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Brand New Clutch Master Cylinder Leaking


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So, I thought I had the new CMC working...

 

But when I got to work the other day, I lost the clutch as I pulled in the parking lot.

 

It appears to be leaking fluid out of the connector to the hydraulic line.

 

Was there a gasket I was supposed to put in? The old CMC didn't have one, and the new one didn't come with one.

 

I've got the hydraulic line on there as tight as I can, to the point that the connector started getting rounded off at the edges.

 

Any thoughts what went wrong?

 

My thoughts are:

 

1) Problem with the hydraulic line (Unlikely, as it wasn't leaking there before I replaced the CMC, the leak was inside the cab)

 

2) Missing a gasket (If it was missing the gasket, then the old one was as well)

 

3) Problem with the new CMC (I looked at the connector prior to install, and it looked identical to the old one)

 

4) Not getting the hydraulic line tight enough (I've got it so tight that any further pressure on the connector results in the connector starting to get rounded off)

 

 

Just for my reference, what size wrench is the hydraulic line connector supposed to need? I believe I ended up using a 7/16" wrench, but I don't recall.

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Not sure about the size of the nut on the fitting, but I try and make it a point to never put a regular wrench on a flare nut. There are special flare nut wrench sets for these. Lots of places a good set can be used, clutch and brake lines, fuel lines and filters etc. I bought a Craftsman set of six, had the most basic metric and SAE sizes.

I would try to fix by tightening with the proper wrench. You are sure that it is not somehow cross threaded? If that is a no go, then take the line back off, inspect and reinstall. If that still doesn't fix it, I'd claim a defective part, request a replacement.

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Not sure about the size of the nut on the fitting, but I try and make it a point to never put a regular wrench on a flare nut. There are special flare nut wrench sets for these. Lots of places a good set can be used, clutch and brake lines, fuel lines and filters etc. I bought a Craftsman set of six, had the most basic metric and SAE sizes.

 

Sigh. Thats what I get for listening to the guy at the auto parts store. I specifically asked "Are there any other parts I need, or any special tools?". He told me no. :wall:

 

I would try to fix by tightening with the proper wrench. You are sure that it is not somehow cross threaded? If that is a no go, then take the line back off, inspect and reinstall. If that still doesn't fix it, I'd claim a defective part, request a replacement.

 

I've removed the line several times and re-inserted, just in case it was cross-threaded. I'm pretty certain its not cross-threaded.

 

the old line is flared on the end. it's possible that the flare is bad.

I'm leaning towards this probably being the case. It's most likely the original line.

 

At this point I think my best bet is to take it to the mechanic my father-in-law has work on all of his vehicles. He's got decent labor rates, and is honest. He'll be able to tell me if the CMC is defective, or if I need a new line.

 

Thanks guys! :cheers:

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I agree with 64 Cheyenne about the flare nut wrench.....flare nuts are notoriously difficult to properly tighten with a regular open-end wrench, and impossible with an adjustable. It takes a lot of torque to tighten a flare to withstand the pressure of hydraulic systems. Whatever you end up deciding has caused your leak, when you finally put it all together again, use an appropriately sized flare nut wrench. Anything else will round the nut before you can get it tight enough.

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