Niagara Gazette

February 6, 2013

TOM'S CORNER: Pressure leak in the transmission system

By Tom Torbjornsen
Niagara Gazette

Niagara Gazette — EDITOR’S NOTE: The Gazette has partnered with local automotive expert Tom Torbjornsen to publish his weekly national column. Tom's Corner will appear in Thursday’s editions. We're kicking things off with a reader question and answers.

TRACI FROM WILLIAMSBURG, Va.: I just purchased a 2004 Ford Explorer Limited Edition with 4x4 and automatic transmission with overdrive. It goes into reverse at an idle, but when the selector stick is put into any forward gear it has to be revved to 2000 RPM in order to go into gear. Once in gear it stays in gear and the transmission shifts tightly with no slipping. My question: What could be causing this issue and how can I fix it? By the way, it has a 4.0-liter V6 engine. I hope I don’t have to replace or rebuild the transmission. Thanks for your help.

TOM: Unfortunately I think you’re going to be looking at rebuilding or replacing the transmission. What you’re describing sounds like a pressure leak in the forward clutch inside the transmission. When you raise the rpm's up, the transmission pump puts out enough pressure to overcome the hydraulic leak; this allows the clutch to fully engage and thus the vehicle moves forward. Once the pressure has built, it will continue to be fine until the fluid pressure bleeds down again, requiring the hydraulic pressure to be built again to apply the clutch. Sorry for the bad news. Confirm my suspicions by having a fluid pressure test done while driving. Also, have a scanner hooked to the vehicle’s data port to see if any codes pertaining to transmission malfunction come up, after which you can proceed in an informed fashion.

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GREG FROM LEBANON, TENN.: I own a 2002 Toyota Camry. The heater doesn’t work too well; the air never really gets hot, just lukewarm at best. The cooling system is full. What’s wrong?

TOM: It sounds like the heater core is partially plugged and needs flushing or possibly replacing. Faulty water pumps (impeller goes bad) can also cause this condition. In this case, the pump cannot circulate and generate enough water pressure/ volume to move it through the system that includes the heater core. Finally, if the core and water pump are working well, then check the duct system for a broken/jammed blend door. This is the device that directs the air within the system in whatever mode is selected. Have these three items checked; you will find the source of the poor heating condition in one of these areas.

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MATT FROM BIRMINGHAM, Ala.: I own a 2004 Grand Cherokee with 204,000 miles. It has a problem starting once the engine is warm. It has a new starter, coil, plugs, wires, distributor, and rotor but still has the same problem. Could a bad ERG Valve be a problem?

TOM: Boy, the parts man must love to see you come into his place of business. First order of business: STOP CHANGING PARTS! Define to me exactly what you mean by hard startin. Does it crank slowly? Does it crank but not fire? If it cranks okay, you have one of three reasons for the no start condition:

• No air (intake leak)

• Incorrect or no fuel feed

• No spark

And not necessarily in that order.

Scan the system to see if the ignition system is failing. Make sure you have fuel pressure and volume. Finally, check for vacuum leaks or blocked airways (which include the possibility of internal engine problems). Once you get answers to these questions, you can proceed with the repair in an informed and financially responsible fashion. Best to you.

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GREG FROM LANCASTER: I have a question regarding my 2006 Nissan Maxima with 36,000 miles. I am the original owner and plan on keeping this car for 200, 000 + miles. When servicing the automatic transmission what would you do? Would you drop the pan and replace the filter, flush the transmission only, or both? Thanks for the advice.

TOM: What does your owners manual recommend for mileage/time intervals? My recommendation is to drain and refill the transmission with a new filter every 30,000 miles or 24 months, whichever comes first. If the fluid looks good (red and clear), then let it go until the next mileage or time interval. If you do service it, have the transmission flushed, replace the filter, and refill it with good quality recommended trans fluid. After re-filling, check the level and top off as needed. Good luck.

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WAYNE, HILLSBORO, Ore.: I own a ‘95 Ford Windstar. There’s no hot air from the heater; I replaced the thermostat and still got no heat. Is there air trapped in the system? How do I solve this dilemma? I’m cold!

TOM: The 3.8 engine in Windstar and Taurus are extremely hard to get all the air out of the cooling system after thermostat replacement. Here’s how to bleed the cooling system of air after having opened it. Once the thermostat is installed, take off the radiator cap and allow the engine to reach operating temperature. When it reaches operating temperature, raise the rpm's up to about 1500 and hold it there for one minute. During this procedure coolant and air will burp out of the radiator and go all over the place. As the coolant level drops, continue to add coolant until the system doesn't burp anymore. Once this is accomplished, you have purged the system of air and it’s time to put the radiator cap back on and let the engine idle. You should have heat at this point. If not, check the heater hoses for equal hotness. If one is cold and the other hot, the core is plugged with sediment and should be replaced. I wish you success.

‘Til next time ... Keep Rollin’

"America's Car Show" with Tom Torbjornsen airs 7:30 p.m. Wednesday, 9 a.m. Thursday and 11 a.m. Saturday on WBBZ-TV.