'97 3.0 Vulcan 172k: Coolant Loss and #1 Plug Connection?

[Colt Hero]

I've been losing coolant now for a couple years or so (and re-filling the degas bottle as necessary). It doesn't appear that the bottle is leaking and there are no hose leaks or signs of coolant spraying anywhere inside the engine compartment. When I get home from work, pull into the driveway, and turn off the engine, however, I almost always smell a whiff of coolant in the air as I close the driver's door and walk toward the house. Meanwhile, I've had to replace the #1 spark plug twice in the last 24 months or so (while the others are still the factory originals ... I know, I shouldn't have left them in there that long).

Is there a connection between these two things? Does this engine have any history of gasket failure around the #1 spark plug? I think I'm headed for another #1 spark plug pretty soon because the idle is a little rough, and although once I get going things SEEM to work reasonably well, I CAN see the Tach bobbing a bit and the ride is a bit rough on the highway (partly because of the front-end vibration, but also - I think - because the engine might be missing here and there).

There's no white smoke out the back that I can see. I'm thinking I've got some kind of gasket leak, but it's a VERY slow one. I'm guessing I fill the degas bottle up about every 3 months or so (right now).

[JohnT396]

I had a coolant loss that eluded me for a long time. I could find no signs of a leak under the car or in the engine compartment. Where I finally found the problem was under the intake manifold there is a metal tube that simply carries coolant under it. It connects to hoses on both ends. Why it's routed underneath, I have no idea. I ended up taking the manifold off thinking there was more to it, but that's not the case. I simply substituted a hose and ran it over/around the manifold. So I had a small leak that dripped on the hot engine and evaporated leaving no visable signs. Good luck.........

[Colt Hero]

JohnT396:

So If I have this problem, I should be able to replace the pipe from underneath without removing the intake manifold (Upper, I presume you're talking about)?

I'll have to remember to take a look at this possibility during my next oil change. I'll get the engine up to temperature, then get underneath (with eye protection, don't worry..) and scope it out.

Thanks!

[JohnT396]

By the time I figured out where the problem was, I had already removed the manifold. What you can do is run a section of heater hose from the back connection on the overflow tank to the connector that comes out of the engine right by the throttle linkage. You will find it on the right side of the manifold in between the linkage and the distributor module. That will bypass the metal section of pipe that goes under the manifold. At least you will be able to see if that is where your leak is...