OM603 Radiator Upgrade? - PeachParts Mercedes-Benz Forum

nyc10009 · #1 06-02-2010, 02:41 AM

Hi All,

I haven't posted in a few years, but I'm glad to have my beloved '87 300TD back on the road-- in fact, It's getting a new coat of Rauchsilber, as I type this. I want to replace the radiator... good insurance, since this 195K car runs amazingly great, quiet w/new lifters, 3min afterglow & no cracks--knock on Aluminum, for good luck!!!

Is the W124 500E radiator bigger than mine? Are any of the 210 OM606 radiators bigger--or will they fit/or can be made to fit my 124 car? IMHO, the stock OM603 radiator is just about adequate. I'd like a bit more safety margain, especially driving in & around hot, humid New York City. I've got the newer sty clutch + 9-blade plastic fan. How 'bout custom radiators? With cost of OE units $300+ I may consider that route.

aaa · #2 06-02-2010, 05:52 AM

The stock radiator barely fits in there. What are you going to do, get a thicker one?

babymog · #3 06-02-2010, 09:56 PM

Pipe/outlet location is the trick.

The stock radiator has plenty of cooling. I did some testing when they were first available, full-throttle summertime runs with A/C, with the original under-engine panels in place, never had a heat problem other than one (defective) hose failure.

The trick is to have everything in good working condition.

compress ignite · #4 06-03-2010, 03:01 AM

'Would be to switch over to Evans Waterless Coolant.
No System Pressure (Usually 1 bar)
AND you'll not overheat it in August ,even in Hell's Kitchen.

Howeveah,
once again Mog's right...
A Clean Cooling System ,with fully functional components doesn't need it.

nyc10009 · #5 06-03-2010, 02:44 PM

Has ANYONE on this list ever driven in bumper-to-bumper New York City traffic for hours at a time, with 90+F, at or near 100% humidity, A/C full-blast? For at least 2mo out of the year, my poor '87 300TD is always challenged in this environment. Evidentally, the Germans ignore the fact that their wonderful products are exposed to this severe environment. Even newer Benzes alongside me in traffic are idling VERY HOT, with their electric fans ROARING at defining sounds.

My Diesel gets hot--more than 100F and at times, higher than 110F. I've replaced everything, radiator, fan upgrade, water pump, and yes my #14 head is OK--no cracks. But woe is the poor radiator, which likely works fine in less severe climates.

I've decided to have a radiator custom made. Heck, the OE Benz unit is $400 (note: it's got 50 tubes vs 48 in OEM Behr unit). A custom radiator is just a little bit more than that.

I've chosen to remove the trans cooler from the radiator, buy a seperate unit & mount it elsewhere--get rid of some of the heat + add 5-7% more fin/tube.

Does anyone know if there's any room in the 124 to make the radiator wider, left-to-right? Even 2" on each end, would add significant cooling advantage.
Also, are there any cooling advantages to the 2-Electric fans mounted outborard vs the 1-Fan setup on my '87?

-Will

Jeremy5848 · #6 06-03-2010, 03:32 PM

I sympathize with your environmental challenges. Sounds like time to find a new place to live/work.

A high-pressure washer applied to the back of the radiator to blast the dirt and insects out of the fins has been known to be helpful in improving the ability of a radiator to cool. But if you've done all of the listed replacements fairly recently there will be nothing to gain.

Do the thermostatically-actuated flaps on the left (driver) side of the engine compartment work? They open when the engine compartment gets hot and help to vent hot air out. The mechanical thermostat and its linkage can get rusty and stop working. Many people don't even know about them. The round thing in the first picture is the thermostat. The next two pictures show the flaps open and closed.

The transmission does not actually generate a lot of heat in stop-and-go city traffic; in fact, the combined engine/transmission radiator is designed as much to help the transmission fluid come up to operating temperature quickly as to remove heat from the transmission. Thus, having a separate transmission cooler may not buy you anything (but see my comments 2 paragraphs further on).

It was said recently in another thread that the electric fans in front of the radiator do not move very much air compared to the engine-driven fan behind the radiator. I have no data, just what was said in that other thread. The dual-fan setup certainly would cover a wider area but I do not know if they would move more air than the single larger fan. Looks like the horns would have to be moved to make room.

Looking at my '87 300D sedan (is yours really a wagon, a TD? with more cubic feet of passenger compartment to cool, I might note), I don't see that there is much room for a larger radiator. You might be able to squeeze in something thicker, there's a couple of inches room between the back of the stock radiator and the fan (I also have the OM606 fan and clutch) but you would lose the plastic shroud. Removing the transmission cooler would allow you to devote more square inches to engine cooling so I suppose that would help. There's definitely no room for a wider radiator unless you completely changed the headlight units and did some sheet-metal work to widen the front of the engine compartment. A custom-made radiator would be expensive, I suppose.

Speaking of shrouds, I notice that the shroud in back of my stock radiator does not cover the entire radiator -- about four inches of radiator on the left (driver) side has no fan-driven air flowing through it at all, only movement-generated air, of which there's darn little in stopped traffic. Perhaps you could have a sheet-metal shop fab you a better shroud (but at what cost?). The dual electric fans might also help.

Jeremy

babymog · #7 06-03-2010, 05:17 PM

Yes, Mercedes did test the car in very hot climates, idling etc., and originally it held up fine. You might note that the gas version even cools the fuel to survive very hot climates.

If your car is running hot, and the solution is more cooling at low/idle speeds, I think I'd first consider up-sizing the electric fan to a higher CFM, change the thermostat that turns it on to a lower temp (I believe that 105* is where it turns on so 110* would be close to normal), add a relay to take the additional load (the resistor and temp sensors won't handle the additional amperage), and up-size the alternator to handle the additional current that the fan requires.

Fortunately, at idle, the engine and transmission generate very little heat compared to the radiator's capacity. The A/C condensor is possibly generating as much heat, more still if it's over-charged. Be sure that the flow through the condensor is good, a dirty condensor will block a lot of flow to the radiator.

You might even start with the alternator upgrade, these cars don't hold their voltage very well at an idle, so A/C running with aux fan might be drawing your voltage down to a point where the aux fan isn't running at an optimum speed. Also, the original fan is probably not as efficient as it was originally, old windings lose their efficiency, many things degrade over 24years of use.

nyc10009 · #8 06-05-2010, 05:23 PM

Thanks Jeremy & Jeff:

Yup, my thermo flaps work--I'm amazed at such a sipmple design! I plan to upgrade my electric fan (single on '87 cars) to a double--or a larger single. Anyone know which works better. Also, which mfgr?

I've upgraded my Alternator to larger amperage, I forget how much; I think it came from an S-class. Radiator & condenser is clean as a whistle & fan appears to come on/off as it should... The only time the car overheats is after an hour or more in NYC traffic. Maybe electric fan/s could be upgraded, but since I have to spend $300+ on a radiator, I'm likely going to get a custom one -- just to give it an extra measure of security. I just don't like seeing the temp guage inching twd 110--ever! And I doubt MB tested these cars--with AC in severe climates/situ like NYC--since nearly everyone I know who owns MB's has this problem in NYC. It's funny, you can idle a Ford Crown Vic in heavy traffic all day--with ICE COLD AC--and the temp needle just sits at normal!!! ditto for any Toyota product. Why can't a Benz do that?

Crazy_Nate · #9 06-05-2010, 05:51 PM

Off topic, but related...

Are there any minor modifications that can be done to reduce engine compartment temperatures? Wrapping the headers possibly?

My car will run warm with 95 degree F ambient temperatures, stop and go traffic and the A/C on (somebody converted it to R134...before my time). If I don't have the A/C on, it's never an issue...

BoiseBenz · #10 06-05-2010, 06:33 PM

How about a fan on the oil cooler?

pawoSD · #11 06-05-2010, 08:28 PM

My diesel and gasser both switch on their aux fans when idling if it is hot out....they've never even gotten close to 95C....even the 300E with the A/C running. MB's are designed to take just about any situation with ease, so long as all components are in good shape.

nyc10009 · #12 06-11-2010, 02:51 PM

Does anyone know if 126 350SD radiator (126-500-53-03) is larger than my '87 300TD unit (124-500-00-02)? It looks like it is. If it MIGHT be made to physically fit--w/minor modifications--into my 124 '87 300TD, I should get the slight cooling 'edge' I'm looking for?

I've gotta buy a new radiator; if the S-class Diesel radiator has larger capacity + can be made to fit, I'll buy it. I've never heard of an S-class Diesel, 126 or 140 that's ever had overheating or hi-temp problems, whereas, an OM603 cooling system MUST be at or close to 100% to achieve just marginal cooling under 'severe' NYC summer, A/C, cooling conditions.

Also, does anyone know why MB practically DOUBLED the size of the oil cooler on the 140 S-class Diesels? My 23yr old oil cooler hoses are due f/replacement (before catastrophic failure), and I thought I could install the larger cooler--it couldn't hurt? Ideas?

I'm planning on adding the additional idler pully, suggested by Dave, to my OM603, as it seems to be a worthy improvement; less stressfut serpentine belt path.

Thanks! -Will

'87 300TD
195K mi
In paintshop; Rauchsilber!

swogee · #13 08-21-2012, 02:47 PM

I know this is a two year old thread but I am curious if nyc10009 (Will) ever got the custom radiator or used another radiator from a different model.

-Steve