1) I know this has been discussed before but i'd like to ask the same thing once more....When I (cold) start my Corolla-04, it revs at 2000RPM which I seem to believe is OK....however, (after waiting let's say 10 seconds or so - no drop in RPMs) when i shift to "D", I always hear some kind of 'thud'....if I wait long enough (2-4 minutes) so that RPMs are down to 1000 or so then this sound is nomore there when I shift to "D". IS IT NORMAL? Car is running fine otherwise.....
2) i need suggestion on something....i know it's no good to idle the car for too long so i just shift it to "D" and moves slowly....i have a signal just after i come out and there i have to wait something like 2 minutes....as engine temperature is still low, i guess it's not a good idea to sit there in "D" with a foot on breaks....is it reasonable to shift it to "N" while I am just waiting there...or this is a bad thing for tranny....thanks a lot.
10 seconds is not enough time to warm up an engine Your engine is revving high, *which is completely normal for a cold start,* to get engine temps up.
Once heat starts to build up in the engine, the idle revs begin to slowly drop.
The thud you are hearing when shifting in to drive is due to 2000 RPM suddenly engaging the transmission and part of the torque converter slams to a stop as you are not moving. Regardless of how high the engine is revving there is always a slight jolt to be felt when placing the car in any forward or reverse gear. The jolt occurs for the same reason I explained only difference is the engine is not revving as high so the jolt is not as aggressive.
I don't know for any reason other than low mpg, or enviromental concerns it is not good to idle for extended periods of time. Idling allows the engine to warm up with the least amount of work the engine must perform.
Leaving it in Drive even when it is revving quite high is fine. When you are sitting in drive and not moving, the only thing occuring is fluid being sloshed around in the torque converter. There is no wear on the components.
I don't know for any reason other than low mpg, or enviromental concerns it is not good to idle for extended periods of time. Idling allows the engine to warm up with the least amount of work the engine must perform.
The simple answer is fuel dilution. When the engine is cold, it runs very rich (way more fuel than normal) in order to run smooth. Since there is excess fuel that doesn't get burned, a lot of it gets into your engine oil. It dilutes the oil, lowers its flash point, increases volatilization, etc. In general, it's just no good.
The best thing you can do for a cold engine is to drive it. It'll warm up in about half the time. As long as you're driving it normally, there's absolutely no harm in driving a cold engine. It's more harmful to let it set there and idle than it is to just drive it.
The best thing you can do for a cold engine is to drive it. It'll warm up in about half the time. As long as you're driving it normally, there's absolutely no harm in driving a cold engine. It's more harmful to let it set there and idle than it is to just drive it.
This is what I kind of thought. And for sure, cold engine gets warm quickly if you drive it. What I am wondering is if "thud" is harmful? if it is, how much? and what does it harm? Thanks
This is what I kind of thought. And for sure, cold engine gets warm quickly if you drive it. What I am wondering is if "thud" is harmful? if it is, how much? and what does it harm? Thanks
It will harm your engine/tranny mounts, transmission and axles. Not sure how long/much damage you are doing but if you keep it up I'm sure you will be able to tell everyone.
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My Cars, 2006 Corolla CE, 2003 Corolla LE
It will harm your engine/tranny mounts, transmission and axles. Not sure how long/much damage you are doing but if you keep it up I'm sure you will be able to tell everyone.
So, I guess idling for about 4 minutes is the thing to do every morning. Right?
So, I guess idling for about 4 minutes is the thing to do every morning. Right?
You might want to plug it in when it's cold to cut down on idle time but your car should be off high idle before putting it in gear to save any damage that may occur. I have a standard so I myself can just idle away in the cold but when it's below freezing I give it a couple extra for the idle to kick down.
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My Cars, 2006 Corolla CE, 2003 Corolla LE
I am digging this old post again as still I am not sure what to do. It takes almost 6-7 minutes before the engine is around 800 and i can put it in "D" without any "thud". However, even if I do it at 1200 RPMs (takes about 4-5 minutes), thud is there. So, I have no idea how other people are managing? They just seem to put it in "D" and go while I am just sitting and watching birds? Is there anything I am missing? Or is it the best way to save Tranny? Thanks again. Madhu \
PS: I live in DC Metro area and temperature at 7AM is around 25F or higher (except some crazy days when it goes down to 6-7).
Other people don't worry about this and deal with the thud. The mounts axles and what ever other parts one may believe it would harm are designed to take the maximum torque the engine outputs. Since at 1500RPM the engine makes very little torque, nothing will be harmed.
Even at slow idle there is always going to be a nudge as torque is transmitted to the wheels when placed in gear.
I live in Colorado and have an 04. I only experience your issue near 0 degrees. My RPMs are higher on a crisp morning (around 25), but I idle for less than 30 sec, back the car out and drive. I do not get a noticeable thud. Is your fluid level correct? Sorry I can not help more than to give my experience-
Thank you. Mine gives me a thud when i try to shift to D even at 1200RPM! Now, as far as the fluid levels - everything is good. If mount is bad, should I go to a mechanic and let him have a look? Or let it be like that? I mean if yours did not give you a thud at 1800 something is wrong with mine. At 800 or even at 1000, there is no thud and everything looks normal. I am just looking to find out if it is only my car or this is more common and not to worry about or the best way to handle it. Thanks.\
Madhu
PS: Car also jumps a bit when put in R or D at higher RPMs with foot on brake. Nothing happens when at 800RPMs. May be this is related too.
Last edited by alpha_1976; 02-23-2009 at 05:34 PM.
I have to say that I am pretty sure that after some thought, mine very rarely spikes to 2000- only when down around zero. I think mostly I am around the 1650 mark on startup. Anyone else know what they usually fast idle at? It may not be anything wrong necessarily. I know at ~1650 there is no thud anywhere. I think a bad mount is a very real thought, but as for a mechanic- I think thats up to your peace of mind. I do 90% of my own car work, so I would just work on it when I had time and the parts and figured out the issue. You could try the wood block and jack method and see if things got better with some slight support. If you just want to have a mechanic check it out, you dont have much to lose except a little cash. I will pay more attention tomorrow when I fire it up for work-
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Your engine is revving high, *which is completely normal for a cold start,* to get engine temps up. 
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