I need some help here. I just finished installing my new 351W and ran it for 20 minutes last night doing the cam break in suggested by Comp Cams. That went smooth, no problems other than my old radiator hoses were leaking. Today, changed the oil, installed new ignition coil, new radiator hoses and refilled the radiator. Went out to take it for a test drive and try to seat the piston rings. Made it 100 feet and realized I had lost transmission fluid and stopped to add fluid. Still didn't feel right (I knew I'd lost some fluid due to a leaky trans. pan gasket) so we headed to the conveinence store to get more trans fluid. Store was no more than 1 mile away, so drove there, got the fluid and decided to head back so I could consult the manual and be sure to check the level properly. On the way back it smelled like something was getting hot. Kinda figured with a new engine, new exhaust, fresh paint on everything a little odor wasn't too bad and we were only going another half mile. When we parked it we shut it off and my buddy popped the hood release and I walked up front and saw flames!!! Got the hood up and saw it was my alternator. Got the flames out, which were mainly coming from the wire connector nearest the bottom on the alternator. After calming down realized I also had a pretty bad coolant leak up on the fitting on top of the lower intake just behind the thermostat housing/outlet. So, any guesses why the heck my alternator caught fire? I can't think of anything that is wired wrong. The only wiring done was unplugging and replugging all the connectors. No new wiring or anything. My only idea is maybe the coolant was spraying on the alternator and caused it to short out somehow. I am sort of at a loss here. We also realized that before running it last night we didn't add coolant to the block, just filled up the radiator. I was worried that maybe without coolant in the block reaching the thermostat it wouldn't open up and take the fluid from the radiator. But, we did run it last night for 20 minutes at 2000 RPM with no problem. It got nice and warm but not more than I would've expected. Right up to the "L" in the Normal on the gauge. But then again, without coolant reaching the temperature sensor is that reading accurate? I put alot of time and effort into this motor, and needless to say right now I am pretty discouraged. Any help is greatly appreciated! Sorry this is so long, BTW. Truck details are in my sig. --Eric

 

WEIRD!

Only things I can think of are:

1) alternator wired up wrong somehow
2) new ingnition module overloaded the electrical system and fried the alt.

I don't think that spray from the rad. hose would short it out to catch fire for one reason- coolant is mostly water and the spray would probably put enough liquid as to not allow a spark. Could happen, but unlikely. I had a leak from the throttle body line just recently and it sprayed everywhere including the alternator. No problems, just coolant everywhere.

Double check the wiring and don't get discouraged.

 

yeah, good point about the coolant on the alternator. Be hard to catch fire if it was being soaked with coolant. I guess I will recheck the wiring, but it bothers me that it didn't do it last night, and last night it ran longer and at higher RPM's. Last night I used my buddies ignition coil off his 302 to 351 conversion project. His is one of the high performance ones. I really don't get it. I think I need a few days off or my head is just going to explode. really got excited to take it out for a drive today and now this.....uugghhhh. Anyway, thanks for the input.

 

Whoops, when I said ignition module I meant an igntion coil. Sorry, I'll go back and edit my post to avoid any confusion.

 

The Ford alternators of this era are know to catch fire at the three wire connector. The current is divided among two of those wires, and over time the conector gets loose. Many times, unplugging it just once and then reconnecting it causes failure of the connection. Temperature builds up inside that plastic snap in connector and catches it on fire. I think Ford now recommends to replace this connector (meaning cut and solder a new end on) every time it is removed. It isn't hard to do - now that you know. You'll end up replacing all of the affected parts due to fire damage, but keep this inherent weakness in mind. Reman alternators for your truck should come with some special grease loaded into the wiring receptacle - it's gooey, and it helps to maintain a good connection. Wiring ends are available pretty cheap at Ford - hope it didn't roast anything else!! Let me know if you need more info. I applied these measures when I rebuilt the alternator in my Bronco, and it's been good ever since.

 

Holy Cow, thanks Cheggie! Wish I had known that before! Luckily enough I think we caught it quick enough to minimize damages. Mainly just the alternator and connector. melted some chaffing material on another wire harness so come daylight I'm going to check it (and everything else) REAL well. Man, I was sure I had some serious issues going on. Looking back, my connector was in sort of sorry shape. Hind sight is 20/20 isn't it? Oh well, another lesson learned. Sure hope things go better my next go around. thanks again! --Eric

 

What Cheggie said.
I replaced the alternator on my 88 ranger some time ago it came with a red Warning label. Basically said if any corrosoin is on connector it will catch fire not might WILL. New alternator had plug socket in loaded with dialectric grease and another warning label over socket.
SORRY ABOUT YOUR LUCK ,sucks when we things the hard way.
By the way what cam are you running . Let us know when it's running well.