjust the thermal gaps in the drive

- Combustion of exhaust valves

Replace the valves and grind them to the seats

- Severe wear, breakage or burning of piston rings

Replace the piston rings, pre-clean the grooves in the pistons

- Wear of cylinder liners and pistons to the limit values (the maximum gap between the piston and the sleeve is more than 0.30 mm)

Replace the sleeves (block) and pistons with rings

- The cylinder head gasket is damaged

Replace the gasket

- Poor combustible mixture

Rinse and purge the carburetor metering systems with compressed air, adjust the fuel level in the float chamber

- Early or late ignition

Adjust the ignition timing angle

- The silencer or intake pipe is clogged with carbon

Replace the muffler, clean the intake pipe

The engine is overheating

- Insufficient amount of coolant in the cooling system

Top up the liquid. Check for leaks in the cooling system

- The blinds are not fully open when the handle of their drive is fully recessed

Adjust the blinds drive

- The fan belt slips

Tighten the fan belt

- The upper thermostat valve does not open

Replace the thermostat

- Scale deposition on the internal surfaces of the cooling system

Rinse the cooling system with special descaling preparations

- Contamination of the inside of the radiator or clogging of the gaps between the cooling plates of the core

Remove the radiator from the car, rinse it from the inside and outside with a jet of pressurized water

- Large friction losses in the chassis of the car

Check the free rolling path of the car and, if necessary, adjust the brakes, convergence and wheel bearings

- Ignition is too late

Check and adjust the ignition timing angle

- The fan coupling is faulty

Replace the viscomufta

- The oil cooler is not included when driving in heat or heavy road conditions

Turn on the radiator

The engine warms up slowly to operating temperature

- The blinds are not fully closed when the drive handle is extended to the end

Adjust the blinds drive

- The upper valve of the thermostat is always in the open position

Replace the thermostat

Increased fuel consumption

- Increased fuel level in the carburetor float chamber

Adjust the fuel level

- The air jets of the main dosing system of the carburetor are clogged

Clean, rinse in gasoline and blow the air jets with compressed air

- The float chamber of the carburetor is constantly communicating with the atmosphere due to a malfunction of the unbalance valve

Eliminate the malfunction of the unbalance valve

- The carburetor air flap jams in the covered position

Adjust the damper drive

- The air filter is dirty

Rinse the filter element

- Fuel leaks in fuel line connections or through a damaged fuel pump diaphragm

Tighten the fuel line connections or replace the diaphragm

- Large power losses due to friction in the chassis of the car

Check the free rolling path of the car and, if necessary, adjust the brakes, convergence and wheel bearings

Lowering the oil pressure

- Sensor or pointer is faulty

Check the oil pressure with a control pressure gauge and replace the instruments if necessary

- Low oil level in the crankcase, which affects the amount of pressure when the car is moving on the ascent or descent

Check the level and top up the oil if necessary

- The gasket in the oil pump or under the flanges of the discharge tube is damaged

Replace damaged gaskets

- Ingress of foreign particles under the pressure reducing valve in the oil pump

Disassemble and flush the oil pump

- Failure of the spring of the reduction valve or loss of its elasticity

Replace the spring or put 1-2 washers of 1 mm each under it

- Wear of oil pump parts

Replace the pump assembly

- Fuel entering the crankcase through the damaged diaphragm of the fuel pump

Replace the oil, repair the fuel pump

- Decrease in oil viscosity due to overheating

Do not allow the engine to overheat, turn on the oil cooler in time

- Clogging of the oil intake mesh of the oil pump

Rinse the oil intake mesh

- Increase in the gaps in the crankshaft bearings above the maximum permissible due to the wear of the liners

Replace the crankshaft bearing liners

Increased oil consumption

- Removal of oil with crankcase gases:

- Leaky seal of the oil level indicator (oil dipstick)

Replace the probe seal

- Leaky seal of the oil filler cap

Replace the cover seal

- Increased breakthrough of gases into the crankcase due to wear, breakage or burning of piston rings, as well as wear of cylinder liners and pistons

To repair the cylinder-piston group

- Clogging of the filter element of the air filter

Rinse the filter element

- Oil ingress into the intake ducts through the valve stem gaps due to wear and aging of the material of the oil-reflecting caps

Replace the oil-reflecting caps

- Oil leakage through oil seals and seals

Replace oil seals, tighten connections, replace gaskets

Extraneous knocks in the engine (if the ignition is installed correctly and the recommended fuel is used)

- Large gaps between rocker arms and valve rods:

- The adjustment of thermal gaps is broken

Adjust the thermal gaps

- Excessive wear of rocker arm strikers and valve stem ends

Replace worn parts, adjust gaps

- "Drowning" of crackers with a valve in the sleeve of the spring plate

Replace damaged parts

- Destruction of bearing liners

Replace the liners

- Formation of a bully on the surface of the piston skirt

Replace the piston and cylinder liner (or adjust the cylinder block)

- Excessive wear of the ends of the pushrods or camshafts

Replace pushrods or camshaft

- The gaps between the cylinders and pistons have been increased above the permissible limit (the knock is heard only on a cold engine)

To repair the cylinder-piston group

- Increased axial play of the camshaft due to wear of the end face of the gear hub on the side of the thrust flange

Replace camshaft gear

- Increased axial play of the crankshaft due to wear of the thrust rings

Replace the front thrust bearing washers and press new pins

The engine does not start or runs intermittently

- The ignition timing is incorrectly set

Set the ignition timing

- Breakdown of the high-voltage wire from the ignition coil to the distributor sensor

Replace the wire

- Large gap in spark plugs

Adjust the gap

- Breakdown of the distributor sensor cover

- There is no spark discharge on the candles when starting the engine:

- Failure of the ignition coil or additional resistance

Replace the cover

- There is no contact in the terminals of the distributor sensor

Replace the coil or additional resistance

Restore Contact

- Breakage of the stator winding of the distributor sensor

Switch to emergency mode. Replace the stator