Crossflow, no thermostat and what coolant level?

[Gridgway]

Just been looking at  the cooling system on the crossflow.  It doesn't look to have a thermostat which was surprising, unless that's the norm with crossflows.  In my short drives, it doesn't look to have a cooling problem, seems to get to about 80 degrees and no further yet.

The coolant level is just below the level of the top hose which means that the fan thermostat is not submerged although I guess it'll get coolant washed over it in use.  What level should the coolant be?

The fan works if you take the connectors off the thermostat and make them together.

Also the long term owner has taken the heater out of the cooling circuit.  The send and return hoses for it are just connected.  That makes me wonder.

So two questions, what should the coolant level be and is it ok without a thermostat?

Cheers

Graham

[AnkerB-S]

The thermostat is there to help the engine warm up quickly, not to prevent overheating.

My X-flow has a thermostat, and my coolant level covers the coolant temperature sensor.

Anker 

[OldAndrewE]

I would certainly add a thermostat and increase the coolant level.  I assume you have an expansion tank so that coolant is drawn back in on cooling down.

The heater disconnected could indicate an issue with the heater (leaking matrix?)

[7 wonders of the world]

Thermostat is also there to maintain correct operating temperature - it should have one, be aware that some are removed to mask an underlying problem though.......

[rkeywood]

Has a restrictor plate been used in place of the 'stat? This was common on race engines and is the way mine has always run. 

[Gridgway]

Thanks all for the info.

Covering the points. no there isn't an expansion tank, so one imagines there needs to be at least some air gap under the cap.  There is an overflow bottle to contain any coolant that comes past the cap, but it doesn't go back in.

I'll try a new thermostat to see what happens and top up the coolant.  If there is some kind of cooling issue, I'd rather find it and fix it.

I'll take the heat off and check for any visible signs of leaks and then plumb it back in to see what happens.

Not come across a restrictor plate before.  How would I find it and recongnise it?

Cheers

Graham

[OldAndrewE]

The restrictor plate would be fitted in place of the thermostat.  If there is nothing there you do not have one.

The overflow bottle should have the pipe down to the bottom and have some coolant permanently in it.  The pipe should always be submerged and have a diagonal cut on the end to stop it sealing to the bottom of the bottle with suction.  Any coolant that ends up there due to expansion will be drawn back in when the engine cools

[Gridgway]

Interesting, I'll have to go and have another look at it.  I assumed - seemingy incorrectly that it was just an overflow bottle.  I can see how excess pressure from the cooling system can vent pushing the pressure cap up.  I don''t understand how it would pull coolant back down as it cools as the cap is sealed.

[OldAndrewE]

The small disc in the middle of the cap is only designed to keep pressure in.  It is on a weak spring and will open up when the pressure in the cooling system is lower than outside drawing the ejected water back in

[Gridgway]

Interesting, just looked and yes there is coolant in the tank, so it could well do that.  Are there different cap types that may not have the centre disc that acts as a one-way valve to let coolant back in or do they all do that?  The one I have is the one with the lever in the top to safely release pressure.

[OldAndrewE]

I use Stent rad caps as well and I assume they have the one-way valve (I will check when I get a chance).  If they did not you would be creating a vacuum in the cooling system and the hoses would start to collapse which they do not

[Gridgway]

Just back in from the garage and the one way valve is definitely there.  So it's time to fill the coolant to a better level and monitor what happens.  My suspicion is that there is something amis, but we'll see.  I'm expecting the coolant to get blown out, and not return.

[Tazio]

Make sure that the bottom of the hose in the overflow tank is cut at 45 degrees, and pushed to the bottom of the tank. The cut is to ensure that the hose cannot seal itself to the bottom of the tank whilst syphoning back into the system