The Saturn 1.9L engine was an engine designed by Small Car Specialists at the GM tech center and was designed for torque more than horse power. After all, torque is what makes things move. The 1.9 engine was mated with an automatic transmission that was designed as an electronically controlled manual transmission. The engineers were proud of the ability of the transmission being able to do a 4-1 down shift allowing the drive train to perform well under all conditions.
As for the engine itself, it started out with a TBI (throttle body injection) induction system, which provided the best gas mileage package in the engine’s history. The 1.9 SOHC engine didn’t remain the same, but continued to develop in all areas. The induction system went to port fuel injection, producing more power and lower emissions out put. Other developments included using a single temperature sensor rather then the original dual sensor set up. The sensor it self went through engineering changes. Originally it had been made of plastic, but this lead to cracking on the early sensors which lead to poor gas mileage and poor performance. The engineer finally changed the material to brass, which fixed the cracking problem.
Strong poinst of the 1.9 SOHC engine were ease of maintenance and constant development and improvement of the design. An early improvement was the upper torque axis engine mount which replace tdhe original shock system mount on the 1991 and 1992 vehicles. This solved the vibration issue of the engine compartment.
Early on, when the the engines were getting actual miles on them by customers and were no longer just an engineer’s design dream, the 1.9 SOHC did have issues. The first issue was caused by the lost foam casting process. Porosity in the aluminum casts of the cylinder head, found more in the DOHC engine, lead to coolant leaks. Saturn handled this concern in various ways, from putting sealant in the coolant to having to replace cylinder heads under warranty. This is an issue that also happens in the new GM 2.2L engine family also.
Other issues for the engine were age related. Carbon build-up on the cylinder rings could cause the engine to use oil at a rate of a quart of oil every 900 miles. Saturn tried to fix the issue with top engine cleaner in an attempt to remove the carbon buildup. This was a short term fix in some cases though – the carbon build-up could reoccur. Another major issue was failure of the timing chain, which was enhanced by the vehicles ability to do a 4-1 down shift. This caused the engine to rev too high and in some cases break the timing chain, bending the valves when they hit the pistons. Of course, this is a common problem with interference engines when the timing belts are not replaced. Since the 1.9 engine did not have a serviceable timing belt, going with a chain to shorten the engine length for a smaller over all package. Chain maintenance was not an issue that the engineers thought of when designing the engine. After all, it was a newly designed engine with no history.
Ignition issues arose also, from coil pack failure, to ignition module failure to corrosion issues at the mounting point of the coil pack assembly, cause by different types of metals contacting each other with salt and water thrown into the mix. GM did learn the value of NGK spark plugs, being better then AC Delco plugs originally sold with the engine.
In all the Saturn 1.9 liter engine was an engine developed from scratch which gave the customer outstanding performance. It met the engineering requirements to provide solid performance along with great gas mileage. I speak form experience of ownership and as a factory trained Saturn Technician. For me and many others it was a said day when the only true Saturn designed vehicle was discontinued from production.
This blog was contributed by Walt Johnson. Walt served his country in the United States Air Force beginning in 1979, where he received his early mechanical training. Later, he finished his training with GM as a Saturn factory trained technician.