#4 misfire on 5.9L, and burning oil badly!

[Internetmaster]

Greetings group, I’m brand new here and would like to explain this issue! My friend has a 2001 Dodge Ram 4X4 with the 5.9L Magnum. He recently put a thermostat in the truck that went bad, and he SEVERELY OVERHEATED the truck. Since he put in the new thermostat, it’s really running rough, and burning oil as fast as gas! I have read on the 5.9 that the valve stem exhaust seats are a common problem? Are they talking about valve stem seals sinking? Or the actual seat of the exhaust valve to the head? Also, please brace yourself for this one! He has been running the truck with “NO o2 Sensors”, and wonders why it running so horrible! I have tried my best to explain how a COMPUTERIZED ENGINE works, MAF Sensor, TPS, Injectors, and o2’s reading all of that! He is getting new o2’s tomorrow, and valve stem seals for the burning oil. I just wonder if he should do a compression check on #4 before he gets to deep into it to see if it isn’t a cracked head. I hope there is someone here, like a MASTER TECH or someone with a lot of experience with this motor that can point us in the RIGHT DIRECTION. Thanks a million, JT

 

[18CrewDually]

Remove the topgat from the throttle body and open the throttle. Look down the throat of the throttlebody and look to see if the inside is coated with oil.
These engines have a plenum cover under the intake and the gaskets fail. When they do, it allows the vacuum in the intake to suck oil from the valley of the engine.
To repair, intake manifold needs to be removed and all the gaskets replaced.
I'm sure there's youtube vids on doing it.

 

[Internetmaster]

Thank You for the advice 18CrewDually. Would this be causing the #4 misfire? I have been doing extensive reading and I’m hearing a possible crack between intake and exhaust valves? I’m also reading about egg shaped valve seats, or sunken valve stem seals! I am going to take your advice and have a look down into the Throttle Body! I suppose it would not hurt to do a compression test on the #4 cylinder to see if he is losing compression there as well. As far as running with NO o2 sensors, I believe that could be damaging as well, being that the engine will be running off of pre-programmed parameters in open loop mode. What are your thoughts on this? Thank You for the input.

 

[Sherman Bird]

"Severely overheated" is a show stopper. I'd begin with a compression test. Make sure the cooling system is full and pressurize the system with a tool. Let the truck sit with pressure on the cooling system, and remove the spark plugs. look for coolant through the spark plug holes.