DIY ud 15 engine repair

In detail: do-it-yourself repair of the ud 15 engine from a real master for the site my.housecope.com.

Engines UD 25 and UD 15 were produced many years ago, but are still used by amateurs of such equipment. Despite the fact that they are more than a dozen years old, they serve faithfully to their owners. Such engines were used to drive electrical power units and mobile power plants, various agricultural, construction and road machines, including MTZ walk-behind tractors, often used on homemade mini tractors.

Stationary subcompact engines UD-15, UD-25 and their modifications are designed on the basis of the MEMZ-966 (965) engine of the Zaporozhets automobile. The UD-15 engine is single-cylinder, and the UD-25 is two-cylinder. Both UD models are made according to the same design scheme and are maximally unified.

Listening to the engine UD 25 and UD 15 in order to diagnose malfunctions

Listening to the engine during its operation allows you to determine the state of the main parts in the places of their connections (landings). The knock of the piston, which occurs when the pistons are badly worn, is well audible on an unheated engine on the left side of the cylinder. The knock of the piston pin, which occurs when there is a large gap between the pin and the connecting rod or the pin and the piston, is heard in the upper part of the cylinder head, and, with a sharp increase in revolutions, the knock increases.

The knock of the connecting rod, which occurs when there is a large clearance in the connecting rod bearing, is best heard in the upper part of the crankcase near the cylinder. The noise of rolling bearings, which occurs during their wear, is heard near their installation sites. Gear noise occurs when the meshing clearance is increased. The knock of the rocker arms, which occurs when the clearance between the valve and the rocker arm is increased, is heard in the upper part of the head.

Video (click to play).

Also on these motoblocks the SK 6 and SK 12 engines were used. Here is the user's manual for these engines.

UD 15 engines were installed on the MTZ walk-behind tractor. Detailed information on MTZ 05, MTZ 06/12 walk-behind tractors is posted on the corresponding pages of the site.

The K-16M (K45M) carburetor is installed on the UD-15, UD-25 engines. The carburetor device is shown in fig. 10, 1 1. Carburetor 3 (Fig. 10) is adapted to work with a centrifugal regulator: throttle valve 6 is controlled by a lever with a sphere, which is acted upon by the regulator lever 7. For manual control of the throttle, there is a leash in the upper part 2. Air damper 9 is operated manually.

The carburetor provides the ability (if necessary) to adjust the engine at low idle speed. The adjustment is carried out by the stop adjusting screw 4 located on the throttle lever in the upper part. Low idle speed should not exceed 1600 rpm. Adjustment of the mixture quality at idle speed is made with screw 5.

Fuel is supplied to the carburetor by a diaphragm fuel pump 10 from a separate gas tank not connected to the engine. The fuel pump is operated by a cam located on the camshaft. The design provides a lever for the manual drive of the fuel pump.

Air enters the carburetor through an inertial oil filter 1. The fuel level in the float chamber is maintained constant (19 ± 2 mm) by means of a float 1 (Fig. 11) and a shut-off needle 2. With the float lowered, the channel through which fuel comes from the gasoline pump, open. The fuel, filling the float chamber, raises the float, which closes the fuel supply channel with a shut-off needle. There is a float sink in the float chamber cover. The carburetor float chamber is not balanced.The idle system is fed with fuel up to the main jet.

CARBURETOR OPERATION

Engine starting... The engine is started with a closed throttle valve so that the air between the valve and the wall of the mixing chamber flows at a speed sufficient to atomize the fuel. In this case, although the fuel is supplied through the main jet, it is mainly the idle system that works. Only a small part of the gasoline flowing from the main jet, mainly light fractions, will participate in the mixture formation.

Idling... When the engine is running at minimum idle speed, the throttle valve is open 1-2 °. The fuel-air emulsion enters through a hole adjustable by screw 4 (Fig. 10) located behind the throttle valve. As the throttle valve is opened further, the second hole in the idle system also enters the space behind the throttle valve, and fuel begins to flow through both holes. When the engine is idling with a regulator (n = 3000 rpm, throttle opening - 5 -7 °), in addition to the idling system, fuel is supplied through the main nozzle-atomizer

Medium loads. As the throttle valve opens, the vacuum in the diffuser increases, and the fuel supply through the main nozzle-atomizer increases. The role of the main dosing system is increasing. Thus, at medium loads, the fuel supply is ensured by the joint operation of the idle system and the main metering system.

You can ask questions only after registration. Login or register, please.Everything for the modernization and repair of the engineThis engine was installed on the MTZ-05 walk-behind tractor. The walk-behind tractor has been in operation since 1990.
Now I will write how you can convert to work on liquefied gas. On the intake manifold there is a twisted plug instead of the plug, you need to make a fitting for a thin hose to dia. 6mm. inside the fitting we press the emulsion tube from the carb. Solex 2108. Screw the plunger into the place of the emulsion plug. tube inside the collector. That's the whole engine rework. Next, we take a gas cylinder, connect it through a reducer (I have an adjustable carbon dioxide) hose and connect it to the fitting. Then we start the engine on gasoline, warm up normally and gradually open the gas, adjust the gas supply by the reducer (it is selected approximately several times, while the engine may stall) With optimal adjustment, we perform the following operations. We start the engine on gasoline, warm it up, then close the gasoline supply valve, and while the gasoline from the float chamber burns out, open the gas on the cylinder while closing the air damper by half, and if everything is adjusted correctly, the gasoline burns out but continues to work from gas

Since my tractor is assembled and adapted for the UD2 engine, I had to accept this ICE with all its whims. And he is capricious as a baby. And so the work plan:
1. Reducing the combustion chamber.
2.Altered intake manifold
3. Conversion of the lubrication system to full-flow
4. Alteration of magneto.
5.And maybe a starter.We proceed to reduce the combustion chamber. We mill the engine heads by 2mm
We cut on the pistons along the third compression ring. There is a place there just for it.
The rings fit from the IZH-Planet motorcycle.
Image - DIY ud 15 engine repair

The intake manifold was redesigned for the installation of a native carb, as well as a motorcycle carb.
I'll tell you how this was done. Cut off the carb mount from the collector, weld the hole in the collector with a plug. then we drill a hole between the intake manifolds and weld the fastener cut off there. And everything is ready, we put the carb and adjust it in place. By the way, for welding, these collectors are well cooked with simple electrodes and a change. see the photo

I also tried to start with a car carb. It works well but lets out a black smoke while it is postponed. I will tune it later, it works briskly with auto carb. Under the Solex, the collector also brewed

But while the native corburetor is installed.work is acceptable and lends itself well to adjustments.

Further, there is a full flow-through lubrication system.

We cut an m10 thread in the channel, screw in a plug made of an m10 stud 15mm long. We make sure that the plug covers only that part of the channel that we are jamming.

Then we drill a hole in the body to the plug and cut a thread in it. The thread depends on which pipes and fittings will be used. I used brake from a Muscovite.

We screw in the union. Fittings from brake vacums Gas 3507 or Gas 53 are ideally suited, there are just 4 of them on the frame. That is what the doctor ordered.

In place of the original filter, we make an adapter, and screw in the second tube.

This is how I brought the tubes to the filter

further magneto, redone very easily. From the old magneto remained the body, cams, slider and ignition timing. Added babin.

I'll wait with the starter, because there is no need for it yet. The engine starts with half a turn.

3.3. GAS DISTRIBUTION MECHANISMS FOR MINI TRACTOR ENGINES

Gas distribution mechanism of the UD-15 engine

To ensure the necessary valve movements, the large rocker arms are 1.3-1.5 times longer than the short ones and end with hardened cylindrical surfaces. In the short arms, there are adjusting screws with a ball head and a locknut 7, designed to adjust the gap between the large arm of the rocker arm and the valve. The rocker arms are located under the head cover 8, where the rods of the pushers 10 enter with their upper tips 9. The rods are hollow for relief, and the tips of the pushers are pressed into the rods and have spherical sockets: the upper ones are for the heads of the adjusting screws, the lower ones are for the pusher rods. The second rod has lugs with through holes through which oil is supplied.

To fix the rod covers in the cylinder head, a second spring 11 is installed between the rod thrust ring and the pusher bushing 12. The pusher bushings are pressed into the crankcase and have holes for oil supply. The correctness of the insertion is controlled by the marks on the sleeve. The pushers 13 are designed to transfer movement from the cams of the camshaft 14 to the rods. The pushers are mushroom-shaped with a flat head. There is an oil hole in the pusher rod. The pusher heads slide along the generatrix of the cams of the camshaft 14, which, in addition, has a fuel pump drive cam. The camshaft is driven by a gear 15 meshing with the crankshaft timing gear. In the engine crankcase, the camshaft is mounted on sleeve bearings 16 made of bronze tape. The gas distribution phases provided by the mechanism are given in table. 3.1, which also presents similar data for the ZID-3 engine.

Stationary grinding engines. UD-15, UD-25 and their modifications. technical description and operating instructions

1 Stationary milling engines UD-15, UD-25 and their modifications technical description and operating instructions ATTENTION! This publication sets out the design features of the engines, the requirements for operation and maintenance of them. Timely and accurate compliance with the rules of care and operation will ensure trouble-free operation of the engines. This publication cannot serve as a textbook for the course of engines, therefore, persons authorized to operate UD engines must have theoretical and practical knowledge of internal combustion engines and their operation. Due to the improvement of the design, non-fundamental deviations in the use of the engine from the text and illustrations of this publication are possible, which do not affect the quality of operation and maintenance of the engines. USSR V / O ENERGOMASHEXPORT MOSCOW 4

Fig. 3 1. Longitudinal section of the UD-15 engine: 1 - flywheel casing; 2 - ratchet nut; 3 - tube for supplying lubricant; 4 - oil filter cover; 5 - flywheel fan; 6 - cylinder cover; 7 - muffler; 8 - crankshaft; 9 nut М20; 10 - cuff of the crankshaft 7 Fig. 2. Longitudinal section of the UD-25 8 engine

6 The head of the UD-25 engine is made common for both cylinders, the head of the UD-T5 engine is two-cylinder in the form of a half compartment. COOLING The cooling system (fig. 8) removes heat from the cylinder walls and head. The engines have a forced air cooling system. The cooling system includes: flywheel-fan 4, flywheel casing 5, cylinder casing 2, air outlet casing 3. The degree of engine cooling is adjusted by opening or closing louvers 1 in the casing of the flywheel fan. Rice. 6. Gas distribution system: 1 - camshaft gear; 2 - a camshaft; 3- pusher bushing; 4 - valve; 5 - barbell; 6 - rocker; 7 - cylinder head; 8 - pusher 13 14

8 The carburetor provides the ability (if necessary) to adjust the engine operation at low idle speed. The adjustment is carried out by the stop adjusting screw 4 located on the throttle lever in the upper part. Low idle speed should not exceed 1600 rpm. Adjustment of the mixture quality at idle speed is carried out with screw 5. Fig. 10. Power system: 1 air filter; 2 leash; 3 carburetor; 4 adjusting screw; 5 screw idle; 6 throttle valve; 7 regulator lever; 8 carburetor throttle lever; 9 air damper; 10 fuel pump Fig. 9. Regulator: 1 - nut М8; 2 - clutch leading magneto; 3 - gear wheel of the regulator; 4 - ball bearing 203; 5 - ball bearing 303; 6 - carburetor throttle valve; 7- regulator roller; 8 - cam; 9 - Balancers; 10 - pushers; 11- lever; 12 - regulator spring; 13 - spring pin of the regulator Fuel is supplied to the carburetor by a diaphragm fuel pump 10 from a separate gas tank not connected to the engine. The fuel pump is operated by a cam located on the camshaft. The design provides a lever for the manual drive of the fuel pump

26 To clean the starting accelerator it is necessary to remove it, rinse it thoroughly in clean gasoline (without disassembly) and dry it or blow it out with compressed air. Then immerse in a mixture of 50% turbine oil L ”GOST with vaseline oil in accordance with GOST and in this way set the lubricated starting accelerator on the magneto. After 1000 hours of operation, clean the crankshaft cavities from deposits, for which: drain the oil; separate the pallet; turn the crankshaft so that the counterweights are at the top; unscrew the plug. Assembly is carried out in the reverse order of disassembly. Attention! When installing the flywheel-fan on the crankshaft, install the key as shown in Fig.

We proceed to reduce the combustion chamber. We mill the engine heads by 2mm
We cut on the pistons along the third compression ring. There is a place there just for it.
The rings fit from the IZH-Planet motorcycle.

But while the native corburetor is installed. work is acceptable and lends itself well to adjustments.

Further, there is a full flow-through lubrication system.

We cut an m10 thread in the channel, screw in a plug made of an m10 stud 15mm long. We make sure that the plug covers only that part of the channel that we are jamming.

Then we drill a hole in the body to the plug and cut a thread in it. The thread depends on which pipes and fittings will be used. I used brake from a Muscovite.

We screw in the union. Fittings from brake vacums Gas 3507 or Gas 53 are ideally suited, there are just 4 of them on the frame. That is what the doctor ordered.

In place of the original filter, we make an adapter, and screw in the second tube.

This is how I brought the tubes to the filter

further magneto, redone very easily. From the old magneto remained the body, cams, slider and ignition timing. Added babin.

I'll wait with the starter, because there is no need for it yet. The engine starts with half a turn.

3.3. GAS DISTRIBUTION MECHANISMS FOR MINI TRACTOR ENGINES

Gas distribution mechanism of the UD-15 engine

MTZ walk-behind tractor motor: gasoline or diesel?

The tiller does not include many parts. Each of them carries a certain burden on itself, and its absence nullifies the whole concept. walk-behind tractor.

The engine, like all cars, takes pride of place in the walk-behind tractor. Using the energy of combustible fuel, all internal components and mechanisms move. Thus, the fuel entering the combustion chamber is ignited by a candle. Fuel, burning, turns into gas, which presses on the piston. The latter is associated with the crankshaft, which provides torque to external mechanisms. Fuel supply and timing is carried out using valves, each of which can have multiple cylinders.

The resulting torque in the motor unit is used for two purposes. One of them is the rotation of the wheels and the movement of the entire block. Second. rotating attachment parts. Here, the transmission of energy is carried out by means of a transmission and a power take-off shaft.

Motoblock engines are required to provide clear and reliable functionality of the entire unit. They should be compact, economical, lightweight, relatively powerful and have a long motor resource.Since they are intended for private use, price matters a lot.

These requirements are met by small, single-cylinder, four-stroke gasoline and diesel engines. Their capacity ranges from 5 to 15 liters. With. This fully satisfies the ability of one person to operate and work with the motor unit.

There is always controversy around the use of the engine on walk-behind tractors. Both devices have their own advantages and disadvantages. Carbureted engines usually have an air-cooled system that allows you to gain somewhat in complexity and size. Liquid cooling is often used in diesel units.

The gasoline engine has a smaller size and weight, which greatly exalts them over diesel ones. It doesn't take much wisdom to get started, and the beginning itself is almost instantaneous. Another advantage of the gasoline unit. relatively low noise level. All these qualities start to disappear when it comes to fuel consumption. For comparison, a conventional diesel with a capacity of 9 liters. from. burns 0.9 liters per hour in medium mode. A gasoline engine, which is often installed on a domestic 5-liter walk-behind tractor. with., consumes twice as much at the same loads. Even after diesel is nearly equal to gasoline, diesel remains much more fuel efficient.