Shaun McRae told Boots 'n' All that Castleford should snub Stuart Raper's offer of taking over on a short-term basis and instead look to appoint a permanent coach.
The Tigers have been without a boss since the sacking of Ian Millward earlier this month and have placed recently-retired Danny Orr in temporary charge until a successor can be found.
Chief executive Steve Gill is apparently considering an offer from Raper, who coached the club between 1997 and 2001, to return and assist the caretaker coach until the end of the season or until a full-time replacement is found.
But Hull director of rugby McRae says they need a permanent appointment to work above Orr and bring some stability to the troubled club.
He told Boots 'n' All: "That buys you time and allows you to mentor Danny, but I still don't think Orr is ready this year - and he won't be ready next year.
"He needs to do an apprenticeship under someone for three or four seasons, maybe even five, and he's already come out and said that so he accepts it.
"The only thing with Raper is it buys you time to look around for a coach, but I would be inclined to try to get somebody in immediately on a long-term basis.
"I really like Raper and what he could offer, but I think you're only sugar-coating the problem.
"I think you need to get somebody in immediately because that gives some stability through the organisation."
Castleford have just appointed their third CEO of the last 12 months and with uncertainty over their financial plight and a proposed stadium move still hanging over them, the club may not be an attractive proposition for many coaches.
Key players such as Rangi Chase and Daryl Clark have been linked with moves and McRae said potential candidates, such as Featherstone Rovers chief Daryl Powell, would need to think twice before jumping into the hotseat.
"There's a lot of questions that need to be asked at Castleford," he added. "One of those is the thing about Stuart Raper coming in, but if you've been approached to be the coach you would surely have a page full of questions.
"You want to know about the future, you want to know about the ground, you want to know about security. Are the wages going to be paid?
"I'm only hearing things like everyone else is, but if Chase is leaving then why is he leaving? If Clark is believed to be sold to another club why is that occurring?
"Do they need the money? Why are all these things happening? If they want me to go in and coach the team then what resources are they going to give me and what do they expect?
"That needs to be resolved fairly quickly."