Here's another example of how investing 25 bucks to become a supporting member of this forum can save you a small fortune. During my last oil change, I noticed there was a quite rusty metal tube beneath the oil pan near the harmonic balancer of my 4100. It's actually two tubes, joined by a 2 inch piece of rubber heater hose. I'd seen it on a diagram in the cooling section of the shop manual, but there was no description of it.

Illumina identified it as the coolant distribution tube. It runs coolant from the water pump to the heater core and other points on the firewall side of the engine. At first I thought this was a crappy design for the 4.X series engines. A steel tube carrying coolant, joined by a rubber hose, right where the average owner will never look, and all the road salt and crap can eat away at it?? My opinon has softened a bit since then.

Anyway, here's how that tube junction looked on my car:

http://i39.photobucket.com/albums/e152/mindstage/Rusty.jpg

I'd encourage you to inspect yours too. If you live north of Kentucky, it probably looks about the same. How you repair it will vary depending on how badly rusted it is. Mine looked awful, but actually there was a lot of solid metal left under there. I drained the coolant from the rad, then cut away the old hose and drained the tube. The tube halves are only about 1/2 inch apart. The front section joins directly into the engine, so try not to mess with that. The rear section is held by two brackets, one near the top and one near the bottom. Both are a bitch to get to, but the upper one is less so, so I loosened it enough to twist the tube for better access.

Both sides of the metal tube were coated at the factory with a heavy enamel paint, most of which had chipped off mine. I packed both open ends with shop towels, then scraped off the worst of the rust with a wire brush, cleaned it up with a Dremel tool, then sanded it smooth. Finished with three heavy coats of Rustoleum paint, it looked almost new again.

http://i39.photobucket.com/albums/e152/mindstage/CleanedandPainted.jpg


To rejoin the tubes, I took a suggestion from Huf and Illumina and put in a longer piece of rubber; in this case, a 5 inch section that will cover and protect most of the exposed area of the metal tube. I also invested in Gates best engineered heater hose (7 bucks a foot!) because I don't want to have to do this job twice. I put WD-40 on both ends of the tube to ease sliding this very heavy hose on. To finish it off, I used 4 hose clamps, two inside to prevent coolant from leaking out, and two outside to keep moisture and road crud from leaking in.

http://i39.photobucket.com/albums/e152/mindstage/4Clamps2.jpg

So for 10 bucks and some bloody knuckles, I was able to do a repair that a shop would have charged me $75 to do, or $250 at a Cadillac dealer. Thanks Huf and Illumina, and thanks Cadillac Forums!

Yes sir! You have the exact idea on that; it's always best to just put the aforementioned length of hose down there and not worry about it. Good job :thumbsup:

Here is mine: :) They were really bad (see the picture). I hed to replace one of pipes and cut off the second. All the corrosion was external. Since the pressure is not high, I would cut off as much of rusted pipe as possible and use even longer 3/4'' heater hose. It will hold very well. There are long heater hoses in the system running from heater valve ( the plastic T) to the heater core and engine.

ah, good to know. the return line went on my car and the shop charged me 100 bucks to fix it. but they fixed it. not bad for a shop considering it was a half hour of labour and 8 litres of coolant

I've got a little rust there too. But i'm not gonna care until i have a problem(s) with it. My dad's 87 had 318,000km's on it, and never 1 problem period!