Radiators

[Brosky]

All good to know information. Thanks.

From this description, I take it that you did not buy a radiator off the shelf, but rather had one custom made? If so, to what specs?

I also presume that you would drill the lower tank for the sensor, as well as the drain petcock?

 

[DrEntropy]

Better to mount the sensor on the top, Paul.

 

[2wrench]

I had my re-cored for $350 down here in SoCal- probably would be similar in Tracy.

Well enough, but need to know if I'm paying nearly
twice what new would cost if what I get is any better
than new by going with recore instead.

 

[Brosky]

Doc,

Stat opens, hot coolant goes to top of radiator first, then to bottom. I guess that you would want it in the area that sees hot coolant first?

Not that it will pickup and run on warm up, but that's what comes out of the block to the radiator.

For some reason, I thought that I've seen them in the bottom, but I could be wrong.

 

[Darrell_Walker]

Where to mount the sensor seems to be a constant debate. I went with a bottom mount, my reasoning is that if the coolant leaving the radiator isn't too hot, then the fan does not need to come on. Putting it in the top means you are measuring the temp before it goes through the radiator, and you don't yet know if extra airflow is needed.

 

[Guest]

Paul, the folks at Ron Davis have the specs for a TR6 and built the radiator exactly to fit. Went in with no hitches, accepting the stock shroud, etc.

There should be no debate about where to place a sensor. You want to know when your coolant is getting too hot, therefore place the sensor in the hottest spot. Ideally this would be in the bottom tank. Placing mine in the down-hose accomplished the same thing. I think I have a 180* sensor. I suppose you could place it in the top and use a really low-temp sensor but not sure they make them. If you used a standard temp sensor and measured the top, your coolant at the bottom would be overheated before you knew it.

Mine is set to run automatic or manual. I used the interior light switch right in front of the shift lever as my switch. (who needs and interior light switch?) I also installed a light in this area to see when the fan is on. Just light lights.

 

[Norton47]

2Wrench
I checked with my local Triumph shop on who they used to do radiator work and went to them.
They rodded both the heater core and the radiator, boiled out and cleaned and pressure tested both for under $140.00.
I expect to have like new performance to go with the boiled out block.
By the way, when I pulled the block plug on mine, it was pretty much plugged up with gorp. I had to clear it out to get much drain flow.
When the block came back, it all looked clean.

 

[BryanC]

place the sensor in the hottest spot. Ideally this would be in the bottom tank.

Hmmm. I was pretty sure that the coolant leaves the engine through the thermostat, to the elbow and upper hose and goes to the top of the radiator. That makes the top of the tank the hot part.

Bryan

 

[TR3driver]

Hmmm. I was pretty sure that the coolant leaves the engine through the thermostat, to the elbow and upper hose and goes to the top of the radiator. That makes the top of the tank the hot part.

I agree, at least for TR2-6. However, it's something of a waste to run the fan when the natural airflow through the radiator will provide enough cooling. Thus there's some argument for having it sense the temperature of the water leaving the radiator.

But in practice, I doubt it makes much difference.

One other argument for not putting it at the top of the radiator, though, is what happens if the engine is a bit low on coolant. If the sensor were in the top tank, it might not be immersed in water and therefore not run the fan right at the time where it's needed most.

 

[Norton47]

FWIW
My fan switch is located at the bottom of the radiator.
I have replaced the temp sender with a new one as the original was not the right value and so am pretty sure the gauge and temp are reasonably correct. The fan for all practical purposes cycles on just before the gauge reaches the 3/4 mark. Then you see it cool down to the 1/2 mark and it shuts off.
In stop and go traffic it seems to cycle to frequently, which is why I fitted a master overide to let me to have a constant on. That keeps a more stable temp in those conditions.
I also agree about not sensing engine temp unless the sender is wet and I would trade the slight temp error for knowing the switch is sensing water rather than error opps air.

 

[DrEntropy]

place the sensor in the hottest spot. Ideally this would be in the bottom tank.

Hmmm. I was pretty sure that the coolant leaves the engine through the thermostat, to the elbow and upper hose and goes to the top of the radiator. That makes the top of the tank the hot part.

Bryan

That's the way it works, Bryan. "Heat rises", too. If you allow the water level to go below the sensor (assuming it isn't mounted VERTICALLY in the top of the rad... bad idea) it'd be considered "operator error" IMO. Additionally, if it's at the top it is monitoring the ENGINE operating temp, notifying the fan it NEEDS to be on, not monitoring the water temp going back INTO the block where it's too late to do much about what the engine temp really is. That'd be why the fan goes on-off-on-off so much. If the water (temp) exiting the engine is the "arbiter" the overall temp is MUCH more likely to stabilize. With a lot less additional relay clickin' and fan cyclin'.

With all that said, put it wherever... it's not MY car. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif

 

[Darrell_Walker]

Additionally, if it's at the top it is monitoring the ENGINE operating temp, notifying the fan it NEEDS to be on, not monitoring the water temp going back INTO the block where it's too late to do much about what the engine temp really is. That'd be why the fan goes on-off-on-off so much. If the water (temp) exiting the engine is the "arbiter" the overall temp is MUCH more likely to stabilize. With a lot less additional relay clickin' and fan cyclin'.

Well, if the point of mounting the sensor on the top is to minimize cycling of the fan, then just wire the thing on all the time. Think about this:

You are cruising down the highway at a fair pace. Since you are moving fast, the engine is working pretty hard, and making a lot of heat. So the coolant leaving the block is pretty hot. The sensor on the top turns the fan on. But is it needed? Since you are moving fast, there is plenty of airflow, and regardless of having the fan on or off, the coolant leaving the radiator is plenty cool.

Put another way, the fan cools the coolant in the radiator, not the engine. The fan is only needed if the coolant leaving the radiator isn't cool enough.

That said, you can certainly make either position work with the right set point on the switch. I believe the top (input) position will result in the fan being on in cases that it isn't needed. But if you cooling system is marginal, then maybe you need to keep ahead of it and have the fan on more often.

My 2 cents, anyway.

 

[Brosky]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Where to mount the sensor seems to be a constant debate. [/QUOTE]

Well, I guess that we proved that point again on this one!!

Thanks to all for the info. I do remember looking at a few cars at the shows this summer and they were all at the bottom.

By design, or because that's where a hole was to mount one? Who knows?? I now have a better idea about what I'm going to do with mine, if and when I swap out the radiator this fall.

Well, not if, but when I swap the block, the radiator goes as well.

 

[TR3driver]

I just checked with Mac's Radiator in Bellflower (near Long Beach, California) and they said $290 for a recore, if you bring the radiator to them. They will also happily do the R&R if you take them the car (but I didn't ask for a quote on that).

No direct experience, but I've heard a few bad things said about the replacements being sold by the Big 3. Weighing an unknown and likely untested Far East part against a quality Modine core in my old frame (100% tested to significantly higher pressure) seemed like an easy decision to me; especially given that it's a major undertaking to R&R the radiator from a TR3 (basically you take the front bumper off and work your way back till you get to the radiator).

BTW, a new TR3 rad from Moss is nearly $500 according to their website. Early TR6 is $320.

 

[Brosky]

If I stay OEM style, it will be a recore. I want to keep my tanks with a better core inside.

Then again, there's Bill, happy as can be down south with his Davis radiator.

I'm glad that there is no rush for me on this.

 

[Guest]

place the sensor in the hottest spot. Ideally this would be in the bottom tank.

Hmmm. I was pretty sure that the coolant leaves the engine through the thermostat, to the elbow and upper hose and goes to the top of the radiator. That makes the top of the tank the hot part.

Bryan

That's the way it works, Bryan. "Heat rises", too. If you allow the water level to go below the sensor (assuming it isn't mounted VERTICALLY in the top of the rad... bad idea) it'd be considered "operator error" IMO. Additionally, if it's at the top it is monitoring the ENGINE operating temp, notifying the fan it NEEDS to be on, not monitoring the water temp going back INTO the block where it's too late to do much about what the engine temp really is. That'd be why the fan goes on-off-on-off so much. If the water (temp) exiting the engine is the "arbiter" the overall temp is MUCH more likely to stabilize. With a lot less additional relay clickin' and fan cyclin'.

With all that said, put it wherever... it's not MY car. /bcforum/images/%%GRAEMLIN_URL%%/smirk.gif

What was I thinking, however, it is best to locate the sensor down low. Maybe that is why Ron Davis, Inc. said to lay the sensor low and use the colder sensor.
Whatever.

Cooling is not an issue for me. The fan only comes on in traffic and stays on about 45 seconds.