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Radiator swap Aluminum to brass.

A

Acesneights1

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You know it's funny, the first post I made at DP was overheating in my Tahoe(which is now an annual event no mater what 6.5 I have) and my point was thinking that a Brass rad would transfer heat better than the aluminum ones. Well, afetr my little heater core experience(6.2 section) I still wonder about that. Anyway My CUCV needs a new rad and I measured it compared to my Burb and as near as i can tell without physically doing the swap, It looks like the brass one from my CUCV(4 core) would fit a NBS. Anyone ever try it ? I think I am going to replace the rad in the CUCV soon and hang on to the old one till I do a spring cleaning on the Burb and then see if it fits...Thoughts ?
 
When spaeking to the guys at my local rad shop they encouraged me to change over to a copper rad and also drop the t-stats to 160 dgrees and only run a 4 psi rad cap.
Thier opinion was that I would never be able to overheat it in that configuration,my argument against the stats was that these diesels need to see 180-200 to run efficently,especially the obd2 engines.
They still reccommended the copper rad in any case and I have yet to get one since the price will be close to $500.00.

My rad is in good shape for now and I have the Ho water pump with the Kennedy special calibration clutch and Kennedy steel fan and have yet to have a cooling problem since installed.I also have yet to haul heavy during the summer but I don't anticipate any problems once I get my 2 1/2" crossover and diamond eye exhaust installed.
 
My plastic tanks are starting to leak - no obvious coolant, but stains are starting to appear. Instead of patching this one up, I'd be really interested in replacing my aluminum radiator with something all metal. This summer, I'm installing an external trans cooler. That'd be the perfect time to change everything. Any info on suppliers or part numbers?

Several months ago, I replaced my 16# rad cap with a 13#. I had been oozing coolant form my thermostat housing. Tried twice to fix it - cleaned the surface, sanded it level/smooth and replaced the gasket. Within a couple of weeks, the seeping returned. This last time, I cleaned, resealed, etc and installed the lower pressure cap. No change in cooling temps, no issues with overheating, NO SEEPING. Simply less strain on the system, with the same benefits.
 
racer55 said:
When spaeking to the guys at my local rad shop they encouraged me to change over to a copper rad and also drop the t-stats to 160 dgrees and only run a 4 psi rad cap.
Click to expand...

Your rad shop guys don't know $hit about GM Diesels, racer ... your opinion is entirely correct.

(BTW, racer, can you fill out your signature so we can 'see' what kind of truck you have?)

Cooling these trucks isn't a matter of doing one thing ... it's about doing all the little things, and they add up to good cooling.

Spotlessly clean rad, inside and out. Nothing in or between the condensers, either. Genuine AC Delco thermostats. Good water pump. Fully-functional or adapted fan clutch. DMax composite fan. 3" downpipe and free-flowing exhaust. Good injectors. Transmission cooling. TCC Lockup if possible. Chip with good program. Turbomaster or good PCM control of wastegate (or ATT), 2 bottles Water-wetter.

If you can check off all of those things, you shouldn't overheat. Period.

My 94, with a factory original waterpump and fan, and most of the above list, did not overheat pulling 9800# through deserts, hills, and mountains in Montana, Nevada, Utah, Arizona, Oregon, Washington, and California... with the AC on. Before those things, the damn thing overheated on the level with that load.

What made the difference?

I think everything contributed... although turbo-master, Heath fan clutch and manual TCC were huge. (If you have OBD-II and can't lock your TCC, you need to add additional trans cooling to keep that heat out of your rad. If your truck is stock, you're working way too hard to keep it cool - adding air and fuel and getting the resultant heat back out of the exhaust is a must, and an un-modded truck won't do that. )

But after all that, probably the biggest thing was driving savvy. I would get into a 6* hill in 100* ambients in Utah and pull in 3rd (TC locked) at 48 mph all day. If I tried for 55 mph, I would overheat. I knew that, so I quit doing it. If the wind was in my face, the same thing could happen. I pulled that high-front 5er all over the western US with no problems because I watched the gauge and drove by water and exhaust temps.

Before all that, the damn thing almost overheated with the engine off ... for damn sure, I never tried to pull even little hills with the AC on... I would end up on the shoulder, crawling along at 25 mph, trying not to blow up.

All the little things add up - everything contributes. Changing the rad, adding a Kennedy clutch, using WMI, or installing a SSD 180* Tstat isn't going to magically cure the problem, despite the hype and the claims.

Unless you're Dave, and the rad is giving up the ghost... that's the time to change it.
 
Deja Vu yet Jim ??.....:D
The rad I measured is in my 86 CUCV M1008 which is equivelent to a K30. I won't say for sure it fits until I have them both out side by side but preliminary in truck measurements shows promise. I still stick by my guns that Brass dispenses the heat better than the Aluminum. I recently proved that theory with my CUCV's Heater Core. No hurry to do anything other than I am rad shopping for the CUCV because it's used up It's leaking and the core looks nasty. The only issue I see with using an OBS Rad in a NBS truck is you will need a differnt overflow. The NBS is pressurized. on OBS it's just an overflow.. I personally like the OBS better anyway. I like to be able to look inside the rad with the cap off.
 
Acesneights1 said:
The NBS is pressurized. on OBS it's just an overflow.. I personally like the OBS better anyway. I like to be able to look inside the rad with the cap off.
Click to expand...

No argument there ... I am not saying that the brass one isn't better than aluminum, just that cooling is all about doing lots of things right, not about one thing solving the problem.
 
I've always maintained copper was better than al., even at the other site. It has 2x the heat transfer.

The only reason al. is used is it's less than 1/2 the cost.
 
Yep, but there are lots of factors involved in rad design... number of tubes, size of tubes (flow rate), spacing of tubes and fins (parasitic thermal transfer).. we used aluminum rads in thermal scavenging applications in the gas plant - they worked great there, but the engineering and design was very involved.

I wager if one took a copper rad from a gas application (say, a vortec 350) and tried to use it in a 6.5 diesel application, it wouldn't work well enough - the diesel has a much greater thermal development coefficient. It wouldn't be tht the rad didn't exchange heat GOOD enough, but that it couldn't exchange heat FAST enough.

This is the same reason why flow control through the rad is so important... if the water goes through too fast, it doesn't get enough time to shed the heat - and returns to the engine still too hot. increasing water flow (upping the gal/minute of the pump) isn't always the answer, for that reason.

Lots of things have to work together in order to have a proper cooling system.
 
It will be an interesting experiment in the spring. I am pricing out new rads for the CUCV now so I will have the old one as a guinea pig.
 
I've always maintained copper was better than al., even at the other site. It has 2x the heat transfer.

The only reason al. is used is it's less than 1/2 the cost.
Click to expand...


As a welder I can tell you that aluminum transfers heat better than all the other metals you are discussing in this post.

Ask anyone that welds or is a metalurgist. The laws that apply are conduction,

I was going to put up the math and conversions but I don't want to come across as a smart a$$.

So I will give an example of the two materials working together and why.

Hydronic base board heaters are made of copper pipe and aluminum fins.

Copper dissipates heat at a slower rate and therefore the aluminum fins are used to carry away as much heat as possible.

While the coppers temp drops only slightly and is more effecient when it returns to the boiler to be reheated, therefore less energy to maintain temp in the system.

Aluminum fins are used because it carries more heat away from itself as air passes over them. This is the exact oppisite of what we try to achieve in our cooling systems. That is why the core and the fins are aluminum.

I hope this helps a little bit in understanding why aluminum is better not just because of price but also performance.
 
That's the heat carrying abilty, not the heat transfer ability. Look at aluminum s # and the coppers #.

Almost twice the heat dissipation of copper. Aluminum asbsorbs/transfers more heat and as a welder in school, ask your instructor which dissipates heat faster aluminum or copper, brass which is copper and tin combined is a little better than copper, at heat transfer.

Or do this simple test heat a piece of aluminum and a piece of copper, same thickness and see how long it takes each one to reach the same temp with the same amount of heat applied.

Please let me know what he tells you as I'm curiuos as to the answer he gives you.

I'm not sure you're interpreting your book properly.

Brass will definetly last longer than aluminum, but the MFG. use it for weight savings as well as being more efficient.
 
well I can tell you the aluminum heater core I bought did'nt put out heat for nothing and the brass one blows me out of the cab. Also I can tell you the OBS trucks with 6.2s (basically same engine) don't have all the overheating problems these do. I'm gonna give it a shot. Gotta try something right ? Now with your metal theories, I don't know as much but even though aluminum dissapates heat faster is it possible it's not absorbing the heat in the first place but more so rejecting it ?? Because after my heater core ordeal, there is something missing from the equation. Maybe the brass absorbs and hold the heat so the fan or airflow can get rid of it ??? well, if I do the swap and it's not better or even worse then I'll know for sure.
 
well I can tell you the aluminum heater core I bought did'nt put out heat for nothing
Click to expand...

It was also less than half the size of the original. Less surface area.

Maybe the brass absorbs and hold the heat so the fan or airflow can get rid of it ???
Click to expand...

Exactly.

The aluminum rejects the heat faster, but in your case the size difference is what killed you.

It absorbs heat faster and therefore dissipates heat faster, as the air passing over it can carry it away with less energy than required by brass.

That is also part of the reason the 6.5 only has a 2 core RAD. versus 4/5 for the brass ones.

Although the aluminum rads have 2 cores they are thicker almost 1 1/4" versus the brass 4/5 core of about 9/16".
You also have to take into account how much air flow [how strong the fan is] to pull through 4/5 cores.


If you do try this and it works better , post the results as I would convert in a heart beat. I'm not trying to dissuade you from doing it. I'm just pointing out the thermal differences as I have been taught. That doesn't mean that it won't work just that it shouldn't be as efficient.

That's why we try different things. To find out what works and what doesn't.
 
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