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Valve Body Repair AW55-50SN AW55-51SN (Volvo S40 V50 S50 S60 XC70 S90 XC90 / Chevrolet Lacetti Captiva Epica / Opel Vectra C)

Valve Body Repair AW55-50SN AW55-51SN (Volvo S40 V50 S50 S60 XC70 S90 XC90 / Chevrolet Lacetti Captiva Epica / Opel Vectra C)
Valve Body Repair AW55-50SN AW55-51SN (Volvo S40 V50 S50 S60 XC70 S90 XC90 / Chevrolet Lacetti Captiva Epica / Opel Vectra C) Valve Body Repair AW55-50SN AW55-51SN (Volvo S40 V50 S50 S60 XC70 S90 XC90 / Chevrolet Lacetti Captiva Epica / Opel Vectra C)
Price: €237.50

1920 pcs (Shipping from Poland in 1 day)

Total in stock: 2828 pcs (if you order more than 1920 pcs - shipping time will be longer at 3-5 days)


Product Code: AW55VBREBUILD

Weight: 10.00 kgs

AW55-50SN / AW55-51SN -one of the most famous and reliable 5-speed automatic transmission Aisin Warner, since 2000 it was installed on almost the entire Volvo lineup, and a little later - after running-in and several upgrades - and other major manufacturers (General Motors, Renault) began to install AW55 series boxes on their front-wheel drive cars with an engine capacity of up to 3 liters.

We can say that the AW55-50SN is a representative of the "old school" automotive industry, when the engineers were interested not only in the race for the number of gears and their shift speeds, fuel economy and following environmental standards, but also in the reliability and maintainability of the unit. AW55 can easily depart 150-200 thousand km. run without any complaints, of course, if the oil changed regularly and the driver did not overload the transmission.

At the same time, when such a mileage is reached, problems usually begin to appear, since no matter how reliable the design - wear of such automatic transmission components as friction discs, bushings, brake bands is just a matter of time.

Generation also appears in the hydraulic control unit of the box - solenoids clogged with dirt begin to wedge, the plungers and channels of the hydraulic plates wear out (as a result of which tightness is lost and the valve body does not work as usual).

Malfunctions of the valve body are expressed in the following symptoms:

  •  pause and thump when DRIVE mode is activated;
  • thumps when braking from 3rd to 2nd gear;
  •  slippage when switching from 2 to 3 and from 3 to 4 gears;
  •  malfunctioning of auto-neutral

We will onsider the valve body repair on a real example. This valve body has a small background, it was repaired before us, and after installation on the car and a test drive, it turned out that after the repair it became worse than it was before the repair.

Let us consider pricing. The cost of valve body repair at Maktrans, as always, consists of 2 components - consumables and work, which means that it is better to carry out the repair when the first symptoms of the  failure appear - it will be cheaper. Below is a table with a calculation of the cost, it turns out $ 350, but options are possible - it depends on the condition of the hydraulic plates.

Works Price
Diagnosis (disassembly, washing, vacuum testing, visual inspection and inspection of plungers for jamming) 100$
Testing solenoids on the stand - 5$ per piece. AW55 8 solenoids. 40$
Solenoids regeneration- 40$  per piece.  # solenoids are being regenerated. 120$
Reaming valvebody channels and installing oversized valves. Reaming of one hole is  - 20$, plunger - 10-12.50$. 2 plungers and 2 booster valves are being installed 90$
Assembly (valve body gaskets- free of charge) and final control  Free of charge Free of charge

If you decide not to repair the valve body and immediately purchase a new one, remember that the Volvo and GM valve bodies are not interchangeable. We have  both options in stock.



We proceed to disassembly and troubleshooting.

Here, the professionalism of those who repaired before us is immediately noticeable. The plate that fixes the PWM solenoids is screwed on the contrary, and in order to screw it so - you need to apply serious force and bend the solenoids.

It is necessary to unskrew  and remove the solenoids. The AW55-50SN has 3 PWM (PWM) solenoids and 5 ON / OFF's


We unscrew and disassemble the plates. Before removing the plungers - we check them for jamming, the standard procedure.


Taking out the plunger and plugs - it is convenient to use a magnet

We carefully remove all the springs, plungers, plugs, booster valves - in no case they should be lost. Such a mistake was made by the master who repaired the valve body before us - a few errors in the assembly; paper gaskets of the valve body were not installed on all separator plates. To understand the problem, the photo below shows the entire contents of the valve body plates. If you repair yourself - we strongly recommend photographing each step of disassembly, it will be easier to assemble.

Diagnostics and solenoid repair

Disassembled hydraulic plates are sent to an automatic sink. While they are being washed, we will begin to check and repair the solenoids. As mentioned above, the AW55-50SN has 3 linear solenoids (SLT, SLS and SLU), dirty oil destroys them much faster than the shift solenoids S1, S2, S3, S4 and S5 due to the higher load:

  • SLT solenoid - pressure control in the entire valve body, that is, the oil coming from the pump passes through this valve;
  • SLS solenoid - gear shift control;
  • SLU solenoid - torque converter lock

Starting test on the stand

 We get such a schedule. It indicates serious problems with the plunger, this can be either because of severe contamination (if the box burns out), or mechanical wear - bushings, washers or plunger.

We disassemble. A special tool is used, it consists of several mandrels for disassembly / assembly and a cutter that opens the solenoid housing. First you need to fix the housing and unscrew the adjusting screw.



As expected, fine metal dust and the washer (plain bearing) have critical wear inside, it must be replaced

 Next is cleaning the solenoid (for polishing you can use sandpaper with fine grain, as in the photo below) and, if necessary, replacing the sleeve and washer. The sleeve is replaced if the valve body has been operated "to the last" and dirty oil as an abrasive has erased the inner surface. The sleeve works as a guide for the plunger, and if there is wear out, there will be distortions during opening / closing, which will lead to shocks or slipping.

Now we can assemble and close the solenoid

Recheck and adjust the solenoid on the stand. In the case of AW55 - you will not be able to repair the solenoids in the "home" conditions, since they need to be adjusted using the screw that we unscrewed at the beginning of the disassembly. The process looks as follows - if the schedule is stepwise - we twist or unscrew the adjusting screw until we get the perfect result. The procedure is repeated for each solenoid.

Diagnostics and hydraulic part repair

We are taking clean plates

We begin a visual inspection. An experienced repairman knows the most heavily loaded sections of the hydraulic plate and immediately draws attention to them. In the photo below - the valve body is cut for a more visual demonstration. This wearout usually accompanies a high mileage with rare oil changes. Visual troubleshooting is important because such damage will not always be noticeable during vacuum testing, but the plunger can wedge. And only at a certain temperature regime, for example, only after heating.

Found a problem area

Now vacuum test

Based on the results of visual inspection and vacuum testing, it was decided to replace the following plungers:

The rest of the Maktrans oversized plungers for AW55-50SN can be viewed here

To install a repair valve, you need to drill a channel in the valve body to a new size, for this we use our own production reamers. We show how this happens on the example of a torque converter lock-up valve. First, the plate is fixed, with particular attention being paid to setting the cut length, since the blocking valve is two-staged. To do this, use the guide, included in the reamer kit. The plate is exposed, securely fixed, we turn on the cooling. It looks like this:

We can start cutting

After reaming the hole, we wash the plate, blow it with compressed air, insert the repair valve and repeat the vacuum test

We have restored the tightness of the channel, which means there will be no pressure leaks. Moreover, the strength of the coating of our plungers (anodizing) is much higher than that of the original valve, so such repairs are not only cheaper, but in some aspects also more reliable than the option with the purchase of a new valve body. We can proceed to the assembly:

                                                                                                   We put a new torque coverter lock up booster valve 




Valve body is collected

For such repairs, we give a 1 year warranty without mileage limitations, but you need to understand that often problems with the valve body are caused by some external factor, for example, wear of the lock in the torque converter. burnt clutches or a collapsed bearing, the chips from which fell into the hydraulic part. Therefore, before installation, we rinse the cooling system, repair the torque converter, put a new filter and change the oil.

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