Rolling in gear

[BenCup]

Let me start by saying I’m not a mechanic, I have a 172 Cup that comes out when the sun is shining, as we live where we do I leave it in gear and off the handbrake (with blocks) which regardless off the blocks it usually holds the car fine, the garage is basically flat but the car will roll without it being in gear however, this is probably a coincidence but I have just had the car serviced (including a gear box oil change) and now the car will not hold if left in gear, fine with the blocks but would prefer it being double protected. Any ideas?

 

[BenCup]

Also the garage is 45 miles away and the car didn’t miss a beat if that make any difference?

 

[McGherkin]

Have you tried switching the engine off?

Seriously though, what gear are you leaving it in?

Leaving in gear isn’t foolproof, the only thing stopping the wheels turning the engine is compression, and the cylinder won’t stay pressurised forever, the car can move very slowly over time. Otherwise if there’s no real resistance then either the car isn’t actually in gear, in a high gear (giving the wheels more leverage over the engine) or the car has serious compression issues which isn’t likely if it’s still driving fine.

 

[BenCup]

Well I tried turning it off and on, I tried 1st, 3rd and reverse. I’m baffled. The car drove perfectly back from the garage (45miles).

 

[BenCup]

If I leave it on the handbrake (max 3 months during the winter) what’s the worst that could happen?

 

[McGherkin]

If you try to push the car, does it move easily, or does it ‘cog’ as the engine turns and different cylinders build pressure (if you can even do that in 1st)?

What sort of timeframe are we talking about the car moving in, and how much?

I wouldn’t leave it on the handbrake, they tend to seize on. Chocking is the only way of guaranteeing the car will never move, leaving in gear means that if someone removes the chocks it won’t roll away quickly.

 

[BenCup]

so without the chocks (bricks) it would roll into my garage door very slowly it really is a slight decline. Just dont understand what’s changed? The engine is good it’s only done 19k.

 

[McGherkin]

Seconds? Minutes? Hours?

 

[Louis]

How far is it rolling and how steep is the driveway? It'll do a revolution of piston.

 

[BenCup]

I would say 2 seconds before I realise it’s not stopping, it’s very flat but it will roll. There is a difference between the service.

 

[BenCup]

Can you put a shirt clip on here?

 

[BenCup]

Short*

 

[McGherkin]

I would say 2 seconds before I realise it’s not stopping, it’s very flat but it will roll. There is a difference between the service.

That is strange. No engagement issues, not jumping out of gear or anything?

Will it keep rolling or will it roll a bit then stop?

Can you put a shirt clip on here?

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