Coolant Loss From Expansion Fan Cuts In To Late

[Bananasplitz 0 1 Cars]

While getting MOT (another story) early morning temp 12degrees

Vehicle was stationary idling warm during emissions testing with no cooling problems over last month though never stuck in traffic

Coolant water erupted from the expansion tank lost about 1.5 litres (fan did not start)

MOT was aborted, cooling fan then started about 1min later as we were about to pushing car out to cool down.

Refilled expansion tank, used heater matrix on full plus fan to help cooling, drove about 3 miles home, the engine bay/engine felt really hot.

 

Questions

Is it safe to drive,

Any idea what may have caused this (radiator replaced by previous owner about month ago)

Fan switch, thermostat?

 

The only advice I have had at local garage is to see auto electrician and wire fan permanently on but I don't thick this is the best thing to do,

I understand that the fan mabye two stage off,low,high. Control.

I have not heard fan on before but that maybe that I have not noticed. Did work after the event.

 

Any advice would be great as only 9 days left to get MOT

Edited June 17, 2013 by Bananasplitz

[welshpug 1,621]

firstly I would change the thermostat and expansion tank cap, then run it up to see if the fans work as intended.

[Bananasplitz 0 1 Cars]

I know the fan is working, because after it overheated it came on, have just had another run in it temperature started to rise once stationary and idling, the pipes all seem to be heating up, I let the temperature rise to the point on the gauge where it was when it overheated (1.5 marks past halfway did not reach red). Still no fan I would not have liked to touch the radiator.

What does the thermostat do on the cooling circuit (I know what they operate at a certain temp) but what is the function does it open a cooling loop or send a signal to the fan. Tried Haynes but the info is nonspecific. Does any one have a diagram of how the cooling system works together (fluid/mech/ elec).

I also noticed that there is no filler cap on the radiator that the previous owner just added., How do I know if the fan temperature switch is below the water level. Is there a way of figuring out if the fan temperature switch is working.

[welshpug 1,621]

thermostat controls the flow of coolant from engine through the radiator, this as standard is set to fully open at 89 degrees, until this point coolant simply flows through the heater matrix.

 

the fan thermoswitch is set at low speed of 97 and high speed of 101, it is positioned below the top hose on later cars, or right down just above the bottom hose from rad to engine on early cars.

 

radiator "should" be full to the top with coolant, hence the use of the small bleed hose from the right hand top corner which goes back to the expansion tank,

[Bananasplitz 0 1 Cars]

Thanks, That would mean that if the thermostat did not open then the radiator would not heat up to allow the fan to operate. This would explain why I was able cook myself inside with the heater matrix as well. But still unsure about the expansion water release, I take it would be from water expanding from the lower hose as opposed to from the expansion hoses from the radiator.

I Don't quite understand the need for the new expansion cap as the overflow from the expansion bottle would appear to be an open tube.

 

Do thermostats normally fail in the closed position?

 

What is the process of filling the system if I drain it to replace the thermostat, I know of a bleed screw on the heater matrix pipe are there others, or is it just a case of filling the expansion tank slowly?

[TheReaperWaits 6 1 Cars]

If the expansion cap is faulty the cooling system will not hold pressure and will reach boiling point at a lower temperature. There is a bleed screw on the thermostat. On mine it looks like a dust cap.

[DanteICE 72]

After having my car overheat the other day because the fan didn't come on I can certainly help here.

 

You should change the thermostat if the radiator isn't warming up.

 

You should change the expansion bottle cap, because they seem to be a common cause of pressure build up and give the signs of a blown head gasket. So change it if you can.

 

The fan system is independent of all the other electrics (just about), there is a thermoswitch screwed into the radiator, just below the top hose. if you pull that plug off the switch and take a piece of wire and connect the top slot to either of the side slots the radiator fan should come on. Now when you connect the top slot to one of the side slots the wiring will pass current through a resistor to the fan (half speed fan) and the other will be a direct connection (full speed fan). If you get this try cleaning the connections to the thermoswitch in the plug and on the switch itself and then see if this improves the situation. If you still get nothing then it'll be the wiring.

 

This is LESS common, but it happened to me. Firstly find the radiator fan wire directly from the unit itself and follow it until you find the plug (normally located behind the nearside headlight). Unplug and wire up directly to the battery, if it spins, great the fan is fine!!! If not, clean up the terminals and try again (I had this issue too).

 

In fact I'll say this now so I don't keep repeating myself - CLEAN EVERY f***ING ELECTRICAL TERMINAL YOU FIND, THOSE LITTLE BASTARDS LIKE TO STORE DIRT FOR THE WINTER

 

Right, so we have the fan working independently and we can bypass the thermo switch with no joy. So the most common issue after those two is the earth plug/socket thing is the common cause. Now most people will tell you to remove it and earth ring every wire to the bolt. But I won't because I didn't.

 

So next to the thermoswitch, attached to the chassis you should see a few wires go to into a little plastic sheath. This is the earth connector for your indicators and fan (don't know if there is anything else, but it's certainly possible). So you can remove the sheath by getting the end closest to the chassis and stretching it over the wires, it's basically got a little rubber band on one end and open at the other. I ripped mine, because it looked at me funny.

 

So you should now see 2 connectors plugged into the socket. Firstly get WD40 (other penetrating sprays are available) and spray the connectors and give them a wiggle while doing so. This is because those bastards are going to put up a fight. Leave the penetrating spray to work for a bit and mentally prepare for some growling. Normally I'd say don't use WD40 on electrical stuff, but we are penetrating here, not cleaning...that can be done after. So remove the plugs (top should be fans and bottom, indicators.) and using electrical spray and wire brushes clean the socket and plug. Now, in the middle of the socket there is a bolt, remove this and the socket will be available for cleaning with sand paper (for the metal bit on the back) and there will be a earth ring behind the socket unit, make sure this is clean too (sand paper is best, we are looking for shiny metal).

 

Once everything is clean, take some sand paper to the attachment on the chassis so that bare metal is showing. Put everything back together using copper slip (it's all going back to earth so don't worry about being messy it'll only help).

 

Check the fan thermoswitch connector now. It should all work, if you're having problems after this get back to us and we shall continue. Oh and if the half speed fan doesn't come on, the resistor isn't working....try cleaning the connector to the resistor (good god this s*it gets dirty), otherwise it's a dead resistor.

 

Hope this helps. Oh and check the indicators (turning left) because you've been messing with the earth for it, so you could have screwed it up like me, but if you've cleaned both connectors it should be fine.

 

Geoff

Edited June 18, 2013 by DanteICE

[Bananasplitz 0 1 Cars]

Thanks, got a good few things to try.

Picked up a thermostat today from hal***ds there system says it works at 82 degrees and it is also marked 82degrees, found a section from peugeot servicebox which has parts nos

1338 37 82 deg vernet

1338 44 89 deg vernet

Hope I've got the right one guess the lower temp if it fit shouldn't do any harm

I'll open it up and see what's in it.

I'll let you know how I get on may be a few days due to work.

[welshpug 1,621]

82 will be fine, most of the later pugs run at 83.

[Henry Yorke 269 3 Cars]

I had great fun one putting the old thermostat in a pan of water on the hob and bringing it to the boil to see how it worked! It worked perfectly and I did not need to change it, but I did put a new expansion cap on as I had the same issue as you (and that gave me a pin hole in the radiator as it held its pressure properly).

[Bananasplitz 0 1 Cars]

Just back from trying to get the thermostat out, 23 years the bolts are locked solid, tried soaking with WD no go, will try again tomorrow, any one got any ideas on releasing the bolts, heating the engine, etc. I don't want to shear the heads.

I think I may have to take the AFM off to get to the lower bolt.

[welshpug 1,621]

I'd take the whole housing off and drill the bolts, i had to do that laat week and the bolts had been in 5 years or so! SS bolts in now though