Ruby overheating :(

[Chris Litchfield]

Hi all

I am worried about Ruby, my 1981 R5 GTL.

On a long hot drive in August the warning light came on in a traffic jam. Switched off immediately, let her cool down and eventually drove home without the light coming back on. Haven't driven her since.

Today was my first chance to look at her. Have tested the thermostat & all ok. Have flushed and refilled the coolant and replaced the radiator fan switch with a new one. Did bypass test on fan and that works.

Have bled the system, heater is warm. Ran her idle and the fan hasn't kicked in. Took her for a little run (she was running fine) and then let her idle and fan still didn't kick in, although hoses and fan switch felt hot.

I noticed a couple of bubbles in the expansion tank, so got scared and switched the engine off. I didn't want it to get to the point of the dreaded light coming on.

Am worried I have damaged her engine. My technical knowledge is limited, so I need to get her checked properly.

If anyone has any thoughts or advice, I would really appreciate it.

Cheers

Chris

 

[mr-reno-139]

without an infra red thermometer which are a lot cheaper than they used to be it is difficult to judge how hot things actually are
Fan switch comes on at 85c bottom of radiator which is usually 95c at top
Red light sensor on head is 115 c these can go faulty and come on too early
It is common for bubbling to occur just before fan kicks in especially after recently filling system

You will only damage engine driving car with light on

stationary it will just boil and you will switch it off in time
Possibility include early stage h gasket failure
Sniff the coolant bottle for traces of petrol exhaust fumes not running though ☺

This can be confirmed by friendly mot tester using exhaust emissions probe over bottle opening with engine running will show excess hydrocarbons

 

[malcolm]

Couple of other ideas - if you have refilled the system then it might need bleeding a bit more. I tend to prop the expansion bottle on top of the engine, remove the cap, loosen the radiator cap until water starts coming out, loosen the bleed screw on the bulkhead until same, then the bleed near the waterpump for a R5. Then quickly squeeze and release the top hose until it feels like it has water in it.

Another possibility is there is a slight leak, likely radiator cap, which is preventing the system from getting up to pressure. Under pressure the water boils well over 100 degrees.

If you can make it to the last junction on the A1 before the black cat I would be happy to take a look.

 

[Chris Litchfield]

Thanks Guys!

I will take a look again at the weekend and let you know how I get on

 

[Chris Litchfield]

I have bought an infa red thermometer. Thanks for the suggestion Paul!

I will follow the advice you have both given me on Saturday morning.

I guess I will be looking for a slightly lower temperature from the top and bottom of the radiator, as the coolant inside will be hotter?

Thanks again for your advice!

Chris

 

[Chris Litchfield]

All sorted!

I bled the system again and managed to tighten the radiator cap a bit more. No smells from coolant bottle. Ran her and checked the temperature with an infa red gun. The fan kicked in and no bubbles! Have been running around in her today and checking. She seems very happy.

Thanks again for your advice. I am really relieved she is ok.

Cheers

Chris