Wots Hot?

[Jonathan Pounsett]

What is the normal operating temperature for an unmodified cih engine?

The Manta gauge usually hovers just above half way but I don’t know what this is in degrees centigrade. 

[cam.in.head]

the guage can vary between cars anyway as its entirely an analogue heat related unit but generally they rest about half to 3/4 of the normal range with a 92 deg thermostat.you can test a guage and use it as a comparison by unplugging the sender and fitting a 40ohm resistor to earth temporarily to see where the guage goes.  this again is not 100% consistent between perfectly ok working cars (2 of mine read exactly half way ,1 reads just under and one reads just over !)but can at least spot issues such as the usual voltage reg failure making the guage read too high. 

best way is to point a temperature gun at the thermostat housing and surrounding areas to get a more accurate idea if required./ comparison with other vehicles .

[Jonathan Pounsett]

If I plug the ecu into my laptop the live adjustments page says the temperature is 90 deg which I thought was okay but the gauge is in the red! I think the gauge may be playing up.

[Jessopia74]

1 hour ago, Jonathan Pounsett said:

If I plug the ecu into my laptop the live adjustments page says the temperature is 90 deg which I thought was okay but the gauge is in the red! I think the gauge may be playing up.

Recalibrate it with a resistor 

[cam.in.head]

if you are also experiencing a higher than normal fuel guagereading then this is the usual issue caused by the dashboard voltage regulator.purely a heat/ mechanical switch and prone to failures.test by putting the sensor wire to earth via a 40 ohm resistor. 

and.

 

as jess says you can fine tune a working guage by adding a resistor in series or parallel depending on which way it is out.

you can also (if im correct) slightly calibrate a guage mechanically.i think they have some kind of screwdriver sliding slot / arm type adjustment internally .

different actual sensors by different manufacturers can also vary a bit too.

 

[plumster]

Get a replacement voltage regulator, before you go chasing ghosts.

[Diego LR]

Hi

I recently bought a Manta A 1.6 rallye S 1972. Currently doing some work with a mechanic. 
he says the car doesn’t overheat but the temperature gauge reading is high. He just replaced the alternator regulator and thinks the misreading is caused by the voltage. He also cleared the radiator which was leaking because clogged with dirt. In that occasion the car was overheating.

i am trying to understand if the car actually overheats or it is just a voltage related issue.

[Jessopia74]

6 minutes ago, Diego LR said:

Hi

I recently bought a Manta A 1.6 rallye S 1972. Currently doing some work with a mechanic. 
he says the car doesn’t overheat but the temperature gauge reading is high. He just replaced the alternator regulator and thinks the misreading is caused by the voltage. He also cleared the radiator which was leaking because clogged with dirt. In that occasion the car was overheating.

i am trying to understand if the car actually overheats or it is just a voltage related issue.

Was engine stat checked? Old school method with dropping it into pan of hot water & thermometer to watch it open at around stamped temperature. Otherwise you can check the rough temp of engine with infrared thermometer on stat housing top. 

[Diego LR]

Thermostat was replaced but he mentioned the old one had a little hole which was done after market to let more water flow (???) I told him to test the car and leave it then idle to see if the actual engine temp actually goes up

[Jessopia74]

1 hour ago, Diego LR said:

Thermostat was replaced but he mentioned the old one had a little hole which was done after market to let more water flow (???) I told him to test the car and leave it then idle to see if the actual engine temp actually goes up

we’ll, need to check temp oh housing tbh, that will give better idea if it’s genuine or false reading. However, it could be the new stat is a different temp!
Also not uncommon for a little hole, it was put there to aid bleeding. Some new aftermarket ones used to have a small hole with a a little ball on a T bar holding it in the hole to stop flow once air out of the system. 
 

have a read through this thread

 

[cam.in.head]

yes it could be thermostat related and different ones will give a slightly different temp reading .the bleed hole MAY lower it slightly but not usually by much. usually just causes a longer warm up.

but most likely to be the voltage regulator thats faulty.

not the one on the alternator (that would cause an overvoltage that could ultimately fry everything !) but the voltage regulator on the dashboard instruments.

this can be checked basically by unplugging the temp sender connection on the thermostat housing and connecting it to earth via a 40 ohm resistor. this will simulate an engine at roughly working temp.

if it goes up into the red then the regulator is faulty and if it stays around the middle then theres a good chance its not.

 

Edited December 16, 2022 by cam.in.head

[Diego LR]

2 hours ago, cam.in.head said:

yes it could be thermostat related and different ones will give a slightly different temp reading .the bleed hole MAY lower it slightly but not usually by much. usually just causes a longer warm up.

but most likely to be the voltage regulator thats faulty.

not the one on the alternator (that would cause an overvoltage that could ultimately fry everything !) but the voltage regulator on the dashboard instruments.

this can be checked basically by unplugging the temp sender connection on the thermostat housing and connecting it to earth via a 40 ohm resistor. this will simulate an engine at roughly working temp.

if it goes up into the red then the regulator is faulty and if it stays around the middle then theres a good chance its not.

 

Thank you!

The one on the alternator was replaced as it was frying one battery after the other. 
I suppose if it is the voltage reulator in the dashboard then other gauges like for example fuel gauge would also produce a misreading iyo?

Edited December 16, 2022 by Diego LR
Forgot thank you

[Jessopia74]

1 hour ago, Diego LR said:

Thank you!

The one on the alternator was replaced as it was frying one battery after the other. 
I suppose if it is the voltage reulator in the dashboard then other gauges like for example fuel gauge would also produce a misreading iyo?

Yes, it affects the voltage to the whole dash

[cam.in.head]

so 

the alternator regulator has been changed. it should now regulate charging voltage to around 14.2v. (higher could be observed on a low battery )

it sounds most likely that the old one has burnt out the dashboard regulator .your lucky it didnt damage anything else.

check as described or replace with a new or known good anyway.

 

[Jonathan Pounsett]

What does the voltage regulator in the dashboard look like? Is it the same as the voltage “stabilizer” on a B?

[H-400]

the top one is original, on the back are three spade connections. The bottom one is after market and electronical. Available at Edelschmiede

[Diego LR]

6 hours ago, cam.in.head said:

so 

the alternator regulator has been changed. it should now regulate charging voltage to around 14.2v. (higher could be observed on a low battery )

it sounds most likely that the old one has burnt out the dashboard regulator .your lucky it didnt damage anything else.

check as described or replace with a new or known good anyway.

 

Thank you

I’ll get the car after Xmas will have the chance to drive it for the first time. My uncle died last Aug and I got it from his family. Had been in the garage since 2017 when he fell ill and couldn’t drive it anymore. Mechanic tried it and he is fairly sure it doesn’t overheat. We’ll see when I drive it myself! 

[cam.in.head]

excellent.

[Diego LR]

8 hours ago, H-400 said:

the top one is original, on the back are three spade connections. The bottom one is after market and electronical. Available at Edelschmiede

Would you say Germany is the best place for spare parts for Manta A? Thanks

[Jonathan Pounsett]

2 hours ago, Diego LR said:

Would you say Germany is the best place for spare parts for Manta A? Thanks

Yes. 

[Diego LR]

Hi All - hope you are all well.  

So I first drove the Manta (A 1972 1.6 Rallye SR) over the weekend and I have a question related to the overheating issue I previously posted above.

What is the optimal temperature the car should drive? What do you (Manta A owners) see in the gauge when driving yours? 
 

2 reasons for asking:
 

1) The temperature in mine goes up quite a bit and the car drives half way between the 110 dgrs and the red in the gauge. Despite that, the water/coolant doesn’t boil and the head gasket is fine. I am getting the radiator checked again, maybe it is still a bit clogged and getting some of the pipes replaced as very old and dry.

2) the original owner’s manual reads the optimal engine temp should be within the black area of the gauge and mine technically is. Doesn’t mention 80-90 dgrs or a specific temp.

So I am confused as Opel seems to suggest as long as it is in the black area then it is optimal no matter the temp which is quite different from any other car I’ve owned in my life.

 

Thank you

Edited February 6, 2023 by Diego LR

[Jonathan Pounsett]

16 minutes ago, Diego LR said:

Hi All - hope you are all well.  

So I first drove the Manta (A 1972 1.6 Rallye SR) over the weekend and I have a question related to the overheating issue I previously posted above.

What is the optimal temperature the car should drive? What do you (Manta A owners) see in the gauge when driving yours? 
 

2 reasons for asking:
 

1) The temperature in mine goes up quite a bit and the car drives half way between the 110 dgrs and the red in the gauge. Despite that, the water/coolant doesn’t boil and the head gasket is fine. I am getting the radiator checked again, maybe it is still a bit clogged and getting some of the pipes replaced as very old and dry.

2) the original owner’s manual reads the optimal engine temp should be within the black area of the gauge and mine technically is. Doesn’t mention 80-90 dgrs or a specific temp.

So I am confused as Opel seems to suggest as long as it is in the black area then it is optimal no matter the temp which is quite different from any other car I’ve owned in my life.

 

Thank you

It’s hard to get A definitive answer as everyone’s experiences are different and there are loads of factors to consider. As you say a clogged system will give you trouble for sure. First step is to give it a really good flush, ideally high pressure or take it all to bits so the rad, heater matrix and all the hoses can be checked.

There has been some recent discussions on here about thermostats and the merits (or otherwise) of using coolant rather than water, so I recommend you look them up.

Remember the boiling point will be much higher in a pressurised system. I was worried as I was always between 100 and 105 C but the car seems happy. (Note: mine is a V8 not a cih so see what others suggest temperature wise).

I need to use an infrared thermometer gun on various parts of my engine/radiator/hoses to get a true picture.

[cam.in.head]

as mentioned earlier .the usual cause of high temp guage reading is the dashboard voltage regulator and this also gives a high fuel guage reading too.

if the engine runs fine and the top hose stays cold until up to temp then the thermostat is not leaking through and the hose should then go hot as it opens followed by a slight drop on the guage.if you point an infra red thermometer at the therm  housing it should be around 92 deg C. every car is slightly different (manufacturing tolerances of thermostat,sender,guage,regulator all make a slight difference to the reading.

one of mine reads dead on half way ,one reads between half and 3/4. both with 92 deg therms.

 

[Diego LR]

2 hours ago, cam.in.head said:

as mentioned earlier .the usual cause of high temp guage reading is the dashboard voltage regulator and this also gives a high fuel guage reading too.

if the engine runs fine and the top hose stays cold until up to temp then the thermostat is not leaking through and the hose should then go hot as it opens followed by a slight drop on the guage.if you point an infra red thermometer at the therm  housing it should be around 92 deg C. every car is slightly different (manufacturing tolerances of thermostat,sender,guage,regulator all make a slight difference to the reading.

one of mine reads dead on half way ,one reads between half and 3/4. both with 92 deg therms.

 

First thing I did was filling the tank and the gauge read full tank so I suppose the dashboard voltage regulator may not be the issue? New mechanic will check with the infrared. Previous one didn’t have one…

[cam.in.head]

if the regulator was  faulty it will read full when only half full.if the tank is full it will still read full !

needle cant go any higher.