radioactive

Noticed yesterday that the exhaust was steaming more than usual during this cool weather, so sniffed it just to check. Sure enough, that unmistakable sticky sweet smell of burning antifreeze nailed me in the 'ol sniffer!

Just flushed the system and put in all new antifreeze a few days ago and the level in the overflow is down a quart or so.
It has no miss or loss of power like a blown head gasket would cause, (at least yet) so is there another way coolant can get to the combustion chambers on a 5.4?

dieselhunter44

To test for a blown head gasket, let the truck sit overnight and pull the plugs. If any of them are wet (with water, obviously) then you know it's HG's.

They also make a kit that you attach in place of the rad cap, with a bottle that contains a special chemical that if it detects combustion gases in the coolant, it turns from bluish-green to pee yellow. But these are kind of expensive for the average garage mechanic, abd are kind of cost prohibitive.

I would try the first thing I listed and go from there

My03fx4

You could also pressure test the system. You should be able to rent a pressure tester from a parts store then just hook it up on the overflow tank pump some air in to build pressure and let it sit for an hour or so and see if it drops any.

radioactive

Thanks guys. Pulling the rear plugs in this baby is not a job for the faint of heart! I've never experienced coolant in the cylinders from anything other than a blown head gasket, but the truck does not have the missing or loss of power associated with a bad head gasket.
Checked the oil and no sign of water contamination. This truck has 325K showing, so the engine isn't worth just a head gasket job without going ahead and doing a complete rebuild

My03fx4

Just because it isn't missing or anything doesn't mean the gaskets are good, we just had a focus in the shop that was doing the same thing as you're truck and it was a bad head gasket.

papa tiger

If U don't have combustion gases in the coolant look for an intake gasket leakage. Much easier to fix. When U have antifreeze smell in the exhaust, if the head gasket leaks U will have combustion gasses in the radiator. Since U R running great I would tend it toward manifold water leakage first. U will overheat either way and damage UR motor further.
All in all I would pull the intake and look for an obvious bad gasket. $$$ saved until U re-man / jasper it.

radioactive

Thanks PT! It shows no indication of overheating and it is a sealed cooling system so has no radiator cap. I will pull the upper radiator hose today and check the coolant. When I drained and flushed the system a while back the coolant was some nasty looking stuff! All brown and muddy looking, so I assumed it hadn't been changed in ages.

The truck had a lean on bank 2 code not long ago and was diagnosed as an oxygen sensor malfunction. Had that replaced and it ran like a champ.
I have noticed the last few times I start it, it will crank normal, then the starter will lug for a second and then it starts. Kinda made me think of fluid in one cylinder trying to hydro lock. It also has a bit of a rough idle for a few minutes, then smooths right out

biglee88

These modular motors are known for the intake cracking on the number 1 cylinder check for combustion gassed in coolant then if that's good pull the intake I just replaced my intake for the exact same reason it was blow out and leaking coolant in number 1

radioactive

Thanks Biglee!

It's still setting and will until after the first of the year most likely. I sure hope it is the intake as I would like to get another 50K out of the engine. It has a ton of miles on it and replacing head gaskets would cost more than its worth for the life expectancy of the engine.

biglee88

No problem man I know the feeling my truck just turned 306 thousand