Is the 2ct cooling system flawed? I have told my story before, but in short fitted a 2ct engine to an old Land Rover. It was allways running in the upper 90-105 (measured with VDO gauge at outlet). Then the head gaskett started leaking - $$$$$. Out of desperation I moved the thermostat to the top and blocked of the cold start bypass hole with a 16mm welsh plug. End of problems, on plus 40 days the engine ran at 92 going 110 km/h on the freeway and none of those alaraming temp rises as you go up a hill. Well I moved to a colder part of the country and did not like the engine taking so long warming up (idling at 80). I moved the thermo down again and from board advice made sure the heater bypass and thermowax bypass were functioning (they weren't originally). Same problem, engine running in the upper 90's on the freeway and edging over a 100 up a hill, and this on a mild winters day. I suspect that the thermo does not open properly at the bottom, thats why some people report success by drilling holes in it. Everytime cooled water comes from the radiator it is going to close surely? Well I put it back to the top, block of the heater and cold start bypass again and now we are running nice and cool, far away from banana head temperatures. An engine running in the upper 90's-100s bracket has got so little margin for error. If it had a high pressure cooling system (such as VW's and Mercs) it would be ok. The worrying factor is that the temperature rises so dramatically when you go up a hill. I think know that the cooling system was designed for town use, it simply can not cope with high rev's and speeds. Try the stat at the top, you will be surprised (it needs a small machining job).

Regards

Leon

- (#11017) Leon, 7 Oct 03 12:09

Leon
upper 90's, low 100s bracket is quite normal for a 2ct engine with the thermostat correctly mounted on the cool feed.

Inside the hole in the block where the thermostat fits, there is a receiving plate mounted on block itself. The result is that the Toyota 30mm wide thermostat rated to 82°C opens when the coolant reaches 82°C. As it opens the disk on the end contacts the plate, and this prevents it from closing until the bottom of the engine block has been reduced to 82°C.

Running the cooling system at 100°C may seem high, but with a 13.5 Psi rated radiator cap, and an antifreeze mixture of 50/50 the boiling point of the coolant is raised to 125°C. that’s still allows quite a bit of margin. Other benefits are that the hotter the engine, the better the combustion, so fuel consumption is better. If the coolant is at 80°C and the ambient air temperature is 30°C then the differential in temperature is 50°C. If the coolant is 100°C with the same ambient air temperature of 30°C there is a differential of 70°C. Therefore the hotter the coolant in the radiator, the quicker it will cool.

The Townace has a finely balanced cooling system, a bit quirky perhaps, but well capable of keeping the engine at its designed temperature. The only real fault is the inaccuracy, or inactivity of the standard, un modified temperature gauge, and speaking entirely for my self here, failure to rectify a cooling problem will almost certainly result in warped and or cracked heads.

- (#11018) dave Bright, 7 Oct 03 13:53

Hi,

on the subject of cooling, I have just repaired our work van's motor for the 2nd time after a second head gasket blew. I'm suspecting the fan - I paid $40 for a tiny bottle of fan oil to replace the oil it had, but no difference - the fan refused to stiffen up even when dunked in very hot water. After a longish run at highway speeds the fan spun happily around with almost zero resistance - is this normal?

I made up a couple of brackets and locked the fan, but to my horror there was a nasty squeal coming from the water pump direction at revs, so the brackets came back off.

How do you test these strange fans?

- (#11121) Rick, 12 Oct 03 22:18

Rick. You will find lots of information in the Ace Answers archives, where these viscous fans have been discussed at great length. In my view, these fans never "lock up" and the drive is quite finely balanced between the temperature and the viscosity of the silicon fluid in the "driving " and "slipping" chamber of the assembly. You can test the fan's operation by tying a fan blade with a cotton thread, and securing it somewhere beside the engine. As the coolant warms up, the bi-metallic valve, on the front of the coupling body, will allow silicon fluid into the "drive" chamber. The thread should break when the drive gets "stiff" enough to turn the fan at increased speed. I put some pictures, of the dismantled fan, ie, the Aisin fan fitted to the Townace range, onto a website and you might like to have a look to see how the internal ports operate.
This is the link.
http://www.marengo.dnsalias.com/coupling/

- (#11122) John Davis, 13 Oct 03 3:54

A kettle of boiling water poured over the the coupling prior to start up should give enough heat to stiffen it temporarily. This would demonstrate its ability to function
Also try driving with engine cover up to observe its operation
A rolled up newspaper in the blades can be another (messy) test
The fan does rely on heat from the radiator though so you need to be sure the rad flow is adequate
I would test the accuracy of your VDO though with the sensor in boiling water (100c) - using faulty equipment recently wasted loads of my time with erroneous readings

- (#11210) chris turner, 13 Oct 03 8:11