C #: line = StreamReader.ReadLine <= item

Вы можете использовать TimeSpan для извлечения и анализа времени суток:

    static TimeSpan? ExtractTime(string logLine)
    {
        var tokens = logLine.Split(new char [] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
        if (tokens.Length < 2)
            return null;
        TimeSpan time;
        if (!TimeSpan.TryParse(tokens[1], out time))
            return null;
        return time;
    }

    static DateTime? ExtractDate(string logLine)
    {
        var tokens = logLine.Split(new char[] { ' ', '\t' }, StringSplitOptions.RemoveEmptyEntries);
        if (tokens.Length < 1)
            return null;
        DateTime date;
        if (!DateTime.TryParse(tokens[0], out date))
            return null;
        return date;
    }

    static void OutputLogLinesBeforeTime(string strLogDirectory, string strLogDate, string strCallTime)
    {
        try
        {
            var time = TimeSpan.Parse(strCallTime);  // Throws a format exception if invalid.

            DirectoryInfo d = new DirectoryInfo(strLogDirectory + "\\" + strLogDate + "\\");

            foreach (var file in d.GetFiles("*.ininlog_journal"))
            {
                try
                {
                    using (Stream stream = new FileStream(file.FullName, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                    using (StreamReader sReader = new StreamReader(stream))
                    {
                        foreach (var line in sReader.EnumerateLines().Where(l => ExtractTime(l) < time))
                            Console.WriteLine(line);
                    }
                }
                catch (UnauthorizedAccessException ae)
                {
                    Console.WriteLine(ae.Message);
                }
                catch (SystemException se)
                {
                    Console.WriteLine(se.Message);
                }
                catch (ApplicationException ape)
                {
                    Console.WriteLine(ape.Message);
                }
                catch (Exception e)
                {
                    Console.WriteLine(e.Message);
                }
            }
        }
        catch (UnauthorizedAccessException ae)
        {
            Console.WriteLine(ae.Message);
        }
        catch (SystemException se)
        {
            Console.WriteLine(se.Message);
        }
        catch (ApplicationException ape)
        {
            Console.WriteLine(ape.Message);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.Message);
        }
    }

Для удобства я извлек следующее:

public static class TextReaderExtensions
{
    public static IEnumerable<string> ReadLines(this TextReader sReader)
    {
        if (sReader == null)
            throw new ArgumentNullException();
        string line;
        while ((line = sReader.ReadLine()) != null)
            yield return line;
    }
}