Radiator question

[GGR]

Hi all,

I would like to know if the radiator is the same on cars equipped with an oil cooler as on cars not equipped with an oil cooler. If not, is the radiator of cars not equipped with an oil cooler of a bigger capacity and is it of the size of the radiator + oil cooler ?

In other words, Can I put a bigger radiator in lieu and place of my radiator + oil cooler in my 280?

Thanks.

[W113SL]

I believe the 250SL radiator is the widest of the three.

W113SL
1967 250SL

[jameshoward]

Is there a specific cooling problem you're trying to solve, or do you just like big radiators?

Assuming the former, a shroud will aid cooling and is a cheap place to start. Thereafter it's worth pulling the radiator to see in what condition the core is. Re-coring with a dual core could make a significant difference.

I am not aware of radiators being difference sizes, although given that the 250 & 280 are apparently more prone to cooling issues, I suppose it would make sense to increase the radiator capacity.

Lots of other novel approaches to cooling on the site, including electric fans, etc. 

[GGR]

No, I don't have a cooling issue for now. I just replaced the water pump and fan clutch. The radiator came out during the process and looked fine. The car now works well without overheating on highway or city traffic, though we are not at the peak of the heat season yet.

My issue is that I am considering swapping the auto trans and 3.92 rear end with a manual trans and 3.27 rear end. I have nearly all the parts already, but not yet the radiator which I would like to replace so as not to have the trans cooler anymore. And this is where I thought: an oil cooler is useful when you keep the engine at high revs for long distances, like on german autobahns. But with nowadays oils and a 3.27 rear end and speed limits on US Highways I don't think I need an oil cooler. Overheating in summer in traffic jams is much more of an issue in my case and I heared these Pagodas are prone to overheating in that kind of situation. So I thought a bigger capacity radiator extending to where the oil cooler was may be an improvement considering the use I have of the car. Is there such a radiator?

[jameshoward]

I don't have a 3,27, I have a 4,08 but am in the process of changing over to a 3,46 this year. I have driven my car hard without an oil cooler and whilst it makes me cringe keeping up with the 280s and 3,46s, the car has never overheated. (I got stuck in London in a heatwave last year on Tower Bridge. Heater on full blast - Scary, but never actually over-heated). The cars aren't prone to overheating in my view, but that said people do have problems. I guess that more don't have problems working on the theory that no one comes to this site and makes a post about a drive they did when the car didn't overheat. If you're car's fine, I wouldn't worry at this stage, and if you have a problem, come back and take advice. 

[stickandrudderman]

If your car has an overheating problem, the problem is with your car. As designed these cars are not generally in need of modification to the cooling system.

[GGR]

My experience is based on a W111 3.5 coupe that was equipped with a 3.92 rear end. The car was running hot in summer at 80mph highway speed, but also in traffic jams. Replacing the radiator only marginally improved things. I then swapped the rear end with a 3.27 one and this cured the issue at highway speeds, but not in hot summer traffic jams. I then swapped the auto trans with a manual one. I also took this occasion to replace the radiator for one that had no trans cooler, and I put in a bigger one while I deleted the oil cooler. This made a big difference and the car is never running hot anymore.

As I want to convert my 280SL from auto to manual and replace the radiator to delete the oil cooler, I thought I would go the same way as on my Coupe. I looked on EPC and found that both the 250 SL and 280 SL have the same p/n for the baffles on each side of the radiator, so the the opening is the same size. I also see that the 250 SL did not come with an oil cooler as original equipment. My conclusion, confirming iW113SL's comment, is that the 250 SL radiator is wider than than the 280SL one, and would fit in the 280SL opening without any modification other than deleting the oil cooler.

My question is now about capacity: How many rows do these radiators have? Would the 280SL radiator have one more row than the 250 SL one, which would negate the the advantage of swapping?

Thanks!

[jameshoward]

Radiators can be re-cored with additional cores, but more isn't necessarily better, since there is a balance between cores and capacity. ie multiple small ones vs a well functioning, clean original radiator. I personally think you're heading down a rabbit hole populated by numerous shoals of land-dwelling red herrings but since I know nothing about differences between the radiators (having only removed mine a few times and had it re-cored, changed the water pump and nothing more) I'll shut-up and let others more qualified speak about capacities.

[GGR]

My question is about stock 280SL radiator VS stock 250SL radiator. Do they have a similar capacity or is the 250SL of a bigger capacity?

[Larry & Norma]

SLS show the same part number for 250 and 280 Automatic car radiators, so I guess they are the same.
Hope this helps.

[GGR]

SLS show the same part number for 250 and 280 Automatic car radiators, so I guess they are the same.
Hope this helps.

Hmmm... indeed. And SLS does not show an oil cooler for the 250SL. This is not consistent with the info I got from EPC. I guess I will have to wait for the next time I see a 250SL so that I can compare. There is an event in the DC area net Sunday gathering German vintage cars. Hopefully there will be a 250SL.

[al_lieffring]

The 250sl had an oil cooler but it was not the same one mounted next to the radiator as the 280sl. It is a water cooled tank that mounts below the injection pump on the motor mount arm. A 250sl would use the same radiator as a 230sl.(this same cooling tank was an H/D service option for ther 230sl)

[GGR]

Yes, I saw such a setup on a W108 250SE some time ago in a JY. I also saw a different setup on a W112 I owned: engine oil was cooled by engine water via a circuit in the right flank of the engine block.

EPC reports different p/n for the 230SL and the 250SL radiators.

[W113SL]

 I know  from experience that the 250SL radiator is just a bit wider than the 230SL I discovered this when I built a vintage race car and attempted to  slide a  250SL radiator into the space that had previously held a 230SL radiator.

Pete Lesler