Anyone have any idea what could cause both intake manifold gaskets to start spewing coolant? The engine is a 2004 5.4 2v. and has not overheated.
Some history:
-months ago found coolant escaping from upper rad hose at the t-stat housing, replaced clamp and all was ok.
-started smelling coolant again, no obvious leaks, minor coolant loss. finally noticed evidence of escapage from reservoir cap, replaced cap, had no effect.
-within a week of replacing cap coolant loss intensifies, find trickle of coolant running down the pass. side head, into the valley, definately not coming from the front crossover tube. Confirmed intake manifold bolts are torqued properly.
-drove it 2 more days keeping it topped off, come out in the morning to a huge puddle under the truck, coolant running from the back along the top of the heads and down into the valley (I park nose down on a hill) from both driver and passenger side gaskets. Overflow reservoir almost empty
Scanguague showing normal coolant temps.
Pulled intake manifold off, found no cracks in it.

Suspicious to me that both gaskets let go. Any advise what to check instead of just replacing the gaskets and hoping?

 

Subscribing.

A while back I found some white crusty skag around the base of my intake manifold, on the right front corner. I cleaned it off and haven't noticed any since but it has me concerned...........

 

How many miles? How often was the cooling system serviced? Living in Canada, your cooling system sees large temp changes over the seasons,far less than we see down here in the Southern US. It is possible that the plastic gasket bodies have been fatigued from high mileage and temp changes over the years,and have given up on you. I've seen it before on 4.6L's that use the same gaskets, and it's usually vehicles that have come from Northern states that I've seen this problem on.
JL

 

About 110,000 miles on the engine, I swapped it into my '99 one year ago, new gaskets were used. The only parts of the cooling system that are older than that are the rad and heater core.

 

That's definitely not normal. What brand gaskets were used? Installed dry? How's the surface of the cylinder head and intake manifold? The gaskets used on modulars are very high quality and a superb design with very few problems typically isolated to installer errors. It's possible that you simply got a defective gasket set.
JL

 

I don't remember what brand they were, bought them at Napa. I cleaned everything real well before putting them on, and the mating surfaces look good. Its always possible that something got messed up on installation, but I'd think it would have shown up much sooner if that was the case. Gonna fish around in there some more tonight, install new gaskets and a new t-stat and see what happens.

 

Good luck,I've never seen any problems with leaky gaskets unless there was a damaged gasket, or cracks in the plastic bodies from age, or mating surface problems.
JL

 

Since I'm the op I figure I'm allowed to bring this back from the dead. It's below freezing here so finding a puddle of liquid under the truck was not a happy occasion. Leaking from the back of the intake gaskets, again. bolts torqued to spec. it's possible, but unlikely, that I ran across two consecutive sets of bad intake gaskets. The engines a 2004, so plastic intake manifold, are these prone to warping enough to leak at the gaskets?

 

i just found the same exact leak from the same location on my 04 5.4 superduty. i only have 85k bought truck new never over heated or even close enough to warp anything. after reading your post i dont know if i shoud just buy a new plastic intake or see if i can just put a new set of gaskets on