Over Heating :(

[lusciousthelock]

So, I finally got around to fitting new Halogen Ring branded headlights to replace the sealed beam units in my Humber Sceptre. It was cold at the weekend, so decided it would be a good time to top up the anti-freeze. She took a full 1litre of antifreeze into the rad (I really should check more often). I started her up to let it move around the system whilst I fitted the headlights. After 10 minutes of running she spat her guts up all over my feet. Weird. Never done that before, so figured the radiator cap had gotten a little weak so purchased a new one 13lb pressure one and another litre of antifreeze.

Today I've driven my car for 30 lovely miles, but if I sit and let her idle then the temperature rises within five minutes and she boils over, cools down as soon as we move and drives fantastic. The heater is amazing and never ran so well...

So do you think It could be a blocked radiator, failed water pump... or something worse???

If the Rad's blocked, whats good for unblocking? On my more modern vehicles, I've just ran a hose pipe through to flush out but I'm sure my 43yr old Sceptre won't be as simple

[colnerov]

Hi, it does sound like a partially block rad, there are various products to flush it with varying degrees of aggressiveness. But you will probably end up with having moved the blockage it will uncover one or more pinholes in the cores of the matrix. So I would not waste money on them and just get the rad re-cored, I speak from experience over the years.

Colin

[optimusprime]

I found a reverse flush through always did the trick, it either cleared the blockage,or showed up any holes/weak spots etc in the rad.
If it did fail i just replaced it.
Not worth in my mind trying to use 'chemical' fixes, esp if its an 'old' rad.

[ChasR]

I would firstly change the thermostat, and see if it opens at the desired temperature. After that my attention would be put towards the radiator. Does the coolant level go up and down in the rad cap upon the engine being revved (i.e, is the pump working?).

[lusciousthelock]

I haven't had good chance to look at it yet, well in daylight at least as it's always dark when I'm out of work (before and after) and I'm working this weekend. First chance I get I'll check for flow although I don't remember seeing any. Externally the rad looks in good condition, I've had some real ropey ones over the years, but this one looks mint with a nice brass top ready for polishing... If it doesn't fall to bits on closer inspection haha.

How strong are rad's inside? I have access to a high pressure jet gun at work. Would this be too powerful for a jet through? I might even try that on the block itself with a reverse flush?

I do know that when I take that radiator out I'm gonna have to replace some very ropey top and bottom hoses, as they appear to be wrapped in electrical tape where the Jubilee clips hold them in place so I best start searching.

The thermostat and water pump seem easy enough to access, so I'll get a tube of instant gasket and have a look. A blocked rad would also give the appearance of a non functioning pump. Is there any way of testing it's effectiveness?

[marinacoupe]

I would say that the pump is working if it is pumping through your heater.

You shouldn't need a pressure washer, if a hose pipe can't push through then, neither would the water pump. Turn it upside and fill from the bottom outlet as it will help to dislodge the crud that came in from the top.

If the rad is blocked, take it to a radiator repair place (yellow pages) if they are any good they will be able to replace the core and keep the original top/bottom tanks.

My Marina had the same problem some years back, they not only sourced a core, but an uprated one as well.

The same crud that blocks the rad will also block the water galleries in the engine, so take the thermostat off and run the hose through the engine, it will eventually come out through the water pump inlet.

[lusciousthelock]

Hopefully I will get chance to have a look on Sunday, If works quiet then I'll give her a go in the car park. This stuff never happens in the summer haha

[ChasR]

My Stag radiator looked fine outside, it is internally that they block up, especially if coolant changes have been neglected as well as a lack of coolant, this being worse in mixed metal engines. Rodding was one service offered to clear out the rad tubes. People have tried all sorts but IMO a new rad is the best solution ; rodding would be my next choice but the costs work out the same as a new radiator...

[marinacoupe]

I don't know if anyone has used one of these 'Radweld' products ever? I learnt something recently that has permanent put me off. They use tiny rubber particles in the bottle which when added to the cooling water, flush round the system until they find the leak and then bind together until it clogs up the hole. Clever - but it means that all the excess rubber particles continue flushing round the system gradually block the rest of the radiator core over time. So useful as a get you home fix, but only if you then get the core replaced as a long term solution.

[lusciousthelock]

Oh dear, I think things just took a step for the worse

I drove my car to work today, so I could take a look in daylight. She hasn't overheated and the temperature reading has always been in the normal position, but does get a bit moody when sat in traffic.

I started her up and removed the rad cap to check for flow. I saw she instantly needed topping up again so used a full kettle to bring her up to the top. I then squeezed the top and bottom hose to check for heat and make sure I saw some movement in the rad. All normal.

Five minutes time and the car was reading normal temperature, and then she boiled over... But she didn't, because it wasn't hot! It looks like, when she gets to temperature the thermostat opens and releases pressure into the radiator, forcing water out of the overflow.

Am I looking at head gasket failure here???

[marinacoupe]

Er possibly, if the rad has been persistently low than the engine can overheat and the head move letting combustion gases break into the water jacket.

[Kieran]

Is it not just a sticky thermostat, being reluctant to open after being open?

If the hg has gone and is releasing combustion into the water jacket, you normally see a constant stream of bubbles in the head tank / radiator.

Try driving it without the cap in (or seal removed). Could be just an air lock.

[colnerov]

Hi, It still looks like a blocked rad, because when the stat opens the water from the engine goes down through the rad and in the water pump and so on. If it gets pushed out then it is because it can't get through the rad. Try taking the bottom hose off and pouring water in the top of the rad and see what sort of flow you get out the bottom.

Colin

[lusciousthelock]

Okay, sounds promising. I'll try and get the rad out this week and give her a flush out and see what happens. I didn't see any bubbles at all, it was just running fine one minute, then all the water just got pushed out of the rad at about the same I would expect the thermostat to open? Squeezing the bottom and top hoses produced movement in the water as expected though. Hopefully get some time off this week to get stuck in.