As some of you may know last September my turbo disintegrated and gave me a £2000+ bill for engine rebuild and turbo re-conditioning on my Masterace. I then went through a month of losing water via my expansion bottle and running backwards and forwards to the engine repairers to see if they could cure the problem. Various things were suggested and tried including 2 * radiator caps, cooling system flushing, pressure tests, gas tests and the possibility of air locks.

Then all of a sudden in October it stopped and I had 5 months of trouble free motoring.......until a fortnight ago. In the 5 months I had various trips along the motorway of distances around 60 miles and ran too and from work 30 miles away 20 times a month. After a month of checking and not losing any coolant I didn't check it again and had no problems.

A fortnight ago I had my new stainless steel exhaust fitted, nothing to do with my main problem, and on the return journey a distance of 55 miles my guage began to rise and I pulled onto the hard shoulder. After a time I checked the cooloant level and found it 1 & 1/2 litres down and topped it up.

My main question is 'Could my complacency in not checking my levels regularly over the past 4 months have been the reason for this overheating ?'

Other questions I would like to ask have regard to components of the cooling system and information I have been told from mechanical fitters at work.

The viscous coupling, Should this engage fully when the engine is being loaded and the operating temperature has been reached or only when the temperature guage is indicating beyond normal operating temperature (ie. in the middle of the guage)?

When the coupling engages should I hear it, is it that noticeable above the whistling of the turbo?

Head Gasket, If the gasket has had it would I be losing water all the time or just at higher revs?

Would I have overheated much earlier if it was head gasket trouble seeing that in the 4 months I didn't have problems I drove over 5000 miles?

How can I test the gasket if it is only failing at higher revs?

I changed my thermostat on Tuesday, I'll be reporting about it next week, and flushed my cooling system through. The different radiator cap that David found, has the test been successful and are we to assume this type is the correct one ?

Many questions but I'm sure you can answer them between you and before any of you state the obvious, I have read the archives.

- (#2860) Mark, 8 May 02

First off, the newly noted cap is a great success, check with Rob for the cheaper ADL equivalent. Loosing coolant means a leak. That's about all you can say. Whether it's leaking out, air is getting in, coolant is being burnt is the difficult bit. Temp guage high = low coolant. On the day of your overheating, or shortly before, did you suffer a long traffic delay or HARD M/way run anywhere? I would have the rad cap tested, or just replaced, as overheating can affect them... If you're still losing water, throw in a small bottle of Bars Leaks (much better than Radweld, sealed up a pinhole I've has for ages first time) And if that doesn't do it, then worry about Head Gaskets. Unfortunately, the leak that will cause these problems is to small to leak water when cold, makes it tough to spot. But yes, not topping up the filler for a while can progressively empty the system,,
the viscous coupllind is always engaged, it just lets more power through when it's hot. The only tests are with thread (attach to fan blade, won't break cold... or drive at speed with the seat up and look.

- (#2862) david miller, 9 May 02

Mark

I bought a new rad cap (small Nissan type) from Halfords at about the same time as David bought his Toyota OEM one. We compared notes and I found that the success of the cap in dragging water over from the expansion tank to be intermittent. Sometimes I had to fill up at the neck, sometimes I didn't.

Since then I have invested in a Toyota cap and have achieved far better results. The heatup/cooldown operation is working properly and water is being pushed out and dragged back in from the expansion tank as it should do. In light of the fragile cooling systems on these vehicles, I consider it worth the extra expense to be a little pro-active. Incidentally, I paid £11.80 for mine as opposed to David's reported £17 (offshore overheads?). Sorry David I'm not gloating honest!

Ian

- (#2864) Ian Dunse, 9 May 02

Mark. Your engine re-build should have ensured that the head gasket etc was fine for many thousands of miles and, I would be inclined to discount this as the reason for the water loss. Yes, if the gasket is leaking, you should lose water at all revs unless there is the tiniest fissure which opens up as the temperature rises. Yes, your mild complacency could, easily, lead to the water loss but, was there no warning that the expansion tank level was low (dashboard symbol lighting up) ? It is a bit of a bind, on these vehicles, to manipulate the seats etc just to check the levels and regular check intervals can easily get too long.
Testing the gasket at high revs ? You can do this by removing the radiator/filler cap (before starting the engine) and watch to see if there is much turbulence , in the filler neck, as the revs increase. There will be some turbulence but, a leaking gasket (leaking into a waterway) will push the water, out of the filler pipe, quite rapidly.
The viscous fan. No, this is not an "instant" engagement, nor will any "clunk" be heard. The viscous fan will be rotating most of the time (except, possibly, when the engine is really cold). It relies on a viscous fluid being passed from an idle chamber to a "drive" chamber, within the fan body, as the engine temperature increases. The best test is as David suggests, have the passenger seat up and observe the fan at speed. Also, when the engine is cold, and switched off, feel that there is some slight "drag" on the fan by pulling on one of the blades. If it spins easily, this might indicate that the viscous fluid is not doing it's work. Also, the cotton thread test will show if it is operating correctly.
Do make sure that the small pipe, connecting the expansion tank to the radiator filler cap location, is in good order. This is the pipe which allows the excess water(expanding as the cooling system heats up)to be stored in the expansion tank. It also has to be airtight so that the same water can be syphoned back into the cooling system. Any air leaks here are not helpful.
If you did not get a warning light showing "expansion tank level low" I should think that the water loss is due to a bit of forgetfulness and, somehow, air has got into the system, and replaced that lost 1.5 litres of water. Check all the hoses and, if yours is a 4WD, the connecting hoses to your second, horizontal radiator.

- (#2869) John Davis, 9 May 02

I had a similar problem recently and found the following....
First head gasket blown (Steam in exhaust).
Then lost water. The water pump failed totally after one week running the new head gasket.
Then still lost water, but now it was intermittent. Replacing the thermostat more or less fixed it but I did find that a very small nick in the filler neck meant that some air may be sucked back instead of water (new cap fitted). I filed the filler pipe slightly just to remove the nick & now all seems OK.

- (#2873) Ray, 9 May 02

I'm trying official Toyota rad cap, too, for mystery
coolant leak - intermittent, no other symptoms, temp gauge never beyond halfway, normal pressure test on system. Knowledgeable mechanic friend says Snap-on do a 'combustion residue detection kit' to identify blown head gasket - magic powder is suspended in rad filler neck with engine running, and if it turns colour then gasket blown. Sounds like a pregnancy test kit and just as frightening. Anyone any experience using it? (Not the preg test..)

- (#2899) Pegwoman, 11 May 02

Generally, combustion gas testers only sense petrol engine gases, not diesel

- (#2900) david miller, 12 May 02

Yesterday, 11/05/02, I met up with Steve FE and feel the viscous coupling is fine but I have a confession to make. After a journey of more than say 10 miles down the motorway, when I pull over and turn the engine off, I can hear bubbles coming through to the expansion tank, only one every 3 or 4 seconds. This makes me think that it would be unlikely for air to be sucked into the cooling system while the engine is running and then pushed out through the expansion tank. Much more likely for the air to get there from being forced into the cooling system from a small crack in the head. This may explain why I seem to lose water only when the revs are high and the engine is hot.

I made sure the coolant was full and took the van on a 120 mile round trip along the motorway, keeping the revs above 3000 cruising at about 70 and left it to cool down overnight on the drive. The following morning I checked the coolant and found it about a mug full low. Fitters from work have said that perhaps it is finding it's own level but I feel that if the system clears the air from itself and is left to cool then water should be sucked back from the expansion tank and a mug full every 120 miles is quite a bit. I have decided to check this 'finding its own level by running it too and from work this week to see if it drops more than a mug full over a greater distance. I have also invested in an ADL rad cap, the new type, which only cost me £9.50.

Any other comments always welcome.

ps. I have carried out both tests on the viscous coupling ie. passenger seat up and running along the motorway and the thread one and passed both tests.

- (#2913) Mark, 12 May 02

My Cylinder Head failed totally after all above symptoms. I had done head gasket, water pump (was broke), rad cap & finally the Thermostat.
The problem seemed to be solved & the van did many miles, Jersey & back, 3 up with camping equipment, luggage & 8 dogs. All still seemed OK.
BUT.....1 week later, total failure.
I removed the head and No.3 cylinder was flooded with water.
Cause.....crack between valves on No.3 cylinder.

- (#2947) Ray, 15 May 02

Sorry I can't help on a lot of the problems but the cap I hope I can.
I bought a new cap for halfords and after fitting developed a leak in the Rad.
Had it recored and all ok.
After a week or so checked the level cold and found I had to topup.
Filled the neck up to the cap all ok.
Checked a week later cold, level down again in the neck but expansion bottle getting fuller.
Anyway the moral of the story is halfords cap is not the same build as a genuine toyota one.
The spring assembly is different and the cooling system would not draw the water back from the expansion tank.
Fitted the toyota one part number T16401-63010.
Cured the fault, so avoid the cheapest it's not always as good.
On the downside the cap is £17.51.
- (#2948) Phil Cook, 15 May 02

hello ive had my toyota townace now only for a week i bought it from birmingham i live in liverpool.i was on my way home and about 60 miles of moterway drivingon my way home my temp guage started to rise it would go to three quqrters and then when i slowed down a bit it would go back to half way . i stopped and i filled the water level up it took arround 3 litres of water .anyway i asumed with it standing in the docks and what not that the levels had just dropped as you do ,but i carried on home and when i reached liverpool it done the same again but this time it didnt loose any fluids cause soon as the temp went up i stopped the bus.but my main question is ive done a few hundred miles in it now and it hasnt overheated ive stood in standing traffic for as long as 2 hours and it hasnt done it ,it is only when i go on the moterway on arun constant for around 60 miles oh and another thing is when this hapens my heaters start blowing cold air ,so now if i do go on a moterway i have my heaters on so i know before it overheats.please can anyone help me or do they know what could be up or have they had simlar problems .oh i must mention i changed the thermostat but that didnt help hope to hear from you my phone no is 0151 481 0967

- (#3057) paul tierney, 22 May 02

Sorry, Paul, sounds like you need a head gasket, and perhaps a head too if you're unlucky... But replace the rad cap first, there is a tiny chance...

- (#3075) david miller, 23 May 02

hi to all townies,,a god send coming across this site im not new to townies but new to recent problem.im also new to computors.my townace overheated last week was driving ok but no heat and temp needle on cold and bubbles when rad cap removed, mechanice( A FREIND )first replaced temp sender unit and temp needle worked but went to red,had head pressure tested and skimmed all ok put every thing together and started and ran fine but on the way home temp needle started to rise to red mechanic was following me. said could be faulty or wrong temp sender unit fitted ealier or bad circulation as engine was not that hot and rad pipes were warm but bottom rad pipe was cold before i end up going round in circles i would be most graeful for any advice.by the way i was shoked at the price sasked for gaskets my mechanic freind refuses to use shim gaskets says has had to much trouble with them in my search i found card gasket almost like the original for £25 so if any one needs one let me know thanking you now javed

- (#3485) javed, 23 Jun 02