Radiator Recore

[dakman29]

Hello:  The radiator on my 68 280sl is leaking badly at the lower tank.  Trying to decide whether the high efficiency record advertised on Gernold's site is a worthwhile fix or should I just have a standard record done locally.  I'm on the west coast so shipping the radiator to him and back won't be cheap.  Any thoughts?  Thanks. 

[jameshoward]

No doubt others will have a different view, but a recore is a recore. Unless one increases the capacity of the radiator then only a finite amount of coolant can be cooled, and that limit is set by the size of the radiator. Increase that size and you get more cooling.

And anyway, if you don't have an over-heating problem, why go to the expense of shipping the rad across the country?

I'd find a good local place that you can have a dialogue with. I had mine record 6 years ago and it's been great since. Nothing fancy; just good old-fashioned (eye-wateringly expensive) German craftsmanship.

[rutger kohler]

I got mine redone here in NZ, in the small town I live in, about 2 years ago.  Very pleased with the results.  The local radiator shop was able to locate the correct core in NZ.

[66andBlue]

.... Unless one increases the capacity of the radiator then only a finite amount of coolant can be cooled, and that limit is set by the size of the radiator. .....

Aahh .. looks like we need a bit of physics here. 
Yes, the amount of coolant that needs to be cooled is constant and the size of the radiator determines how much heat can be transferred to the surrounding air.
But the speed by which this can be done is not determined by the "size" but by the surface of the radiator and that is what changes  in a "high efficiency" recore, the more copper lamellae (or fins) the larger the surface area.
Still, that is not all that goes into the equation, one also needs to take the air flow into consideration. It is easy to increase the surface area - one could just use a copper sponge - but that would not help because the air can't be moved fast enough through the sponge. Thus a larger surface area recore will only bring an advantage as long as sufficient air is moved past the fins. At high driving speeds that is not a problem but when you are standing still in traffic at 37ºC ambient temperature you better hope your radiator fan moves enough air. Better to use one with 5 or 6-blades than 4.

[Rolf-Dieter ✝︎]

In my case the thermostat housing is not in best shape and I may source a new one to replace the one now on the car. When my car was last at the Benz Dr. we had problems sealing the joints, Dan managed to do it in the end. Still the joint face is in very poor shape and it warrants replacement or repair perhaps with devcon (plastic metal filler) and re-machining the joint??? Perhaps the best solution is a new housing?

I'm just wondering if the OP has checked the exact location of the leak, the joint face of the thermostat housingh is certainly a place to have a close look at.

[Jordan]

I just went to a local rad shop to get mine recored 2 years ago.  Just phone around and ask them what they do and how they do it.  Most rad shops will also repaint them but I didn't as I wanted to see the welding before it got painted.  I also had them install 3 cores instead of the two that were originally inside the rad.  Didn't change the thickness of the rad and the engine runs at a steady 80-82C now.  Very happy with the improved cooling.  While you have the rad out it is a good time to replace belts and the water pump if it hasn't already been done.

[mdsalemi]

No doubt others will have a different view, but a recore is a recore.

Not so. Typically here in the USA today, a "recore" involves removing the upper and lower tanks, and then buying stock "cores" from the people who make them, or distributors, then soldering it all back together. Which cores does the shop use? Are they all the right size?

The story I heard from Gernold (SL-Tech) was that he tried to find someone who would work to his specification, but doing so with stock cores was not possible. So, he found a guy who actually had the equipment to make the cores, and the re-cored radiators from SL-Tech are custom made; not stock cores. Pricey? sure. Old world craftsmanship.

For what its worth, I had a recored radiator from the start on my car since the restoration, and it always ran hot, and in conditions that Albert described, stop and go at 37c with little air flow, was always on the hairy edge of overheating. I bit the bullet in 2011 and bought a recored rad from Gernold, and it has never run cooler. Much improved over the old recored unit, which was 3-row. Others have reported similar results, while some have no problem with any old re-core from any shop. I'm just happy I have something that works.

[Garry]

There is two parts to the radiator recore saga.

You can just remove and replace your radiator, and you should get some improvement in cooling, or as Michael/Alfred said get one with greater surface area, but with out properly flushing the water lines through out your engine, and whilst you are at it replace the water pump, you are only doing half the job and unlikely to be really successful in managing the ‘whole’ cooling system.  It is a combination of surface area and water flow through the system combined that equate to the amount of cooling that can be achieved.

Many fall in to the trap of just replacing the radiator and then wonder why they still have some over heating problems when they have not done a proper chemical flush of the whole system, nor replaced their water pump which probably has a corroded impeller that is also reducing the water flow as well..

My pennys worth.

Garry

[jameshoward]

I was going to add that you should replace the water pump (and banjo bolt) at the same time. Garry beat me it it.

It's good advice, not remotely hard, and relatively cheap.

[stickandrudderman]

A couple of years ago I had a 230 that was overheating.
Naturally we ensure that every part of the cooling system is in order before concluding that a new radiator was required. I fitted a second hand radiator that I had lying around and the overheating problem was gone. I sent the original radiator for re-core and then re-installed it; overheating returned! I removed the rad again and sent it back to the rebuilders asking them to check it. No fault found. I asked them to put in a high efficiency core and then re-installed the rad. Overheating problem persisted. I re-installed the second hand rad; problem cured!
I ended up having to leave the second hand radiator in the car and still have that re-cored radiator waiting to be tried in another car.
Weird.

[kampala]

Here's a shot I took of a Pagoda radiator being tested for flow ... The flow was quite weak in the center part as you can see from the photo --- ended up doing a re-core. 

[KevinC]

In my case the thermostat housing is not in best shape and I may source a new one to replace the one now on the car. When my car was last at the Benz Dr. we had problems sealing the joints, Dan managed to do it in the end. Still the joint face is in very poor shape and it warrants replacement or repair perhaps with devcon (plastic metal filler) and re-machining the joint??? Perhaps the best solution is a new housing?

I'm just wondering if the OP has checked the exact location of the leak, the joint face of the thermostat housingh is certainly a place to have a close look at.

I found that my housing cover was quite pitted and I replaced it last year with one from the Classic Center. $55 if I recall correctly.

[dakman29]

Thanks to all for the responses.  I am going to speak with the local shop to see if they can add a third row of tubes/fins.  I've not had overheating issues with the car so I think that if all they can do is a standard recore, then I'll probably go that route.

[Rolf-Dieter ✝︎]

First of all ... Great Tread!!!

Here is my situation, My radiator is leaking now and has been in the past. First it became evident when Dan (Benz Dr.) replaced my fan clutch when we put things back together in his shop coolant was leaking when i pointed out that the leak is from the horizontal joint of the thermostat housing. Dan's people managed to seal that leak somehow. Now I do have a leak at the bottom area of the radiator.

My plan is to change the radiator (like Michael did get a new one from Gernold) and arrange to change the water pump and belts at the same time since the hood has to come off and with the radiator out of the place it can all be done in one wash. At the same time I'm thinking to replace or repair the thermostat housing. It would be a nice winter project. I will do some research as to the aforementioned replacement parts.

BTW I asked our friendly Mercedes Dealership (near my home) to give me a quotation for the work ... it be interesting to see what price for parts and labour they come up with.

Any thoughts ... is my plan logical or not?

[Jordan]

R-D, you do not have to remove the hood to get the rad out.  You can raise the front end and take it out the bottom.  There are several threads describing it if you do a search.

dakman, you should be able to add a 3rd core without changing the original dimensions of the rad.  If your rad shop says they can't then I would talk to a different rad shop. 

[Rolf-Dieter ✝︎]

Thanks Jordan, I think I will have a good flush done at the same time, so it will be done at a shop. May aswell do a 100% job when all is apart including some new hoses.

Did you have your rad re-done or did you get a new one?

[garymand]

Jordan is right!  But it sounds like you really want to do all that stuff and you have more extra money than I do...  They didn't tell you what was wrong and what they did to fix the thermostat leak?  And now, you are concerned that their fix was not professional, (permanent as opposed to temporary)??  I'm confused.  
There isn't much there but an O-ring.  If it wasn't a metal corrosion or crack thing, all they did was replace the o-ring.  If that is the case, problem solved, permanently, professionally.  Atleast until you need a new o-ring or thermostat, 10 years from now.  Call them and ask what the problem was.

With a leak from your radiator and not just a hose, you have no choice but to drop the radiator.  Make sure its not one of the hose or hose clamps.  I would never pull the radiator: you have to remove and replace the hood.  The hood is custom fit to your engine bay, with a crazy technical tortion bar spring that you don't want to mess with if you are skiddish about a thermostat housing.  It takes an artist with a minor in mechanical engineering to get it back in there.  

I just had a local 3 row high efficiency re-core.   Cost $425 due to the high cost of brass and copper.  It is supposed to have little fins in the tubes...  What is a new one $850?  The local $425 rebuild radiator works fine and is new except for the top and bottom caps.  The actual radiator part is all new.  Comes out the bottom and with the radiator and fan out you get to the front of the motor from below.  

Great picture of the flow test! 

[Jordan]

R-D, I used my existing rad and replaced the 2 row core with a 3 row, as Gary describes.  As he says, only the top and bottom caps are retained, the fins get discarded for new ones.  Two years ago it was $400 to have the rad recored, welded/soldered and pressure tested.  I did not have it repainted, I did that myself.

[Rolf-Dieter ✝︎]

Thank you both Gary & Jordan!

Gary, the problem with the thermostat housing was corrosion very bad indeed. I will make sure it is the rd and not the hoses or clamps.

[mdsalemi]

Dieter,

As I did this myself it was about a 10 day project, merely because there are so many items to remove, and I elected to have the bulk of them powder coated. So, the fan shroud, air cleaner components, fan itself, etc. were all sent out.
I would suggest replacing the water pump too, and pay particular attention to the "long/short" issue on that. You probably have a short pump and want a long pump.
Obviously you want to change that cracked housing, and probably some hoses and belts while you have it all apart.
All doable from beneath the car, slow and steady.

[pablo_o2]

I also had issues with the radiator. 3 row recore did the job. Cost: 240 euro
No more overheating problems since then.

[Rolf-Dieter ✝︎]

Thanks for the heads up Kevin, I will order one and have it on hand.

Thanks Michael, I will tackle the project on my own (after all that is part of the reason I purchased this car to keep me out of mischief LOL), I purchased 2 ramps last fall since I needed access from below to install a missing part after I had the fan clutch changed. I guess my long trip to Williamsburg, Virginia last September brought the radiator to it's well deserved final rest Looks like the original to me. A local shop here in London, Ontario that does mostly radiator work will re-core it for me for $400- once I got her out.

[garymand]

You might ask them if they will "Rod It Out"  They do much the same work, so the labor is similar, but you don't have to pay for a new core.  They flow test the core, and gently run stiff rods of incremental size through each tube.  I would think some old Brits would be familiar with saving a radiator this way.  Of couse, it is more profitable and a much cleaner proceedure to order a replacement core, charge you double, and have an easy time soldering the three parts back togeather.

[Rolf-Dieter ✝︎]

Fruit for thought ....

I've been thinking back to last week when the fellow pulled my car in neutral up to his flatbed truck, he used the tow hook on my car (on the driver side front) I made sure it did not touch the radiator when he pulled the car up. However, once the car was up on the truck or even during the removal of the car into the shop (he backed right into the shop to unload) it may have made contact with the radiator. I say this since ...

A) The radiator was fine before the car gave up on me on the highway (also no evidence in my garage of a leak).

and

B) the leak is right over the tow hook on my radiator.

To late now, I have to pay the piper to fix it, I just pass this on to you fellows to keep a sharp eye out during the entire operation(s) of getting the car up and back down from a flatbed should you ever be faced with that situation.

[Jordan]

R-D, if you are going to remove the rad yourself, make sure you pay attention to how far away the fan blades are from the fins on the rad.  I don't have a shroud so it was important in my case.  I took lots of measurements before I removed my rad so it went back in the same spot.  The rad has some play once you start loosening the screws on the sides so you want to make sure you put it back in exactly the same spot.  There are also thin strips of rubber on the sides of the rad to prevent it from rubbing up against the bracket.  You will want to replace these as well no doubt if they have never been removed before now.