Why is my US Radiator cooling better than South African?

[LeiseyJr]

I installed a genuine US style radiator from 1995. I was having trouble keeping the car cool with the a/c on with a brand spanking new Behr South African from FCP Euro.

Installed US style radiator and I am dramatically cooler running. Why? The South African is better, no?

[tschultz]

Also interested in this. I recently swapped in a SA radiator and the car has been running warmer than I remember with my Nissan's us radiator.

Using megasquirt and looking at datalogs, same thermostat and sensor I used to see ~180-185 temps and now I am seeing above 195 regularly in the same July temperatures.

Following

[LeiseyJr]

viewtopic.php?t=144685

No other BMW radiator I’ve seen has these damn round tube design?

From the e36 to the e92 m3 they have the same flat tube as the OE BMW radiator.


Another example after searching on here:

viewtopic.php?f=3&t=148912&hilit=genuin ... r&start=25

"I’m the OP with an update.

So I decided to purchase a new radiator and thermostat from a BMW dealer (Husker). What I discovered was, there are indeed some differences between a BMW-branded radiator (made by Behr in Germany) and a Behr radiator (made in South Africa) sold through retailers.

The BMW radiator uses 45 “flattened” coolant tubes running crossways, while the Behr uses 25 either round or oval (hard to tell) tubes, in each row. I don’t know how many rows there are in each radiator; I assume 2 or 3. But it does appear that the BMW radiator’s core has more surface area and I would thereby assume it’s more efficient for heat transfer.

The plastic used in the header tanks on each one is different. The BMW’s tanks have a rougher texture, while the Behr’s are smooth. I’ve read that some radiator manufacturers have been using recycled plastic but I have no idea how to tell by appearance and feel.

Also, the header tanks on the BMW radiator are crimped as well as bonded; the Behr’s are simply bonded. The BMW’s appears to be more costly to manufacture, but more rugged.

So I drove my car today with the new “genuine” BMW radiator and BMW thermostat, and took some readings with an infrared thermometer. (Note that the ambient temp today is about 80*F, whereas it was about 85*F last time I drove it.) The temp gauge still fluctuates somewhat under different driving conditions, but it stays between 10:00 and 11:30 and never goes beyond the 12:00 position. Previously, with the Behr radiator, it would sometimes go beyond 12:00 and approach 1:00 while under load, going uphill on a long grade. My readings on the radiator, thermostat housing, hoses, etc. confirm it’s now running about 10*F cooler than before. I feel this is about where it should be.

BTW, the BMW-branded t-stat (made by Wahler) appears to be virtually identical (aside from the “BMW” logo) to the Wahler t-stat I removed. I tested both of them in hot water and they perform the same. So don’t waste your money by paying extra for one of these at a dealer”

[Mike W.]

I took some comparison pics of the BMW and Behr radiators and will post them if I can figure out how.

viewtopic.php?f=1&t=147488

It's easy, but the pics just have to be hosted elsewhere. http://www.imgur.com Seems to be the easiest free one these days. Test by copying the image location and testing, not the page location.

[adam_poll]

My car came with a newer round tube style radiator from the previous owner. It was perfectly adequate on the street from idling in hot stop/go traffic to highway speeds. However, on the track the car was overheating after a few laps of Toronto Motorsports Park, my car being a euro car with no A/C the only air coming into the rad was through the grill and no aux fan. I opened up all of those extra holes, ducted it, checked the water pump and t-stat with no real change. I finally replaced the rad with a new flat tube style and haven't had an issue since, the car is the same temp whether I am flogging it around a track at high rpm or going to the store.

I don't know what brand the round tube was but I will avoid that style from now on. I think the coolant was flowing too quickly through it at high rpm which wasn't giving it enough time to transfer the heat out of it into the rad (but that is a guess).

[LeiseyJr]

OE style:
https://www.turnermotorsport.com/p-4571 ... -bmw-part/

South African style:
https://www.fcpeuro.com/products/bmw-ra ... 7111468546

[Shadow]

i had one of those radiators in a turbo project
cut it open because the inside looked weird.

Inside of a Behr radiator by jet jones, on Flickr
Inside of a Behr radiator by jet jones, on Flickr

[LarryM]

Another example after searching on here:

viewtopic.php?f=3&t=148912&hilit=genuin ... r&start=25

"I’m the OP with an update.

So I decided to purchase a new radiator and thermostat from a BMW dealer (Husker). What I discovered was, there are indeed some differences between a BMW-branded radiator (made by Behr in Germany) and a Behr radiator (made in South Africa) sold through retailers.

The BMW radiator uses 45 “flattened” coolant tubes running crossways, while the Behr uses 25 either round or oval (hard to tell) tubes, in each row. I don’t know how many rows there are in each radiator; I assume 2 or 3. But it does appear that the BMW radiator’s core has more surface area and I would thereby assume it’s more efficient for heat transfer.

The plastic used in the header tanks on each one is different. The BMW’s tanks have a rougher texture, while the Behr’s are smooth. I’ve read that some radiator manufacturers have been using recycled plastic but I have no idea how to tell by appearance and feel.

Also, the header tanks on the BMW radiator are crimped as well as bonded; the Behr’s are simply bonded. The BMW’s appears to be more costly to manufacture, but more rugged.

So I drove my car today with the new “genuine” BMW radiator and BMW thermostat, and took some readings with an infrared thermometer. (Note that the ambient temp today is about 80*F, whereas it was about 85*F last time I drove it.) The temp gauge still fluctuates somewhat under different driving conditions, but it stays between 10:00 and 11:30 and never goes beyond the 12:00 position. Previously, with the Behr radiator, it would sometimes go beyond 12:00 and approach 1:00 while under load, going uphill on a long grade. My readings on the radiator, thermostat housing, hoses, etc. confirm it’s now running about 10*F cooler than before. I feel this is about where it should be.

BTW, the BMW-branded t-stat (made by Wahler) appears to be virtually identical (aside from the “BMW” logo) to the Wahler t-stat I removed. I tested both of them in hot water and they perform the same. So don’t waste your money by paying extra for one of these at a dealer”

This was my post. I had just completed a manual swap on my E24 and purchased a new South African-made Behr radiator (for a manual tranny car) with the round tubes containing the plastic rotini. As my post reads, my car ran noticeably warmer with the SA radiator, especially going up long grades. After switching to a BMW-branded Behr radiator, it ran at normal temps and I haven't had any problems since then. For anyone needing a new radiator, I would recommend spending the extra $ for a BMW radiator and be done with it.

[BRRV]

I have the SA radiator, and, although it seems okay, I will note that the temps on the gauge on my car does funny things, and always has, and it 's a little scary to suddenly look down and see it at 1 or 2 for some reason when it really shouldn't be doing that, and then it comes back down quickly, for no reason (even if I'm just sitting). I shrugged it off as a cluster issue, but now I'm not so sure. I'm beginning to think you're onto something. Once again, it appears there's an advantage to Original BMW. Maybe Kohler will chime in, because I think he's used the SA ones...

[Mike W.]

There are also the Nissens radiators which appear to be flat tube and are showing at only $140 at FPC for a bargain. They currently seem to be on the shit list over at Bimmerforums E39 forum, but I've used them for the E36 with no issues and have one ready to go in the E39 when I get around to it. Being the cheapskate I am I'd give one of them a try before the $500 one.

[LarryM]

I paid $367 for mine in 2018, from Husker. I see they're now up to about $395.

[harrypalmer]

FWW when I replaced my12 year old SA radiator for a brand new SA radiator two years ago (along with all the switches, even a 32c degree for the aux fan to kick in early, OE hoses, except the upper radiator which was/is NLA) I also noticed the temperatures in general a bit too high for comfort.
I mean, who could think a new radiator will not be better that the replaced one that worked fine until then. Bad from me not having taken the readings before the swap in the first place.

Anyway, the fact is that on long steep runs here in Colorado the temp needle will rise past 12, whereas before it never did. Solution has been to back off the throttle, and the temp needle does come down right away while cruising which is OK but not alright. Bottom line I agree with LarryM and BRRV, and most likely will get a BMW rad on my to do list.

[BRRV]

Darn, Harry, that is EXACTLY what happens on my car.. that odd rise from time to time and then it settles down. I chased this relentlessly all the way across the country to and from Vintage.. and nothing makes me more nervous than a rising temp for no known reason.

[adam_poll]

For what it is worth I went back through my order history and I bought the flat tube Nissens rad in 2017 through Rockauto and it has held up fine since. Lots of waiting in autocross grids on hot days and 20-30 minute sessions on track with no issues or alarming rising temps (needle moves up a bit and settles at idle, drops back to normal with a bit of rpm to get the fan spinning more or as soon as I start moving).

[Shadow]

it makes sense since the SA pasta radiator cools worse because if you look down the hole.
coolant flows through one hole and the pasta is just to slow it down, the modern ones have way more tubes per core.

[harrypalmer]

OE style:
https://www.turnermotorsport.com/p-4571 ... -bmw-part/

South African style:
https://www.fcpeuro.com/products/bmw-ra ... 7111468546

Just to add a note here, the part number 17111712448-genuine-bmw-part/at Turner posted above is for an automatic car (according to what I've found). According to RealOEM the radiator for a E28 535i manual is 17111712447 -genuine-bmw
BTW, the Nissens 17111468546 at Turner is about $30 cheaper than at FCPeuro for those interested.

[tschultz]

Thanks for sharing Jack. Autohauz AZ also has that price.

Not the best photo, but in focus is the normal style radiator. You can see the finer fins of the SA radiator in the background.



Jack, report back if you also see the change with the different radiator-- I suspect you will.

[harrypalmer]

Tom,

Thanks for the pictures. Great help there. Reading the previous comments above I'm going to give Nissens a try, hoping it may do the trick. If not, I'll pony up $453 for the OE BMW. Def will post before and after temps. BTW, congrats on your future Speed Racer.

[HayekFan]

Very interesting thread. I now realize that my Behr radiator is the South African version. Very distinctive with the fine fins and flat top.

I'm guessing it's the cause of my annoying temp needle rise. I installed it shortly after buying the car over ten years ago and have never suspected it because it was new. I bought it from AutohausAZ figuring it was the same Behr as sold by BMW, but wow, bad assumption.

Now the question is Nissens or bite the bullet and go genuine BMW. My main hesitation with the Nissens (other than generally preferring OE) is that I saw on another thread where someone said the fan shroud didn't fit quite right. But that seems to be an outlier. Has anyone else had a fan shroud issue with their Nissens?

[harrypalmer]

Very interesting thread. I now realize that my Behr radiator is the South African version. Very distinctive with the fine fins and flat top.

I'm guessing it's the cause of my annoying temp needle rise. I installed it shortly after buying the car over ten years ago and have never suspected it because it was new. I bought it from AutohausAZ figuring it was the same Behr as sold by BMW, but wow, bad assumption.

Now the question is Nissens or bite the bullet and go genuine BMW. My main hesitation with the Nissens (other than generally preferring OE) is that I saw on another thread where someone said the fan shroud didn't fit quite right. But that seems to be an outlier. Has anyone else had a fan shroud issue with their Nissens?

Personally, no issues with the Nissens that I installed some three weeks ago. Shroud fits fine. The hollow top does not allow the plastic fan cover protector at the top to seat correctly since it is not flat like the ZA, just as you mentioned. But if you angle the plastic piece a bit, it will seat semi sideways and I was fine with that.

Most importantly, the Nissens design is much better and in my case, its working really well.

Had the opportunity to test it while the daily temps around here were in the mid upper 80’s and for lack of better words, it takes longer to get hot at idle speed whereas the ZA Behr rad would just make the whole system hot in a jiffy.

At sustained 85 mph and in fourth gear trying to stress the engine and make it get hotter (replicating the Behr hot syndrome) the needle remained steady at 11:30 and never climbed at all, and I really pressed my car with both AC on and off just to test it’s limits.

My own conclusion: With a perfectly running cooling system, thermostat water temp switches and a throughout coolant bleed, the Nissens rad fins and passages have a better flow so the heat dissipates more efficiently and faster. I do recommend it.

[HayekFan]

^^Good info. I'm nitpicky enough that the upper fan guard needing to be angled is probably going to tip me away from the Nissens. The genuine BMW Behr seems to have the recessed top but apparently there's a little more space so the guard can sit flat.

[harrypalmer]

^^Good info. I'm nitpicky enough that the upper fan guard needing to be angled is probably going to tip me away from the Nissens. The genuine BMW Behr seems to have the recessed top but apparently there's a little more space so the guard can sit flat.

I get what you say as usually I am like you. Now if anyone wants the fan guard to seat perfectly; then smooth sand it either from the front or the rear edges just a tiny bit (less than a 5 minute job) and it will fit right inside the hollow top of the Nissens. Still a bargain. Good luck!

[HayekFan]

How much material would need to be removed? Sounds like it's very slight.

[harrypalmer]

How much material would need to be removed? Sounds like it's very slight.

Your are correct. Most likely two to three millimeters.

[LeiseyJr]

https://dergipark.org.tr/tr/download/ar ... erformance.