Before describing the problem, let me give some background on the car. The car is a 99GT 5spd coupe that had an 01 4.6 SOHC swapped in after the 99 motor blew. During installation, the tech broke a coolant line coming out of the heater core and went ahead and plugged it up (seen this on other mustangs who want to eliminate the heater). Anyway, the new motor had 40K miles at the time.
Currently the motor has about 100k miles (the car itself has 157K). Everything is stock on the motor performance wise. Since Ive had it, the basic maintenance has been taken care of:
Last week, I was driving the car aggresively and missed a shift. After a few miles, the motor began to overheat and coolant smoke wafted in through the vents in the cabin. I had the car towed to the shop and they advised that the intake manifold was cracked. Upon looking at the old mainfold, I can see that the little port where the hose from the heater core goes in is completely cracked:
So I got a brand new replacement FRPP intake and some Ford gaskets and pulled the old intake and replaced it with the FRPP one. I torqued (18ft/lbs) everything down properly and followed the tightening sequence called for in the manual.
However, taking the car for a test drive cause the car to overheat. I can start the car and leave it idling for 20 minutes and the temp guage wont go past the mid point, but a 5 mile drive will cause the temp guage to slide to the "A" or "L" in NORMAL. There is no white smoke from the exhuast however. The car runs a little bit rough and has an obvious miss - it is not throwing an CELs yet and I ran a number of tests with my OBDII scanner with no codes. If I put my ear next to the exhuast pipes, I can hear a bit of a rattle that sounds like its being echoed from the motor.
Its going in to the shop tomorrow for a compression check. Do you guys think its likely I blew a head gasket? Is there anything I may have overlooked aside from a head gasket that could be the issue?
Thanks.
Currently the motor has about 100k miles (the car itself has 157K). Everything is stock on the motor performance wise. Since Ive had it, the basic maintenance has been taken care of:
- Mobil 1 5w-20 and filter every 3-5k miles
- motorcraft plugs & coils
- coolant replacement
- new vacuum lines
Last week, I was driving the car aggresively and missed a shift. After a few miles, the motor began to overheat and coolant smoke wafted in through the vents in the cabin. I had the car towed to the shop and they advised that the intake manifold was cracked. Upon looking at the old mainfold, I can see that the little port where the hose from the heater core goes in is completely cracked:
So I got a brand new replacement FRPP intake and some Ford gaskets and pulled the old intake and replaced it with the FRPP one. I torqued (18ft/lbs) everything down properly and followed the tightening sequence called for in the manual.
However, taking the car for a test drive cause the car to overheat. I can start the car and leave it idling for 20 minutes and the temp guage wont go past the mid point, but a 5 mile drive will cause the temp guage to slide to the "A" or "L" in NORMAL. There is no white smoke from the exhuast however. The car runs a little bit rough and has an obvious miss - it is not throwing an CELs yet and I ran a number of tests with my OBDII scanner with no codes. If I put my ear next to the exhuast pipes, I can hear a bit of a rattle that sounds like its being echoed from the motor.
Its going in to the shop tomorrow for a compression check. Do you guys think its likely I blew a head gasket? Is there anything I may have overlooked aside from a head gasket that could be the issue?
Thanks.
