Head gasket or plenum??

[bcownie]

I have a 2002 dodge 1500 with a 4.7 that i just purchased. The seller said it was overheating and had a knock after it overheated on him. I have it home now, good oil pressure, no indication of water in oil, smokes bad (white) like coolant. Slight miss under load. Everything seems like blown head gasket but why the knock?? I haven't looked at plugs yet or put air to cylinders to check for leaks yet. Just looking for advice. I saw on the web that a plenum leak has done this. How?? If I discover head or plenum leak is there other preventive maintenance I should do? Thanks

[hundahunta]

the plenum is dry and does not carry any water and has no valley pan

[callihn]

Originally Posted by bcownie

I have a 2002 dodge 1500 with a 4.7 that i just purchased. The seller said it was overheating and had a knock after it overheated on him. I have it home now, good oil pressure, no indication of water in oil, smokes bad (white) like coolant. Slight miss under load. Everything seems like blown head gasket but why the knock?? I haven't looked at plugs yet or put air to cylinders to check for leaks yet. Just looking for advice. I saw on the web that a plenum leak has done this. How?? If I discover head or plenum leak is there other preventive maintenance I should do? Thanks

Check/watch your fluids and see what's vanishing.

You can look down the throttle body and see the bottom of the plenum pan, if it's oily then the gasket is probably split, pretty common, APC has a kit with a billet to replace the pan which is supposedly to fix it better and supposedly the replacement gaskets are improved as well, so pick your poison on that one, if it is a problem.

An internal manifold gasket leak can let water/oil into the intake, often you'll know this because it will take more than two < 10 sec attempts to start before you get sucess, commonly getting worse and worse, until you find you just don't have time to start it or simply can't get it started. Not always the case though if it's not sucking air.

I had both at the same time.

Best guess is that your intake gasket is leaking and letting water into the intake.

[jpb53]

hundahunta is correct!!! The O.P stated it is a 4.7 engine.

[callihn]

Originally Posted by jpb53

hundahunta is correct!!! The O.P stated it is a 4.7 engine.

You say that as though someone else is wrong, the engine size in this case is irrelevent.

The plenum doesn't carry anything but air and gas, regardless of the engine, that's irrelevent, the plenum still serves the same purpose and is located in the same place and sucks oil in when it's spilt, which of course could also cause smoke, I beleive the O.P. was wanting to verify that the plenum gasket was not split and not the cause of his smoke, though he could have both the plenum and intake gaskets split, in which case the fact that the plenum gasket is spilt would not eliminate the intake gasket, but he has the information.

I think he may have an intake gasket leak, though of course it could be the head, on the knock issue, it could be a seperate issue all together caused by running the engine too hot or it may be a spark knock from an intake leak, hard to say without being able to hear it.

[hundahunta]

head gasket due to overheating the knock could be due to detonation or water in cylinders. the engine is not able to combust the water...This intake will not suck oil anywhere if it leaking. depends on where the leak is it will have a high idle of engine miss.....

[callihn]

Actually the intake can suck oil in if it's leaking bad enough on the inside, and of course water as well since that gasket also surrounds the water jackets, my intake and plenum gaskets just feel apart around the same time, It was sucking air from the outside through the intake gasket plus water and oil from the inside and the plenum gasket was allowing oil through it as well. It got to the point that it was sucking so much air it wasn't worth the time it took to get it started.

It could go either way or all three and it's always a difficult call from a distance and without some investigation, it will be interesting to see what the you find with this information, some things are for certain if it's the head gasket your going to have to replace the intake gasket and might as well take care of that plenum while your there, same if it's just sucking oil through the plenum, you'll need to replace the intake gasket too, but it would benefit you to find out what the problem is before hand if possible.

Again plenum is easy to check, if your loosing oil and don't have a leak and you see oil or where oil has stained the bottom of the plenum pan through the top of the intake then it's leaking, the others are going to be a little more difficult, check the head and if it's fine you know it's the intake and you can be prepaired to do the intake and plenum.

Good luck and let us know how it turns out.

[bcownie]

Thanks everyone, the head were bad .017 warpage. I replaced them with heads that I had machined. I still have the tick/knock in the motor. Gets worse as engine warms. I tried a stethoscope but couldn't isolate. If I was to guess I'd say lower right. There was a lot of sludge in the front of the valve covers when I removed them. Could the oil channels be clogged? I dropped oil pan, not to bad, check pickup screen and tube, nothing, but it has the sound of and engine with low oil pressure. Pressure does not drop when engine warms up. No engine light and idles well. Idea??? thanks.