This was a very common issue in the 1999, including e99, and early 2000 model years, until about the middle of 2000, if I recall right.

According to International, the turbo bolts backed out due to "heat jacking", where the cyclical effect of the up pipes pushed the turbo counter clockwise (in the direction that bolts loosen) when heat lengthened the up pipes. Once cooled, the pipes would contract, and be coiled at the ready for another pump on the heat jack when heated up again.

International didn't notice this on their 444e engines, because their engines had bellowed up pipes that helped absorb the expansion and contraction cycles of the up pipes, better isolating their heat induced change of length from the turbine housing than the Ford stiff tube in a donut design apparently did.

The in field fix for the Ford trucks that were already out of the barn was a 12 point "wavy bolt" kit. These bolts had threads cut in such a way as to require a prevailing torque within the female threads in the turbine housing for the entire length of travel as the bolt is threaded in. The new bolt threads were slightly eccentric to the housing threads, which helped hold them in place to keep them from backing out.

In production, the fix was a change in manufacturing procedure, as well as bolts.

My bolts backed out. I caught it very early on, only because I knew about it, and periodically checked the center housing rotating assembly (CHRA) with an inspection mirror held against the firewall while aiming a narrow beam pencil light into the mirror. The mirror reflects the light on the bolt heads that back out, and at the same time enables you to see their position.

The shanks of the two tall vertical CHRA mounting bolts capture 2 or 3 of the small horizontal bolt heads that get heat jacked out, so usually only one bolt ends up backing out all the way and getting lost in the valley, or more often, lost down the road, falling over the transmission tunnel. Glad you caught yours in time.





As for what a damaged turbo looks like... you'd probably have seen it. High speed rotation balloons super heated parts radially, so the turbine wheel would likely crash against the turbine housing should a housing misalignment have occurred due to loose or MIA bolts.

International suggests removing and reinstalling only one bolt at a time, so as the other three bolts can help keep the alignment during the procedure.

 

Nice write up!

Thanks again, I'm glad I caught it because I thought the boot may be leaking.... I seen a little soot where the bolt was missing and the next bolt was loose, so figured that was enough to make the squeal I heard. When I rebuilt my tranny I found a 12 pt. bolt lodged in the frame rail and couldn't figure out where it came from. Now I know.