Phenolic smell

[DonaldSmith]

Today I took the 47 DeSoto Suburban to the Orphan Car Show and back, 40 miles each way, mostly steady speeds, up to 60 mph. The car started and ran well enough for the most part.   At various times we could detect a strong burnt phenolic smell coming from the engine compartment. 

(Phenolic products are like Formica plastic laminate or circuit boards.  The don't melt.  They char.)

Possible sources? 

Alternator internal circuit board. 

Transmission relay circuit board.   

Junction board that I added? (It's molded plastic, with screws each side of the junction bars.  No hot screws.)   

 

Any experiences with alternator circuit boards charring? What else could cause a strong burning phenolic smell?

[JerseyHarold]

Starter relay?

[DonaldSmith]

The starter relay is only powered when cranking the starter.  However, the one post of the solenoid carries the main current from the battery to points downstream.  I'll check it, although I sensed no loss of current to anything.   No problem cranking the starter. 

[Dan Hiebert]

Last time that happened to one of our cars it was the "usual suspect", poor ground on the generator that was causing the generator to overheat.  I would suspect the newest electrical item you've added, and the old broken record of check connections, especially on newly added items.

[DonaldSmith]

What does epoxy smell like when it gets too hot?

 

Almost twenty years ago, with the manifolds removed, I had a hard time separating them, because the four bolts that connected them had rusted in place.  Areas of the intake manifold that covered the bolts had broken away, probably from the expansion of the rusty bolts.  I patched the areas with epoxy, probably JB Weld.  No problem for years.    

 

Last Fall I removed the manifolds again, since I suspected the exhaust was leaking.  I re-patched the old epoxy areas.   (Incidentally, I found one hole in the block that had little usable thread left, so have no confidence that the bolt there is tight.)   Since repairing the manifolds last Fall, I hadn't gone any distance until the car show last Sunday, a forty-mile trip each way.  Maybe finally the manifold got hot enough to fry the epoxy.  I'll see this Fall.  

 

This Fall, I'm removing the manifolds again, to check for exhaust leaks at the gaskets,  to Helicoil the bad hole in the block, and to use the proper conical washers and brass nuts, once the manifolds are out of the way, I'll cold-set the valves.  (My back won't let me adjust the valves from the wheel well.)  I'll check he condition of the epoxy patches.  (Maybe I'll be sure to use high temp epoxy, if  I use it at all.)