DIY 4hp18 automatic transmission repair

Installing an unrepaired torque converter on a newly restored automatic transmission, you risk immediately breaking the gearbox again, because it will contain all the wear products of the torque converter, and in the worst case, the metal parts of the bearings or blades.
Do you want to buy a used torque converter? Don't rush to make a mistake! It is impossible to guess the quality of the automatic transmission fluid coupling used, moreover, purchased at the same price as a reliable repair. We offer the exchange of your torque converter for an already repaired one from our warehouse, or we can carry out a high-quality overhaul in our workshop.

We also carry out a quick repair of your torque converter in 1-2 hours right in front of you. You yourself will see all its breakdowns. At the same time, we do not make an extra charge for the urgency of work.

1) Cutting the torque converter.
The weld seam, which connects the two halves, is carefully cut, leaving as much metal as possible. With proper cutting, the torque converter can be easily disassembled and reassembled 2-3 times on occasion. Unfortunately, many transformer repair shops remove all metal from the body the first time they cut it.

2) After cleaning all parts of oil and wear products, the repair itself begins. If necessary, a new torque converter lock-up clutch is glued on, the body surface is leveled under the new clutch. And here unscrupulous repairmen again have problems out of the blue. They grind the body for the new friction clutch so that they cut off almost all the metal through and through, because of this, through cracks then appear. A normal craftsman is neat and does not remove excess metal. Then other necessary parts are replaced - bearings, O-rings, oil seal, etc.If necessary, a new neck is welded into the transformer cover. This procedure requires accuracy and precision, since usually unskilled workers are not able to cut a hole in the lid to fit the new neck, but drill it half a millimeter more, which is fraught with runout and imbalance.

3) Assembly.
It is imperative to weld both converter halves back as factory. In this case, it is necessary to minimize the axial runout between the two halves (balancing) and ensure the tightness of the seam. For a good craftsman, even the appearance of the repaired unit matters, which is why, after being repaired in GIDROTOR, the torque converter looks the same as a new one made at the factory.

In the video, the usual average result of our repair is a runout of 6 hundredths of a millimeter with an allowable runout of 3 tenths.

An automatic transmission is an expensive component. There is no point in delaying the repair if it starts to work incorrectly. In a car service, such repairs are expensive. You have to pay for the work of specialists and for the details. Having studied the market and the price range of services in this segment, motorists come to the conclusion that repairing automatic transmissions with their own hands is not such a pointless undertaking. The prices of the workshop masters cannot be called modest, and the professionalism does not always correspond to the price. And, after some thought, motorists can decide to fix the problem on their own.

Wherever you decide to repair the gearbox, the whole process goes according to the following scheme:

• diagnostics,
• dismantling the box,
• disassembly of the box,
• complete set with spare parts,
• assembly (installation),
• installation on a car,
• diagnostics after repair.

To fix the problem yourself, you will need some car mechanic skills, tools, time to work, patience, and perseverance.

All automatic transmissions are arranged the same, but there are two types of transmission control - hydraulic and electronic. Their renovation has some differences.

It is important to notice transmission problems at the earliest possible stage. Then, with the correct diagnosis, complex repairs can be avoided. Quiet and smooth operation of the automatic transmission is considered normal. There are a lot of signs that something is wrong with the box. Most often these are extraneous sounds when changing gears or during robotic transmission. It can be crunching, clicks. An unpleasant smell also speaks of problems. It can appear during long-term or short-term operation of the box. It is worse if the gear shifting slows down, or one of them does not work at all. Then immediate intervention is required.

Do not be lazy to look under the car, it should be clean there. Red spots will indicate an oil leak from the transmission. Checking the oil level regularly is a must. Normally, it should be translucent, reddish in color. No burning smells or muddy shades! If they appear, it's time to change the oil.

Automatic transmission malfunctions often arise due to improper operation. The transmission becomes unusable due to insufficient oil level or overheating. For this reason, the gears wear out, the machine can jerk when changing gears. As a result, any part of the automatic transmission may fail. Shocks while driving indicate overheating of the oil and the appearance of problems in the valve body.

Aggressive driving with hard acceleration and braking will erase details. Does not add durability to the box and driving in traffic jams, slipping. All this leads to overheating of the box and has a bad effect on its general condition.

All faults are divided into two subgroups. They can occur in

• electronic control system,
• mechanical and hydraulic parts of the gearbox.

If a malfunction occurs, the automatic transmission goes into emergency mode, that is, it goes to third speed and does not switch. The corresponding icon appears on the display.

If problems have arisen with the electronics, then it will not be possible to fix them by repairing the automatic transmission. Therefore, it is important to understand the nature of the faults.

In diagnostics, the main thing is to collect the necessary information and interpret it correctly. Therefore, it is better to consult a specialist. Determine what the problem is at the service station, and take care of the repair yourself. Without proper experience and equipment, you will spend a lot of time on diagnostics. There are mechanical and computer diagnostics.

General scheme of diagnostic procedures:

• check the oil,
• check the operation of the engine at idle speed, the connection points of the wiring and cables,
• determine the error codes of the operation of the control units (CU) of the gearbox and engine,
• check the box on a car without movement,
• check the automatic transmission in motion,
• check the pressure inside the control system.

If the cause of the malfunctions is electronics problems, then most likely you will not need to dismantle and disassemble the automatic transmission. Diagnostics of malfunctions in this system is carried out by the control unit. It monitors the sensor signals, the transmission ratio and the resistance of the output circuits. Malfunctions of such parts and assemblies may occur:

• input sensors,
• electronic control unit,
• executive devices of the control system,
• violation of the integrity of the electrical wiring connections.

The transmission computer receives signals from various sensors. If some parameters are out of order, it writes the code of this problem (DTC) into memory. You can decrypt such numbers using a special scanner.

These are the main problems of the automatic transmission itself. They are conventionally divided into three subgroups:

1. Damage to friction groups, bushings and housings, calipers, planetary gear sets, pump and other mechanics.
2. Defective transformer. This includes:
   • breaks in the splines of the wires,
   • mechanical destruction of the blades,
   • overrunning clutch,
   • wear of the main blocking clutch,
   • depressurization of the piston oil seal.
   • Problems with the mechanics of the hydraulic plate.

If the diagnostics were successful and you cannot do without dismantling, then we proceed to this stage of the automatic transmission repair.

You will need a special lift, or at least a viewing hole. As well as a transmission jack and a set of keys. It is better to perform this procedure in a specially equipped garage or box. It will not be superfluous to invite several physically strong guys to help you move the removed box. Its weight is beyond the strength of even a very strong person. Further action plan:

1. disconnect all communication tubes and cables;
2. unscrew the torque converter mounting bolts, as well as the motor flywheel membranes;
3. remove and move the gearbox;
4. assess the scale of the breakdown and start repairing.

Before removing the gearbox, the oil does not need to be drained from it. However, then do not forget to substitute the container in the place where the oil supply pipes are attached when you disconnect them - otherwise you will get an ugly puddle under your feet.

All actions must be careful. Sudden movements can damage the splines on the input shaft of the diaphragm.

It is better to do automatic transmission repair with your own hands, having it at hand proprietary manual and a printed diagram of the gearbox. First you need to inspect all the systems that serve the gearbox, mounts and blocks. Then we proceed to the repair. For this:

1. We disassemble the gearbox, wash and dry the parts and check them for defects.
2. We change all gaskets, seals, as well as worn out parts.
3. Remove the inhibitor block and sump. We clean out the dirt inside. It looks like metal magnetic shavings.
4. We remove the wiring of the ring from the plug and push them inside the plug.
5. Remove the valve body, loosen the brake band bolts. We wash the valve body.
6. We check the clutches, gears and planetary gears for wear.We will replace it if there is such a need. All internal rubber bands must be changed!
7. We open the oil pump. We check all the details, especially the filter. We change what has already served its term. We use the manual so as not to swap parts.
8. We take out the valves and springs. We wash the valves. Their sticking can be the reason for incorrect operation of the automatic transmission. Replace the accumulator springs if they are broken.
9. Putting everything back into place. It is important not to confuse anything!
10. We replace rings and friction bolts.
11. We check the gear shift assembly and the large piston and put the oil pump in place.

Assembly takes place upside-down.

There are some points that it is advisable to take into account when repairing. Often a transmission problem is related to the filter. It will not be possible to change it without removing the valve body. And when it is removed, the gasket breaks. To replace it, you will need to disassemble the valve body completely. The same applies to the accumulator spring from first to second gear. A special stopper does not allow you to remove it without disassembling the valve body. All valve body gaskets are very similar, do not mix them up. Assembling the valve body, we tighten it with a torque wrench. It is important not to overtighten here.

If all the breakdowns are eliminated, we install the automatic transmission. The moment is responsible, haste is inappropriate here. During these works, the following recommendations should be adhered to:

• When installing the automatic transmission in its place, the diaphragm is checked for end runout using an indicator head. If such a defect occurs, then it must be replaced.
• The radiator is flushed until the gasoline is clean. Then a liter of transmission oil is poured into the gas turbine engine and put on the input shaft. You need to achieve a secure connection and a complete fit. Then you need to dock the engine with the box along the guide centering pins. The crankcases must abut completely.
• Tightening the bolts in the box is the next step. After that, the absence of gaps along the entire plane is checked. After connecting all the highways, the correctness of the connections is checked.
• At the final stage, oil is poured and the operation of the automatic transmission is checked at low engine speeds.

Beginning the installation of the box, be sure to check for the presence of centering pins on the crankcase flange - there should be two of them. If at least one is missing, the automatic transmission cannot be attached.

Automatic transmission repair and diagnostics do it yourself - not an easy but feasible task. Choosing a car with an automatic transmission, novice motorists believe that repairing it at home is impossible. This is not true. But before deciding to carry out such important work at home, you need to weigh all your possibilities. Then you will not be in for unpleasant surprises during the renovation.