Hey guys, first post here.

I have a 2003 Durango SLT, 4.7. The thing has run like a champ since we purchased it. It's got a little under 97,000 miles on it. Regular fluid change, etc.


The water pump started to go we replaced it before anything major happened. Driving home a couple of weeks later, driving home from work, the temp gauge stayed dead center, until about 3 miles from home. Then within two blocks it went from dead center to 3/4ths to red.

I shut it down and coasted to the end of my street.

We let it cool then drove it the last 1/4 mile home.

Replaced all the hoses and refilled the reservoir. Fired it up and it was missing and throwing a code for a misfire in the #8 cylinder.

Now, we've done everything but pop the heads.

Changed the plugs,
swapped the coilpacks,
changed the coilpack
changed the fuel rail
checked the oil for rad. fluid
checked the rad. fluid for oil

We even drained a quart of oil into a bucket and let it sit for a day to see if we got some water on top. Nothing!


There is NO OIL IN THE FLUID! The radiator is clean, and there is no smoke coming from the right bank.

We've driven it a little bit, the thing still has some torque and doesnt seem like its lost power. It just sounds like it has a miss.

If there is a crack in the head it must be tiny.

That, or the head is warped, but why wouldn't there be oil in the radiator fluid or milky colored oil? Or even a tiny bit of water in the oil?


Any thoughts are appreciated....

 

First off you are mistaken as oil will be on top of water! When you drained the oil you should have let it sit for a while and cool then open the oil plug and look for coolant! The coolant will come out first. If coolant is mixed with oil then the oil will be frothy brown.


I want you to do a compression test and come back with the readings per cylinder. You can pick a compression tester cheap at Harbor Freight.

 

Sorry dude. Proof read that twice and still managed to put something in there backwards.

And I did not add that Pops had done the compression test. The numbers came out pretty close. I'll get out there with him and redo it and post the numbers.

 

Have you done a running compression on the number 8 cylinder,it should be half of the dry compression reading. You either have head gasket starting to go or a burnt valve. Also do you have a radiator pressure tester? If you do....remove the number 8 plug and pump up the pressure.Let it sit for 15 mins and crank the engine and see if water or coolant comes out of the spark plug hole.If it does,head gasket.