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  #1  
Old 12-04-2022, 11:09 AM
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1984 300D turbo: is the oil cooler really necessary?

Does very much oil actually travel into and out of the oil cooler during normal operation? Could the car operate normally if the oil cooler were removed?

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Old 12-04-2022, 11:34 AM
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Oil definitely degrades with heat, and there is enough flow to drain the sump in a matter of seconds when a line breaks. The oil cooler is pretty important on a turbo 617.
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  #3  
Old 12-04-2022, 11:37 AM
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Originally Posted by merc lover View Post
Does very much oil actually travel into and out of the oil cooler during normal operation? Could the car operate normally if the oil cooler were removed?
The oil sprays up inside of a special cavity inside of the pistons to cool the piston heads.

There is a thermostat in the oil cooler that starts opening at x temp. Once it is full open, I thought all of the oil goes through the oil cooler.
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Old 12-04-2022, 12:14 PM
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I'd say it matters but don't know how to quantify how much. Even NA 220 & 240D's have them. If I had to run without one it would be only for a short time, driven easily and on synthetic oil.

As a reference point I've seen US gas engines without them while the same model in euro trim had them. Removed a cooler on a '81 380SEL because a euro radiator was $$$$ but the car would never be on the Autobahn. Didn't have any problems but it was a NA gasoline engine.

Good luck!!!
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Last edited by Sugar Bear; 12-04-2022 at 01:49 PM.
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Old 12-04-2022, 12:44 PM
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https://carpart.com.au/blog/is-an-engine-oil-cooler-necessary

It is your car. Do what you like.
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Old 12-04-2022, 08:26 PM
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Originally Posted by merc lover View Post
Does very much oil actually travel into and out of the oil cooler during normal operation? Could the car operate normally if the oil cooler were removed?
Yes, and conditionally yes. The oil cooler is there to keep the oil life at an optimal range. OE designers have to account for the worst case scenario use, and keep cost of ownership down, so they're challenged to manage that balance. For all they know you're towing a camper every time you use the car. Or live in a very hilly area and have 4 passengers with a full trunk...etc.

If you want to understand it, measure it. If you eliminate the cooler, and maintain the same oil type and change interval, pull your next interval ahead and get a used oil analysis. CAT dealers sell a kit for a reasonable sum (bottle within a bottle and a label). Look for oxidation. If it's creeping, then eliminating the cooler wasn't a good choice for your duty cycle. Many full synthetic oils have good resistance to oxidation. Also bear in mind oil today is better than it was when the car was made (in most cases - trusted brands).

You have to loop the cooler, don't just pinch lines. Use hose rated for oil.
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Old 12-05-2022, 07:39 PM
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I was looking at how Mach4 retrofited the oil cooler lines to beefier, aircraft style hoses....it looks very interesting. I've also looked at stacked plate fluid coolers. The only issue I can see is the inlet/outlet would come out right where the windshield washer fluid bottle sits.....might be a problem although I can't say for sure....

My concern on this car is I don't know the age of the oil cooler lines....they are at least 25 years old which to me says time to replace.
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Old 12-05-2022, 07:47 PM
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ml:

Install an oil temperature gauge, and then, following the advice of the above sages as to temperature limits, decide whether or not a cooler is required for your situation.
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Old 12-05-2022, 08:44 PM
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I will get an oil temp gauge, probably a good idea no matter which direction I go with this. Right now I am running dyno diesel oil because the engine has a few oil leaks. As soon as I repair (most of) the oil leaks, I'm going back to synthetic oil which has a wider temperature range.
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Old 12-05-2022, 10:03 PM
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my euro 240 does not have an oil cooler. there are no ports on the oil filter housing like the us models and the area where it goes is just open.
The car has 240K on it.
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  #11  
Old 12-06-2022, 12:45 PM
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My concern on this car is I don't know the age of the oil cooler lines....they are at least 25 years old which to me says time to replace.
Why don't you just change the lines? I changed mine last year.

Overheated oil will certainly degrade faster. But perhaps the change in viscosity when in use could also be important?
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Old 12-06-2022, 01:45 PM
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Why don't you just change the lines? I changed mine last year.

Overheated oil will certainly degrade faster. But perhaps the change in viscosity when in use could also be important?
This. Your suggestion is exactly what I am thinking of doing. I don't like the rubber lines but at this point changing the lines with OEM lines might be the most time and cost effective.....
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Old 12-06-2022, 02:25 PM
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Nothing at all wrong with rubber lines. Swap them out and they'll last you another 20 years (you will not be driving this car in 20 years).

If you want truly cost effective, browse some of the threads about rebuilding your own lines with a crimper and AC hose at home. I did this and my hoses are absolutely bulletproof.

Oil cooler line hose/crimp type
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  #14  
Old 12-06-2022, 03:43 PM
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Originally Posted by merc lover View Post
This. Your suggestion is exactly what I am thinking of doing. I don't like the rubber lines but at this point changing the lines with OEM lines might be the most time and cost effective.....
OE lines may be hard to find. I used one OE line, but the other was aftermarket (Ordered from Europe).

Installation is a bit of a trick. The lines have to be threaded through a tortuous path or the engine mount has to be disconnected. (I think there are threads here about this)

At the filter housing, you need some large but thin wrenches (known as cone wrenches), I ground down some cheap standard open end wrenches. Care is also needed at cooler so as to not damage the aluminum threads.

I had a young competent friend with a hoist - He did the hard work

My 72 R107 needs new cooler lines. I have them, but haven't dived in yet It does not need an oil cooler, but heck, it's there...
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Old 12-06-2022, 03:58 PM
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Shern those Galaxy hoses came out great.

I’ve had mine in a few years now and they look and feel like I just installed them. I do think they will last longer than the rest of the car…or me for that matter. It’s worth having some hoses fabbed up or making some at home. The replacement stuff like Trucktec looks really bad.

I strongly recommend rebuilding the hoses this way. I may be wrong but I don’t think they’ll be weeping and getting loose in 30 years. That is really tough hose made with modern materials.

Speaking of that maybe the engineers who spec’d the oil cooler were taking into account conventional oil. The manual suggests regular SAE oil not Rotella T and others. The car was probably found to benefit from extra heat removal under dyno and road testing. I don’t think the engineers would have added the extra cost and complexity for fun even though they’re Mercedes. Basically repeating what was said ->


Quote:
Originally Posted by tqwrench View Post
Also bear in mind oil today is better than it was when the car was made (in most cases - trusted brands).

You have to loop the cooler, don't just pinch lines. Use hose rated for oil.

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