I parked my car in my driveway today and put it in first after I shut it off like I always do and the car would not hold itself in gear anymore. Anytime I back my car into my driveway I always let it roll a tad until the transmission grabs, and then I pull the e-brake. I do this because I dont like the suspension sagging in the rear when you pull the e-brake first.

The car held for a second, then slid, held again, then slid even further. I did this in reverse gear too, same thing. What could be the problem? the car shifts fine. and no, I did not have the clutch in.

 

Does this happen only in first gear?

-Jorge

 

Happens in first and reverse... havent tried any other gears. the main point is that it didnt do this before in first.

 

It's the force of the car's weight / incline overcoming the engine compression. It's slipping, then cylinder-number-next hits compression stroke; that will hold for a bit, then...slips again.

My classic VW Beetle would do this. Amusing to sit through it, not funny if your car slowly lets itself down an embankment, into the street, etc.

I've heard using 3rd or higher may help; that's reducing the gearing factor (it's easier to move the car from stop in 1st, ergo the car moves the engine easier in first) but I never got that far, and just started using the parking brake.

Why is it doing that now, versus not before? Engine wear, valves not seating as air-tight as new, rings not sealing like new, etc.

 

Thanks alot. Is this normal for a car with only 58k miles? Should I get the valves checked?

 

Use the e-Brake when you park. That's what I always do. Than and leave the transmission in 1st.

Never trust the tranny to hold the car and neither the e-Brake. You need both.

 

I don't have a feel for normal / or at what mileage, but it's not necessarily an indication of anything particularly wrong. It could be just the difference in brand new and now more-worn parts.

For example, if you read about cylinder leak-down tests, where they pressurize each cylinder and measure the rate of loss, it's the rate of loss that's measured. Meaning, there *will be* some loss, generally, and differences in cylinder to cylinder are the major concern, not that there's any at all. Of course, if all cylinders leak like sieves, or one does very badly, there'd be a performance impact (runs on 3 cylinders, or like cr@p).

A visual that might help: parked in gear, you have 2500+ lbs being held by the compressed air of ONE 3" x 3.4", 400cc cylinder. That's not much. Or this one: I have a 500cc single-cylinder motorcycle. It has a compression release, so that I can easily get it past TDC on the compression stroke and kick-start it. If I don't use it: VERY hard to kick! If I don't kick it, but just "stand" on the starter lever: eventually, it will sink/move past the compression, as it's one cylinder can't hold pressure forever. It just needs to hold long enough to fire, and when that happens, there's extra gas pressure generated to force the rings against the cylinder wall very tightly for the power stroke.

HTH.

 

Ahh I see. Thanks for the visual, that definitely makes ALOT more sense now. I may eventually do a compression test just to make sure its ok, but then again the car does run fine. It has a slightly rough idle sometimes, but its been doing that since I got her at 18k miles, so whatever.