VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 Best position for temperature gauge sender

Hi all,
Which would be the best position for the temperature gauge sender unit?At the front of the head,as on a '29,or at the rear of the head as in later models?
Any thoughts appreciated.

:confused:

The rear of the head up against the firewall will give the highest temperature readings for several reasons.

Hi Chipper,
Thanks very much for your reply.Would there be any reason why the '29 Chevs had the sender unit at the front of the head,and not at the rear?
I have a mate with a 1930 Chev,and his sender unit screws into the rear of head,beside the rocker cover,right over the exhaust port for No.6 cylinder,and his gauge is always reading near boiling point,even though his coolng system and radiator are spotlessly clean.
I'd like to know for sure which would be the best position to use for the sender,as I have either a 1929 or 1930 head I can use,and I would like to be sure before I spend the money on getting the gauge repaired and fitting a NOS sender unit.


:confused:

The 1929 Chevrolet had an electrical sending unit and it was mounted at the front of the head. A capillary tube type of sending unit was used in 1930 and up and it was installed on the back of the head. Go with the cylinder head that is correct for your year of vehicle.

Even though your friend has a clean radiator he can still have issues with overheating. If he is using an original radiator it could still need replacing. There also could be other reasons why his car is overheating as well; timing, blocked passages in the cylinder head, water pump and etc.

Hi JYD,
Thanks very much for your invaluable advice.
The head for my car is the '29 one,with the sender unit up the front.
To my way of thinking,and please correct me if I'm wrong,having the sender unit at the front of the head would virtually only indicate the temperature of the water as it exits the head,and possibly the temperature of the water in the radiator itself,much like a motometer does.

:confused:

The indicator in the front of the head may be more or less accurate than one at the back. It depends on several possible scenarios. If the one in the back is in a steam pocket (high heat and low flow) [which is likely for the thermowell] then all you will measure is the steam temperature or that of boiling coolant. If in an area with flow (like at the front) then the gauge will not be affected by a steam pocket. If the flow is sufficient and heat less than that required to boil then the back location would most likely measure the max. temp in the system. There are others but you get the idea that one location is never the best for all possibilities.

Guess that means that no matter the location if the guage is relatively accurate and you establish the norm and only react to those situations that are well out of the norm, the guage will do what it needs to do, alert to possible problem.

Hi Chipper,
Thanks for the all the information,I really appreciate it.My '29 has a '30 head on it at the moment,but the engine is up for a re-build,and I have a mate who has a couple of '29's,who has a spare crack free '29 head he's wiling to sell me.
Once it's going again,like you say,I'll establish what the "normal" running temperature is,and look out for anything out of the "norm".


:)

Hi!
Chipper pointed out to us the possibility of a steam pocket at the rear of the head. Is there any way to prevent this from occuring?
John Lanning