I have a 1985 Accord, 5 speed MT, 1.8L carbureted.

UPDATE

I replaced the temperature sender located in the intake manifold. See pictures in posts below. Although, the gauge didn't read any further than 1/4 or 1/3 like it used to. I am leaning towards the engine not getting to temperature now, rather than a faulty sender. So that is where I am currently going with this. I am asking for your help in determining why the engine does not get to full temperature even with the radiator falling apart the way it is.

Original Post Information

I am trying to fix the temperature gauge because it is reading at about 1/4 the way instead of half way like it used to. I believe it to be the sensor. I have replaced the thermostat 3 separate times, and it doesn't fix the problem. I believe it to be a coolant temperature sensor, or cylinder head sensor. Not sure if it has both or just one.

So I am using a shop service manual specific for my vehicle only. It doesn't include a picture, or location evidence as to where a coolant sensor resides. It suggests that a "TW" sensor is all that it has. It doesn't say anything else when it comes to engine temperature nor go in further detail about this "TW" (coolant temperature sensor). It says only how to test this sensor. Not where to find it etc. And it doesn't even say a single thing about the temperature gauge in the dash.

(Extra Notes)
My radiator is garbage. The fins are falling out of it, and it needs to be replaced asap. The thing is, my temp gauge never reads higher than what it should. My car should essentially be overheating I think. But, it ACTUALLY doesn't get to proper engine temperature and I know this because I can have my hand on the engine for 10-20 mins after the engine has been started.

Extra Info For Original Post

I looked all over on the block/cylinder head for the temperature switch leading to the gauge. No switches or anything on passenger side. Not enough room for one, too.

So I did some research and called some Honda dealerships to find out what temperature switches / sensors are on this vehicle. They could tell me the part numbers and where they were located, but they could not tell me what the corresponding responsibility of each switch/sensor was.


I was informed a temperature switch resides on the intake manifold - 37750-PC-1004

One on the engine block - to the right of the oil filter - 37774-PD-2661

And the one on the bottom of the radiator - 37773-PB-10003 (autozone sources say it is the fan switch, dealership says fan switch too)


With this new information - is there anyway to tell what each part's responsibility is for engine management? I am asking you to help me with that, and to narrow it down to part that controls the temperature gauge in the dash.

 

The temp switch for the gauge should be a single pin switch, look in the end of the cyl head - pass side.

 

I looked all over on the block/cylinder head for the temperature switch leading to the gauge. No switches or anything on passenger side. Not enough room for one, too.

So I did some research and called some Honda dealerships to find out what temperature switches / sensors are on this vehicle. They could tell me the part numbers and where they were located, but they could not tell me what the corresponding responsibility of each switch/sensor was.


I was informed a temperature switch resides on the intake manifold - 37750-PC-1004

One on the engine block - to the right of the oil filter - 37774-PD-2661

And the one on the bottom of the radiator - 37773-PB-10003 (autozone sources say it is the fan switch, dealership says fan switch too)


With this new information - is there anyway to tell what each part's responsibility is for engine management? I am asking you to help me with that, and to narrow it down to part that controls the temperature gauge in the dash.

I have an extra engine for this vehicle, out of the car, so I can gather some pictures together in order to help with visible seeing these parts (I am not sure if I can find the one on the Intake). I will be uploading these pictures later today or tomorrow.

 

Here are the pictures of the extra engine and what sensors I could find.

I took the initiative of replacing the sensor in the intake manifold with the one from my extra engine. For some reason, the design of this engine has the coolant running through the intake manifold...Weird. There was a coolant hose leading from the thermostat housing into the intake manifold. Bingo. That has to be my temperature sender.

Take a look.



In the upper right is the coolant hose with the metal squeeze clamp. To the left of the hose is the sensor. Has to be the temp sender to the dash gauge. Weird spot to have the coolant run through the intake...

Here it is again with rubber boot taken off.


Incredibly tight squeeze to put the extra sender into my engine in the car.





ANYWAY
After all that hard work - the car temperature remains the same. It doesn't pass over 1/4 or rarely get to 1/3 when it needs to be at 1/2.

So there must be a bigger problem, or I have another faulty sender. Either way, in addition to replacing the sender, the problem still remains that the engine doesn't seem to be getting to heat as quick as it should in the first place. So maybe the sender is reading the information correctly. But why in the world would an engine not overheat if my radiator is missing fins, should be replaced, and the car can be run sitting for an eternity without getting "hot" to the touch in a matter of 15 mins or so idling?


Here is the engine cylinder temperature sender.