C63 - Should it limit revs when cold?

[funtimee]

I test drove a C63 today and on the test drive it seemed to limit the revs in manual mode when the engine was cold. The salesman seemed to think that the C63 limits the revs in manual mode until it's heated up, which doesn't seem right to me. I literally had my foot flat to the floor and it wouldn't pass 4k revs or there abouts.

It felt like something was not right at all and I can't find anything on the web to back up his theory that the car will change up early when cold in C or S gearbox mode but just limit the revs in M mode. The car had just had a full service at Mercedes and it didn't throw up any warning lights so not sure what to make of it. Just thought I'd check with you as the car was nice apart from that! It's a 2008 with the PP. It also had a DMS remap so not sure if that had anything to do with it...

Cheers,
James

[ecain63]

C63 only takes a mile at most to warm up. It sounds like the car was being electronically limited, possibly a dealer fit??

BMW M cars have limiter that increased with engine temp but never heard of this on a merc. How old / how many miles did the merc have?

[funtimee]

Didn't think so - it was this one... http://www.pistonheads.com/classifieds/used-cars/m...

[AdamFX]

Thats the same for my RS4. It may be standard

[ecain63]

But, the C63, unlike many other cars warms really quickly. Mine hits the normal operating figure within a mile or so. Surely, on a test drive youre not looking to max the revs out as early as a mile down the road?? I'd be inclined to think it was a fault with the car or a dealer code (valet mode) that limited the cars capability. Ive never known mine to limit the revs at any point. Id never over-rev it when cold anyway but it just doesnt take that long to warm up.

[ecain63]

On another note, was the salesman allowing you to push the revs that high with a cold engine? Did he drive first or did you drive from the off?

[funtimee]

This was a few miles into the test drive on national limit roads. Nowhere have I suggested that I was trying to "max the revs out" - but yes I was trying to rev it above the 3/4k revs that it seemed to be limited at. As I said in my post, in C or S mode, it seemed fine, just not in M mode so it won't be a valet mode. And if it was a valet mode then the salesman would have said that when I suggested there was a problem.

Seems there is a problem with the car as this obviously isn't a standard feature.

Thanks

[ecain63]

Honestly I wasnt saying you were abusing the car at all. I was questioning that if the salesman knew there was a problem or had a limiter installed then he'd not be so keen for you to go above 4krpm / 'max it out'. As he didnt know what was wrong we can only assume the issue is with the car and it needs investigating. A couple of miles in on NS roads should have easily seen you past getting the car warm too.

Apologies if it sounded like i was questioning you, that wasn't the intention. The way it reads to one person and then to another.............etc

I'll have a look at mine later today but ive never noticed a limiter in force in any mode. Normally in manual it goes all the way to the redline, at which point you get a big red display pop up that says to change up a gear.

Eddie

[coetzeeh]

ecain63 said:

But, the C63, unlike many other cars warms really quickly. Mine hits the normal operating figure within a mile or so.

Water temps may be approaching "normal" after a mile or two, but the oil will not be anywhere near operating temps - not even close.

[ecain63]

coetzeeh said:

ecain63 said:

But, the C63, unlike many other cars warms really quickly. Mine hits the normal operating figure within a mile or so.

Water temps may be approaching "normal" after a mile or two, but the oil will not be anywhere near operating temps - not even close.

So what do we gauge the safe temperature of the car as then? How do we know when its safe to put your foot down?

I was always lead to believe that modern oils in modern engines are safe at all temperatures so long as the coolant is up to temp. The real danger is in having cold coolant circulate over hot parts, not cold oil over cold parts (oil will always match the temp of the engine as its in direct contact as it circulates). The oils we have these days dont need the nannying they used to. Yes thay have an optimum operating temperature, but they are safe from standing so long as the coolant is warm enough.

[V8 DUH]

I usually wait until the oil temp stops flashing at 80 degrees before nailing it. I assumed it was flashing as a guide to tell you when its at a happy temp

[ecain63]

Yeah, you'd think that when it had got past the 80 marker it would be more than happy to vent its pent up anger!

[SimonSh]

V8 DUH said:

I usually wait until the oil temp stops flashing at 80 degrees before nailing it. I assumed it was flashing as a guide to tell you when its at a happy temp

Same here I get in AMG mode so I can watch the oil temp rise to over 80C before I get enthusiastic!!! Usually takes a good few miles of normal driving on empty country lanes.

[coetzeeh]

ecain63 said:

So what do we gauge the safe temperature of the car as then? How do we know when its safe to put your foot down?

I was always lead to believe that modern oils in modern engines are safe at all temperatures so long as the coolant is up to temp. The real danger is in having cold coolant circulate over hot parts, not cold oil over cold parts (oil will always match the temp of the engine as its in direct contact as it circulates). The oils we have these days dont need the nannying they used to. Yes thay have an optimum operating temperature, but they are safe from standing so long as the coolant is warm enough.

That is the reason why your car has an oil temp gauge and warning light fitted.

Oils need to be heated to close to their optimal temp window to provide safe lubrication, especially to the bearings at the bottom of the engine which take much longer to warm up compared to the cyl head where combustion takes place. Cold oil does not flow or lubricate as well as hot oil.

As others have stated, wait for the oil temp to reach 80 deg before giving it welly.

[ecain63]

coetzeeh said:

ecain63 said:

So what do we gauge the safe temperature of the car as then? How do we know when its safe to put your foot down?

I was always lead to believe that modern oils in modern engines are safe at all temperatures so long as the coolant is up to temp. The real danger is in having cold coolant circulate over hot parts, not cold oil over cold parts (oil will always match the temp of the engine as its in direct contact as it circulates). The oils we have these days dont need the nannying they used to. Yes thay have an optimum operating temperature, but they are safe from standing so long as the coolant is warm enough.

That is the reason why your car has an oil temp gauge and warning light fitted.

Oils need to be heated to close to their optimal temp window to provide safe lubrication, especially to the bearings at the bottom of the engine which take much longer to warm up compared to the cyl head where combustion takes place. Cold oil does not flow or lubricate as well as hot oil.

As others have stated, wait for the oil temp to reach 80 deg before giving it welly.

It doesn't have an oil gauge. It actually only has a coolant temp gauge. The oil temp reading is in the AMG window of the DIS settings. Not exactly an obvious reference. So if oil is so in need of heat to make it safe why do oil manufacturers, especially performance oils, harp on so much about reduced friction and viscosity at low temps.....and that oils cause little or no wear at start up, unlike the old st that needed to be carefully warmed over a fair distance. If oil temp were so critical vs coolant temp then we'd have an oil temp gauge like old cars did, when it actually was important.

[ecain63]

Apparently: water temperature does show you when the block is up to temperature, at which point piston clearances are no longer a worry. The rest should be well within tolerance.

[2 5HAN]

coetzeeh said:

Water temps may be approaching "normal" after a mile or two, but the oil will not be anywhere near operating temps - not even close.

Ditto this

The oil temp takes quite a while to heat up and the temp stays blue until its warmed up.

I try not to give mine too much stick until its really warmed up, have to admit though on the face of it the water temp warms up really quickly.

[ecain63]

2 5HAN said:

Ditto this

The oil temp takes quite a while to heat up and the temp stays blue until its warmed up.

I try not to give mine too much stick until its really warmed up, have to admit though on the face of it the water temp warms up really quickly.

Does the facelift c63 have an oil gauge shan? Pre FL doesnt. Interesting if it was added.

[coetzeeh]

ecain63 said:

Apparently: water temperature does show you when the block is up to temperature, at which point piston clearances are no longer a worry. The rest should be well within tolerance.

The water temperature shows that the water temp is up to temperature, not the block. The water (or coolant) flows through the cylinder heads. The oil typically lies in the sump at the very bottom of the block which is last to warm up.

[ecain63]

coetzeeh said:

The water temperature shows that the water temp is up to temperature, not the block. The water (or coolant) flows through the cylinder heads. The oil typically lies in the sump at the very bottom of the block which is last to warm up.

And how is the coolant heated?