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Discussion Starter · #1 ·
I noticed an issue with the girlfriends new Forte & was wondering if anyone had info/if its a problem? The car has ~2400km on it currently. When its parked in my driveway, which is probably around a 30deg slop, the car now rolls back slowly when left in 1st with no ebrake. I tried putting it in reverse & the same thing happened. Wasn't sure if it was a clutch issue, so popped the hood & saw the engine is turning over as it rolls back. Does this sound normal? If an engine is turning over like that, typically it would be from really low compression. Only thing I could think of was the rings were seated properly yet but after 2400km you would think the compression should be good? I haven't actually checked compression (or even know what it should be) but was wondering if anyone else has noticed this issue?
 

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my koup has 7992 KM :D and i did not here something like that but what u should do is get the car to ur dealer or mechanic to see what is wrong !??!?!

and if u ever noticed a strange or something unusual in ur engine do not think too much and go for a mechanic that what i used to do with my old car :)
 

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Always use your ebrake!
 

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Discussion Starter · #4 ·
ebrake is always used when parking (no matter hill or not). I noticed the issue because she said the car rolled back with the car in gear & ebrake up. Think she may have just not pulled the ebrake far enough but when investegating, I found this issue. The car will defently being going to the dealer to check out. I was just curious if anyone here had this issue & it was considered "normal" (piston rings leak pressure while not running or something else that isn't typical for most other cars).
 

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Parking Brake not ebrake.

The gears on a manual tranny is only touching by 1/16th of an inch. I think i'll put on my parking brake when parking no matter what.
 

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e-brake is the emergency brake which is the same as the hand brake which is the same as the parking brake. We all all talking about the same part.

just to clarify.. lol
 

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Discussion Starter · #8 ·
Guys, I've already mentioned the parking brake (or e-brake) is always used, no matter where the cars parked. But in my experience the compression of the engine alone should be enough to hold the car, what if the ebrake breaks or doesn't happen to be pulled hard enough? You can't be on a hill or it will roll? I've had 4 cars that were standard including one thats a turbo 4 (so lower compression then NA cars) & it doesn't have any issues. Had atleast another half dozen std. cars parked in the driveway without this issue. Thats why it seemed strange to me.
 

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I still ALWAYS use my parking brake AND put the car in a gear, just force of habit lol. I would take it to the dealer to have them look into it and see if theres any issues, you never know, they may spot something.

Also, I believe the compression for both the 2.0 and the 2.4 should be 10.5:1
 

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things to consider.

The engine is small in size so it doesn't take very much to turn it over. I would try when parked to put trany in the highest gear 5th or 6th. This will take more energy to turn the engine over when the gearing is higher. Also remember that a 30 deg incline is 1/3 of straight up and down so gravity does play a strong factor here.

I don't think it has any thing to do with engine compression, or the engine not being broke in enough. Now if you had a big V8 under the hood that would be a different story.

Today try putting the car in it's highest gear, set the e-brake and see if it moves?
 

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Discussion Starter · #11 ·
things to consider.

The engine is small in size so it doesn't take very much to turn it over. I would try when parked to put trany in the highest gear 5th or 6th. This will take more energy to turn the engine over when the gearing is higher. Also remember that a 30 deg incline is 1/3 of straight up and down so gravity does play a strong factor here.

I don't think it has any thing to do with engine compression, or the engine not being broke in enough. Now if you had a big V8 under the hood that would be a different story.

Today try putting the car in it's highest gear, set the e-brake and see if it moves?
Believe you have it backwards, putting it in a higher gear is more likely to roll, because of the gear ratios. You want to put it in a lower gear, that is why 1st or reverse is ideal. You want to put the car in a higher gear if your trying to load the clutch to see if it slips.

I can see it being easier to trun over then a big V8 but I would think it should still have some sort of resistance. My winter car is a 2.2L NA & it'll hold fine. My summer car is a 2.0L 8.5:1 compression turbo car & its fine as well. These are both "small", easy to turn over motors.
 

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Keep in mind that compression inside an engine is produced by rings (metal) sealing against the cylinder wall (metal). There's no such thing as a perfect metal-to-metal seal. It's adequate to produce 10.5:1 compression for the millisecond before ignition when the engine is running, but it's not guaranteed to hold that pressure indefinitely.

You don't have an issue. I've NEVER seen a manual-transmission-equipped car that would stay parked on an incline like that without the parking brake engaged. All engines have leakdown...some more than others.
 

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Believe you have it backwards, putting it in a higher gear is more likely to roll, because of the gear ratios. You want to put it in a lower gear, that is why 1st or reverse is ideal. You want to put the car in a higher gear if your trying to load the clutch to see if it slips.

I can see it being easier to trun over then a big V8 but I would think it should still have some sort of resistance. My winter car is a 2.2L NA & it'll hold fine. My summer car is a 2.0L 8.5:1 compression turbo car & its fine as well. These are both "small", easy to turn over motors.
Not to be a smart ass or anything, but you kinda answered your own question as far as "is this normal" Looks to me like you may have a problem. Possibly your brake needs to adjusted. Even if it is pulled up all the way. Take it in under warranty. See what they say. And ask the servicer if this is normal or not.
 

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At any one moment in time the engine is only making compression on one single cylinder... so it's not like you have four pistons all sitting there with a 150psi hold on the engine and gravity is beating it...

As well, rolling backwards is going to actually be AIDED by the compression on that one cylinder! Think about it, stop a piston on it's compression stroke (and at almost any moment there is always one) what will it want to do? It wants to get rid of the pressure. So that's either by leaking down past the rings (which takes moments) or the most instant thing is to push the piston back down... which rolls the engine backward... which technically would push the car backward! Now the reason we don't 'see' this happening is because most people who drive manuals don't leave their cars in gear, along with the fact that through gear ratios the 3 inches the piston moves down equals like 1/4" at the wheel...

A 30 degree incline is considered to be quite extreme... you will need to make sure that parking brake is well adjusted and never forgotten to be applied.
 
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