We worked on the Mercedes 280 SE, and I found an assembly error that should have been designed out! While reassembling the radiator system (it has two radiators) my Son cross threaded an aluminum fitting. I told him that he should be More careful on reassembly.
The damaged part is welded on to an aluminum sub radiator used to cool engine oil. It is a 22 by 1.5 metric thread, and they want $1068.00 for a replacement part! We found one online for $200, but it looked the same as the one we had.
Time for Dad to get involved:
This is the be sub-radiator commection involved, along with a new threading die to fit. I bought the die because I didn't want to single point a new metric part this big on my engine lathe.
The first step was to clean the old fitting to see if it can be salvaged. This is where I found the design / assembly error! This fitting had to be aluminum in order to weld to the aluminum sub-radiator. This causes a specific risk that should have special treatment. Aluminum is a soft metal, so it should be hard anodized; once it has need welded on.
The second issue is that the threads MUST be perpendicular to the surface of the sub-radiator! These are Not, and That is why my Son cross threaded this part. It was welded at about a ten degree angle off square, on a direction that is impossible to observe!
This, combined with a steel hose fitting; guarantees this problem must occur!
The threads cleaned up:
This made the die a very good purchase! I threaded this myself because of the offset from the factory. We ended up with a 95% thread, which was more than enough; since the seal is on the inside.
I had the brass located for the replacement part, but we got lucky; and got good cleanup!
This assembly has been repaired before:
In the past, a good mechanic had this unit off, and repaired it properly on this drain hole. Since it is alinum, this smaller hole, that shows up in the first picture on the lower right; has been repaired with a helicoil! You can see the trailing edge of the helicoil insert here.
With the touted quality of Mercedes-Benz,this sub-radiator should have been copper! This was designed badly and assembled poorly, which is unusual for a Mercedes-Benz design!!!!
We had the same problem reassembling this system; but I told him no wrenches, and it must be fully tightened first by hand. I ended up doing this part myself, because I knew the incorrect angle on the assembly! It screwed all the way to the bottom, then I torqued it about a third turn for final sealing.
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Thanks for the curation! I'm glad you likedy post.
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Those helicoils are very useful indeed, for the other fitting I would have used a rubber hose with a hose clamp and clamped it down after the thread and joined the two hoses with an adapter to match.
Sadly, there was little space there, or the hose could work. I bought a new steel fitting, planning to tap the I.D. on the damaged part; but it was too close. I would need to cut away most of the existing part; then tap it, to add the brass piece I was making.
I was relieved when the tap cleaned it up so well!
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You have to take half the engine compartment out, to get to the oil filter..
My Brother had a 69 GTO that had that problem. We cut an access hatch in the wheel well; remove the tire and hatch, and the rest was easy.
Big engine, nice old car!
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Have you seen or heard of the kit cars from England, the Ultima GTR, poor man's fastest, most agile and best breaking car, while holding the most g's before sliding in turns, ever?
https://en.m.wikipedia.org/wiki/Ultima_GTR
No,but I'll look at it. I bought plans for a Doran 3 wheeled car, and have been collecting parts for it.
I plan to run it electrically, and I'd like to use vanadium redox batteries.
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What's the point of two radiators? Some kind of redundancy? It hardly seems appreciate that should one fail that other can keep up, maybe if that little one failed but then you'll have to shut off both in and out so it doesn't lose all water.
This small one is an oil intercooler, they just bolt together. On my Porches to they run some tubing into the radiator fluid, then run the oil through that to cool it. I'm not sure the pressure on this one, but the Porche runs about 80 pounds. This one would likely be lower.
We're getting close, she will be back on the road soon! This rebuild from the under hood fire has taken 3 years
We had to totally rebuild the wiring harness, one wire at a time. All the injectors are new, and the fuel rail came direct from Germany! But it's all 100% now, and brand new.
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Duh, the oil that is cooled by the engine block?