You know the story, a '99 5.7L has 79K miles on it and is beginning to lose
coolant!!! Changed the oil this evening and discovered white streaks
trailing down the front of each side and along the bottom of the oil pan and
a closer look shows white powder on the front half of each head.... :-(
This engine has also been throwing P0304 codes lately indicating a misfire
on cylinder 4. It only does this when climbing a hill at highway speeds or
entering a highway. Was just hoping for a bad injector on cylinder 4, but
can't get that lucky! I guess the increased RPMs and slight heat buildup may
cause some coolant to seep inside and mess up the firing of #4. No white
clouds out the back or anything like that, but it runs horrible when #4 is
messing up. Get off the gas a bit and it settles right back in and runs
My question. What is an "average" cost to have a shop replace the head and
intake gaskets. I'm in Ohio. I just don't have the time to tackle this
project myself, like I'd prefer.
Good ol' Chevrolet.....
Whatever you do, don't just go into some shop telling
them that you need head gaskets. I can tell you the ratio
of intake gasket replacements to head gasket replacements
on that engine in our shop.......5000 to 1....maybe!
It's most likely to be the intake gasket. Along with the
coolant leaks on that engine, the intake gasket is also
known to warp around the cylinder head ports. Often,
it is bad enough to cause a vacuum leak at the port. You
get a nice miss that is virtually impossible to detect by the
old "spray" method along the exterior of the intake manifold
to cylinder head parting line.
Thanks for the reply. The odd thing is that there are coolant trails down
both forward sides of the block and down the sides of the oil pan. I could
see one head gasket weeping, but both simultaneously seems incredible! It
runs great, never overheats, but does have the cylinder 4 misfire, more
often these days, when on strain that settles down once you get off the gas.
Could some coolant be getting into #4 or a vacuum leak on the intake at #4
cause this misfire code?
I do plan on taking a very close look this weekend, before taking into a
shop, to see if there is an indication of a trail from the intake manifold
all the way down..
This actually occured to my 96 Tahoe with the 5.7 just a couple of weeks
ago. It was leaking on the front and back, 2 different gaskets. There
had been a slow leak previously, but something caused them to pop and
antifreeze was flowing out like a hose.
You can't get coolant into the cylinders on these engines due to
a leaking intake gasket. The coolant ports and cylinder ports are
too far apart for that to happen, plus they are side by side, so
gravity will dictate that the coolant either leaks outside (down the
front of the engine, or over the rear of the bell housing...sometimes
the coolant will follow the parting line of the cyl head to block, which
can fool you into thinking that the head gasket is leaking) or inside,
straight into the lifter gallery and down into the oil pan.
It's usually very hard to see the front parting line of the cyl head/intake
from the front. You can just see the drivers side, but the passenger
side is blocked by the alternator bracket. Another common place
for the coolant to appear is the starter area, passenger side rear.
Also...you can take the oil filler cap off, check and see if you can
detect either a creamy looking substance or beads of what appear
to be moisture. Taste it....(just a little...don't want you keeling over
from the chems)...if its sweet, it's coolant in the oil.
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