[jimren]

hi i have just bought a 1995 lucida

the blowers only blow cold air, there is a slight difference between cold and hot.

temperature gauge doesnt show any signs of overheating in engine as it stays safely around the midpoint.
air conditioning works fine on cold.

not losing any coolant. all fluid levels are sound.

i have done around 200km since buying and bus drives perfectly well.

any idea please, i cannot think what it could be.

many thanks

james

[jondaw]

Hi James, to the forum, could be your Thermostat...

[Sir Henry]

Four possibilities come to mind:
1) The serious one. You could have an air lock. If this is the case then the temperature gauge won't show you're overheating until the car grinds to a halt with a blown head! This is because the gauges as fitted to these cars are notoriously unreliable unless a Mason alarm has been fitted to overcome the limitations of the device.
2) The heater matrix could be blocked.
3) The thermostat might not be a proper Toyota one - not recommended.
4) A previous owner could have bypassed the heater matrix because it was leaking. Not uncommon as dismantling the whole dash area to replace the matrix is far from a DIY proposition and costs the proverbials if carried out by a garage.

[jimren]

jrobertsondj, on 10 March 2010 - 12:01 AM, said:

Hi James, to the forum, could be your Thermostat...

cheers henry,

is there a remedy to the air lock?

gonna change termostat tomorrow.

[pheasant_plucker]

Four possibilities here!

The head is gone and you have air in the system (air doesn't appear from nowhere).
The Thermostat is either stuck open or has been removed.
The heater matrix has been bypassed due to a leak.
The control cable has come adrift from the heater (next to the battery on the side of the heater).

The temperature gauges work just fine on these contrary to what anyone says.

Gerry

[Sir Henry]

pheasant_plucker, on 10 March 2010 - 06:07 AM, said:

Four possibilities here!

The head is gone and you have air in the system (air doesn't appear from nowhere).
The Thermostat is either stuck open or has been removed.
The heater matrix has been bypassed due to a leak.
The control cable has come adrift from the heater (next to the battery on the side of the heater).

The temperature gauges work just fine on these contrary to what anyone says.

Gerry

I think not. The consensus of opinion is that they don't move above the 'normal' range until the water is beginning to boil by which time the head is seconds from terminal meltdown. The only known 'cure' is to fit a Mason alarm or a gauge from a different car.

[paul9]

Sir Henry, on 10 March 2010 - 03:37 PM, said:

I think not. The consensus of opinion is that they don't move above the 'normal' range until the water is beginning to boil by which time the head is seconds from terminal meltdown. The only known 'cure' is to fit a Mason alarm or a gauge from a different car.

must be a common problem on japanese vehicles,as the mazda bongo is the same,sits at the same position and only moves when its too late.

dave mason makes mason alarms for the bongos also

[pheasant_plucker]

paul9, on 10 March 2010 - 06:33 PM, said:

must be a common problem on japanese vehicles,as the mazda bongo is the same,sits at the same position and only moves when its too late.

The gauge is designed to be dampened within the normal operating temperature range of the engine. If it wasn't (and it is the same for all cars) the gauge would swing about wildly during normal use. The water system is designed to protect your engine if the temperature rises too high. The pressure cap raises the boiling point of water above 100 degrees. If the water goes above this (which is usually when the gauge is well up the top if not right up) the water will boil and turn to steam. As it does so the pressure cap opens. This has two immediate effects. First the pressure drops quickly and the boiling point is reduced back down to 100 degrees. This causes the water to boil instantly and vent. In the process of doing so excess heat is removed very quickly from the engine. Secondly it will remove excess pressure preventing a blown pipe, radiator or gasket.
There's absolutely nothing wrong with the water system or it's indicator gauge on these engines and most problems will be down to poor or non existent servicing.

Gerry

[paul9]

i ran a few tests,using an aftermarket temp gauge with a dial,and there was different readings under different driving conditions,but the temp gauge on the estima didn't move from its normal position at all,imo, its useful to know how your engine is reacting to different driving conditions then you know beforehand if it is going to get too hot,the estima gauge ,just like the bongo gauge ,doesn't give you any warning of rising temp.

[Sir Henry]

jimren, on 10 March 2010 - 12:55 AM, said:

cheers henry,

is there a remedy to the air lock?

gonna change termostat tomorrow.

There is. Attention to detail!

First it will pay you dividends to flush the whole system thoroughly. Remove the old 'stat and then put the cover back on without replacing the 'stat. With the top & bottom rad hoses removed shove the business end of a garden hose in the bottom hose and wedge it in place with some rags wrapped around it. Turn on the water, make a cup of tea - and drink it. After 20 minutes or so transfer the hose to the 'stat outlet and backflush the engine block for a similar period of time.

Now you can change the thermostat for a Genuine Toyota on with a new sealing ring (for some reason the ring doesn't come with the 'stat so has to be ordered separately) and replace the hoses securing them with the original hose clips or new ones if they're the least bit suspect. Closely examine the pressure cap on the expansion bottle and replace that as well if looks even slightly 'hooky'!

At this point you will need to decide whether you want to use Toyota Red or 'ordinary' anti-freeze. Having flushed the engine with water you'll probably lump for the regular stuff as Red reacts badly to being mixed with tap water and it can be an absolute sod to get all of it out first - also Red is hellish expensive If you go for the 'cheaper' option you should start the refill by pouring 5 litres of it directly into the expansion bottle. Slowly add water (some advise the use of de-ionised rather than tap water - yer pays yer money & yer teks yer pick) until it fills to the top of the bottle. Replace the pressure cap and start the engine. Turn the heater controls to full (air con off) and put the blower on 'fast'. While it's warming up you should rev the engine from time to time as a diesel engine will rarely achieve full operating temperature at idle. If the heater now starts to blow warm or even hot the job is done apart from possibly continuing to top the water up to the 'full' mark. If not ...

Lift the driver's seat and carefully feel the hose coming from the 'stat housing. If you can take the heat you should massage it to encourage air to be 'swished' into the top of the rad and on into the expansion bottle. Another trick is to slide the top hose clip, at the rad end, down the hose a couple of inches and very carefully insert a slender tool (flat bladed screwdriver?) between the hose and the stub pipe without totally taking it off the stub. Any air should bubble out along with a small amount of coolant which can easily be replaced. A tip to ensuring a good 'pressure head' of water during filling is to either raise the front of the car on ramps (rear wheels securely chocked) or axle stands. Alternatively you can make a funnel from a 2 or 3 litre pop bottle by cutting off the bottom and jamming it in the expansion bottle neck by wrapping tape around the neck of the pop bottle.

Job done

[Sir Henry]

pheasant_plucker, on 10 March 2010 - 06:48 PM, said:

The gauge is designed to be dampened within the normal operating temperature range of the engine. If it wasn't (and it is the same for all cars) the gauge would swing about wildly during normal use. The water system is designed to protect your engine if the temperature rises too high. The pressure cap raises the boiling point of water above 100 degrees. If the water goes above this (which is usually when the gauge is well up the top if not right up) the water will boil and turn to steam. As it does so the pressure cap opens. This has two immediate effects. First the pressure drops quickly and the boiling point is reduced back down to 100 degrees. This causes the water to boil instantly and vent. In the process of doing so excess heat is removed very quickly from the engine. Secondly it will remove excess pressure preventing a blown pipe, radiator or gasket.
There's absolutely nothing wrong with the water system or it's indicator gauge on these engines and most problems will be down to poor or non existent servicing.

Gerry

You've got a lot of the physics right, but not entirely.

There is no reason for any temperature gauge to 'swing about wildly'. Damping the response would be irrelevant as it would slow it's response time just when you need to know what's going on in the system. That would indicate sudden and 'wild' temperature changes which do not occur in an infernal combustion engine's cooling system.
Yes, the pressure cap does raise the boiling point of the coolant - approx 1C per extra psi. Also it does release the pressure if there's too much in the system, but not as catastrophically as you indicate - fortunately! Similarly the regular venting of excess steam would rapidly deplete the coolant level exposing parts of the head - not recommended! If things happened as you state there would be a strong possibility that 'removing the excess heat very quickly' could cause thermal shock in the head and increase the chances of it cracking Even without the minor weakness of the system - partly caused by using an engine designed for a different application, but mostly by (as you say) poor maintenance - even Toyota recognised that they had to design a new head gasket to increase the coolant flow around the rear of the head to reduce the thermal stresses that were beginning to show up. Pity they didn't think of the gauge 'sticking' at normal over such a wide temperature variation

[adamcrossland]

hi, yes id agree, check the colour of the water in your tank, if it looked like mine when i bought lucy (like mud)then i took the radiator off and flushed that then flushed all the engine etc...dont do it on a block paved drive lol like i did, i also found my heater matrix was leaking until i noticed water was going,by putting a bottle on the drain pipe i could see how much water was being lost. I changed the heater matrix myself with my father inlaw, it was a pain to do but do-able, saved alot of money.