Thanks all for the help with the overheating issues i was having. I took the number 6 and 8 spark plugs out and saw a little coolant, not good!!! Just today took ti havhe entire thing apart, when I took the head off, there was coolant in the 2 cylindars, but the question is how it got there? The 2 middle head bolts werenot as tight as the rest,and the head gasket looks in great shape with no breaches.Could the coolant have been forced in from somewhere else, or might the head be warped? Thanks for the help.

 

YUP
I would replace the head gaskets, have the heads plained, only if necessary and put it back together.
At that point, a leak down test, coolant pressure test and possible compression test will be in order.
Roll of the dice is in your favor.

 

When I overheated my heads were warped pretty bad. Have em check the valve seating too as I also had a warped exhaust valve.

 

should we change out both head gaskets, being there was not any other misfires? I am taking the head in the morning to a machine shop who will pressure test and plane if necessary. Compression test before we started was fine except for 6 & 8 which did not pressure test, only fired coolant into the guage. Does anyone know what color the original wires are for the plugs, and does LR put Champion in at the factory? Only asking bcause they look original..

thanks

 

sorry forgot about this, but when it originally overheated, the temp guage went dead. when i tested it, by touching the two contacts together, the guage went up when ignition was turned on. Also, on the intake manifold, where the sensor sits, it read a resistance of 2500 ohms, does this sound right, or should this also be changed?

thanks a bunch

 

When it overheated was there no coolant in it? If not then the temp gauge will not work.
Yes replace both head gaskets. Why do a half a$$'s job.
Plug wires are black/grey, Champion plugs.

 

If it overheated enough to cause the failure of the fire rings between two cylinders, it is only a matter of time before the same happens on the other bank.

If I am going to take the time and effort to remove a cylinder head, you can bet everything you have and hold dear that I will also do the same to the other bank, along with having the heads resurfaced, valves ground and the heads pressure and vacuum tested. While you're at it, replacing the water pump and all the coolant hoses is a really good idea, along with having the radiator flow tested and chemically cleaned.

Your truck has suffered a major blow. This is a great opportunity to do things right by it and make sure it doesn't happen again.

 

Look carefully at the cylinder walls while the heads are off. Cracks in the cylinder liners are common when these engines are overheated. If that is the case, you will need a short engine. (Hey, how about a 4.6!)
Once the heads are reinstalled, perform a cylinder leak down test. (Compressed air required) Test each cylinder with the piston as close to bottom dead center as possible.
While you are performing the test, have a pressure tester on the coolant reservoir. If pressure is escaping into the cooling system after the heads have been cut and new gaskets installed, it's going to be one of those liners.

 

Thanks for all the info. Replaced all gaskets, had the heads planed (one was terribly warped), and put it all back together today. I am happy to report that all is fine and good with the disco. Even the temp gauge is back in working order. The only problem I have is that the service engine soon light is on (one good thing is that the 3 amigos are gone), but does anyone know of a trick to reset this. I went to discoweb.org, and the instructions they have are for a DI, not a DII. Thanks for the help

 

And just how many cracked cylinder liners have you seen?

It is somewhat common for the liners to move, thus allowing coolant to mix with combustion gases, but I have not found it to be as common as some might make it seem.

Let's not scare this poor man too much without more info.