Which parts fail
Components named in complaints (engine, cooling system, oil leaks, timing chain, exhaust).
Mileage when the problem started
Owner reports
Selected complaints filed with NHTSA by 1999 Ford Mustang owners, lightly cleaned up (personal details are redacted by NHTSA).
I have experienced a spark plug blowout in my 1999 Ford Mustang with 4.6l v8. I have since read about the vulnerability of these engines to experience spark plug blowout. The first blowout was experienced prior to changing any spark plugs and therefore can not be deemed to be a cause of improper torquing, etc. A heli-coil was used to repair the spark plug blowout, only to have the spark plug blown out again at a later date. This time the cylinder heads were damaged and required replacement. The cylinder head replacement was a major inconvenience both in cost of repair, and in the severity of the malfunction. I am very disturbed to hear the number of complaints and number of other individuals who have experienced this same problem without any proper recognition or action by Ford. …
On January 3, 2005, the heater core on my 1999 Mustang had to be completely replaced, including the thermostat. The windows had fogged up before and the car smelled like syrup but I thought it was just vents. The heating core had to be replaced and the coolant had to be recharged and replaced also this came up to $700 dollars. On August 16 2005, 2 weeks after changing the coolant the water pump had to be replaced, once again the system had to be flushed the cost was$400. On July 2006 I had the coolant system flushed and changed, 1 month after the coolant was changed the windows starting fogging up, I was driving my vehicle and I was unable to get a clear view of the road due to the foggy windows, the heating core once again has to be replaced, is going to cost me another $600 dollars to fix this, I have all of the paperwork from Firestone, I have kept up with all of the maintenance …
1) a ticking noise began coming from the upper middle of the engine. After a month, 2) the ticking became a 'tapping' that became increasingly louder. Enroute to have it examined by a local performance shop, there was a loud sound similar to a gun shot and an instant loss in power. This occurred at 2000 RPM. Upon examination, the spark plug had been ejected from the 2nd from the last cylinder on the pass. Side bank. Such force was exhibited that the mounting tab of the ignition coil was broken and the coil was shattered. Upon examination of the head itself, the plug threads were completely stripped. 3)true blue performance, a Mustang specialty shop, examined the parts and concluded that the only remedy viable was to replace the head, plug, and coil.
I have a cracked intake manifold on my 1999 Ford Mustang gt with a 4.6 l engine. It have gained knowledge that this has been a common defect on this engine since the 1996 model year on almost every Ford motors vehicle with this engine setup. Ford has not issued a recall on this known defective part and does not admit to this problem in their vehicles. Upon contacting their customer service, they will not offer any assistance on the repair that will cost their individual customers hundreds of dollars to repair and replace. I find this unacceptable from a company that markets their quality to the American public while not fessing up to a manufacturers defect that has been known for at least seven years. * cb
I have a 1999 Mustang 3.8l-v6. Recently, the car began to expel a white vapor from the tailpipe when the engine is hot, along with a vibration noise. This has happened as many as 2-3 times per day. I took the car to a Ford dealer for service and replaced an air pump. This did not correct the problem. I did some research on the internet and found that many people have had the same problem which turned out to be due to blown head gaskets. I discussed that issue with the dealer representative and they said that there is no record of that kind of problem with a 1999 Mustang. I have found that this is not true.
Tl* the contact owns a 1999 Ford Mustang gt. The contact stated that while driving approximately 30 MPH, she smelled a strong odor of antifreeze. The contact pulled over and noticed a crack in the plastic manifold and coolant leaking from the vehicle. The vehicle was taken to an independent mechanic for diagnosis, who stated that the manifold would need to be replaced. The vehicle was not repaired. The manufacturer was notified and informed the contact that there was not a recall related to the defect. The approximate failure mileage was 75,000. The was unavailable.
The car was built with a plastic intake manifold. The manifold began leaking at the thermostat housing and then the heater hose connection on the intake manifold suddenly broke. I now have to have the entire intake manifold replaced because of poor design and material selection. Ford knew of the problem but refuses to address the issue and hopes it will just go away. They should reimburse the owners of the vehicles for repairs that were due to poor design and materials used to make this part.
Car stalls when slowing to a stop and has happened several times. Took the car to Ford and cleaned the throttle body and reflashed the computer. The problem came back several days later and changed the idle air control valve yet the problem still arises. When slowing to a stop the RPM drop to 500 RPM and then bounced back up to an idle at 700 RPM. Other times that it will drop below 500 RPM, and the car starts to stall.
Tl contact owns a 1999 Ford Mustang. The contact stated the vehicle had a cracked manifold and it was leaking antifreeze. The vehicle was taken to a mechanic who stated that the manifold needed to be replaced. The dealer was contacted and offered no assistance. The manufacturer informed him that there were no recalls or warranties and offered no assistance. The failure mileage was 67,000.
Check engine light stays on constantly. Engines idles rough and stales at about 1500 RPM's. If you turn on the heater or ac. The problem gets worse. I scanned the car and got a misfire code and an EGR code. Replaced all ignition parts and all emission parts and the code and problem won't go away. Help please. Any info can be sent to [email] thanks
NHTSA investigations
Spark plug ejection from cylinder head
On September 6, 2005, odi received a petition requesting that the agency investigate allegations of engine spark plug ejection in certain model year 1997 through 2004 Ford vehicles with triton v-8 and v-10 engines.odi received a total of 474 non-duplicative complaints on the subject vehicles where the complainant, or the dealer repairing the vehicle, reported that a spark plug detached from the cylinder and/or…
Engine complaints in other Mustang years
Frequently asked questions
How common are engine problems on the 1999 Ford Mustang?
NHTSA has 57 complaints about the engine & cooling of the 1999 Ford Mustang, 22% of the model year's 258 complaints. The component named most often is engine › gasoline (19 mentions).
Is there a recall for 1999 Ford Mustang engine problems?
No. NHTSA lists no engine & cooling recall for the 1999 Ford Mustang, though it has 3 recalls for other components. If the problem is widespread, a repair may still be covered by an extended warranty or a manufacturer service bulletin — ask a dealer.
At what mileage do 1999 Ford Mustang engine problems start?
Half of the complaints with a recorded mileage happened before about 65,000 miles.
Source: U.S. National Highway Traffic Safety Administration (NHTSA) — owner complaints through October 20, 2026, recalls and defect investigations; fuel economy from the EPA. Complaints are unverified reports and are not proof of a defect. How we rate model years.