Deep rumble in my 98 Forrester

[Forrester98]

Her mileage is 79,499. She was in the Suburu dealer recently and I was told she's in good shape for her age.

 

Yesterday as I was driving at regular speed on local roads around town. The roads were mostly clear but have some slush. Rumbling started in the engine, then stopped a few minutes. The car gets its regular oil changes and maintenance. We don't neglect her.

 

It also mysteriously lurched forward yesterday as I was stopped. Has anybody experienced that and what in the world could that be? That's never happened. Could have been my fault. It happened so fast.

 

I am calling the dealership to discuss it, but also had the idea of joining this board to ask others when they think. I have not heard that's a possible fault with Forresters. I have had her for 13 years and she has not been in any accidents.

 

Thanks in advance for your input.

[MilesFox]

That is a remarkable low mileage considering my 98 forester has 240,000 on the clock.

 

Considering the miles and the age, the car my have sat for long periods of time.

 

Please state if she is a manual or automatic. For sake of discussion, i'll assume an automatic trans.

 

The engine should know if the car is in gear or not, therefore adjusting the idle in neutral or park up a notch when in gear for the load against the torque converter. The idle will be controlled by the idle air control valve which is located near the throttle body. This part my be slow to respond if it needs a good cleaning, causing the idle to fluctuate in gear.

 

If this is the case, try soaking the component in sea foam deep creep (in the spray can, or remove it fro the throttle body and clean it by hand, and replace the gasket. It is simply an electric solenoid with a pintle valve.

 

Along with this, it would be a good idea to replace the engine temperatire sensor as preventive maintenance, since this communicates with the engine computer the temp for cold and hot starts, and also control the idle air control valve. This part should be 20-25 bucks at parts counter, and can be installed with a 17mm wrench. 

 

Also, considering the age and mileage of the engine, i would suggest a total coolant change to avoid any cooling issues, as old coolant can lead to head gasket corrosion failutes, and the engine in the 98 forester is known or head gasket premature failure.

[Forrester98]

Thanks for your advice. She is an automatic and I drive her four or five times a week on local roads.

[MilesFox]

I am assuming the rumbling was at a stop while in gear. Otherwise, if you are getting a misfire while driving, suspect the spark plug wires. Use only NGK brand for replacement, as these engines are finicky about plug wires. You will know this is a misfire if the check engine light is blinking in real time with the misfire.

 

Good luck and i wish you many miles