alk247

My 2003 SL500 developed a coolant leak. Using rented tester from AutoZone (amazingly enough it is free to rent - just pay ridiculous price, use it and then return, they allow you to keep it for up to 90 days) I found the leak from the top of the upper radiator hose (where it is connected to the radiator).

https://www.autozone.com/loan-a-tool...ure/449951_0_0

Per WIS the pressure test must be run at 1.4 Bar (20 psi). Up to about 8 psi there is no leak, so it makes me believe that there is no crack in the radiator. Before I replace the entire hose (about $80), I wanted to try a new o-ring in the hose fitting. And here lies a problem. I can not locate the p/n. There is no o-ring in the part breakdown that I have available. RMeuropian and some other online stores do show the radiator hose o-ring p/n 0269976745. When I tried to look this p/n up on MB dealer sites, they all show that this p/n is not suitable for my car. It is 39.3 mm ID o-ring. I did get one from my local dealer and sure enough it is too small. The existing o-ring is about 41mm ID and it has a large cross section as well.
Before I go on a goose chase looking for a generic 0-ring with similar dimensions, I wonder if anyone has dealt with this problem before? Is there MB exact part? Is there a known generic equivalent? Or am I better off just going for a new hose?

Thanks.

FxFormat

Just replace the whole thing, not worth the time and hassle, part is only $80. I had to shell out $1200 to replace one bad coil pack on my V12, now that was a kicker, $80 is chump change.

eatmycrackers

I had my coolant reservoir crack clean off at the hose connection for both hoses that feed into it from the front side of the car on a long road trip. The plastics under the hood become very brittle over time and are susceptible to cracking.

My view is that it is not worth trying to save a few pennies to spend dollars later on. Just fix it with a new OEM hose and you won't have to worry about that again for another 10 years.

fraktv

Sorry to resurrect an older thread. I’m running into the same problem. I went to the dealer and they were able to look up that o-ring P/N, which is Radiator Hose O-Ring 027 997 18 48 64. Looking at some of the YouTube videos, it looks like the leak may be in the body of the radiator, at the outlet. I guess I’ll find out when I attempt to change it out.

marko69

I and others have found it to be a teeny tiny crack just above the upper radiator hose connection. You will swear it's coming from the hose but it's from the radiator itself. I messed with the oring for awhile then bought a new hose and it was still leaking, I only found the crack while doing a pressure test. If you confirm that it is the radiator, I would highly recommend spending the extra money for a BEHR radiator for replacement. I bought a Nissens and it leaked after a month where the plastic meets the aluminum.