Overheating

[vanman2004]

Hi all,IMAG0657a.jpg
Is this too hot?
Up until recently my Stag has been running fine. A weekend away to the Cotswolds was no problem, first decent run since the engine rebuild and she didn't miss a beat and the temperature gauge didn't move from strait up. A couple of weeks ago she let me down as the Piranha electronic ignition packed up and I had to be helped home by the AA. This was replaced by my garage as car electrics are beyond me, but on the way home I noticed the needle went higher than usual. On checking I found the neck of the overflow bottle had a tiny split. I decided to replace it with a H.T. but the gauge will not stop at upright. It goes just to be beginning of the red. I left it idling for a while but it didn't go any further. Is it possible that the gauge has decided to play up? Not sure if it helps but my cheepo IR thermometer shows temperatures of 105, 108 and 104 degrees C in between pots 2/4, 4/6 and 6/8 and 80,88 and 88 on the other side. Rad filler area was 77 and at the bottom 55. Are these temperatures acceptable? How can I be sure there is no air trapped somewhere. It says fill rad with heater on hot, my valve is stuck shut , would this cause a problem? Sorry to go on but I thought I'd give you the info I have. Thanks in advance for any help you can offer.

Mike

[DJT]

Mike,

The temperature sender is in the water transfer housing on the rear of the LH head. If that head is running hotter it could explain the high gauge readings. The fact that the LH head is hotter could indicate an airlock. Have you tried moving the heater valve itself, not with the slider knob?
If you can't move the heater valve, then try disconnecting the hoses that supply the heater and join them together with a short length of copper pipe to bypass the valve and matrix, after bleeding any air out of the hoses first.
On a slight tangent, have you noticed any odd readings with the fuel gauge lately? Fuel and Temp gauges are supplied by the voltage stabiliser and this can fail giving high readings on both. The stabiliser has a 10v output, so if it fails these instruments can get the full battery voltage.

[Andrew S]

Hi Mike, sounds like an air lock to me. Air will get trapped in the heater if it can't run through it. In addition to what Dave has suggested, whilst the engine is running, remove the top heater hose from the bulk head as its high up but don't do this when engine is too hot. As water is coming out push it back on and do up. It may allow the air out using the waterpump pressure to push water through.
I am happy to come and have a look.
Cheers
Andrew

[deanoed]

You have to have the heater on hot if it's stuck then you need to unstick it or bypass it but no heater if you bypass it

[Lingen]

Mike. Just a thought,. You say this happened after your garage had replaced your Piranha system. I wonder if they have set the timing correctly (12deg btdc). If it is retarded, particularly in this very hot weather, that may be the cause. Your gauge seems to roughly agree with the readings from your digital thermometer.
Mike.

[Guest]

I had the same issue when I refilled, I ended up having heater on full and also took the Bung out the top of the rad. Check to see if you have water in the top hose too.

[Lingen]

Andrew. Me again. It sounds as though you have got your heater hoses connected the wrong was round. The top hose on the bulkhead should go to the metal pipe that goes to the water pump. Being the higher pipe means that any air being fed into the heater from the L/H cylinder head will always find its way out again, even if the heater valve is only slightly open. Connected the other way round makes airlocks in the heater matrix inevitable unless the heater valve is fully open.
Mike.

[John Hoggarth]

I'm also having air lock problems and have been following the advice on earlier threads and will also take account of what's said above.
A mechanic suggested I insert a bleed valve somewhere in the system, maybe in one of the heater hoses. I appreciate this is a remedy rather than cure but I wonder what others think or if anyone else has done this?

Thanks

John

[Guest]

I fitted a stagdad water pump kit, this has a bleed point int the heater circuit

[Bandit1200]

Andrew. Me again. It sounds as though you have got your heater hoses connected the wrong was round. The top hose on the bulkhead should go to the metal pipe that goes to the water pump. Being the higher pipe means that any air being fed into the heater from the L/H cylinder head will always find its way out again, even if the heater valve is only slightly open. Connected the other way round makes airlocks in the heater matrix inevitable unless the heater valve is fully open.
Mike.

Hi Mike
My understanding, having consulted the Manual, is that on early models the top bulkhead hose goes to the lh cylinder head and the bottom goes to the metal pipe leading to the water pump.
On later models, they are connected as you describe.
Steve

[flying farmer]

Mike. Just a thought,. You say this happened after your garage had replaced your Piranha system. I wonder if they have set the timing correctly (12deg btdc). If it is retarded, particularly in this very hot weather, that may be the cause. Your gauge seems to roughly agree with the readings from your digital thermometer.
Mike.

I remember watching one of the mobile mechanics at the TR register international trying to figure out why the Stag he was working on was timed about 90 degrees retarded until I pointed out he should have timed it off no2 cylinder not no 1. Just as well he hadn't got as far as resetting it!
I would also favour an airlock as the main problem though.
Neil

[seadog]

I posted about the temperature gauge needle position a short while ago, mine was running with the gauge at about a third of the way up for the first ten or fifteen minutes driving then going up to vertical, then staying there for the rest of the drive, however, I wasn't very happy about this, something just didn't seem right so yesterday I took the plug out of the top of the radiator, took the cap off the expansion bottle, put the heater on hot and ran the engine on idle until it started to get hot, as I watched, lo and behold, bubbles of air came out, I kept topping up the level till it stayed constant with no bubbles then re-fitted the plug, the water by now was very hot (scalding fingers- be careful) and the temp gauge at about one third of the way up. Checked the level in expansion bottle was at about half and put the cap on. Took about fifteen minutes from cold.

I then took the car for a short run and the gauge never went above the third position. So hopefully sorted. Appears to have been an air lock which could have happened when the system was flushed and refilled before I bought the car last year.

[Lingen]

Apart from the heater, the Stag cooling system is self-bleeding. If it is not filling quickly and fully then something is wrong. It could be that the thermostat hasn't got a jiggle pin / hole to let the air through, which is vital,or the two small bleed water passages in the front of the inlet manifold are blocked with crud. If they are, then there will be airlocks at the front of each head which will take ages to clear. Unfortunately it will mean removing the manifold to poke them clear but it is well worth doing.
Only the heater needs to be bled by running the engine.
Mike.

[tjk]

Hi
When I change the water/anti, I put the car on ramps at the front so I can drain the block and always refill with the car still on the ramps and found this guarantees no air locks

Tim

[Lingen]

Hi Tim.
Then it seems you have the correct thermostat, and the inlet manifold isn't blocked!
Mike.