hoveyjk08

It has been really cold in UpState NY for the past few days <10 degrees in the morning. When cold starting my 2008, auto I am getting a really sharp noise when it first turns over. Almost sounds like metal on metal coming from the trans case. Anyone else experiencing this? I am warming it up for 5 - 10 minutes on average.

Noxian

5 - 10 minutes, yikes thats WAY too long

All that is needed is to start it, let the RPMs drop to near normal idle, and start driving avoiding high rpsm until the engine reaches operating temperatures.

hoveyjk08

I am more concerned about the sharp noise when intially starting the jeep. Anyone experiencing this? I have only heard this when its really cold outside <10 degrees

Noxian

Some people have identified it as "dry start" mine does it when its cold and my jeep isn't plugged in but only for less than a second

MADMAX07

Yes I experience this also, during cold temps below 32 degrees F. I think it might be a belt squeek on initial start up. I switched to Synthetic motor oil about 4,000 miles ago to help with cold start up. I run Syn year round, for better start up protection.

Incognito

Mine does the same thing. I'm using Pennzoil Ultra Synthetic and Purolator PureOne filter, both top of the line. So if the engine blows up, then hopefully it'll be while under warranty. Otherwise I'm not going to lose sleep over it.

The tapping noise we hear at start up comes from the hydraulic lifters. If the engine has been sitting a while without running, the oil leaks out of the lifters. When it's cold out, the oil thickens and doesn't reach them as quickly thus you get the momentary noise. Lowering to say an 0W-20 oil ought to help with eliminating cold start noise but then you run into the warranty issue.


From Wiki on hydraulic valve lifters:

SNOWHARA

If I don't plug mine in it will do this from around -10 Celcius and colder. I'm thinking it is a water pump bearing that likes to make noise on start up. Sometimes the lifter noise is there if it hasn't been plugged in. No sharp noises like the OP described though. This 3.8 is an engine that likes to be plugged in and warm when started. I know it will start at -30 without being plugged in etc etc, but this engine just seems to need that warm up for it to start quietly. And 5 to 10 minutes of warm up is okay when it is -30 or worse, but from 0 deg C to -20 deg C, 2 or 3 minutes is plenty. Any engine, and this one in particular it seems, warms up a lot faster while being driven somewhere. Of all the vehicles I have owned over the years up here, this engine seems to be the most sensitive to cold starts and the related noises that the cold starts can produce. I just hope it doesn't get worse with more miles and time.

JKU Rubicon

Samething here when the temp. is under minus 10 deg Celsius.

I hate to hear this noise

The dealer said to me this is normal

Blakspire

Mine did this on the colder days. I plug it in every time it drops below freezing, cold starts are hard on stuff. A block heater should make this problem go away.