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Chris Wright's Turbocharger FAQ

Q: Is it okay to put a restrictor in the oil supply line to the turbo?  

A:  The turbo cartridge as its own restrictor built in.  The restriction is internal. Any "additional" restrictions prior to the internal one may shorten the life of your turbo.

turbo restrictor

The turbo is one of the weakest links in the oiling system. It can spin in excess of 150,000 RPM while also being subjected to extreme temperatures. Turbo failures can be a sign that all is not well in your engine. The excessive engine bearing material and other debris associated with imminent engine failure will destroy a turbo in short order.

The Chrysler TII turbo does not use rubber O-rings around the turbine section because they would not stand up to the extreme temperatures. Small piston and carbon ring seals are generally used in this area. Not only do these seals keep the oil from escaping, but they also keep the exhaust and compressed intake air out of the oiling system.

"Coking" of the oil can be caused by operating at extreme temperatures and improper or "Hot" shutdown.

Extreme temps can be caused by improper air/fuel ratio, timing problems, restricted exhaust systems, malfunctioning O2 sensor, high boost levels or other engine control system problems.

Balancing the turbo is a must. Not balancing the internal components is like not balancing your wheel when replacing tires only about 10-20 times worse because of the higher speeds.

Can I turn my engine off right away, or do I need to idle for a while after the turbo has been used?

Hot shutdowns cause extensive deposits of carbon and shellac on the turbine end. As the deposits break up and flow into the oil they score and wear the bearing bore, bearing and shaft journal. This problem is pretty much self-explanatory and you should all know how to avoid it. Always allow your vehicles to cool down prior to shutting them off. DON'T rely on water-cooled bearing housings and synthetic oil to prevent this from happening to you.

Q: Can I get a new turbine wheel, slap it on, rebuild the turbo then get it balanced?

A: Obtaining a new turbine wheel/shaft will not solve your problem. You need a new bearing housing where the bearings are seated. Your turbo will not survive with improper external bearing clearance. You may also need to replace the turbine wheel/shaft if any damage or excessive wear occurred there.

Q: What could make the bearing fit into the housing so loosely?

A: Hot shutdowns cause extensive deposits of carbon and shellac on the turbine end. As the deposits break up and flow in the oil they score and wear the bearing bore, bearing and shaft journal. Fine contaminants will score and wear virtually every bearing surface in your turbo while the larger particles will usually confine the damage to the journal bearing on the outside, such as in your case.

Why does my new or rebuilt turbo smoke?

There are many things, which could cause a new or rebuilt turbo to smoke. Here are just a few common causes and their solutions:

#1. Cause: Existing oil in exhaust system still burning off from previous turbo failure.

Solution: Continue running car until smoke disappears. Plan on replacing catalytic convertor soon because burnt oil will quickly restrict air flow and lead to other problems later including turbo failure.

#2. Cause: Oil pressures build up in turbo bearing housing caused by one or all of the following reasons:

1) Restriction in oil drainback tube/line.
2) Oil feedline pressure exceeds drainback tube capabilities.
3) Blow-by in crankcase caused by worn engine, cracked pistons, rings, faulty PVC systems, etc.

Solution: This could be caused by one or all of the following three things:

a) Drainback hose.
Verify there are no foreign objects in drainback tube/hose. This could be the paper towel or duct tape you placed there during the removal of your original turbo to prevent anything from falling in to your oil pan during the swap. This also includes not using the factory silicon drainback hose. These are heat and oil resistant hoses where most other hoses cannot withstand these extreme conditions for very long. Most automotive hoses are actually 2 hoses (inner and outer) separated by braided nylon. When this is used in place of the silicon hose the nylon can actually shrink from the heat restricting the inner hose while leaving the outer hose looking perfect from the outside. Use the factory hose whenever possible. There are no advantages to using any other type of hoses for this application. Turbo removal not required. Once issue is addressed piston seals should reseat on their own and oil seepage will no longer be a problem.

b) Oil return flange gasket issues
This is a “dry” gasket so do not use RTV on it. Even the slightest bit that may get squeezed into the flow of the return oil will impede the gravitational flow of oil back into your oil pan. Pressure will build up in the turbo bearing housing to the point where oil is pushed past the seals. Remove all RTV from the area and replace the gasket. Seals will reseat on their own.

c) Wrong oil drainback line angle.
Turbo oil drainback is powered only by gravity. Angles in excess of 20 degrees will impede oil return flow and pressure build up in the bearing housing may result. Also be sure to maintain a smooth curve from turbo to engine and prevent any kinks in the line, which may cause a back-up and eventual pressurization of the bearing housing.

2) Verify oil pressure is not excessive.
60 PSI at idle for a warmed up engine is WAY too much. 10psi per 1000 RPM is a good rule of thumb. To much oil can pressurize the turbo bearing housing if the gravity fed drainback cannot keep up. This pressurization will force the oil past the turbine shaft piston seals and into the exhaust or compressor side of the turbo. Over time, too much pressure can actually be harmful to your entire engine. With excessive pressure, impurities in your oil can actually eat away at your
bearing surfaces and increase tolerances much like extrude honing works.
Conclusion: Don't use the MP Oil Pressure Relief Spring Kit unless you absolutely have to but remove it right away if your turbo smokes. Turbo removal not required. Once issue is addressed piston seals should reseat on their own and oil seepage will no longer be a problem.

3) Crankcases pressurized by blow-by can also cause oil to be forced past the turbine shaft piston seals. Complete a compression check and leakdown test to check the condition of your engine. There is also a blow-by detection tool which is placed over the oil cap opening while the engine is running and measures crank case pressures. Be sure to inspect your crankcase evacuation system to make sure the issue is not being caused by a bad PVC valve. If you find your oil dipstick out of the tube a few inches after some spirited driving you are most likely experiencing blow-by. Turbo removal not required. Once issue is addressed piston seals should reseat on their own and oil seepage will no longer be a problem.

#3. Further diagnosis:

Check the plugs to see if they show any signs of oil.

If the plugs are dry then the source of oil is either from the exhaust valve seals or the turbo. Replace the exhaust valve seals and hopefully the problem will be cured. If not you may be in the market for a new turbo or rebuild.

If all the plugs are wet then check the turbo to throttle body hoses for signs of oil.

If the hoses are wet inside the oil could be coming from either the turbo or PVC system. Check the PVC system and replace any items which may be faulty and causing the problem. Clean the hoses and see if the oil returns after some driving. If signs of oil return in the hoses then you may be in the market for a new turbo or rebuild. If the hoses remain clean but you are still burning oil then you need to look at the combustion chamber for the source of oil. Complete a compression check and leak down test on all cylinders. You may find that the plugs showing signs of oil are the cylinders with the lowest compression. Squirt some oil in each of the low compression cylinders and recheck compression. If it goes up then you have a ring/cylinder wall related issue. If the compression remains unchanged then you have a valve or head gasket related issue. In either case the head needs to come off to visually inspect to determine the cause.

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