I noticed that my lower oil cooler hose (72 450SL) is leaking badly where the steel fitting fits over the rubber hose. I've put off the job for over a year cause I hadn't taken the time to locate the leak. Now it is very obvious where the leak is from. I ordered a new one and should have it next week. It looks like the hose is ready to go at any moment during my 75MPH commute to work.

I just changed my motor oil and I'm nervous about waiting 3K for the next oil change beforre replacing the hose. The lower cooling hose goes from the radiator to a pressure regulator looking object (it has no electrical connections, is it a temperature activated thing?). Does anyone know if this "object" will prevent oil from escaping from the cold engine block when i disconnect the hose, that way i only loose the oil in the radiator cooler and don't have to dump/waste all the crankcase oil?

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1972 450SL
1982 300D Turbo

I'm not sure how much oil you will lose but I expect it would be minimal. Just put a pan under it and change it.

I am probably one of the worlds biggest pinch pennies so I understand why you don't want to lose oil.

That said, a few quarts of oil are very, VERY cheap compared to what a spoiled MB V8 would cost you. I really think since you already have the hose you should replace it.

BTW, the next time you have a hose like this leaking, you can save the cost of that lost oil and then some by simply going to an industrial hydraulic shop and having them replace the rubber hose. They can cut off the ferrule, reuse the fittings, cut new hose to length, put on and crimp in place the new fittings.

Good luck,

Thanks Larry,

I've heard that shops exist that will make up these kinds of hoses and AC hoses but i have not looked for/found one yet. thanks for the reminder, maybe next time. I confess that the loss of oil that i'm worried about is a bit silly on my part but for some reason i hate the idea of wasting 8qts by draining ahead of time or making a mess by not draining. The pan will go underneath per your advice.

Should i flush the oil cooler radiator or something while i'm at it?

The same car (daily driver) is starting to weap some coolant at the upper tube-to-tank area. I beieve I had it recored in 1986 when i did the engine overhaul myself. Do you have any recomendations/experience with this? I finally oredered 4 gallons of expensive ($10/gallon) MB coolant for my 2 MBs. I really dont want to buy a new radiatoir at $735. Many years ago i used to periodically put some solder on my pickups radiator but I never could really get it to adhere for more than 6 months. Maybe I could pull the radiator out, cut off the bad tubes, clean the area and solder them shut?

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1972 450SL
1982 300D Turbo

You are very close to one of the best radiator shops in the world...Reseda Radiator on Hart St. in Reseda, a quick jaunt to the valley. Take it to them for some honest, fair advice

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The Golden Rule

1984 300SD (bought new, sold it in 1988, bought it back 13 yrs. later)

Thanks,

Per your recommendation i contacted Reseda by email. They have recored originals in stock on an exchange basis. at $250 it looks like a deal. thanks for the tip.

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1972 450SL
1982 300D Turbo

If you pull the line with a drain pan underneath you will not lose all your oil, you will probably lose no more than a quart or two.

Good luck,

Conclusion:

My radiator was original from 1972, it has never been recored (just boiled out in 1986). I brought the radiator, oil cooler and overflow tank to Jerry, the owner of Reseda Radiator in Reseda, CA. He did a great job recoring this 31 year old radiator. I finally got to see what you get done when recoring a radiator. It really makes your metal radiator as good as new and saves a bundle of cash.

He also replaced the brass fill nozzle on the copper (brass?) overflow tank. For the last few years the top of the overflow tank was a mess because of a minor coolant leak. I had replaced the pressure cap a few times in the past thinking that was the problem. It was only after boiling/cleaning the overflow tank that we could see the barely visible hairline crack in the fill nozzle. Also boiled out the oil cooler which was still in excellent mechanical shape, although somewhat sludged up. He even painted all three parts to the original black. All this for just under $300 ($250 for the recore). I highly recommend him as he is an expert on MB radiators (plastic too). I believe he does shipping if you're not in the area. Just google Reseda Radiator if you want to get his web page and phone #.

It's important to unscrew the two (I have a V-8) engine block coolant drain pugs to completely empty the coolant. There is a lot that stays in the block after draining the radiator. I also decided to replace the thermostat for cheap insurance. Before putting in the new one I shoved a hose in the thermostat opening and trickled water for 30 minutes. I used a rag to stuff close the thermostat opening around the hose so that the water actually fills up the passages in the block before exiting out the two drains. The rag does the job supprisingly well. Jerry advised me to stay away from an acid chemical flush since my engine is over 30 years old. He felt a clean water flush would be good enough.

Under 1/2 qt of oil lost from disconnecting the oil cooler lines. About 4 qts of trans fluid is lost from the transmission cooler line when they are disconnected from the radiator.

Used MB coolant for the first time in decades for this engine. Was using any coolant I could get on sale up to now (Prestone, Texaco...). After reading the posts here on coolant I decided to get religious and buy MB stuff. 50-50 mix with water. Car is back on the road as my daily driver

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1972 450SL
1982 300D Turbo