I use different distributives (Mandrake, Slackware, ASP. Kernel version is 2.4.??) and mount my file system (e2fs) with sync key. I create a small file (512 bytes< filesize< blocksize), look its i-node and the number of its block. Then I use dd, bpe, lde to look my file's data. OK! I delete the file (rm myfile) and create a new one. The new file occupies old file's block. cat newfile shows new data but dd, bpe, lde show old file's data even 1 hour later (sync and mount with remount key don't change anything)! Why? I disconnect (plug off) my computer from electric power, restart... Wow! dd, bpe, lde show new (real) data! I think caching is guilty of this situation. Can I turn off (temporarily) caching in my file system?
PS. I did't have this trouble with old versions of kernel (2.2.??)

A few suggestions:

Did you try actually remounting ro and then remounting (again) rw (or if you are able to, unmount completely and then mount)?

I can't tell from your comment, did you try using the sync(1) command?

Also, can you provide in detail how you did what you did, so it may be easier to reproduce.

Thanks!
I did'n remount the filesystem because it was mounted as /
I used only mount with 'remount' option.
The sequence of my actions:
#fillfile 900 a //my program to create a file with a homogeneous content (900 characters 'a')
#ls -li a //get the file's i-node (INODENUMBER)
#lde -i INODENUMBER /dev/hda3 //get the file's data block (DATABLOCK)
#lde -b DATABLOCK /dev/hda3|less //ok! data are present
#rm a //delete the file
#fillfile 900 b //create a file (900 characters 'b')
#sync //from 3 to 5 attempts of synchronization
... //or remounting
#sync
#ls -li b //the same i-node (usually)
#lde -i INODENUMBER /dev/hda3 //the same data block (usually)
#lde -b DATABLOCK /dev/hda3|less //OLD data are present! bpe, dd show the same too
#cat b //I see NEW data!!!
lde, bpe, dd ... //OLD data again

fillfile is a simple program. It uses open (fname, O_WRONLY|O_CREAT|O_TRUNC|O_SYNC) to create and write(...) to write data. Other version of fillfile uses fopen, setvbuf(fs,NULL,_IONBF,0), fwrite, fflush, sync. But there are no differences between the end results.

Now I have solved the problem. I use #hdparm -f /dev/hda3 instead of sequence of sync!