Overheating!!!

Very confused right now

Last year I bought the car and it sailed through the hot days.

Since then I've cleaned out the coolant radiator and the aircon rad, decatted it and have been running on optimax...and sometimes with a dash of Toluene too!

Now today I was coming back from Homebase with crappy £20 barbie in the back, just strolling along at about 80-85 when I got a nice clear stretch of the A11 which is "safe" from unwanted attention.

I accelerated in 6th at about 70% throttle to about 115 and the engine temp rose with the speed! 70% throttle mean't about .9 bar which isn't out of the ordinary. The needle got within 1/2 a cm of the redline!

Why is it overheating??

Is it detonating? No judder just smooth acceleration..no strange noises.

Is the radiator fooked?? The expansion tanks has twice recently coughed up some water after engine has been shut down but the level is still at full (making me think it was too full to start with).

Could it be the intake charge is just too damned hot (pod filter with only a half arsed heatshield)

Is my intercooler (stock) fooked?

Could it be year old sparkplugs (HKS "I'm a sucker" plugs) which have seen the thick end of 1.4bar at times :0

Am I running lean on these very hot days?

Really unhappy at the moment this is the weather I've (we all) have been waiting for to let rip on hot tarmac, and all I can do is pootle about.

Oil last changed 1000miles ago

Coolant has not been changed persay, but I've had the radiator out to change the cam belt 'bout 3 months ago.

Filled up today with Optimax so the fuel is fresh...if it matters

Very very

And definately not

Perhaps your water pump is on the way out, that may explain the expansion tank over flowing, hot spot in the system due to inadequate flow. Just a thought.

Could the pipework be blocked?? Can I run a cleaner through it...whilst adding some nice new Samco hoses! Are there only two hoses that carry coolant externally of the block?

I've got that rad deflection plate as well but I left the rubber strip in place which seals the bonnet...I've now removed the rubber strip in the hope it aids cooling.

Anyone know the price of a waterpump?

May be the dreaded blown head gasket syndrome...hope not.

does the car have the official Toyota mix in the rad?

Have you still got the 'normal' viscous fan ?

On BMW's these REGULARLY fail - still spin but fail to 'lock-up'

at temperature.

Does anybody know if the Soop viscous 'locks-up' or is like the

older Ford ones = gets 'tighter' when hotter ? ?

I must say I'm not a fan (!? sorry) of Viscous Couplings. I like an electric

fan which you can hear/see is working (although BMW etc still use

them so can't be 'bad' ? )

[ Must be to/from pipes to rad, and, at least, to/from matrix ]

IF needed, a head gasket ("gas") test is very quick/cheap:

a hand-held reservoir is clamped onto the rad' in place of the cap

and the engine is run allowing any combustion gases in the coolant

to bubble through a CO (CO2?) indicator solution.

It's not infallable BUT if it changes it IS gone / if it doesn't it

only means it hasn't gone ENOUGH to change the fluid ? ?

ps. If you know all this already - SORRY - Haven't quite grasped

Who knows What about Which ? ! ?

( I really DO only want to help - NOT act superior - 'COS I'M NOT ! )

pps. Think we charge ~£20/30mins to do test on NORMAL cars,

obviously quadruple rate for performance cars ( sorry, thought

I was a Toyota dealer for a mo' )

Steve.

Alex, I think Pete Betts had a similar thing happen with his - and that turned out to be the water pump, and IIRC Chris Wilson thought that was becoming a point of failure on the older MKIV's

You can get it changed when you do the cam belt and save on paying the labour twice... oops already done that.

I'm pretty sure the head gaskets are a very uncommon fault on MKIV's (as you probably know), the two known cases having been caused by other problems. So wouldn't worry about that.

And we've got a really good barbie spare, should have asked... saved some money towards that engine rebuild

Alex,

To me that says one of two things. Either a blocked rad or failing water pump. I'd go with the blocked rad though.

As the engine is moving faster the pump is trying to pump enough water round to cool the engine, but if there is a block then the water won't be able to flow fast enough and hence the heat build up. This could also explain the overflow tank filling up, because the water cannot flow fast enough it has to go somewhere or it will build up too much pressure, so off it goes to the overflow / expansion tank.

If the temp comes back down as you slow down then I think it just about confirms the above?!

Alex , have you tried a new rad cap??

If not , give it a whirl it could be that simple....

Although , now it has overheated slightly you'll prolly have to bleed the air out aswell.......

When did you change the coolant ? the soop can be a pain sometimes to get the air out of system after a flush.......

I've done it three times ........ twice trouble free

But one time it took a while to bleed........

another thing to look at is the 'stat ..........

Prolly is the pump ............ but , like the pump, the cap and 'stat are service items and as such should be replaced periodically anyway .........so it won't hurt

Plus you can prob get a suitable cap and stat on a holiday weekend .............

I'd spend an hour trying it in the a.m if there was a chance of getting out in the Soop on a nice sunny day ..... ( I have withdrawal soooo bad its hurtin man!)

Alex, these are the symptoms of the BHG I had last year.

I would drive 100 miles to work, normal driving with a few 'squeezes' now and then. The expansion tank was at 'MAX' after I stopped. In the evening the expansion tank was empty and taking the radiator cap off there was no visible water. Filled it up and drove home, same again in the morning

If I went loony for 10 minutes the temp would shoot up to max and then drop straight down whe I slowed down and it would get rid of all the water as well.

Sometimes looking at the expansion tank after a drive, pulling the top off, it was blowing lots of steam out of the pipe......

Temp needle was about 1/3 up. (later turned out my stat was stock open, it's fine now it's got a new stat in)

Two places tested it and found no problem, pressure test, test drives ( I DON'T want to go there...) and sniff tests.......

I don't know what caused it, but when the took the head off the gaskit had gone on two cylinder and the head bolts down the exhaust side wern't tight...

As Gareth says, they are very uncommon and could be lots of other reasons. BTW it's about 12-15 hours labour for a HG , hope thats not your problem.

Originally posted by matt

Alex , have you tried a new rad cap??

 

If not , give it a whirl it could be that simple....

 

My thoughts exactly, try a new rad cap before anything else.

Cheers so far

The coolant was last affected by the removal of the rad 3+months ago so can't see it being that.

The expansion tank does NOT empty just coughs up a bit of fluid...though after writing my initial post I checked it and found it to be down to low.

The cap looks very shady I've been meaning to change it as it looks a bit funky on the inside.

I will try a new cap first...but again if its a blockage in my 9 year old radiator (which wouldn't be surprising) how do I clear it.

Where is the thermostat?

Thanks for the idea's/info so far.

Oh and the temp does come down as I back off, takes about 1.5mins to fully return to normal...if I stay below the second turbo's rev range 3,500 or less it seems to be fine. Thoug nailing it in first doesn't seem to bother it...then again you don't do it for a long time!

The thermostat should be just on the engine side of the radiator top hose.

If the rad is blocked you can often feel hot and cold spots on it with your hand when the engine is warm - it should be a uniform temperature all over. The best way to try and clear it is by removing it, and running a hose through it from the top inlet and then from the bottom outlet.

If it 's badly clogged I would be tempted to buy a new one though.

Alex

I have just been through exactly the same situation as you have described, though before I realised the temperature was high the crappy plastic Toyota radiator blew it's top, leaving a big 6 inch crack next to the cap.

I first changed the radiator for a Fluidyne one and the thermostat but still had problems. After a couple of trips to the gargae it turned out that the pump had packed up and the viscous coupling on the fan was not working properly. New water pump and repair to fan seems to have sorted out the problem, fine now poutling around and on spirit runs. However I did take the car for a high speed run in 5th at the weekend and the gauge started to rise. In my case I think this may be due to the FMIC blocking the airflow to the radiator and 36 degree temperatures here in HK!

I suggest you speak to Chris W he helped me out diagnosing the problem with mine.

Good luck,

Nic

Check the viscous coupling is working correctly. Unless you work with lots of them it's hard to describe how stiff they should feel (ooh err, missus :-0) try and compare it with someone elses known good one (wish I'd not started this, snigger).

Could be the rad cap, for what they cost just renew it as a matter of course. Could be the pump, seeing these fail now, or could be the rad, either clogged internally or the external finning is corroding and getting loose on the tubes. VERY much doubt it's the head gasket unless it's been detting. If it is a combustion gasses in the water test should show it.

Originally posted by Adam Wootten

The thermostat should be just on the engine side of the radiator top hose.

Not sure if I can see what you mean.

Right next to the block is two electrical wires going into a hard pipe that come out of the block...is this the thermostat?

Also,

Could I please have the part no.s of the

1) the rad cap

2) the water pump

3) a thermostat

Think I'll make a trip to IanC's and see how his viscous coupling is!! :eek:

Cheers All

Originally posted by Alex Holdroyd

 

Not sure if I can see what you mean.

 

Right next to the block is two electrical wires going into a hard pipe that come out of the block...is this the thermostat?

 

Also,

Could I please have the part no.s of the

1) the rad cap

2) the water pump

3) a thermostat

 

Think I'll make a trip to IanC's and see how his viscous coupling is!! :eek:

 

 

Cheers All

The thermostat is WITHIN the housing that fits the top rad hose to the head casting, or at least it should be. It's a purely thermo-mechanical device, a wax pellet expands and opens a valve allowing hot water to flow through the rad. t may have been removed at some time... They are usuakky brass, but some are cadmium plated steel (silver in colour). Sorry, don't have my EPC loaded on this machine.

Oh my, CW must be having an off day!! The MKIV thermostat is at the end of the bottom hose where it goes into the block.

Part numbers are :-

Rad Cap : Can't find on EPC

Water Pump:16100-49845

Thermostat: 90916-03093

Originally posted by Martin F

Oh my, CW must be having an off day!! The MKIV thermostat is at the end of the bottom hose where it goes into the block.

 

Part numbers are :-

 

Rad Cap : Can't find on EPC

Water Pump:16100-49845

Thermostat: 90916-03093

Ooops, sorry, thought we were talking MKIII then. A track day in the hot sun is obviously too much for me, must go and lie down :-)

Originally posted by Chris Wilson

 

Ooops, sorry, thought we were talking MKIII then.

The cheek of the man!!

Cheers for the part no.s

16100-49845 didn't exist

They gave me

16100-49837 @ £92.49 and

16100-49846 @ £110.73

Can anyone confirm which one I need?

PS..the MKIII pump was £500!!!!

Thanks again!

I'll be testing the coupling on Thursday...just getting prices till I can fully diagnose the problem.

Originally posted by Chris Wilson

 

Ooops, sorry, thought we were talking MKIII then. A track day in the hot sun is obviously too much for me, must go and lie down :-)

Should have spent all day tackling a MKIII lower wishbone and complete brake refurb like me..........................Errrrr maybe not.

Alex, I think those part numbers may supersede the one i gave you. Unfortunately my copy of the EPC doesn't recognise them. May want to give them your chassis number if the time comes and ask them to match it up.

Something dawned on me today.

A couple of months ago after the rad had been pulled off to fit the cambelt I noticed that when I needed full heat I couldn't get it!! Whacked the knob ...round to 30 and it didn't dish out loads of heat infact I got more heat at 25...but it was still not hot!

Could the heater matrix be shafted??? And causing my other complaints!!?????

It spat out some more water today

The top pipe gurgles when I shut the engine down...is that normal? Is that an air lock?

Cheers

Alex "I'm gunna keep this thread alive forever..." H

Could be an airlock. Bring it round thursday night and I'll break something else on it, er I mean scar myself for life on it, no, sorry, have a look - that's it.

-Ian

Just pray it's not the heater matrix, that is one major PITA. Did you try a rad cap?? I have a TRD one if you wish to relieve me of it on the cheap when we meet.