• Welcome to the new SAOCA website. Already a member? Simply click Log In/Sign Up up and to the right and use your same username and password from the old site. If you've forgotten your password, please send an email to membership@sunbeamalpine.org for assistance.

    If you're new here, click Log In/Sign Up and enter your information. We'll approve your account as quickly as possible, typically in about 24 hours. If it takes longer, you were probably caught in our spam/scam filter.

    Enjoy.

1959 Rapier Overheating

C

Chrisp Rapier

Donation Time
I am now driving the car around the block or so. After about 5 minutes of driving, stop and go under 30, my gage jumps up to over 200 degrees. I had the car idling in the driveway for several minutes and it pegs at about 175. This was the case for many months.
I have a new lower radiator hose. The top is not but it is wire reinforced and does not seem like it could collapse. I did my best with the radiator. It had a leak in the top reservoir, so I removed the top and was running water down through the down tubes. It certainly looked like I had good flow everywhere. I resoldered the top back on but the outside of the radiator surfaces are very rusty and could very well be restricting air flow. About the engine. I had the heads off and the freeze plugs off. I did a good job of clearing out the water jackets. I removed quite a bit of sand.
The water pump is the old original. It was very rusty. After cleaning it up inside and out and painting, It seemed good to me but who knows. Is the sensor and gage, correct? I have no idea, but when it creeps up high when driving, some coolant spits out the overflow of the radiator. I suspect the cap is good. The coolant could be a contributor in that I am not sure of the ratio of coolant to water. I do believe I have a high ratio of coolant to water in the order of 60 to 70 percent coolant. I was running no thermostat during all of this. I have now installed a new thermostat and it does the same.
My guess is the radiator is the culprit. I did try to use a hand brass wire brush to clean the "fins" of the radiator to very moderate effect. I was afraid to do anything aggressive. Is there some good way to deal with the rust of the delicate fins? Is there anything else I should do or consider?
 
Last edited:
Did you bleed your cooling system properly? If not there is a big chance that the engine is overheating!

Regards,

Peter
 
As Peter says.
And have you looked to see if the water is flowing through the system. IE, let it warm up, get hot, with the rad cap and watch to see if the water is flowing through the rad. Is the lower hose a little cooler than the top hose when the car is at operating temperature? Any cool spots on the rad when warmed up?
 
You mention your gage. Have you checked it against a thermometer? Any particular reason you'd expect a 70 y.o. gage to be accurate?
Bill
 
I'm assuming that the Rapier has a crossflow radiator much like the S1-2 Alpine, and they do need to be bled
so air pockets aren't formed in the system. From your description of the age of the radiator and water pump
you should, at the very least , take your radiator to a shop and have it cleaned. That way you'll know that the rad
either is or isn't to blame. On cross flow radiators it's hard to see the coolant flow in the tank as you really have to look into the tank and even then the flow isn't easy to see. The advice on using an infared thermometer is a also something to try, but I'll bet your radiator is bad.
 
sunalp said:
crossflow radiator much like the S1-2 Alpine
Click to expand...
No, it's a normal down flow radiator. It should have the small, short style water pump like sI Alpines.

sunalp said:
they do need to be bled
so air pockets aren't formed in the system.
Click to expand...

Yes, and getting the heater core bled can be challenging at times. The H/C sits even higher above the engine than the Alpine's core.

C/R,

Try this for bleeding your cooling system:

>park the car with the nose as high as possible and you feel safe to have the engine running and you under the hood.

>run the car until up to temp, radiator cap off, and thermostat open.

>set the engine at about 2000 RPM'S which should cause the coolant to drop below the core top in the radiator.

>add coolant to about an inch below the fill neck, replace cap, go for a ride and see if your problem improved.

> if you loose a lot of coolant as overflow after this, you probably need a new cap.

Hope this is helpful,
 
husky drvr said:
No, it's a normal down flow radiator. It should have the small, short style water pump like sI Alpines.



Yes, and getting the heater core bled can be challenging at times. The H/C sits even higher above the engine than the Alpine's core.

C/R,

Try this for bleeding your cooling system:

>park the car with the nose as high as possible and you feel safe to have the engine running and you under the hood.

>run the car until up to temp, radiator cap off, and thermostat open.

>set the engine at about 2000 RPM'S which should cause the coolant to drop below the core top in the radiator.

>add coolant to about an inch below the fill neck, replace cap, go for a ride and see if your problem improved.

> if you loose a lot of coolant as overflow after this, you probably need a new cap.

Hope this is helpful,
Click to expand...
I will do as you say.


Before I started this thread, I want to note that I ran the car at idle several times and drove the car around a few times. I then started the thread and later I went to my local parts store for a thermostat. I was not sure if I was running without a thermostat or not. It ended up I was experiencing the high temp on the gage with no thermostat. I then installed a 180 degree thermostat. It is what they had in stock.
So today I warmed up the car in the driveway with the radiator cap off. I do not have an infrared thermometer. I did have a candy thermometer, which I inserted into the radiator. The gage read 210 and the thermometer read 175. Clearly either the gage or the sensor are not working properly. The thermostat housing was hot but not crazy hot. I could put my fingers on it for 2 seconds. Same with the top of the radiator. the hoses were both hot but not crazy hot. I could hold them. the lines in and out of the heater core were both quite hot.

What can I conclude from all of this?
 
Bill Blue said:
Your Rapier is not overheating.
Bill
Click to expand...
Thank you! It would appear so. Which is awesome!!

The reason I thought it was not the gage or sensor is that all last summer when I was getting the car running, It was high idling in my driveway and the gage would go to 175 degrees and stay there. Never any sign of over heating. Then this Summer, I get it on the road and the first ride out it jumps up to 215 degrees. It seemed like it was the driving that caused the high temperature. Now after all of this, the gage goes over 200 just idling in the drive.

Is there a way to figure out whether it is the gage or the sensor? My guess it is the sensor.
 
So..... I forgot I had many shelves of used Rapier parts, in the garage, from a parts car. I dug up the 2nd engine head which had the Thermostat housing with a temperature sender in it. I installed it and drove the car up to temp. Unlike the prior reading I was getting of 215 degrees, this one took a long time to get up to a steady reading of about 155 degrees. I am thinking this tells me that the problem is not the gage but rather it is the sending unit.
 
The only way to be sure, is to use a thermometer or thermal heat sensor and see if it agrees with the guage.

Sender units work by measuring resistance, therefore choosing one can be a lottery.
 
Also remember they measure total resistance. Not just the internal resistance of the sender, but the resistance of all the connections and crusty threads in the system. Also, do not overlook the influence of teflon taped threads.

Bill
 
beamdream said:
The only way to be sure, is to use a thermometer or thermal heat sensor and see if it agrees with the guage.

Sender units work by measuring resistance, therefore choosing one can be a lottery.
Click to expand...
With my original sensor the temp of the coolant was 175 degrees in the top of the radiator. The gage showed 215. When I changed out for another used sensor the temp in the radiator was again 175 but the gage showed 150. I have not measured resistance, which would be a better way to take the gage and the wiring to it out of the equation. Given that one sensor is way over the actual temperature and the other is way under, it suggestes to me that the gage is not the issue so much.
 
Bill Blue said:
Also remember they measure total resistance. Not just the internal resistance of the sender, but the resistance of all the connections and crusty threads in the system. Also, do not overlook the influence of teflon taped threads.

Bill
Click to expand...
Yes I was wondering about all the wiring and connection resistance issues. I gather that if there was additional resistance in the connections that it would show a higher temp on the gage than was actual.

There was some tiny bit of white on the threads of my replacement sensor, no doubt Teflon tape. I cleaned that all up.
 
Chrisp Rapier said:
With my original sensor the temp of the coolant was 175 degrees in the top of the radiator. The gage showed 215. When I changed out for another used sensor the temp in the radiator was again 175 but the gage showed 150. I have not measured resistance, which would be a better way to take the gage and the wiring to it out of the equation. Given that one sensor is way over the actual temperature and the other is way under, it suggestes to me that the gage is not the issue so much.
Click to expand...

Can I ask why you wouldn't just put a thermometer in the radiator and see whether it and the guage readings correspond.
I don't understand your pursuit comparing two unknown sensors and suggested guage diagnosis.
 
An infrared thermometer is quite useful. You can check the temperature of the temp sender housing against your gauge reading, check the temperature of the coolant going to the radiator, check how much the radiator is lowering the coolant temperature between the input hose and output hose, check temps on different parts of the block, etc.

Mike
 
beamdream said:
Can I ask why you wouldn't just put a thermometer in the radiator and see whether it and the guage readings correspond.
I don't understand your pursuit comparing two unknown sensors and suggested guage diagnosis.
Click to expand...
I did. I drove the car, then parked in the driveway and opened the radiator cap and inserted a candy thermometer. I did this with the old sensor, and I did it again with the other sensor I installed. Both times I got a reading of 175 degrees. The thermostat I have installed is a 180 degree unit. I am sure that is why I got a 175 degree reading both times.
 
Chrisp Rapier said:
I did. I drove the car, then parked in the driveway and opened the radiator cap and inserted a candy thermometer. I did this with the old sensor, and I did it again with the other sensor I installed. Both times I got a reading of 175 degrees. The thermostat I have installed is a 180 degree unit. I am sure that is why I got a 175 degree reading both times.
Click to expand...

Excellent, I must have missed that somewhere.

Keep up the good work.
 
You must log in or register to reply here.
Back
Top