This is a baffling situation that we can't quite figure out. This truck had overheated and the heads were ground and reinstalled truck ran great and it wasn't until a few weeks after the fact when the truck sat for a week that we found we had a problem. If the truck sits for a few days coolant somehow is getting into Cylinder #8 causing the truck to run rough and blow white smoke for a minute or two...The longer it sits the worse the smoke and time it takes to clear out. When we do a compression check it holds for 10 minutes at 170 pounds. We removed the intake to see if there was any possibility of coolant getting in via the manifold but saw no indication of that there.

Any thoughts on what might be causing this phenomenon?

 

Are you sure there was no crack in the head between the water jacket and the valve ports?

 

I have the same problem with my 2004 Ram 4.7 88,000 miles on it. White smoke on start up, running rough, no milky oil. I have not done a compression test yet or any work on it. The check engine light just came on, misfire on cylinder 3.

I was hoping bad gas but I think I know better.

Keep us informed.

 

For sure no visible crack. The question is how can the cylinder hold compression if there is a crack in the head letting water into that cylinder. The only idea I ad was that there might be a crack in the block below the piston rings. In the up stroke beyond the crack it would then hold compression but allow water in if in the downstroke...what makes that unlikely is that that would let coolant into the oil and that isn't happening...this is a weird one.

 

Is the cylinder holding pressure, or is the gauge holding the pressure? On my compression tester, it is designed to hold it's reading, until you release the pressure. (little button on side of gauge) pressure in the cylinder bleeds off fairly quickly around the rings.

 

That's a good question that I need to figure out. After reading your question I googled the topic and it seems a cylinder once at Top Dead Center only holds compression for about 5 seconds at best...So either my mechanic is unaware of this ( worrisome ) or was pulling a smoke mirrors dance on me.."See it holds pressure for 5 minutes, it can't be the gasket or head". I suspect the new gasket failed or he didn't torque the head properly when he installed it. I wasn't there when he finally pulled the head this time but he said that the gasket looked fine and there was no sign of coolant other than in the cylinder.

 

Oops double posted

 

May need to have the head magnafluxed. (checked for cracks) They are not always obvious.......

 

I swapped the coil packs around and different codes came up. Bought all coil packs for under $100 and all is good. Thanks for all the help.

 

Tomco, any updates?