Siezed Alternator Mounting Bolt

[rbhollabaugh]

The steel bolt that mounts the alternator on my car is rusted into the aluminum mount on the trans.
This alternator has a front and back mounting tab. The bolt goes thru the front tab then thru about 1.5 inches of aluminum hollow tube on the trans and then into the alternator back tab.
The bolt has corroded itself into the aluminum "tube".
I've tried tons of penetrating oil and some gentle heat from a torch.
It won't budge.
Any ideas?

Thanks,
Rich

[Mike_Dumond]

Prayer might help [img]/forums/images/icons/grin.gif[/img]

Seriously, you sound like you got a real problem there. Try tapping on the end of the bolt while heating it. Might be enough to break free of the threads. But, chances are, the threads will get messed up some. Have a tap set ready to increase it to the next larger size, just in case the threads let go. You might also check into heli coils if the threads mess up.

[Al_Wa]

I think you have Galvanic Corrosion and the steel and the Aluminum have become one. The alternator return current flows thru the alternator frame to the engine/transmission and back to the battery. You might try a "rust desolver" that is safe on aluminum or CLR.

[Autotech]

What kind of car is this? You said the alternator is mounted to the transmission? Are you replacing the alternator or rebuilding it? If replacing, how much was the "core" charge on the replacement?

Gregg

[rbhollabaugh]

The car is a Citroen. Made in France. All the accesories are run off the camshaft (pushrod type). The camshaft goes thru the bell housing and the accessories and belts are over the bell housing and trans. The engine is transverse mounted like most front drive cars. One of the accesories is the alternator. I think a previous reply about galvanic action and the steeel/aluminum corrosion is a prime suspect.
I was a Citroen mechanic for 10 years but never saw this type of corrosion so bad.
Since the alternator has not gone bad yet, there is no hurry. I was replacing the alternator as it has over 200K miles on it.
The Citroen alternators are available but I have always used Volvo or Mazda alternators because they are more reliable and mount with very little modification (and they are $10+$5 core charge at the local junk yard).
I'll just keep dousing it with penetrating oil and hit it with a little heat from time to time.

Rich

[Bird]

Rich, does anyone still sell the Citroen in the USA? They were amazing autos years ago, but the last time I was even in one was in July, 1972.

[rbhollabaugh]

Citroen pulled out in 1972 and 1973 from the US market. You probably saw a DS model. DS production ran from 1955 to 1975. I still have a couple of them but I drive the CX. CX production ran from 1975 to 1990. I have two 1986 CXs. They were brought in as grey market vehicles. Someone prior to me did the red tape and conversions to meet US specs. So, by the time they needed repairs that stumped the local garage, I bought them for a reasonable amount.

[Bird]

Rich, the only ones I recall ever seeing were 4 door sedans; don't remember model names or numbers at all. I just took one for a test drive in the early 60s at a dealership in Dallas; used to see them on the streets here quite commonly. Then in '72, I was visiting in Alaska; don't even remember exactly where we were, but left my truck and travel trailer on the side of the road where the pavement ended and went up a little mountain with my brother in his Olds and on the way back down a Jeep pickup came around a blind curve on the wrong side of the road and hit us head-on. No serious injuries, but the first car to come along was a Citroen and they took me down to my truck, I unhooked the trailer, and went back to the first sign of civilization and called for a state trooper. The thing I remember most about Citroen was an incredibly smooth ride, even on a rough dirt and gravel road.

[rbhollabaugh]

It's the smoooth ride and the carrying capacity of the station wagon that I love about these cars.
Now, if I could just get that darn bolt out.

[Autotech]

Well...of all the answers I anticipated, Citroen was definitely NOT one of them!
I agree with the refit method you are using - later model Nippondenso stuff is cheap, plentiful, and most importantly, dependable.
Since you plan to discard the original alternator an alternative you can use is to cut the mounting ears of the alternator, then cut the portions of the bolt and ears still attatched, etc. This way you can work down to the point that all you have remaining is the mounting boss with the section of bolt seized in it. At that point judicious use of heat, and a large hammer with a drift punch should do the trick. I'm unfamilier with the particulars of Citroen assembly, so I'm guessing that you'll have sufficient room to work.
However, since you don't seem to be under duress to remove the unit, your soaking method seems best for now. I would also leave the mounting bolt loose to allow vibration to help your cause along (if you're concerned about parts falling off you can loosen the nut, then double nut it in the loosened position). Its kinda like leaving the keys in a car for the towtruck driver - it won't run anyway!

Gregg