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 Jeep Wrangler owners, lightly cleaned up (personal details are redacted by NHTSA).
Sudden acceleration occurred while idling in traffic while the brakes were being applied. This caused the vehicle to run in back of a truck. No injuries reported. Dealer was notified. The consumer stated that the dealer downloaded software to power train computer from the 1998 service bulletin. The bulletin stated that when the temperature rose to 103 celsius it could cause high RPM in parking lot maneuvers or stop and go traffic. The consumer stated that this should have been done to all 99 models. The consumer sold the vehicle.
Tl* the contact owns a 1999 Jeep Wrangler. While driving approximately 40 MPH, the speedometer failed and the engine warning indicators illuminated. The contact stated that this was a recurring failure. The vehicle was not taken in for diagnostic testing. The vehicle was not repaired. The manufacturer was not notified. The approximate failure mileage was 146,000.
I have a 1999 Jeep Wrangler which was manufactured in oct of 1998. My OEM exhaust manifold had two cracks in it as of December of 2003, with the milage on the vehicle being roughly 42000. I replaced the manifold with an aftermarket manifold purchased from o'reilly auto parts in springfield, mo. Eleven months later, the aftermarket manifold cracked also. There is too much heat and pressure in the 4.0 engine for the manifolds to be able to handle, causing failure. Jeep dealerships replace hundreds daily, and are well aware of the engine problem, but also that the stock manifolds are made out of weak materials. Any muffler shop or tech will agree with this, as did 8 Jeep engineers at camp Jeep. I am currently going on my 3rd, and plan on changing to either a borla or banks header to try to solve the problem. …
On February 4, 2004 I took my 1999 Jeep Wrangler to bob mayberry Chrysler Dodge, Jeep, inc. It was very noisy and more gasoline than usual. They said that my exhaust manifold was broken and that this was a very common problem in these vehicles. Mileage at that time was 61,935. The warranty for that year was only 3 years 36 months I was told. This repair was nearly $700.00 and is somethng that I have never had go wrong on any other car I ever had. This was something that the company has known about for some time now, and refused to recall the poorly designed and poorly constructed exhaust manifolds. I would like to see you force them to fix these problems and return all or part of my service bill. My VIN is 1j4fy9s7xp414936. When I called the daimler Chrysler customer service number, I was told that this was just too bad, but there was nothing that they were going to do about it.
Experianced headaches, nausea, as well as audible knocking from under hood. My 1999 4.0 liter 6 cylinder was found to have broken exhaust manifold, leaking hot gasses and exhaust into engine compartment and passenger compartment. Dealership aware that there is problem with manifold, as have redesigned it and replacement cost in excess of $500.00 contacted Chrysler and filed complaint, told they area aware of problem, but will not stand behind it or issue recall. Local exhaust shop advised they do several per month with this defective exhaust manifold, both Wrangler and cherokee between 1996 and 2000 model year. Exhaust was revised in 2000 because of problems, but Chrysler will not stand behind product denying the problem is a defect. Chyrsler should warranty this problem as they did with the 2.5 liter. Milage at time was only 39,000 when cracked.
Many Jeep wranglers built before 2001 have a defective manifold that cracks, causing exhaust problems. This is the reason Jeep completely redesigned the manifold in the newer models. They have yet to send out a recall to fix this problem. When I first noticed the loud noise resulting from the cracked manifold, my car had approximately 37,000 miles on it. Not high mileage by any means. The main concern I have with this problem is the health hazard it poses to the driver. The section of the Wrangler where the cracked manifold is located is underneath the front of the car, where exhaust fumes leaking from it seep up into the cabin very easily, especially when stopped at lights or in heavy traffic. I believe the manufacturers of Jeep are very aware of this problem but don't care to do anything about it.
First heard a problem with the exhaust system just prior to the easter holiday 2002 and took it to the dealership to be investigated after the holiday weekend. I was told the was a crack in the exhaust manifold and the vehicle was one day out of warranty (due to the holiday weekend). After considerable debate, the dealership agreed to repair the vehicle for a $150.00 deductible. Now a year and a half later the exact same issue has arisen and the factory repair is only warranted for 12 months/12,000 miles. After an exchange of 4 emails with daimler/Chrysler they continue to tell me there is nothing they can do and I am liable for the full repair cost.
I was forced to get a new exhaust manifold for my Jeep at 76,000 miles. The dealer's price was $1,300 for the repair. I've seen all over the internet and on the NHTSA's site that this is a common problem. I've been told by mechanics that the Jeep's manifold is a lesser quality. I lodged a complaint with customer service who called the dealership and, after talking with the service tech, said that he couldn't do anything because it wasn't a "defect" but rather "normal wear and tear." I' can't believe this is true after seeing this common problem!!! Chrysler -- why is this not a factory recall?
I love my 1999 Jeep Wrangler and have been very happy till now. My husband and I have owned many new cars over the years and this is the first time either one have heard of an exhaust manifold going bad. When having the manifold replaced we were told it has been redesigned and is different than the one replaced. It had cracked in several places, mainly at the welds. I fill since I never take it off road that this should not of happen. Not to mention it was very costly. I fill since this is a manufacturer problem I should be reversed for something like this.
52,000 on my 1999 Wrangler (have never been "off roading in it). I just replaced the radiator with an after market brand - not jeeps radiator. I'm in the process of ordering a new exhaust manifold (mine is cracked). Once again I was advised to buy an after market manifold because the Jeep's manifold is a lesser quality. It has been explained to me that both of these repairs are frequent on this model and should be a factory recall.
Engine complaints in other Wrangler years
Frequently asked questions
How common are engine problems on the 1999 Jeep Wrangler?
NHTSA has 51 complaints about the engine & cooling of the 1999 Jeep Wrangler, 24% of the model year's 213 complaints. The component named most often is exhaust system › manifold/header/muffler/tail pipe (34 mentions).
Is there a recall for 1999 Jeep Wrangler engine problems?
No. NHTSA lists no engine & cooling recall for the 1999 Jeep Wrangler, though it has 1 recall 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 Jeep Wrangler engine problems start?
Half of the complaints with a recorded mileage happened before about 58,000 miles, and 7% before 25,000 miles.
Is it dangerous?
Owners linked 2 crashes, 1 fire and 1 injury to engine & cooling problems on this model year. If you notice symptoms, have the car checked before driving further.
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.