What Results in Rubbed Comp Housing and Damaged Heat Shield/Shroud?

One of the most returned turbo failures we see has rubbed compressor housing and damaged heat shield/shroud. This is usually due to irregular circumstances in connection to the compressor side. In the discussion we’ll focus on air leakage. Another cause would be setting your boost too high.

When you hear noises coming out from your engine, it is strongly recommended that you check all the parts connecting to the turbo especially all the pipes, make sure that all the pipes are not cracked. Once one of the pipes are cracked, air leakage, if not found in time, the pressure imbalance of the compressor end and turbine end cause the wheel assembly to push towards the compressor cover, therefore leading to rubbed compressor housing and eventually damaged heat shield/shroud.

As people usually pay more attention on the main parts like the turbo and other “bigger” parts, some people neglect the importance of the connections in the middle. Using factory pipes or used pipes are fine, but checking every pipe for leakage is imperative.

Another case we usually see from customer is boost setting being too high. When the boost is much higher than factory recommendation, back pressure cause the wheel assembly to also push towards the compressor end, leading to rubbed compressor cover and damaged heat shield/shroud. Upgrading your turbine housing with bigger A/R and/or changing to turbine wheel with less blades will reduce the back pressure, but this might cause turbo lag.

Besides high boost setting and air leakage, we have also seen cases in which the customers inject nitrous oxide into the engine, sudden increase in back pressure also cause the wheel assembly to be pushed towards compressor end, resulting in damaged heat shield/shroud and rubbed compressor cover.