40flier

99 GT 86k was an estate car. Just getting ready to drive on a two day trip. Changing oil (no milkshake) find the dreaded sludge. Coolant has been going down over a month period. Old wrench friend says if it was a headgasket it'd be overheating so its most certainly an intake gasket.

Agree or disagree?

I'll do the intake myself but pulling the heads could be a project.

cliffyk

Disagree.

The intake manifold is always under negative pressure (-1 to -10 psi), and the cooling system is always under pressure (10 psi or so) so a leaking manifold passage or gasket will pull coolant into the intake, but not inject anything back into the cooling system.

OTH a bad head gasket, depending of course on where it has failed, can on the compression stroke force air/fuel and a bit of oil back into the cooling system--and on the intake stroke pull coolant into the combustion chamber where is will be burned. With the coolant only "...going down over a month..." this might not even show up in the exhaust.

Failed head gaskets do not always result in overheating, unless it is a BIG fail...

BraMas

I'm kinda confused by your post. Did you pull the oil cap an there was white sludge on it? If so that is completely normal and is just condensation and oil mixing on the cap. Very normal for a MI car with the weather being so cold and warming up like it has been

cliffyk

Yeah,

I misunderstood as well, my brain told me the sludge was in the coolant, however it is not stated where the "dreaded sludge" was observed...

40flier

There was a heavy layer under the oil filler cap and also on the oil filler tube going down into the engine. Appears very reminisicent of the dexcool problem GM had on their v6's that
I've encountered.I have added about 32oz of coolant this summer to maintain the fill line. I have only had the car for five months and put 4k gentle miles on it. There was a class action suit which ford addressed on these models by extending the warranty to seven years. My dealer says all of that is gone BTW.

I don't have condensation issues here on my other cars including a vette.

The question seems to be whether this amount coolant loss is normal on the 4.6 and not related to sludge? Believe me, if it ain't broke I don't want to fix it!

40flier

Changed oil, 90 miles on xway, next morning the oil cap looks like this. Well, I can't post attachments but the bottom of the cap is coated with white sludge. Gotta be a gasket or something in the polution system. There isn't a PCV valve in the 4.6 is there?

uberstang1

The sludge on the cap is normal

cliffyk

Not on any properly functioning engine I have ever owned...

uberstang1

In climate changing states it's common with winter it's condensation and oil mix, every single cap u pull around me right now will have it.

uberstang1

As condensation builds up in fall when the temp changes condensation builds up in the cap, short trip driving causes it to build up. A lot of newer cars have a recess in the cap to catch it and keep it away from the valve cover, my f150 has one