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  #1  
Old 11-22-2014, 02:10 PM
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Leak at Oil Cooler

I've searched around quite a bit and I did not see an answer to this question...

I've got a leak at the bottom hose, and I assume the threads are weak. Without researching matters, I lightly tightened the nut hoping to fix the problem and the k I made it slightly worse (didn't turn it more than a third of a flat). So I am anticipating having to replace the nipple, and I don't like the idea of threading in repair nipple without locking them in some how...

Question- could I have the repair nipple welded in after threaded in place? Or is there not the room to do this?

TIA

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  #2  
Old 11-22-2014, 02:20 PM
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If you're concerned about locking them in, just put a bead of JB Weld on the threads as you install them.

For my part, I went with AN fittings and stainless braid hose as a "permanent fix".
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  #3  
Old 11-22-2014, 02:24 PM
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I am pretty sure that is aluminum.... thus you are not the first to overtighten it...
Not sure what you mean by nipple.... you mean the hose connection ?
You are not likely to be able to address it without taking it out of the car... best to find a replacement.... but if out and cleaned properly... and a good solderer is available it can be fixed...but that is a lot of ifs..... and might cost more than a replacement one....
lately there was a thread about fixing aluminum ... there is some stuff which is pretty much magic... but cleanlyness is paramount on anything like this....
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  #4  
Old 11-22-2014, 03:21 PM
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The Hose Nuts do not seal on the Threads of the Oil Cooler. The sealing is done by the Rounded Hose Fitting Face on a sort of coneshaped face on the Oil Cooler Nipple.

Removing the Hose Nut often resuts in stripped threads on the Nipple.

If the threads get buggerd up the Nipple Threaded area can be sawed off and the Hole drilled and tapped for a Steel Repair Nipple; at least it is thaty way on the Turbo Diesls.
The Repair Nipples are the same Nipples the screw into the Oil Filter Housing.
The Details of that are found in the:
Repair Links
Fast navigation Fast navigation Do It Yourself Links

Some Members have complaind that the fittings on their New Hoses did not seal. Sometimes it has been the Aftermarket Hoses and sometimes it has been that the Oil Cooler Nipple is split/cracked.

The Oil Cooler Nipple threads could be welded but I don't see how someone could run a Die over them to re-thread them and keep the threads centered to the interior Hole on the Nipple. The Steel Repair Nipples seem to be the best answer if you are going to use the stock type Hoses.

Lots of suggestions for alternative Hoses in the Repair Links.

The normal place for the Oil to leak out of is from under the crimped Collar on the Hose. The Rubber under the crimped Collar srinks and causes a leak.

You could degrease the area with Brake Cleaner and determing exactly what is leaking.
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Old 11-22-2014, 03:55 PM
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I thought the OP was referencing the repair kit for stripped fittings on the oil cooler the MB sells.
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  #6  
Old 11-22-2014, 04:26 PM
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When I mentioned soldering I was assuming a crack at the base of the nipple... in the actual body of the cooler.... but that does not apply if the problem is out at the threads..
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  #7  
Old 11-22-2014, 05:19 PM
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I recently went through this. Sealing is accomplished by the close fit between the ball of the line and the mating part of the cooler. Threads do not aid in sealing unless you resort to JB Weld or similar.

The actual fitting on the oil cooler side can crack most likely because of over tightening &/or age (and over tightening). You need to get an up close look at the fitting while the hose is disconnected to be able to see the crack. This meant pulling the cooler for me.

There is an OE fitting available to repair the cooler. The process involves cutting the old fitting off, drilling and tapping the cooler for the replacement fitting. The drill bit and tap are odd sized and will cost ~ $30 - $40. You also need a drill press.

My press was stolen a while back so I had a local NAPA with a semblance of a machine shop attempt the tap. They screwed it up and I had to take it to a local fabricator who welded a bung on assembled, then welded the fitting on. I could have sourced a cooler cheaper and easier.

The part number & drill and tap size come up in Professor Google.
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  #8  
Old 11-22-2014, 05:25 PM
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Quote:
Originally Posted by mach4 View Post
I thought the OP was referencing the repair kit for stripped fittings on the oil cooler the MB sells.
It is not actually a Kit. It is just the same Nipple/Fitting that is used on the Oil Filter Housing. There is also a Crush Washer you need to order.

You need to scrounge up the Drill Bit and the Tap on your own. Sears and OSCH Hardware used to have the Tat for about $13 each. The Drill Bit with the reduced Shank so if fits a 3/8" Drill Motor Chuck can be pricey unless bought on eBay or some other internet site.

I have done this job on My Oil Cooler and to Me the Crush Washer is useless unless you drill the Hole Straight and then file the area you cut the Nipple off straight.

In My case the Hole did not go in straight even with the use of a Drill Press so the Crush Washer was not going to seal.

So I just tapped it, degreased the internal Threads on the Oil Cooler and the Threads on the Repair Nipiple and I used JB Weld Epoxy on the threads of the fitting that screw into the Oil Cooler itself.

I have had no issues with it.

Pic with the Part Number. Remember this is for a 617.952; not sure what other Models the will work on.
Attached Thumbnails
Leak at Oil Cooler-oil-cooler-nipples-package-part-number-nov-14.jpg  
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Last edited by Diesel911; 11-22-2014 at 05:36 PM.
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  #9  
Old 11-23-2014, 09:46 AM
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Thanks all for your contributions on this...

I can appreciate the JBWeld in between the hose and the cooler approach, but did not want to go that way if I could help it, not with engine oil, on something I may have to disconnect in the field. I am not happy with the crush washer idea, but I can appreciate that, and perhaps some JBWeld in between the nipple and the cooler? Steel to Aluminum welding is a no-go.

I'm pretty sure the leak is at the threads, but I Will clean it off as directed first. Should have been a bit more careful with this on the first go-round; Mercedes and its' intricacies, woooohoooo!
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Old 11-23-2014, 10:48 AM
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Quote:
Originally Posted by fahrvergnugen View Post
Thanks all for your contributions on this...

I can appreciate the JBWeld in between the hose and the cooler approach, but did not want to go that way if I could help it, not with engine oil, on something I may have to disconnect in the field. I am not happy with the crush washer idea, but I can appreciate that, and perhaps some JBWeld in between the nipple and the cooler? Steel to Aluminum welding is a no-go.

I'm pretty sure the leak is at the threads, but I Will clean it off as directed first. Should have been a bit more careful with this on the first go-round; Mercedes and its' intricacies, woooohoooo!
JB Weld is a steel reinforced epoxy so "welding" steel and aluminum is no problem. But it would be a huge mistake to put JB Weld on the nipple. When I brought up JB Weld originally, it was with my understanding that you were planning on using the MB fix for stripped cooler threads which involves drilling out the old fitting and drilling and tapping for a replacement one. JB Weld on those threads to provide sealing and preventing the fitting from backing out would be appropriate.

Do it right. Either get a new cooler, do the MB fix or replace the fittings on both ends and use aircraft grade AN fittings.

Just my opinion, I'm sure others will chime in with others.
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  #11  
Old 11-23-2014, 11:04 AM
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Mach4, you and I are on the same page. I will probably also go to a local PAP and get another cooler and install it so I can drive it without delay.
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  #12  
Old 11-23-2014, 11:57 AM
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Quote:
Originally Posted by fahrvergnugen View Post
..... Steel to Aluminum welding is a no go ......
Used to be a hard and fast rule... but welding industry is really amazing... not for this project...just FYI....

https://www.youtube.com/watch?v=YEQ0dL4R-rQ
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  #13  
Old 11-23-2014, 12:36 PM
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When I was at the Junk Yard I was able to remove 2 out of 6 Oil Coolers with out stripping the threads.

That means one of the Oil Cooler Nipples stripped on 4 of the Oil Coolers I attemted to remove.

If you find that happening at the Junk Yard while you are there you can remove 2 of the Oil Cooler Line Fittings from the Oil Filter Housing and you will have 2 Repair Nipples to repair your original Oil Cooler.

If you buy the Repair Nipple from Mercedes they are agout $11 each (that was about 4 Years ago).
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  #14  
Old 11-23-2014, 01:16 PM
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Quote:
Originally Posted by Diesel911 View Post
When I was at the Junk Yard I was able to remove 2 out of 6 Oil Coolers with out stripping the threads. That means one of the Oil Cooler Nipples stripped on 4 of the Oil Coolers I attemted to remove.
I've never encountered any stripped threads on any oil cooler connection - I've always assumed this was a rust belt phenomena...apparently not.

When I did my conversion to AN fittings I was able to use Teflon tape to prevent any dissimilar metal corrosion at that point.
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  #15  
Old 11-24-2014, 12:00 AM
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Quote:
Originally Posted by mach4 View Post
I've never encountered any stripped threads on any oil cooler connection - I've always assumed this was a rust belt phenomena...apparently not.

When I did my conversion to AN fittings I was able to use Teflon tape to prevent any dissimilar metal corrosion at that point.
I thought that while I am at the Junk Yard looking for Parts for My own Vehicles I might as well pull some Oil Coolers off to sell later. As I said 2 out of 6 came off with out stripping the Nipples.

As a side Story I had stripped like 3 threads off the Upper Nipple on the Oil Cooler on My own Car. And, I had done like one of the other members suggested and put it on with JB Weld.
It worked fine.

Since I decided to change the Hoses I thought I would use one of the good Oil Coolers I got at the Junk Yard to speed up the Job. Good idea except that I forgot where I put the Junk Yard Oil Coolers.

So, I ended up having do the Steel Repair Nipples. Fortunately I had many years ago bought the Drill, Tap and Nipples to do the Job so I did not have to wait on Parts.

Of course 2 weeks after the Oil Cooler was repaired I found the Junk Yard Oil Coolers while I was looking for somethng else.

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