Coolant System Problem

[FredTransit]

wiring is relatively simple if you work through things logically

So glad you said that GS, co eletrics are a complete mystery to me!

[transitgeoff]

plastic t-stat housing or ali

[tractive-effort]

Tis' plastic sir, though I am 99% sure it is the sender-unit and/or gauge, so I will be replacing both tomorrow hopefully.

One other thing, I was told that the temp gauges should stay static (like the fuel gauge does) relative to the temperature of the engine when switched off. Then it just drops back to zero as it cools. Is this right?? Mine just drops totally to the little white thermometer motif at the bottom of the gauge. The gauge still shoots across to the red sporadically and drops down just as quickly when driving. The engine is not overheating though.

Also, the Haynes manual says that if the electrical connector is taken off of the sender-unit and the gauge drops to zero, then this indicates a faulty sender and/or gauge (if either was suspect in the first place that is...)

[Gunslinger]

cant see how that is right, if you remove the connector then the electrical circuit is broken and the gauge will return to the rest position

[MarkM]

It's a mis-read of Haynes you remove the connector and short it against the block or wherever if it (the needle) goes right over it proves the gauge is good, So now you change the sender, if nothing happens then the gauge is bad.
I seriously doubt this issue is that simple...I am still waiting on the picture.
The temp gauge always resets to zero when you turn it all off...well all the vehicles I have ever driven have so....

[tractive-effort]

Doesn't seem to be a mis-read of Haynes - probably more a misprint IN Haynes....

Anyway, I've been driving it around without the thermostat in now for about 4 days and the needle will sit just above the white block at the bottom of the gauge. Intermittently it will move to about half way over, sit there for a minute or so and then return to just above the white square. The heater blows VERY tepid air out, even with the gauge at halfway, so the engine is not getting too warm. I have fitted a new temp gauge tonight (I got it NOS cheap) and will be picking a new sender unit up tomorrow. I will also put a new thermostat in too for good measure, though for the summer I will probably just omit it..

PS: It has not used any water

[daddy cool]

One other thing, I was told that the temp gauges should stay static (like the fuel gauge does) relative to the temperature of the engine when switched off.

My mk6 does. My temperature gauge only moves when the ignition is switched on again.

[MarkM]

Doesn't seem to be a mis-read of Haynes - probably more a misprint IN Haynes....

Anyway, I've been driving it around without the thermostat in now for about 4 days and the needle will sit just above the white block at the bottom of the gauge. Intermittently it will move to about half way over, sit there for a minute or so and then return to just above the white square. The heater blows VERY tepid air out, even with the gauge at halfway, so the engine is not getting too warm. I have fitted a new temp gauge tonight (I got it NOS cheap) and will be picking a new sender unit up tomorrow. I will also put a new thermostat in too for good measure, though for the summer I will probably just omit it..

PS: It has not used any water

Haynes mis print or whatever the test is how I wrote it above.
If you are getting no heat then something is wrong...too cool is as bad as over heating.. you said you are getting gurgles...this is air in the system and symtomatic of Low water...when I say air I mean it in that there is a gap rather than a leak...you have a blockage somewhere.
The header tank return hose hole is favourite...I was waiting for the picture to show which header tank you had. Check that water is flowing through this by taking the header tank cap off and putting your hand inside...you will feel the water flowing since you now don't now have a thermostat...high flow not a dribble...if a dribble use a drill and bore out the hole. The other problem is the heater matrix which sounds blocked as even if the engine is showing correct or near to correct temp a blocked heater matrix will not allow heat into the cab. Hoses off and a garden hose attached and S-L-O-W-L-Y turning the pressure up to free any crud....actually easier and less messy if you leave the heater matrix hoses attached and fix the garden hose to the hoses themselves, really a two person job and you have to do it on both hoses to really flush it out...after that if still no joy a new matrix will be needed, they are common to block up, the blockage will force the water to find another route and given how awkward the heater matrix hoses are to get to not a hose you would want to fix at the roadside.

[tractive-effort]

My header tank is the round version with one outlet at the bottom and two smaller hose attachments on the front at the top. I'm still getting gurgles and the water in the header tank seems to rise and fall accordingly. There is heat in the cab now

Could the header tank be faulty?? There is the sound of an airlock (gurgly) from the area of the stat housing. All this seems to have got WORSE since putting in the new sender-unit. Water came out of the hole where the sender should go (naturally) and no doubt air got in. This air though has not been displaced by the header tank and yes I have checked the pipe that goes to the stat housing and it is clear!! Any more ideas??

[MarkM]

Changing the sender unit will not add an airlock into the system, well it shouldn't if ALL the hoses are clear. When cold unscrew the cap from the header tank and run the engine, since the return pipe is at the top right and you have no thermostat this should be a torrent of water coming through. See what you have then...

[tractive-effort]

Righty ho - many thanks, will give it a go tomorrow sometime......watch this space

[tractive-effort]

Hmmm - a strange one this! I checked the return pipe and there is a steady flow. I then took the return pipe off of the header unit to check consistency of said flow. On doing this I noticed there was probably as much air coming through with the water given the amount of bubbles apparent.

So, an airlock, but where in the name of hell does air get into the cooling system?? Also I decided to turn the engine off and blow down the return tube (in the direction of the stat housing) and this raised the water in the header tank! I would of thought seeing the air bubble up through the water would have been the correct scenario??

[MarkM]

Ok air in the system has got in somehow...which means there IS a leak of some kind...it 'might' be just one of those things, to attempt to remove this air lock run the engine with the cap off...you do have to be careful as the temp will rise and the system is supposed to be a pressure related one hence the screw cap but running with the cap off will allow the air to filter through to the header tank, you have a slight advantage since you removed the thermostat, but with the warmer weather coming no thermostat will only be hiding a problem. The blowing on the hose wouldn't bring air bubbles out as you can't blow has hard as the pump can pump, so it wasn't that strange for it not to happen as you expected.
The good flow has proven that the water pump is also working as it should so you have removed that as a possible problem.
Is the viscous fan unit working properly? Siezed will cause over cooling, too loose will mean over heating. First check for too loose with the engine off...there should be some firmish resitance assuming all is cold if this is ok then you will have to run the engine to proceed to the next test. Be very careful when attempting to stop the fan rotating with the engine running...if it stops then the viscous unit is fine. If your fan is the open bladed version be extremely careful if it is the enclosed fan then it is a heck of a lot easier to stop and even if the viscous unit has siezed touching the fan is not so dangerous with this version but still be careful....a siezed viscous unit will mean that the fan is always cooling and this could be a cause for erratic temp readings and they are no fun at all to replace.

White fan with connected blades = easy-ish to stop
Red or yellow with open blades = lot harder to safely stop and if siezed it will potentially take your hand/finger off (worst case, best case rip the tool you use out of your hand and puncture the radiator)

Replacement should this be the problem is on paper simple but you must replace with like for like, a cold chisel and a hammer are the simplest tools plus the special fan spanner (Drapers do the cheapest one)
be warned some viscous units are anti clockwise threaded some are clockwise..this is why you replace like with like...having the replacement in hand already will let you know which thread you have so then you will know which side of the nut to clout. You can get the viscous units from ebay but as they do differ thread wise so you are taking a chance but the Fords price is not a nice one. There is a thread somewhere on here about how to replace the viscous fan unit.

[tractive-effort]

Things have gotten much worse this afternoon, there is a leak somewhere and I now think it is the water pump. One minute, overheating and the rad is cool. The next minute the temp goes down and the rad is hot again. Run with the cap off and there is a backlog of water one-minute and sometimes will overflow, the next nothing! Also a large squeal came from the vicinity of the water pump at one point and the flow from the return pipe was paltry and sporadic (like it was spitting). Fan seems ok, though I'll check tomorrow! Water pump is a bitch to do no doubt as you have to remove the fan too. Oh well, I have the Haynes manual (whatelse can you do but smile eh, and dissapear into the distance in true Morecambe & Wise style.. )

[MarkM]

You have a blockage too as even with the cap off it shouldn't suddenly rise like that...the pressure isn't that great to force it around...though take the cap off when it is at temperature and the pressure is rather a lot...been there done that....at least the older designed cap had a sort of slow release and a nice simple rubber seal

Try the hose pipe on the heater matrix hoses as I said before and then see how you get on...the squeeling I wouldn't worry too much about that just yet since you have spilled water over the engine bay and that is more likely just water on the fan belt.

You were advised right at the beginning to flush the water system and not just me