Under cooling

[dazzz]

My Mk1b is now driving around under normal conditions with the temp gauge reading at a quarter rather than half, and is taking a long time for engine idle speed to drop to 1200, ( it won't drop further now ).

Is this a faulty thermostat?? There is plenty of coolant and no leaks.

Any advice please???

[cartledge_uk]

My Mk1b is now driving around under normal conditions with the temp gauge reading at a quarter rather than half, and is taking a long time for engine idle speed to drop to 1200, ( it won't drop further now ).

Is this a faulty thermostat?? There is plenty of coolant and no leaks.

Any advice please???

Almost definitly the thermostat is stuck open

[dazzz]

Best place to purchase???

[MartG]

Toyota - only about £12 IIRC

[Neil_turbo]

just had exactly the same problem - changed the thermostat and all is good again

[dazzz]

Could somebody please confirm the location of the stat? is it in housing with white wing nut.

[MartG]

Yes - it's easier to remove the cover if you first remove the large diameter hose that comes out of the front of the housing. You can then get at the lower housing bolt quite easily.

While you've got the hose off and the stat out, its worth bunging a hosepipe in the end of the hose and giving it a good flush through.

[dazzz]

I rebuilt the car and finished it 2 months ago, the coolant is still lovely blue, just contacted MrT, ( not helpfull) they said they didn't know which part it was, Choice of two parts, £30 or £50,

Would anyone know the part number??

[MartG]

I rebuilt the car and finished it 2 months ago, the coolant is still lovely blue, just contacted MrT, ( not helpfull) they said they didn't know which part it was, Choice of two parts, £30 or £50,

Would anyone know the part number??

End with 16331A, but don't know the prefix ( see diagram here http://opc.mr2oc.com/online_parts_catal ... ooling.gif )

[MartG]

Alternatively the Halfords part number is HTK630 - about a tenner I think

[dazzz]

Cheers

[rootes]

just fitted a toyota one myself last week and has cure cold running..

http://www.imoc.co.uk/forums/viewtopic.php?t=22434 -see end)

bit more that £12 though try £20 from octagon Toyota in Bracknell..

dead eacy to fit, did not even need to remove hoses - just removed battery, used 10mm af spanner on the top bolt and a 10mm socket on an extension to get the lower.. managed to get house off , thermostat out, housing cleaned, fit new thermostat in (remember to get jiggle pin at top) and refit.. all without the need to remove/disturb hoses



Si

[Knightkiller]

Blue coolant is a bad choice for Jap engines, blue is primarily for European engines, such as MB and BMW aluminium blocks as its phosphate free.

Japanese engines typically need the red stuff as it has higher levels of phosphates and need to be free of silicates and borates instead. Just an FYI. Toyota's long-life is good stuff

[anthonyg]

Shouldn't this be titled 'Over Cooling'

[weegaz22]

Blue coolant is a bad choice for Jap engines, blue is primarily for European engines, such as MB and BMW aluminium blocks as its phosphate free.

Japanese engines typically need the red stuff as it has higher levels of phosphates and need to be free of silicates and borates instead. Just an FYI. Toyota's long-life is good stuff

any ethelyene glycol coolant should be fine, the mk1 was made in the 80's so its 20 years old, coolants have came on a bit since then, im not knocking the toyota stuff, but its pricey, and a complete flush out of the system and a refill with a good quality coolant should be fine imo

[Knightkiller]

I've seen the damage the wrong coolant can do, it affects seals and the tiny water channels around the head quite badly and can result in cooling system failiure and the MK1's cooling system isnt exactly basic.

Toyota's stuff is upto date anyway, it used to be for-life and now its long life. You do know, if you ask for coolant from toyota its the same stuff they put in their cars now? They dont store it from the 1980's specifically for the MK1!!

The point I made though is to use the red stuff not the blue stuff which is meant for the euro blocks. The Jap engines really need the coolant to be free of silicates and have the phosphates, which is the exact oppisate of the BMW coolant I have sat in my shed for my E38 7 Series.

[rootes]

I find Comma X-stream red is a good coolant

[jimi]

This is a direct quote from the BGB aka the Toyota Repair Manual.

Use a good brand of ethylene-glycol base coolant mixed according to the manufacturer's directions"

The Toyota 4 age engine book repeats this statement and goes on to add

we recommend a mixture of more than 50% coolant to water but not in excess of 70%

The colour has nothing to do with it and isn't representative of what type of coolant it is, the manufacturers can make it any colour they want

[weegaz22]

This is a direct quote from the BGB aka the Toyota Repair Manual.

Use a good brand of ethylene-glycol base coolant mixed according to the manufacturer's directions"

The Toyota 4 age engine book repeats this statement and goes on to add

we recommend a mixture of more than 50% coolant to water but not in excess of 70%

The colour has nothing to do with it and isn't representative of what type of coolant it is, the manufacturers can make it any colour they want

cheers jimi

I've seen the damage the wrong coolant can do, it affects seals and the tiny water channels around the head quite badly and can result in cooling system failiure and the MK1's cooling system isnt exactly basic. [Mr. Green]

Toyota's stuff is upto date anyway, it used to be for-life and now its long life. You do know, if you ask for coolant from toyota its the same stuff they put in their cars now? They dont store it from the 1980's specifically for the MK1!! [Laughing]

well as said the 4age is 20 years old, how do you know that the damage hasnt been caused by running it just on water? or a low strength mix of coolant? or coolant well past its expected lifespan? or different coolants mixed into the system? (which is bad, hence why i said flush system and fill with decent coolant)

its pretty much impossible to know unless you owned the car from the day it left the factory up until present day and have done all servicing yourself

and what is so complex about the mk1's cooling system?

[jimi]

and what is so complex about the mk1's cooling system?

Nothing ! it's a basic engine cooling system, the only difference being the engine is further away from the radiator than normal ( just like the X1-9 ), which makes bleeding the system properly of paramount importance. Sometimes it can be a swine to get right, but with trial and error I now have a system ( based on Mr T's procedure ) that works every time, for me