240 General: New (to me) 1980 Volvo 244

[Clifford Pope]

That's a switch isn't it? I'd hazard a guess it's the one that turns the lights on - the threaded boss fits on the steel of the dashboard, the long plastic stem projects through the gap before the plastic dash and the knob.

You can test the temperature gauge and sensor by removing it and connecting an extension wire so you can dangle it in a pan of boiling water. Use a battery charging cable with a crocodile clip on each end to supply the earth. Then as the pan cools you can calibrate the gauge accurately against a mercury thermometer and see what temperature it actually indicates.

It appears there is a circulation problem. You've flushed the radiator? Have you removed it, filled with hot caustic, then blasted the inside by backward circulation with a garden hose?
It might then leak of course - perhaps it has been partly blocked by use of Radweld at some time?

Is the water pump OK - vanes intact and turning?

When you start the engine from cold you can feel the top warm up, and the heater pipes get hot. The heater gets its feed even when the thermostat is closed.
Then when the head is hot, the thermostat will open and you should feel the top hose and the top of the radiator get hot very quickly as the water circulates. The bottom of the radiator and the return hose will always be appreciably cooler if the radiator and fan are working.

[Laird Scooby]

Originally Posted by Othen

Right chaps, I may need some help with this.

As per my last, I flushed the system, fitted a thermostat (you will recall, there wasn't one) and filled with water ready for a test drive.

All started well, the temperature got to half way quickly and the heater now works properly (I had not noticed much, but it was giving hardly any hot air previously).

I suppose I'd got about 2 miles, the temperature gauge continued to rise to the very top of the green part, so I headed for home. Here are the instruments when I got back:



... as you may see, the gauge is at the very top of the normal range, but otherwise the car is running fine, normal tickover and so on. I popped the bonnet and could feel the top hose getting warm (warm but not unduly hot) so the thermostat must be opening. The radiator had hardly warmed up at all, just the left side was hot to the touch, the rest was cold.

There seem to be 2 possibilities:

a. There really is something wrong with the cooling system, either the thermostat isn't opening fully or there is some sort of blockage somewhere preventing cooling. The evidence doesn't really seem to support thus though as the top hose is warming up, but the radiator isn't, the heater is working (well) and the motor seems to be running well otherwise.

b. The sender for the temperature gauge isn't working properly. I'm suspicious that this might be the case because I found what appears to be another one in the spares box:



I had a look around the engine bay and couldn't find where it goes, the Book of Haynes isn't much more helpful - perhaps one of you knowledgeable chaps would tell me. The easiest thing would probably be to just swap it out and see if the problem goes away.

What do you all think? I had to stop looking for faults when I noticed the rubber seal around the 50050 switch was leaking quite badly. I'll probably change it for the shorter one that came with the component (rather than the one that was on the original bung - and may well be a decade or two old) and see if that solves the problem once I've walked Bob.

The good news is that the bits to fit the electric fan arrived in the mail today. Once I get this issue sorted out I can get on with fixing that.

Alan

Wait until it cools down Alan, not much you can do until then but i wonder if the rad is blecked or the water pump is knackered.

The bag you show with a component inside looks very like a switch or potentiometer and there appears to be a flat on the shaft, i don't think it's a temperature sensor of any description. In fact, i'm comvinced it's a spare headlight switch :

https://www.rockauto.com/en/moreinfo...868&cc=1287367

Usually the temp sender is near the thermostat housing, on yours it's probably a single wire animal, pull the connector off and switch the ignition on. If the temp gauge doesn't move, reconnect the wire and see if it starts moving. It could also be the sensor is FUBAR or incorrect.

It could be your gauge reads naturally high, do you have an infra-red thermometer at all?

https://www.amazon.co.uk/Infrared-Th.../dp/B071NBJJ2Q

If so, check the temperature of the 'stat housing but it sounds as if you either have no or restricted flow through the rad or a mahoosive airlock in the rad.

Any history of the water pump being changed before you got it?

[Othen]

Hi Clifford and Dave,

How embarrassing, I've failed my Volvo parts recognition test miserably! Now I look at that part again it is obviously not what I was looking for - I just jumped to a conclusion because it was in the same box as the thermostat.

I have to collect Dan from school now, but when I get back I'll start eliminating things it can't be so I can fix whatever in the problem.

Alan

[Othen]

I’m just thinking about this problem whilst waiting for Dan in the school car park.

The Royal Barge indicated normal temperature when running without a thermostat, but warmed up very slowly. The only thing that has changed (apart from flushing the system out) has been inserting a thermostat.

I flushed the system with a garden hose via the top radiator spigot and clean eater came out of the end of the top hose, so it must have been able to complete the whole circuit via radiator, bottom hose and block? I also filled it via the expansion bottle with the top hose loose on the radiator spigot so I could see when the level had reached there before tightening it up, so it must have traveled up through the radiator. It took about 9 litres of water to fill it, so one would imagine there can't be too many voids inside the cooling system.

I’m thinking the engine could have perhaps run as a thermosiphon device without the resistance of a thermostat, but with one the water pump can’t manage?

What do you guys think? Dan is here now.

Alan

[Laird Scooby]

Originally Posted by Othen

I flushed the system with a garden hose via the top radiator spigot and clean eater came out of the end of the top hose, so it must have been able to complete the whole circuit via radiator, bottom hose and block?

Get some flushing agent Alan, add it to the system and take it for a half hour or so drive.

Let it cool a bit, remove the 'stat and refit the housing.

Remove the top hose from the radiator stub and put the garden hose into the radiator top hose - NOT the stub on the rad but the hose itself.

Most garden hoses will fit snugly into the top hose.

Turn the garden hose on and go for a coffee, come back and check to see if it's running clear.

In effect what you've done is forward flush it which won't dislodge any gunge/goo in the radiator.

That needs reverse flushing.

Hence putting the garden hose into the top hose and not the radiator - that gives a through reverse flush.

Make sure the heater is set to hot at all times from when you put the flushing agent in whether it's something like Comma X-Stream Flush or caustic soda as Clifford suggests - i've used both but the caustic soda needs a lot of care as it can dissolve the solder used in the rad!

[Othen]

Originally Posted by Laird Scooby

Get some flushing agent Alan, add it to the system and take it for a half hour or so drive.

Let it cool a bit, remove the 'stat and refit the housing.

Remove the top hose from the radiator stub and put the garden hose into the radiator top hose - NOT the stub on the rad but the hose itself.

Most garden hoses will fit snugly into the top hose.

Turn the garden hose on and go for a coffee, come back and check to see if it's running clear.

In effect what you've done is forward flush it which won't dislodge any gunge/goo in the radiator.

That needs reverse flushing.

Hence putting the garden hose into the top hose and not the radiator - that gives a through reverse flush.

Make sure the heater is set to hot at all times from when you put the flushing agent in whether it's something like Comma X-Stream Flush or caustic soda as Clifford suggests - i've used both but the caustic soda needs a lot of care as it can dissolve the solder used in the rad!

Thanks Dave,

Roger, I'll pop over to Wilco in a mo and get some flushing agent.

I flushed the system both ways with a hose this morn Dave, via the top hose (through the head) and via the radiator spigot. Fortunately I only filled with water, so I'll just repeat the whole thing as per your instructions in the morn and see where we end up.

The good news is that the new 50050 seal seems to be dry.

Alan

[Laird Scooby]

Hopefully it's as simple as that, i'm wondering (on a hunch) if it wouldn't pay to fit a new temperature gauge sender. The Intermotor part number is 52260 and it looks like this :

https://www.fpukfindapart.co.uk/find...nal=Intermotor



Thinking about it, it might not be near the 'stat housing but further back on the head, not sure which side but probably the left as viewed from the drivers seat.

Wilco should either have them in stock or be able to get them.

[Clifford Pope]

I think radiators can become unclearably blocked over time. I've had ones that I've rigorously flushed out with boiling caustic off the car and then backflushed from every hose connection with a garden hose, but they still run too hot.
It's as if the metal sort of swells or grows an immovable deposit which narrows the passages between the cores but also reduces the heat transfer.

There comes a point when getting a new one becomes the best option - they are quite cheap I think, and I have always been surprised how effective a new one is compared with one that I thought was clean.

With a good one you hardly ever need a cooling fan. When some cars back I fitted an electric fan it rarely if ever needed to cut in, just for a very short time on a very hot day or when pulling a heavy load up a long hill, or stuck in an endless slow-movingtraffic jam.
That of course is their danger - when you do need it, it doesn't work.

[Dippydog]

For the minimal cost I see no harm in changing the temp. sender.I imagine a previous owner has butchered the thermostat to "cure" the overheating and given your description I'd say the radiator is blocked[although It could be an airlock]whether it will respond to flushing or not I don't know but on the odd occasion[once or twice over nearly 50yrs of motoring]when I've had this I've always found it better to just change the radiator for a new one or get the original re-cored.

[Othen]

Right chaps, again thank you for your replies and advice.

I think I'm getting somewhere. I had another look at the car this eve. The radiator and hoses are quite new I'd say. Well, I didn't have time to get to Wilco before closing time so I back-flushed the whole system again with water, gallons of it. First I flushed just the radiator, then just the head and block, then the whole thing: in through the top hose > out through the top radiator spigot:

https://1drv.ms/v/s!Ask6E_1jz4xI81Xv...SSUMS?e=JavvDg

(I hope that video works).

So, I put the thermostat back in and screwed everything together, started the motor and then remembered I had an IR thermometer in the garage (Dave had suggested it previously). The motor soon warmed up and was ticking over with no choke or fast idle, everything seemed fine but the temperature gauge was close to the top of the green segment, as previously.

I took few readings of the thermostat housing over about 10 minutes, it stayed steady and consistent at 81-82C:



then followed a path to the radiator inlet, which remained at 62-63C throughout, down to the left side of the radiator (42-43C):



... and to the right side of the radiator (23-24C):



I'm 99.9% everything is fine with the cooling system, except either the sender or the gauge is defective.

I'll see if Wilco has a sender in the morn (Dave kindly found the part #) and swap it out, I suspect that will solve the problem (I found the sender - middle of the head under the intakes on the left side). I suspect that will sort the problem, so then I'll drain the system and refill with coolant.

I'm pretty sure we are there - hopefully get this bit finished tomorrow and if so get the fan fitted.

Why has this happened? I'm guessing the PO panicked a bit when the temperature gauge kept rising inextricably, and so removed the thermostat, so the engine may have been running too cool for some years (probably explains why it did almost no miles in that time). It probably also explains why the tick over was set to 1500 RPM - it never really got warm enough to tick over properly.

I hope I'm right.

The seal for the 50050 switch seems to be fine.

Many thanks again chaps.

Alan