I'm new to the forum but have been reading it for a long time figuring out how to fix things on my 1997 RR 4.0.

Recently, it overheated and started sucking up coolant faster then I could add it. I checked the oil and it was clean of water. It started running really rough with a loss of power and check engine light.

I read the check engine light codes and it said both knock sensors and misfiring. I removed the knock sensors and they disintegrated in my hand.

I replaced the knock sensors with the newer Bosch style knock sensors with a custom fabricated bolt / connector to make them work. This remedied the knock sensor code but the engine still ran really rough and was going through coolant like crazy.

So I purchased some radiator stop leak and replaced the spark plugs / wires. As per directions for the coolant stop leak I ran the car for 15 minutes. The car still runs really rough and throws a random misfire code. It has a loss of power as well and can barely move.

There is now water in the oil, should I bother with more radiator stop leak or just bite the bullet and tear the heads off? Is the blown head gasket (I assume thats what it is) related to the engine running so horribly or is that an entirely different issue? Will bosch knock sensors not work on the 1997 4.0?

 

For starters, the radiator stop leak will not help out the headgasket if it is leaking into the oil, you need ot rpelace the gaskets and do it soon or it will cause other damage and more time to fix. I have been needing to do my head gaskets since I have a very small leak in the from of it but none in the oil.

I am not sure about the knock sensors. Running rough can be from a couple different things like a bad plug or wire or coil to an exhaust leak. You just need to keep looking if you are not getting a code for it. You could have a MAF issue as well that is causing it to run rough and loss of power. Check that and see what it looks like.

 

I don't mean to be a grim one here, but I'll bet the engine overheated and slipped a cylinder liner.... You will need to remove the heads to confirm. As Rob stated, no amount of additive is going to fix this problem. The misfires could be caused by many things, If you have an OBD scanner, read the data coming from the MAF and O2 sensors. As previously stated also check the plugs and wires. They need to be changed every 30k miles. OH, and BOSCH knock sensors.... well... Its a GEMS engine not a BOSCH engine. So no, they probably wont work. The knock sensors are to prevent "knocks" not preventing the engine from running like crap. The engine will still operate normally without the knock sensors, but might have some extra engine knocks and ticks.