1959 Rapier Overheating

[hartmandm]

Chrisp,

Does your temperature gauge provide immediate readings? E.g. if you warmed up the car and then turned off the ignition does the needle instantly park to the left? And if you then switched the ignition back to “run” the needle immediately jumps to the prior warmed up position?

Mike

 

[Chrisp Rapier]

Chrisp,

Does your temperature gauge provide immediate readings? E.g. if you warmed up the car and then turned off the ignition does the needle instantly park to the left? And if you then switched the ignition back to “run” the needle immediately jumps to the prior warmed up position?

Mike

It is very interesting you should ask this. I thought it a little odd and I noted that this was happening, that when I turned the ignition off the temp would park left and then if I immediately turn the ignition on it does not go back to the temp it was at before. Instead, it is at some temp many degrees cooler. It will then slowly creep up to where it was.

 

[hartmandm]

When you turn the ignition off, does the needle immediately (like in a tenth of second) park to the left, or does it take multiple seconds to park?

Are you able to determine the temperature gauge part number? I expect the part number will be on "second" face plate, hidden behind the front plate. You have to get up close and look at the gauge at an angle. There is a gap between the two plates and you should be able to make out a part number. Pictures below are Alpine gauges showing where the part number is on those ...

 

[Chrisp Rapier]

When you turn the ignition off, does the needle immediately (like in a tenth of second) park to the left, or does it take multiple seconds to park?

Are you able to determine the temperature gauge part number? I expect the part number will be on "second" face plate, hidden behind the front plate. You have to get up close and look at the gauge at an angle. There is a gap between the two plates and you should be able to make out a part number. Pictures below are Alpine gauges showing where the part number is on those ...

View attachment 32900

View attachment 32901

I believe the needle immediately parks left when the ignition is turned off. I would have to warm the car up and try it to make sure this is the case. my gauge is a different unit than yours. I did just now look at the gauge with a flashlight and could see there is no part number in the location you indicate. All I could see is the insect that is trapped under the glass.

 

[hartmandm]

I am guessing you have a Jaeger "semi-conductor" type temp gauge, like the Alpine series 1 & 2 had. Here is an Alpine series 1 & 2 temp gauge. Same scale as yours. Later Alpine gauges (series 3 and later) used a different technology and different temp scale.



You have tried two different temperature senders and the gauge reads high with one and low with the other. Do the senders have part numbers? Here is an example of a part number (TT4802/00) from a later Alpine temp sender:


The Alpine temp sender threads are 5/8"-18 TPI. Check the thread sizes on your senders.

Now the tough part. The original temperature sender needed for the Alpine series 1 & 2, which is what I think you also need, was a Smiths TT4800/00. That part is no longer available. Some parts suppliers have substituted a Smiths TT3800/00. The 3800/00 appears to have slightly different resistance values than the 4800/00. A good thread from a member who was trying to get an accurate reading using a 3800/00:

Is the Series 1/2 temperature gauge adjustable?

I've got a Series 1/2 temperature gauge TC4304/00 and got a new sending unit p/n 52700 from Speedy Spares with the number 3800/00 stamped on it. I'm testing the combination using heated water in a pan with a candy thermometer, and car battery. The gauge is reading about 10 degrees F below what...

forum.sunbeamalpine.org

I've attached a PDF with some more background on these types of gauges.

Mike

 

[Chrisp Rapier]

I am guessing you have a Jaeger "semi-conductor" type temp gauge, like the Alpine series 1 & 2 had. Here is an Alpine series 1 & 2 temp gauge. Same scale as yours. Later Alpine gauges (series 3 and later) used a different technology and different temp scale.

View attachment 32906

You have tried two different temperature senders and the gauge reads high with one and low with the other. Do the senders have part numbers? Here is an example of a part number (TT4802/00) from a later Alpine temp sender:
View attachment 32907

The Alpine temp sender threads are 5/8"-18 TPI. Check the thread sizes on your senders.

Now the tough part. The original temperature sender needed for the Alpine series 1 & 2, which is what I think you also need, was a Smiths TT4800/00. That part is no longer available. Some parts suppliers have substituted a Smiths TT3800/00. The 3800/00 appears to have slightly different resistance values than the 4800/00. A good thread from a member who was trying to get an accurate reading using a 3800/00:

Is the Series 1/2 temperature gauge adjustable?

I've got a Series 1/2 temperature gauge TC4304/00 and got a new sending unit p/n 52700 from Speedy Spares with the number 3800/00 stamped on it. I'm testing the combination using heated water in a pan with a candy thermometer, and car battery. The gauge is reading about 10 degrees F below what...

forum.sunbeamalpine.org

I've attached a PDF with some more background on these types of gauges.

Mike

Hey Mike,

The part number on my sender is F8 and nothing more. Well, it says Made in England 12v. No doubt an ancient unit made of unobtainium. My main concern was whether I was overheating. Thankfully it is not the case. I may try reinstalling the first unit again as there was a lot of white corrosion on the threads, no doubt creating additional resistance. Beyond that, I can live with an inaccurate gauge, knowing 150 degrees means 175. I have a lot of other issues to deal with in the suspension. I may revisit this issue later and refer back to your kind information here, in the near future. I am happy to put around the neighborhood knowing my engine is not about to fry. Thank you and everyone else here that gave me info to zero in on the issue. Much appreciated.