Checking the CRD Airbox Hose and Turbo
As the youngest of the KJ CRDs is now over five years old there are a couple of additional maintenance items that believe are worth including on the list of items that the obsessive CRD owner might want to check now and then (certainly annually). These are not covered by the normal service schedule:
The first is the Airbox to Turbo hose - this is the black ribbed hose that comes off the airbox lid and runs down to the inlet on turbo. This hose is developing a reputation for cracking down at the bottom where it turns to go into the turbo. This is more likely to occur on vehicle which do not have a Provent fitted to remove the oil mist from the recycled cranckcase fumes. The easiest way to check this hose is to look from below up to the bottom of the turbo; on the front of the turbo where the hose turns to go into the turbo your looking for any evidence of oil dripping, staining the hose, or even a crack or tear.
If the hose is cracked it will allow unfiltered air (and thus dirt/dust) into the turbo inlet, intercooler and engine.
New airbox to turbo hoses are available from US online suppliers and you will need the parts number. The number shown on the parts fiche for a late model 2.8L CRD is:53013104AE; but check yours before ordering because there were two possible airbox configurations. The number should be molded onto the hose itself.
Secondly, check your turbo for vane damage and shaft play. According to our breathern over on the US LOST forum, the turbo is supposed to last at least until first rebuild at 300,000 or so miles (that's 485,000kms people)!!. Most do. But it is still a good idea to check it once and awhile on these aging vehicles. This is best done in conjunction with removal of the airbox to turbo hose discussed above. Remove the turbo to intercooler Samco or OEM hose to allow room to work, and this gives you a chance to look down into the turbo discharge port. Remove the clamp bolts holding the airbox to turbo hose in place and wiggle it free from the airbox lid and turbo inlet flange. You will probably need to disconnect the temp sensor and MAF from the airbox lid for ease of access and to move the lid out of the way. The aibox hose will have the PCV hose connected to it but unless you are replacing the airbox hose you can leave that in place and simply rotate it to move the airbox hose out of the way to facilitate your looking at the turbo. Shine a torch into the inlet port of the turbo (where the airbox hose attached) and you will probably see a lick of oil laying in the bottom of the inlet mouth (this is normal and doesn't mean anything bad). Inspect the turbo blades and shaft for damage: what your looking for is nicks, chips, or pitting or erosion in the edges of the compressor blades (sa this will mean the shaft is out of balance and shaft where could be occuring). The blades should be clean, and free of any damage. Next with your hand reach down and grab the turbo shaft with two fingers - gently. You want to check for shaft play, both fore and aft and side to side. On a good turbo there will be slight fore/aft play and no more than a hint, if that, of side to side play. What your feeling there is the small gap between the shaft and the bearing surface which is normally filled with oil under pressure when the turbo and engine are running. If the shaft play is more than this you may have a developing issue with the compressor shaft or bearing wear. A bearing that is too tight is also a bad sign as this can indicate oil starvation due to varnish formation inside the bearing grooves.
Note the turbo compressor runs in a metal sleeve bearing and there are no ball bearings in there. These turbos use a bronze "sleeve" bearing with tiny oil passages and feeder grooves so that the turbo shaft rides on a film of oil "above" the bearing. The play you feel is the at rest relationship between the shaft and the bearing sleeve.
If your turbo compressor shaft is leaking alot of oil this is a concern and may point to eventual failure due to wearing of the shaft. I should point out the worse thing you can do to this turbo is to turn off a hot turbo without letting it cool down - this can cause varnishes to form on the shaft that can block the oil grooves and eventually starve the bearing of lubrication and then it will overheat and fail. Remember that the oil is also the coolant for the turbo as there is no other coolant system. Turbo timers are usually not necessary but just use common sense, like not driving off a freeway and just shutting down the engine and walking away, give it a few minutes to return to idle sort of temps before turning it off. The second deadly sin is running dirty oil which carries soot through the turbo bearing, soot is an abrasive and will wear at the oil grooves in the bearing surface. Keep the oil as clean as you can, certainly long drain intervals are not a good idea.
If your turbo is starting to go it is much better to do something about it before it fails, because a broken shaft will likely cause a loss of oil to the engine and potentially be much worse than a simple turbo replacement. Turbo's are not cheap, some people believe that they can get them rebuilt, but Garrett does not recommend trying to rebuild the centres because of the specialist tools and tolerances required; and that they don't last as long as a new one would. I guess if you were just rebuilding the centre to sell the vehicle as a running vehicle then a rebuild might be ok. You can get them new from the US for anywhere from $1000 upward to around $1600. If you tried to source it from Jeep AUstralia you had better have won the lottery. It's much better to look after it in the first place.
I should add that there seem to have been very few turbo failures in Australia, compared to the number in the US. I don't know why that is so, but it maybe due to us being abit more obsessive about maintenance. Turbos need clean oil, of the right spec, and attention to the change interval.
That's all for now.
Last edited by glend; 21-10-2012 at 02:15 PM.
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