| View previous topic :: View next topic |
| Author |
Message |
Spyderman
Alfasud
Joined: 04 Sep 2003
Posts: 48
Location: Hampshire
|
 Posted: Mon Jun 12, 2006 12:13 pm Post subject: Cylinder head switch |
 |
|
Hi guys any idea what temp the little switch on the cylinder works at?
(the one near the dipstick tube)
Its in my kitcar and seems to come on at not much over 80 degrees according to the water temp gauge.
Have replaced the switch with new and it still does it ,so wondering now if the water temp gauge is accurate.
I assume the switch is an overheat switch as the engine is not in an Alfa |
|
| Back to top |
|
 |
tvatavuk
Gold Cloverleaf
Joined: 13 Mar 2003
Posts: 673
Location: Split, Croatia
|
| Posted: Tue Jun 13, 2006 9:26 am Post subject: |
|
|
AFAIK overheat switch was on back of engine near oilfiller tube, it's little cube.
Coolant temperature gauge switch was near oildipstick tube on top of engine.
_________________
Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo |
|
| Back to top |
|
|
Scott Sander
Alfa 33
Joined: 20 Feb 2003
Posts: 419
Location: Sydney, Australia
|
| Posted: Thu Jun 15, 2006 1:13 pm Post subject: |
|
|
I agree with Tino about the overheat switch being a cube, however on my 16V it is on the left hand side of the engine (RHD).
The oil pressure light switch is near the dipstick or could be right in the centre of the motor near the back (that's were mine is).
The coolant gauge sensor is in the radiator.
What could be happening is that your thermostat is stuck shut, so you get very little coolant to the radiator and the water in the engine is too hot. I had this happen on my first 33 1.5 many years ago.
_________________
Scott Sander
'91 Alfa 33 Boxer 16V Monza - Awesome
http://www.sanderfamily.com |
|
| Back to top |
|
|
Spyderman
Alfasud
Joined: 04 Sep 2003
Posts: 48
Location: Hampshire
|
| Posted: Thu Jun 15, 2006 11:12 pm Post subject: |
|
|
| Scott Sander wrote: |
I agree with Tino about the overheat switch being a cube, however on my 16V it is on the left hand side of the engine (RHD).
The oil pressure light switch is near the dipstick or could be right in the centre of the motor near the back (that's were mine is).
The coolant gauge sensor is in the radiator.
What could be happening is that your thermostat is stuck shut, so you get very little coolant to the radiator and the water in the engine is too hot. I had this happen on my first 33 1.5 many years ago. |
I'm actually running thermostatless, the car only comes out if its warm enough enough and not raining.
It is the little cube sender nearish to the oil filter I have replaced which is still indicating overheat, the coolant sender on mine is in one of the manifolds.
Have fitted a second rad fan which helps a bit, plus an additional manual switch for the fans, which has improved things
Think some of the prob may be no through air draught ventilation over the engine as it is mid-mounted, rather than receiving forced air it would get in a sud/33.
MGF's, Elise's, MR2's etc seem to have a little fan in the engine bay to create some air movement, to remove heat build up, so may have to look at that again.
Back to the cube switch though, at what temp does it come on? |
|
| Back to top |
|
|
Scott Sander
Alfa 33
Joined: 20 Feb 2003
Posts: 419
Location: Sydney, Australia
|
| Posted: Fri Jun 16, 2006 1:34 am Post subject: |
|
|
Ah silly me, the sensor on the radiator is for the fan, not the temp gauge, sorry.
If you don't have a thermostat then it can't get blocked  . However the engine may not get up to normal operating temperature. Although while you are having this discrepancy I wouldn't change it.
On the 16V there are a couple of sensors for temperature on the throttle bodies/manifold. The left side sensor goes to the ECU. The right side sensor goes to the temp gauge. These sensors are different part numbers, I’m not sure of the differences between them so would mix them up, if that is possible.
The temp warning light is supposed to come on at 105 degrees Celsius.
_________________
Scott Sander
'91 Alfa 33 Boxer 16V Monza - Awesome
http://www.sanderfamily.com |
|
| Back to top |
|
|
Spyderman
Alfasud
Joined: 04 Sep 2003
Posts: 48
Location: Hampshire
|
| Posted: Tue Jun 20, 2006 7:13 am Post subject: |
|
|
Have tried a replacement overtemp switch and got no difference
Have fitted twin electric fans to the radiator, with manual overide, plus an oil cooler. and got no difference
Sunday it happened again, and I am not sure if I have a problem or not
Decided to buy a digital thermometer to check the accuracy of the water temperature gauge and sender.
Measuring the temp in the header tank I am getting reading of about 90c which is what the engine is meant to run at. this ties in to what the sender and gauge is telling me.
Slighty perpelexed as to whether the engine is overheating or not now
Edited from a Haynes manual this is effectively my coolant circuit now
Only thing I can think of is to try use the digtal meter and measure the head casting temp where the overtemp switch is, or try to measure water temp on that side of the block. Reckon I'll put the original over-temp switch back on, as the new one seems keener to come on than the old one, and try and find a way of measuring the coolant temp on the same side as the over-temp switch. Possibly the coolant is cooler on the side of the heater tank as it is near the water pump and after the radiator.
Given the digital meter is accurate to + - 1C would trust that over any in car switches gauges
 |
|
| Back to top |
|
|
tvatavuk
Gold Cloverleaf
Joined: 13 Mar 2003
Posts: 673
Location: Split, Croatia
|
| Posted: Thu Jun 22, 2006 2:38 pm Post subject: |
|
|
Spyderman sorry for missinforming you, info I was giving was for 16v engine.
If you can check temperature of engine casting as you said, and you'll know if it overheats or not.
In case it is, I presume problem would be not enough air circulation around engine, althrough I'm bit confused why oil cooler didn't lower temp?
Have you taken off sparks on that cylinder that has sensor near it?
In normal conditions in alfa engine bay reasons for overheating can be numerous from lousy ignition timing, waterpump failing to headgasket, cyl wall holes.
_________________
Tino Vatavuk
Little black dress which replaced Alfa Romeo 33 S 16v Permanent 4 GMo |
|
| Back to top |
|
|
|
