The Stovebolt Site Forums The Shop Area General Truck Talk Old gas and bent valves

Ezekiel's thread made me think about something. I am taking out the tank in the cab of my old C-30 and going to a saddle tank. The old tank had so much gunk in it that it plugged up my fuel filter and carb every time I tried to run the truck and the engine would overheat (from running too lean when the filter was plugging up?) Anyhow, because of this problem it has been sitting in my driveway for 2 years now. Is there a chance my intake valves could be 'glued' shut? Should I drizzle a small amount of kerosene or diesel into the intake manifold and let it set a few days before I turn it over?
David :confused:

Oly Kutznsandz,

I'm not a big believer in 'varnish' but some folks are. I think your valves would be just fine. If your engine is having heating problems, I would suspect the radiator long before I ever thought of a lean fuel condition. I'm not sure a automotive engine could run lean enough to increase its operating temperature.


Stuart

Yes, an engine can lean out enough to overheat, but only under full-throttle, max load conditions, like pulling a heavy load uphill, with a vacuum leak, a partially restricted fuel passage, etc. It won't happen at idle, even with late ignition timing.

I'd suggest getting a can of Kroil from Kano Laboratories in Nashville, Tennessee, and give all the valve guides a good squirt from the top side, through the valve springs. If there's any varnish buildup, the Kroil will loosen it in a matter of a couple of hours. Adding a little to the crankcase oil won't hurt, especially if you run a few miles, then change the oil and filter.

www.kanolabs.com

Jerry

I've been wondering for years where I could get Kroil!!!! We used it a LOT in the plywood mills for loosening frozen bolts, etc. in the veneer dryers. BEST stuff I have ever seen! Thanks!

Oh, btw...the overheating was on a very hot August afternoon, coming home from a cabinet installation job. I had just got the truck running again after putting yet another fuel filter in and putting another kit in the carb. I think this was either the third or fourth time I had to clean out the carb in about a month or so. The truck has been sitting ever since. It was under full throttle as that was the only way I could keep it running for a few yards. Then it would die and I would have to wait a few minutes to try starting it again. I litterally came home 50 yards at a time this way. It took me over 3 hours to go less than a mile. The truck was not the only thing overheating!!!!
David :mad:

I am a HUGE believer in varnish for good reason. I bent this intake pushrod plus one more and when I got the head off the other four intake valves had to be driven out too. All from varnish. Do as you wish but the only safe way to procede is to pull your head, pull, clean & lap the valves. I tried all of the quick fixes of dribbleing stuff on the valve guides but it didn't work. I had to pull the head anyway. Do what you think is best but don't be surprised if you take the shortcut and bend pushrods.

I've never bent pushrods, but I did have some valve sticking problems. My '59 F-350 had sat for about 10 years, with a nearly full tank of gas. When I first got it going, it ran like a swiss watch. But after it sat for a week or so, the next time I started it, it missed, and ran like crap. Turned out, my valve had stuck open. This happened a couple times, before I finally replaced the tank. The old one had so much gunk in it, it never would have come clean.

You can straighten push rods. I BROKE several rocker arms. Best thing I have done was to use wd40 and a tiny little brush and scrub the valves as good as you can, keep turning over the engine and scrubbing and spraying and tapping the valves softly with a hammer all the while. Its a pretty long process but it was easier then pulling the head which I might have done if I had easier access, the coe does NOT have good access! I also flushed the engine with a few gallons of diesel before running it.

Jeff

I am now a firm believer in varnish. I ran my GMC 248 engine on 30 year old gas and it ran like a top for about an hour. I shut it off and let it sit for a few days, when I tried to start it again, it made some LOUD bangs and missed like crazy. I bent 4 push rods and stuck 4 valves. I ended up pulling the head and having a valve job done. It was a good $200.00+ lesson, $95.00 for a gasket set and $120.00 for the valve job (included new guides). I bought a new gas tank and replaced all the lines before starting it again. Don't believe the guys that say there is no problem with old gas, there is! Don't take a chance, drain it out!

I am in the process right now of installing a new aluminum saddle tank and the one behind the seats is going to the wrecking yard. I'm not even going to try to clean it out.
David