Hi.
I have recently replaced all the heater and radiator hoses on my 1989 Town Ace Royal Lounge 2.0 EFI due to a hose failing while returning home from a trip to Blackpool. Since relacing the hoses the engine is overheating. I have found no leaks but once the engine has reached operating temperature the coolant is being forced out of the header tank which is draining the system of all its coolant. I suspect that air might be in the system (how do I go about bleeding the system) or the radiator cap because a new TRD radiator cap was fitted before I had the hose fail on me. The original cap was a .9 operating pressure but the new TRD cap is a 1.3 .Will the increase make a difference? Got to sort the problem soon because I am going on holiday in the Townie in August. Head Gasket and fan are ok so its not that.
- (#9320) Bill Dickinson, 29 Jun 03 15:47
Hello Bill.
I’m not sure what TRD is, but are you sure the TRD cap is 1.3 Bar and not 13psi ?
0.9 Bar is 13psi. 1.3 Bar is 19psi. If the cap is definitely 1.3 Bar then yes, the additional pressure could have been the cause of the blown hose.
From the way you describe the loss of coolant now, I believe that it is due to boiling. Your original blown hose will have reduced the pressure, and therefore the boiling point of the coolant. As the coolant has boiled and turned to steam, it will have vented through the radiator cap as well as the broken hose. Radiator caps are prone to failure once an overheating event has occurred, so Whatever your radiator cap used to be, it is unlikely to be any good now so you should replace it with a correct Toyota cap for your type of engine. If the old cap was 0.9Bar then go for the latest float type of cap.
Hope that helps you
dave Bright
- (#9321) dave Bright, 30 Jun 03 1:54
Bill, the cooling system is complex and full of areas where air can be trapped. A large amount of air will compress and, then expand and push coolant out. If the system was OK before you replaced the hoses, it is likely that you have, inadvertently, introduced the fault. Also, the higher pressure cap will allow any air to be compressed more that the lower pressure one but, as the pump is only a circulator and not a positive displacement device,it is, usully, some other source which pressurises the system. I would certainly check the turbulance, at the rad cap, with the engine running and some increase in throttle.
To bleed the system, take one or two hoses off their spigots, especially at the rear heater or the oil cooler, let some coolant out and then re-fit. Also, I find that VERY slow filling of these systems helps a great deal. A lot of water, rushing in, traps air in a number of locations. If you drain again and re-fill, taking about five minutes, with small amounts at intervals, this allows the air to escape before being trapped and the coolant settles. Replacing those small heater hoses and the larger rad hoses, would, I should think have introduced a lot of air which is likely to still be in the system
- (#9322) John Davis, 30 Jun 03 2:03
Bill, why would you be using Toyota Racing Division parts on a Townace? As said many times before, the cooling system is finely balanced, even the cheapo rad caps can cause a problem. Get the right cap from Toyota. Well worth the £11+
- (#9399) Ian Dunse, 30 Jun 03 7:26
Air will find its way to the 'highest point' in the system so bleed from there.
Also make sure your heater settings are set to hot - otherwise you are excluding the matrix's
Judicious massaging of top hoses suspected to contain air will move it along a bit
Use the old pressure cap if ok until you get a correct replacement if required.
As John highlights - fill slowly slowly
Check regularly for the 1st couple of weeks as air in the system can hang around a bit - (when you think its all gone you can find more a couple of days later)
Hows the thermostat? - if it was renewed be wary as I am convinced my new one has been sticking shut (on the inbuilt rubber seal) when left a couple of days - though would expect it to improve with use and longer journeys
- (#9400) chris turner, 30 Jun 03 8:49
Thanks for all your tips and sugestions. The TRD (Toyota Racing Development) cap has been replaced by a correct Toyota Cap for the Townie and all seems to be fine so far.
- (#9401) Bill Dickinson, 30 Jun 03 12:20