My Vehicle: 2000 Saturn SL2 Complaint: Leaking coolant from... Somewhere... Diagnosis: Pressure tested the system and preformed a visual inspection while the system was under pressure. I found coolant leaking from a crack in a plastic heater hose connection that is part of the intake on this vehicle. A new intake would be about $300 so I was wondering if there was a way to fix the plastic rather than buying a whole new part. I tried to use JB Weld to repair the crack and it passed the pressure test, but I drove it about 20 miles and it started to leak along that seam again. Why did the JB Weld not work? Did I not clean the surface good enough? Did it get too hot? I did some research and found that the original JB Weld will not bond to Polypropylene plastic, or Polyethylene plastic. So, my next question was “what is this intake made of?” After more research I came across a thread on a Saturn forum talking about the type of plastic the intake was made out of. There was lots of speculation but no real facts to back it up so I decided to do some more research. Here is a summary of the information I found: If you look in the service manual under throttle body assembly and description, there is a note that says "Use a shop towel and carburetor cleaner that does not contain methyl ethyl ketone." If you look up "Chemical resistance of Poly Propylene (PP) to some common acids, bases, organic substances and solvents" at engineeringtoolbox.com, it lists Methyl ethyl ketone as being unacceptable as a cleaner because it damages parts made from polypropylene. Another document from Spilltech.com lists Methyl ethyl ketone as being unacceptable for storage in a polyethylene container. "Products may be suitable for intermittent contact; however, some deterioration in properties may occur." There is also an ASE technical paper that was published in December of 1999 talking about the "new" process at the time of using nylon 6,6 as an air intake manifold. So, during the Saturn SL years (1999-2001) the nylon intake was still a new process, and I doubt they would use a new process on a low-end commuter car. So, from my research about chemical properties and warnings about cleaners and manufacturing technology available at the time, I would conclude that the intake is made from polypropylene or polyethylene. There is also the fact that the JB Weld didn’t work on it. When working with chemical bonding materials, it is important to know what the materials you are bonding are made of and the capabilities of the bonding agent you are using. So how did I fix the problem? Dorman has a solution: https://www.youtube.com/watch?v=blgRq_BXv8s The two pictures above are screenshots from the Dorman video.
I ordered the Dorman water pipe kit from Amazon and the intake gaskets and went ahead and removed the intake, cut off the plastic water pipe, and installed the metal one. It really wasn’t too bad to do. The YouTube video from Dorman that explains step by step how to do it. The hard part was test fitting the intake on the head with the new water pipe in place to make sure I had cut enough off to clear it without cutting through the intake gasket part. Here’s a tip: when removing the intake, take out all the studs except the lower outer one on the driver’s side and last one on the passenger side; this will let you take the intake on and off more easily while you are test fitting. If you just take your time and make sure you don’t cut the space for the intake gasket or cut into the intake runner, you will be just fine. When you remove the intake, there is an extra bolt hole that is revealed under the intake. Watch the video and you will see it. Also, there is no torque spec that I could find for the new pipe so I just torqued it to about 15-20 ft lbs, which is a typical torque for that size of nut and stud. I’ve been driving it for a year or so now with no problems from that part. I think I paid about $70-80 for the pipe kit, intake gasket and throttle body gasket on Amazon. Took me about 3 hours total to do the repair and saved about $200. My takeaways from this experience: Chemistry is cool. When working with chemical bonding materials, it is important to know what the materials you are bonding are made of and the capabilities of the bonding agent you are using.
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AuthorWalker Crystal Archives
May 2019
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