Money-shift..lead to overheat?

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Jun 27, 2008 | 03:22 PM

np20412

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From: Florida

Money-shift..lead to overheat?

So I mini-money shifted my BMW yesterday...for those that don't know, a money shift is when you shift into too low a gear at too high speed, generally causing bent valves, etc. and costing you lots of monies.

I was going about 70mph, and shifted accidentally into 2nd gear. Now 2nd normally rev-limits at 65mph, so I revved up over 7k (redline is 6200 or so). The car still runs fine power is there, no hesitating or bogging so I don't think I bent anything.

However, today, the car runs abnormally hot. Temp gauge went into the red for me today. The cooling system on e36s is weak as is, and I have all original parts in there for 75k miles (its a 1999). Is it possible that my money-shift blasted the cooling system apart? I scheduled a service appointment tomorrow for a radiator flush and inspection of water pump, radiator hoses and t-stat/housing. Just wondering if mechanically my over-rev caused the weak cooling system to finally give way?

Jun 27, 2008 | 05:22 PM

Och

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From: NY

Time to torch it and sell it to your insurance company.

Jun 27, 2008 | 07:06 PM

ElitistK

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if you are loosing coolant, you might have blown a headgasket. do a leakdown test.

Jun 28, 2008 | 03:38 AM

Big Andy

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Sounds coincidental to me. You can't over rev modern engines because they are electronically limited. Once you rev past the limiter the fuel's cut off so you shouldn't have done any damage.

Jun 28, 2008 | 05:08 AM

Zoraone

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Quote:

Originally Posted by Big Andy

Sounds coincidental to me. You can't over rev modern engines because they are electronically limited. Once you rev past the limiter the fuel's cut off so you shouldn't have done any damage.

You can easily over rev a modern engine.

No electronic device can limit the forces of a mechanical over rev.

By selecting a lower gear than intended, the gearing will force the engine well beyond any electronic limiter.

The amount of damage can be determined by how high you go. 3 to 2 accidental shifts could throw the engine 1,000 sometimes even 3, 4k rpm over their recommended maximum engine speed.

I somewhere remember reading on an Acura forum that a person with a K20 powered RSX-S did a 3-2 shift accidently at the 8k rpm redline and afterward (the engine didn't have much metal left in it) recorded a 13k rpm maximum speed when the connecting rods let go and thus took out the pistons, heads, block.

Jun 28, 2008 | 05:28 AM

toy4two

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From: ca

my friend threw a rod through the block of his 96 Civic EX by missing this exact same shift getting off the freeway. KABOOM

Jun 28, 2008 | 06:25 AM

np20412

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From: Florida

Yeah mine was a 5-4 shift that accidentally landed 5-2....

I was going 70ish in 5th, wanted to shift down to 4th, instead hit 2nd. 2nd gear @ 6300 revs (redline) generally gives me 65mph which is just before it would bounce off the limiter otherwise. So it wasn't a terrible over-rev, but it was an over rev nonetheless. Car is in the shop right now, I'm praying as hard as I have ever prayed that it's a coincidental coolant/radiator leak and NOT a blown head gasket!!!

Jun 28, 2008 | 10:37 AM

np20412

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From: Florida

Quote:

Originally Posted by Lsportline43

Wow. I've driven couple manual cars, but never owned one. Never thought of this happening. Good luck with the car and hopefully this never happens to me if I decide to buy a manual car.

Yeah, most cars only have a lock to prevent shifting into 1st gear. Otherwise any gear can be used as long as the clutch is disengaged.

The easiest way to avoid this is to use proper 5-speed shifting technique. It differs slightly for a 6-speed, just an extra step. For 5-speed, Overhand with thumb pointing up to go from 1-2. Backhand, thumb pointing down to go from 2-3. Backhand thumb pointing down to go 3-4. And finally backhand thumb pointing down to go 4-5.

downshifting is similar, thumb pointing down to go 4-5, thumb down to go 4-3, thumb pointing up to go 3-2.

easiest way to remember all of this is that you ALWAYS want to shift backhand with thumb down except when going INTO 2nd gear, that's where you want to go thumb up.

I always use this technique, except this one time! I was on a rather important phone call and honestly just wasn't paying attention

Luckily, the source of the problem was ONLY a water pump failure and thankfully no BHG!!!!