Radiator Leak - PeachParts Mercedes-Benz Forum

Don Moranville · #1 06-28-2006, 03:33 AM

I have a small crack in area of upper hose connection. The crack is 3/8" long and on top and easily accessible between hose and radiator tank, but can not be covered by hose because of tank molding. Has anyone tried to repair or know type of plastic material that MB uses in the construction of the radiators found in 92 500SL. The purchase of a new radiator seems excessively expensive considering the size of leak.

rickpark · #2 06-28-2006, 11:54 AM

Happened to me on my 1990 300SE except the failure was catastrophic - neck broke off and coolant spilled all over the place.

You can try to reinforce the neck with a piece of copper tubing if you can find one that fits snugly and use some high-temp epoxy like JB Weld.

There is a description of the problem and a repair kit at: http://www.**************.com/. It is in the section called 'Maintenance Alerts'.

Many threads on this problem here - a $200 radiator makes the problem go away for a long time. The wiki section has a replacement guide.

Don Moranville · #3 06-28-2006, 07:53 PM

Thanks rickpark for responding. The use of a tube to reinforce neck as preventive measure makes alot of sense. I have considered using a copper sink drain pipe used for traps and install inside the neck but only size available is 1.5 od, similar to od of neck pipe. May work if split longitudinally to leave a gap to adjust od and locate gap opposite to existing crack then collapse od to fit. Type of plastic used by Behr/MB still a factor to consider when using adhesives and, hopefully, someone on forum has this knowledge. Super glue would probably work but it sets so fast and is so permanent I am afraid to use it.

Ferdman · #4 06-29-2006, 06:37 AM

Don, your problem involves a risk/reward philosophy. A Rube Goldberg fix may work indefinitely, or when/if the radiator upper hose connection separates from the radiator at highway speeds you may be facing extensive engine damage/repair. I understand your reluctance to replace the radiator ... at $500 online that's reason to pause; however, peace of mind is priceless. The upper hose connection on our 1991 300CE developed a circumferential crack and came apart while my wife was parking the car. The remaining stub was long enough to accept the radiator hose so I could drive the car a short distance home ... replaced the radiator before driving the car again. It's an easy DIY job on a 300CE ... probably a bear of a job on a 500SL.

rickpark · #5 06-29-2006, 12:06 PM

My 300SE radiator was around $200 but obviously a different car and radiator.

And the R&R procedures are likely very different.

If you do try the neck reinforcement approach, assess the condition of the plastic carefully as the crack may be indicative of rotting of the plastic which would make any repair strictly temporary.

Also make sure your choice of adhesive is rated for the expected operating temperature and make sure both the neck and the reinforcement piece are clean, dry and well roughened to give the adhesive something to bond to.

david s poole · #6 06-29-2006, 01:48 PM

read the posts and felt had to post.what you are all missing is this.mercedes radiators are made of plastic and aluminium and as they age[6-8yrs]two things happen.1 the plastic petrifies[meaning that when you fix a hole a new one will arise to take it's place].2 over temperature cycles the aluminium core will shrink and cut down on the quantity of water moving through the tubes.a classic case of this is sitting at idle foot on brake car in drive ac on and temp starts to rise but when you hit the gas and take off[speeding up engine and therefore water pump]you can watch the gauge drop.if you dont want to be constantly fixing the cooling system and maybe an engine bite the bullet and buy a new radiator. david poole owner european performance dallas texas

EricSilver · #7 07-01-2006, 02:39 PM

Quote:

Originally Posted by Don Moranville

I have considered using a copper sink drain pipe used for traps and install inside the neck but only size available is 1.5 od, similar to od of neck pipe. Super glue would probably work but it sets so fast and is so permanent I am afraid to use it.

1-inch copper bushing from Home Depot fits perfectly.

Superglue will not work. It cannot withstand the heat and water.

Standard JB Weld is not waterproof and will deteriorate. There is a waterproof JB Weld, but I don't know how heat resistant it is. Steel epoxy works best.

EricSilver · #8 07-01-2006, 02:34 PM

Look here:

Radiator Neck Fix/Preventive Maintenance

For now, I would suggest getting some QuickSteel epoxy from the automotive section of WalMart, or an auto parts store. If you do a good patch job, it will seal the leak for at least a year, but the crack will slowly continue to spread.

Use more epoxy, and cover more surface area, than you think you will need. That will help slow the spread of the crack.

In the end, water + heat will win the battle, but I have fought it successfully for 4 years with this easy, fast fix.