Sticky Shifter

1996 Aurora with 98,000 miles. I just bought the car.

On cold starts, the shifter gets stuck in park. I have to press really hard on the button to get it in, and then it shifts.

When I get the car in gear, there is a big knocklike jerk. A mechanic informed me that the engine mounts need to be replaced, but I think the mounts were torn because of the jerk, so replacing them for $700 may just lead to more broken mounts. ($225/mount, $250 install)

At a babcox site, the following is a problem that I think may be related:

"On 2000-'01 Northstar V8s, a buildup of carbon deposits in the combustion chamber can cause a cold knock condition. Bulletin 99-06-01-101A says to use top cleaner to remove the combustion chamber deposits."

other problems include lower crankcase leak ($900 fix) and coolant system problem - overheating when left in neutral.

Anyone have ideas on this or had similar problems?

Are you sure its your shifter button and not your brake-shift safty switch?


BKVic

I think the big jerk you are describing has something to do with a high pressure safety mode in the transmission. I'm not exactly expert on this- just regurgitating what I read a while back. This problem does light up the SES light. My car does this maybe 2 or so times a month going from park into D or R. It goes away after driving forward a very short distance usually. On a side note- while this might prove tricky if you're having trouble getting the shifter to move out of park, putting the car into neutral and THEN into drive or reverse turns my loud clunk into more of a lurch in the appropriate direction.

One guy said this will lead eventually to a tranny rebuild, but most others said there is a variety of things that can make it do it, but it is difficult to diagnose correctly. The consensus seemed to be it wasn't really hurting anything- though I didn't think about the engine mounts. Mine has done this for the last 73,000 miles. It seems to happen a little more often in cold weather, but not realibly so. It was a bitch to even get it to my mechanic with the SES light on so he could scan it, and then he got nothing out of the ordinary (my wheel speed sensors are bad).

As for the oil leak, if it is VERY slow, don't worry about it- it likely won't get worse. The bottom of my engine is always a little oily, but it doesn't really drip. It could be a few problems. There is a known problems with older auroras about porous aluminum leading to oil seepage while running. Another problem has to do with the split block design allowing a slooow leak. I've also heard about a redesign of the rear main seal. The fix for this sounds like what your mechanic has in mind based on the cost. Search for a thread on 'valuable northstar info' for a very informative article about these engines. I recall it covers some of the oil leakage issues.

Make sure ATF is fresh and at the correct level, checked "hot". It helps to let it warm up for a few minutes in cold weather. GM's idea was to mate the block halves with only sealant, no gasket. Obviously didn't work. IMHO, a re-seal is not worth the risk of releasing the torque on the main bearings, since the main caps are an integral part of the lower block half.

Do you park it on a steep hill ?

Yeah,...the dreaded "torque lock". I missed that possibility. Good catch.

i dont park on a hill. what is torque lock? The knob only sticks in the morning when it is cold.

So it's just the button sticking, or the whole shifter handle?

Just the button is sticking. Once i get the button in, it is easy to switch gears. Every once in a while (once a week or so) when i do put it in gear, the engine jerks - only when i havent driven the car for several hours.

The button sticking seems to be tied to cold weather, being that the problem started in the winter and only happens in the mornings. My brother suggested that it may have to do with metal contracting.

Sounds like that button setup needs lubed. When you push that thing it goes across and forces a rod down through the shifter and under the console.

I would think there should be a lubrication point somewhere in there. Try carefully spraying some silicon or something through the straw into the button cavity. I don't know if it's a fixed detent or pull cable design, but more lube is always good.

maybe try and heat up the shift handle with a hair dryer to see if the problem is there. My ignition switch on my truck gets really hard to turn when cold but if I heat it up then it works fine.

I have a very similar problem. Ussually when its cold the shifter button is hard to press in, but in my case it is also hard to move the stick (out of park) as well. When I do get the button pressed in and the stick into drive the car jerks foward (or jerks backwards if I drop it into reverse).