Originally Posted by Junkman

I'm debating. I shouldn't have to pull them again but want it easy in case I do. There really isn't much room to install another connection and I haven't looked at what's available.

I need to find some motor mounts. These show cracks in the rubber when unloaded. I don't remember Lemforder being readily available. Who filled their mounts? I wonder how they are holding up. (OOPS, sorta off topic.)

Originally Posted by Junkman

I need to find some motor mounts. These show cracks in the rubber when unloaded. I don't remember Lemforder being readily available. Who filled their mounts? I wonder how they are holding up. (OOPS, sorta off topic.)

Originally Posted by Junkman

Does anyone think it's worth the effort to figure out how to break the upper line to shorten it so it is easier to install? On one hand, I don't expect to ever have to remove it again. On the other hand, it's an old car & things happen. The AN fitting & bung is over 2" and it is thick so finding a place to cut & patch the line may not work without other considerations.

I have an extra line to play with & would only be out the time to get the fittings and a few dollars.

Originally Posted by mach4

A common and recurring question on the forums has to do with leaky or aging factory oil cooler hoses. Aftermarket hoses can be a problem due to quality and changing lines can be a pain. The idea of using aircraft quality AN fittings and stainless braided hose has been documented in various places on the forum, but not all in one place. This post rectifies the situation.

Here is how to make the conversion, if desired.

The oil cooler needs to be converted to an AN fitting as do the hard lines coming from the oil filter.

The first question is what size hose to use. I determined that the -10 size is an almost perfect one for this application based on the following research data.



There are two potential ways to modify the oil cooler end of the line to use the AN fittings.

The first method is to use the standard metric fitting from the stock hose and braze on a -10 AN fitting. This is the easiest and most straightforward method, but the downside is that the hose length is reduced, resulting in a tighter radius and more stress on the fitting. In addition, there is a longer effective lever on the fitting that could cause a problem. Here is how that strategy might look.



I rejected this solution, opting instead to modify the cooler to take a 90 degree fitting which is 1/2NPT on one end and -10 AN on the other.

It should be clear how much cleaner the 90 degree adapter is.



To use the 90 degree adapter, the cooler must be modified to take a 1/2NPT fitting. To do this it is necessary to cut off the old fitting and drill out the stock port to the size needed to tap for 1/2 NPT. This is easily done using a 3/4" step drill. (Note: do not attempt to use a standard twist drill for this operation as it will grab and likely damage the cooler) A common question is whether there is enough "meat" to handle the fitting. The answer is definitely yes - in fact the Mercedes repair kit for stripped fittings also calls for drilling out this fitting in the same manner and replacing it with a screw-in adapter.




Then carefully tap the fitting with a 1/2NPT tap



Test the fitting to make sure it fits properly



The next step is to modify the hard lines from the oil cooler. Just cut off the barb portion of the line and braze on -10 steel bungs. Note: I've removed the stock R4 Harrison compressor and bracket, so I've used a custom support bracket for the hard lines so this may be different from your own setup.



Then just make up the hoses...



...and install.



There is plenty of clearance



A question that occasionally comes up has to do with possible flow restriction using a 90 degree fitting. It turns out that the flow is actually quite low and any potential restriction is likely offset by the slightly larger -10 hose and fitting ID.

Making up AN hoses can be done with hand tools and is extremely simple.

There are countless links on the net for how to assemble braided steel hoses using AN fittings. Here is one to start with - How to Assemble Braided-steel Hoses

Sources for materials are numerous. I got mine by shopping on eBay, but hot rod shops, off road shops and other custom automotive suppliers are also good.

I don't have the expertise or tools to braze so I used a local radiator/air conditioning shop to do the brazing. It was very reasonable.

The beauty of using this system is that replacing a hose is a DIY job and there is no need to source new fittings as the fittings are designed to be reusable.

While this howto is focused on 617 MB engines the basic techniques should be able to be adapted to other engines as well.

Hope this helps for those contemplating a custom setup for oil cooler lines.

Originally Posted by mach4

Some people have eliminated the hard line altogether and gone with steel braided hose for the entire length.

Originally Posted by Matteo_300D

That's me!!! You will need (2) -10AN to M18 x1.5 adapters to screw into the oil filter housing(which is aluminum and has the same tendency to gall threads when removing the old fittings.)

I ran my lines over the motor mount arm, around the lift pump, and under the power steering pump using my klima kit oil line bracket and modifying my clamp to accommodate the larger hose diameter.

Originally Posted by Shern

Curious to see a photo of this