Toyota Crown Royal MS112 (1981) Information and hints.

I had this car for 16 years and did all of the servicing. It was modern for it's time with multi-point fuel injection 4 wheel disks and all the gismos like rear radio controls, separate rear A/C with a mini fridge , climate control etc. etc. It proved reliable and solid . The new owner has had it re-sprayed and my guess is that it has another 20 years in it.

The engine was not for the feint hearted as a lot of the control was by vacuum lines that all had to come off every 20,000k to adjust the valve clearances.


The short fuel hose on the top of the inlet manifold that connects to the cold start injector can crack and spray petrol over the engine.

This occurred on my car at about 160,000k. On talking to other owners of both Cresidas and Crowns with 5ME engines it seems to be a universal problem.

When I cut the hose open it was found to have deep cracks all along it's length that were not visible AT ALL on the outside except at the one point where it finally failed ie, IT WAS A DISASTER WAITING TO HAPPEN.

If the hose on your car has not been changed DO IT NOW. If your not sure of the its history and the hose shows any signs of cracking or if it is hard it may not have been changed.

I have talked to a mechanic and he said that the life of this hose is reduced by its location at the top of the engine where it is subjected to additional heat. This can occur when when the engine is turned off as the heat rises and the fuel pressure stays high.

bits in oil came from this idler wheel5ME BLACK PLASTIC BITS IN OIL

At about 150,000 k I found 1 or 2 small (2mm) bits of black plastic when I changed the engine oil. Later oil changes were clear. The mystery was solved years later when I visited a wrecking yard and found that it was common for the timing chain idler pulley to loose its teeth. The pulley has a steel centre hub with a moulded on plastic section that the chain runs on. Next time you have the rocker cover off have a look at the pulley. I don't know what problems if any this causes as what is left of the idler seems to run on the chain and keep it in tension.

It is common to see rust bubbles about 2 cm above the centre of the rear wheel arch.

This occurred on my car and was traced to rust holes behind the chrome trim that slopes down from the rain gutter above. The chrome is held on by two nuts behind a section of inside trim that pops off. It is obvious now that dirt will get trapped behind this chrome and cause rust so when replacing it I spaced it out from the body with plastic washers just enough to help with hosing it out and to let the air in to help keep it dry. When Fixing the holes I sprayed in anti rust oil from the top. The bubbles have not increased in size in 10 years.


The trunk lid develops cracks where the ends of the hinges are bolted to the lid. I was told about this but could not see it until I was shown. If you hold the lid open and move it up and down you can see the trunk metal flexing at the end of the hinge ( near centre of the lid) this movement leads to cracking. When the metal is weakened by cracking it is difficult to get a good seal with the rubber especially when the air pressure builds up at speed.

The fix is to put a sheet of steel between the hinge and the lid. This has to be big enough to spread the load over all of the raised area that the hinge bolts to. The steel sheet will need two holes for the hinge bolts and turned down edges to give it strength. I used a scrap (from fencing) of 2.6 mm thick 65mm square galvanised tube 230 mm long cut down the middle at a slight angle. With the corners rounded this gave two neat wedges. Thinner material would be better as with the extra weight the lid opens but does not fly up, probably a good thing.

Fitting it is not hard if you prop the trunk open with a padded length of wood and do each side in turn. I had to insert a washer between the hinge and the plate to adjust the angle of the lid for a good weather seal.

MS112 Fuel gauge repair.

Disclaimer I am not an expert and the following may be wrong or misleading.

If your fuel gauge starts behaving erratically you may have the problem described below.

The first step is to prove that the problem is in the gauge.

Disconnect the wire harness from the fuel sender (in the boot) then turn on the ignition. The gauge should move to empty. Connect a 33 ohm 1 Watt resistor across the pins attached to the yellow-red and white-black wires of the fuel sender harness. When the ignition is now turned on, the gauge should head towards ½ full and stay there. If you are tracing an intermittent fault crimp a couple of connectors onto the resistor and plug it in for a good connection, insulate with tape and drive around until you are convinced where the fault lies. If the gauge fails to stick near ½ the problem is in the wiring or more than likely the gauge.

Getting the gauge out.(RHD car with round gauges)

Disconnect the battery.

Remove the steering column cover.

Remove the "wood" section of the instrument panel by removing screws as follows

5 across the top, 1 above radio, 1 behind Dual A/C panel

1 behind the coin tray next to panel dimmer

1 behind aerial control (The switch only comes out)

Remove the dimmer knob and disconnect the various plugs that attach to switches

The bottom edge is held by tongues that slide out of clips.

Remove the 4 black screws holding the instrument cluster

Remove the speedometer cable (easier said than done any advice welcome)

The speedometer cable is held to the back of the speedometer by a plastic clip surrounding the cable. If you squeeze the back part of the lever it raises the front tooth and it can be pulled off. I found this part hard perhaps the cable could be removed at the gearbox end allowing the cluster to come forward so you can see what needs doing.

Remove the 3 plugs at top of cluster.

To test a gauge measure the resistance across the 3 terminals. The biggest side of the triangle should read 87 the next clockwise 328 then 241 within about 3 ohms is ok, do this before disassembling the cluster and check continuity from the gauge to the plug on the cluster.

How the gauge works.

There are 2 coils at right angles, one coil is in series (130 ohm coil with a 62 ohm resistor across it) and one coil (239 ohm) is in parallel with the sender variable resistor. As the sender moves to increase current in the series coil less current flows in the parallel one. The pointer moves to align with the field between the coils. It can not move with the ignition off because it is perfectly balanced, there is no spring and it is in a viscose bearing so it just sits there telling you what petrol you had when you last had the ignition on.

What often fails.

Bolted on the back of the gauge is a circuit board. Soldered and glued to the board are 2 ceramic resistors of 62 and 45 ohms. It is the solder joints beneath these that fail and go intermittent.

The fixes are.

Re solder in place using enough heat to melt the solder under the resistors. This will work but may fail later.

Remove the resistors tin them and re solder. It is hard to remove them but it should be reliable.

Substitute a combination of resistors for the ceramic ones (handy if you break one). Using miniature ½ watt 1 % metal film resistors. A combination of 6 x 270 paralleled gives 45 ohms and 3 x 240 and 1 x 270 paralleled gives 61.7 this combination will dissipate the 1.3 and .8 watts respectively that is necessary and they can be arranged so they do not foul anything when installed.

door1981 MS112 Crown Royal Interior renovation

My car was losing its a appeal because of an ageing interior caused by the Australian sun. The cracked dash problem was solved when I discovered that car carpet specialists could hand form dash mats. The result was not up to a manufactured unit but covered the problem nicely. The main problem was cracked vinyl on the ledges below the side windows and I repaired it as follows.

DISCLAIMER I am not an expert. The description of what I did may not be accurate and may not describe the best way to carry out this repair.

The door panels were removed by unscrewing the arm rest and door latch. I found this better than bothering to pry up the panel to disconnect the wiring to the windows first. Then the "pop" clips were sprung around the panel and it was lifted up. The drivers side had a mirror adjuster that needed removing first.

The metal strip at the top that holds the window rubber and the "tin" wood panel were removed by straightening the metal tags.

The rotten vinyl was removed by running a blade along the top of the plastic chrome strip and around the ends of it a little leaving the chrome strip attached to the backing board. I was careful not to cut into the backing board.

A soft automotive grade vinyl was cut using a straight edge to fit hard up against the plastic chrome strip, around the ends of it and under the "tin" panel and down the door to be tucked under the velour section. For this repair to work a 6mm edge of the vinyl had to be securely glued to the backing board above the plastic chrome strip. For this I used Fullaprene 303 a grey construction grade adhesive that was recommended for gluing rubber around bathroom floors. It is available in Australian hardware stores.

Jell type contact glue was used in less critical areas.

When the Fullaprene was fully dry new foam was installed ensuring that no excess permanent tension was applied to the critical glue joint.

Replacing the rear door panels is a little tricky as the rubber that holds the fixed glass has to be manoeuvred out of the way but I managed it ok.

The vinyl did not match the original exactly so the lower section of the centre pillar was recovered. This tied the new colour in nicely.

This job made a huge difference and has not deteriorated in the last 5 years.


With age your distributor can develop all the normal problems such as broken flexible wires, arcing rotors, worn bearings etc. but these are extremely rare as it is a quality unit. There are however two things you should check for.


As RPM increases a couple of weights fly out against the tension of 2 springs and cause the upper part of the distributor shaft to rotate forward thus advancing the timing. The maximum amount of advance is determined by the amount of movement of a pin in a gap.

There are at least 2 different types of advancer plate and each has 2 different sized gaps that can surround the pin and give different maximum advance. I believe that the number stamped near the gap represents degrees at the distributor (1/2 the crankshaft amount). My car uses a plate with 8 & 10 with the 8 being used, later models are marked with a 6 & (blank). This leads me to believe that the initial advance + the maximum advance from the distributor = 24 ie. for my car (1981 Aust. Spec. 8 :1 Comp. Min 89 Octane.) which uses 8 Degrees of initial timing the total advance would be 8+ (2 X 8 )= 24 and for later models with higher compression 12 initial + (2 X 6) = 24.


A sleeve that surrounds the pin comes off and you get about 50% too much maximum advance. A secondary effect is that the springs run out of tension before they can pull the advancer plate back against the now smaller stop pin.

A quick check for this problem is to feel if the rotor is being held back against the stop. The definitive check is to disconnect the vacuum lines and check the maximum advance with a timing light.

Adding a sleeve .9mm thick to the pin gives advance that matches the stamped number. I used copper wire wrapped around the pin then soldered. A friend used plastic tube. Before I found this problem my car had pinging on 91 octane with standard timing. I noticed the slop in the rotor and when it was not fixed by new springs looked further in to it. I found 2 halves of what could be the sleeve in the bottom of the distributor and I think I can see the sleeve in a picture in the service manual but I have never seen a distributor with an intact sleeve. If you have please let me know.


The vacuum advancer has 2 diaphragms. The one closest to the distributor is used only during warm up and gives a constant 8 degrees of advance. The outer diaphragm can add to this a maximum of about 4 extra degrees during acceleration. When the inner diaphragm is not activated the outer diaphragm can provide up to 12 degrees of advance depending on the vacuum during acceleration (as measured on my car). Later distributors use vacuum units with different part numbers so the specifications may differ.


The inner diaphragm is the first to fail and you may notice that cold idling is slower than usual. The outer diaphragm recently failed on my car at 240,000k ( the inner failed way back but I lived with it) and it took some searching through stock at the wreckers to find a good one of the correct type.

Most of the information above is the result of my investigation of faulty units and I have not been able to confirm it from official sources. If you have different information please post a correction.

The Automatic Air Conditioner

The following is my non expert understanding of how the automatic air conditioner works. If a shop manual exists please advise and I will scrub this.

The air conditioner

The compressor runs all the time when the air flow control is in the A/C or the DEFROST position and the fan is on.

The temperature at the evaporators (front & cool box) is set by the pressure acting on the boiling refrigerant. This pressure is held constant by a valve in the engine bay. The outlet air temperature is adjusted by mixing the cold (3 C ?) air with warm air. The amount of liquid flowing to the evaporators is controlled by individual metering valves near the evaporators.


The solenoid valve that turns on the rear cool box rusts up and clogs.

The aluminium return tube from the rear cool box cracks in the boot or under the car. This is usually discovered by the oily patch that forms. A fix that has worked is a hose clip and inner tube rubber. Soapy water is one way to check for leaks.

The heater

The heart of the heater is the servo located near the heater core. This device shifts to blend hot and cold air and as it shifts electrical contacts adjust the fan speed (in auto) , the hot water flow and the air outlet location (face or feet).

The movement of this servo is controlled by 2 solenoid valves located in the black box in the engine compartment. One solenoid provides vacuum down line 9 to shift the servo against spring tension the other releases the vacuum down line 9.

These solenoids are controlled by an amplifier. A combination of the inside thermo sensor in the dash, the outside sensor at the front above the horn and a variable resistor attached to the servo is compared with the temperature dial variable resistor to provide power to one or other of the solenoids.

Basically if the ambient is not the same as the dial setting then the servo shifts one way or the other and hotter or colder air is provided until it is.

If the incoming ambient air is not hot enough the servo will shift to a position that un powers the solenoid to line 3 and the resulting vacuum operates the water control valve.

The black box in the engine bay converts electrical signals into vacuum . Some lines (5,6)? give vacuum with power others (3,10)? when un powered. Line 2 is the vacuum in line.

Low cost kit for vacuum fault tracing.

A rubber bulb eye dropper (to show vacuum)

A length of vacuum hose

An aerator "T" from an aquarium shop (to tap into lines)

A golf Tee (to block hoses)

A bit of tube from inside ball point pen (to join hoses)

This kit makes it easy to sit in the car and watch the vacuum on a selected line while changing the heater controls.

Your driving experience can be destroyed by a small rattle in the steering that seems to appear in a lot of crowns by 150k.If you have about 7mm of wheel play between the steering wheel and the connection to the flex plate at the end of the steering column the problem is probably worn anti-rattle rubbers. These little (approx. 6mmx6mm) rubber cylinders are located in the bearing blocks of the trunion joint in the bottom end of the steering column. Repair involves removing the steering column, the snap ring holding the rubber boot and trunion and replacing the anti-rattle rubbers with the chamfered ends outward.

All the necessary information is to be found in the Toyota Crown Chassis repair manual.

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