It's always disheartening when a star portfolio manager packs up and leaves a fund. But when he does so with no warning and no explanation, that really raises a few eyebrows. Such was the case with First Eagle fund manager Charles de Vaulx, who announced two weeks ago that he was stepping down from his post at four First Eagle funds (First Eagle Global, Gold, Overseas, and U.S. Value).

It would appear that his announcement even caught the funds' advisory firm, Arnhold and S. Bleichroeder, off guard. The firm has said it can offer no further insight into the reasons behind de Vaulx's hasty departure. Apparently no one even knows if de Vaulx, who is French, is still in the country or not. Now of course, it would be all too easy to imagine all kinds of Hollywood-style scenarios to explain de Vaulx's move -- running from the mob, recruited into a top-secret counter-terrorist organization, snatched up by aliens -- but the harder part is deciding what effect his departure has on the First Eagle Funds he leaves behind.

Out of retirement
After likely picking their jaws up off of the floor, officials at the advisory firm announced that the funds' former longtime manager, Jean-Marie Eveillard, will come out of retirement to run the four funds until a permanent replacement can be found. Eveillard served as portfolio manager for each of these funds from the time they started until December of 2004, when de Vaulx took over. While many no doubt welcome the return of Eveillard, he has made it clear that he's only stepping in temporarily, and won't stay more than two or three months on a full-time basis.

Three good funds ...
Under Eveillard's management (and to be fair, de Vaulx had been on board each of these funds as co-manager for several years before Eveillard retired), three of the funds have managed to amass pretty decent track records (Global, Gold, and Overseas). Unfortunately, these funds are closed to new investors, so the question becomes one of whether current fund holders should sell based on this recent management change. 

The problem with manager departures of any kind is that once a manager leaves, the fund's past performance, whether good or bad, likely matters  very little in predicting how the fund will perform in the future. In the case of the First Eagle Global, Gold, and Overseas funds, the funds' entire performance history was based on the stock-picking skills of Eveillard, and then de Vaulx. With both of these managers soon to be out of the picture, a brand new manager, likely an analyst or team of analysts at First Eagle, will need to step up and fill the void. And even if these individuals have a vast amount of experience, they likely don't have an established history of making portfolio management-level decisions for any of these funds, which means that you can pretty much kiss the funds' prior track records goodbye. I'm not saying a new manager couldn't do as well as or even better than Eveillard or de Vaulx: I'm just saying the funds' favorable performance shouldn't factor into whether or not investors decide to hold on to their shares once a new successor is named, because that performance doesn't mean much anymore.

... and one not so good fund
The one fund affected by de Vaulx's departure that is still open to new investors is the fund that Foolish investors should most avoid. The First Eagle U.S. Value fund has been around for a little more than five years, and employs the same value-oriented, all-cap approach as the Overseas and Global funds. Its top holdings include Costco (NASDAQ:COST), Blount International (NYSE:BLT), and Apache (NYSE:APA). The main fault I find here is that this fund routinely holds insane amounts of cash. Now, 36% of the fund's assets are sitting in cash. At one point in 2005, cash holdings made up almost half of fund assets! If you are paying a fund manager to invest your money in stocks, there is no reason why a third or more of your money should be parked in cash. You can do that on your own, minus the management fees.

Time to leave the nest
Ultimately, I think the time has come to kick these four First Eagle funds out of the nest. Unfortunately, investors have lost a good manager in de Vaulx, and once Eveillard heads back into retirement, they will (again) lose another. If any of these funds had been managed by a team instead of one single portfolio manager, investors could be more confident that the investment process would remain consistent. Alas, that is not the case. Knowing when to sell a fund is just as important as knowing when to buy one. And when your fund manager has made a sudden run for the door, there's a pretty good chance that the time to sell is now.

To learn more about how manager departures affect you, take a free look at the Fool's Champion Funds newsletter. Fool fund expert Shannon Zimmerman not only recommends funds but also tells you when it's time to say goodbye to them. Learn about the best mutual funds you can buy when you start your free 30-day trial today.

Fool contributor Amanda Kish lives in Rochester, N.Y., and thinks that if she can still hear the grinding noise made by her car, the radio isn't loud enough. Amanda does not own shares of any of the companies or funds mentioned here. Costco is a Stock Advisor pick. The Fool has a disclosure policy.