Jews don't believe in eternal hell. Souls in Gehenna are eventually released after they have made satisfaction for their wrongdoing.
I had a short time on a computer and was able to copy the material on the Jewish views of the afterlife: Sorry for the bold colors, they were saved in the document like this... it was very long so I cropped it....
Simcha Paull Raphael is adjunct assistant professor in Jewish Studies at Temple University, is a spiritual director at Reconstructionist Rabbinical College, Rabbinic Pastor, ordination by Rabbi Zalman Schachter-Shalomi, Adjunct Faculty, Department of Religion, La Salle University, Philadelphia, Pa., Spiritual Director (1999-2009, Ph.D., Psych, California Institute of Integral Studies, San Francisco, Ca.
and he states that gehennah was in fact more than simply a garbage dump, (which actually is innacurate to say the least- as there is no evidence of garbage in the valley of hinnom) anyways...
according to jewish tradition there were seven levels/names of gehennah, and one of them was sheol. ANyway here is an excerpt of it while he quotes from the traditional texts of the apocrypha to gain context and bearings of this tradition:
" Sheol as a Realm of Torturous Punishment
Associated with Sheol in this period of Jewish history are very strong, harsh images of punishment, affliction, and torment. Sheol never appears as a desirable place to be; it is usually rather dreadful. In the texts of the Apocrypha, we find a proliferation of depictions of torture, punishment, darkness, fire, burning, and so on. The Book of Enoch, interestingly enough, is a precursor to an entire genre of literature—referred to as “Tours of Hell”32—that describes with vivid detail the torments and punishments of the underworlds. In the “tour of hell” given to our antediluvian hero of 1 Enoch, Sheol is unequivocally a realm of postmortem punishment, and it is described with far more imaginative detail than anything we have observed thus far in Jewish afterlife literature.
First Enoch 54, for example, describes how on “the great day of judgment” even lofty rulers will be subjected to burning fire, imprisonment chains, and iron fetters of immense weight before finally being cast into the abyss of complete condemnation (1 Enoch 54:1-6).
Elsewhere we encounter a similar negative fate ascribed to those souls condemned to Sheol: “Woe unto you sinners who are dead! ... You yourselves know that they will bring your souls down to Sheol; and they shall experience evil and great tribulation—in darkness, nets and burning flame” (1 Enoch 103:7).
Other Images of Gehenna/Sheol
While there is a diverse collection of horrific images associated with Sheol at this point, we do not yet see any comprehensive structural pattern in place. The well-developed “Tour of Hell” motif, which comes into place somewhat later, is in a nascent state at this time. However, to understand the historical evolution of afterlife teachings, it is useful to observe and to catalog recurring motifs and themes of postmortem torment in this period which bridges biblical and rabbinic Judaism. Thus, the following passages from 1 Enoch illustrate the landscape of the underworld in the apocryphal era.
Fire and Burning
In numerous places Gehenna is described as an “abyss... full of fire (1 Enoch 90:26ff.) or a place where there is “a burning worse than fire” (1 Enoch 100:9).
We find more of these images of fire and burning in a section of 1 Enoch (chapters 91-104) dating from the early first century C.E.,33 which speaks of Sheol/Gehenna as follows:
Therefore they shall be wanting in doctrine and wisdom, And they shall perish thereby together with their possessions. And with all their glory and their splendour, and in shame and in slaughter and in great destitution, their spirits shall be cast into the furnace of fire. (1 Enoch 98:3)
In a similar vein, 1 Enoch 90 describes how the fallen angels and shepherds are subjected to judgment and condemnation to burning by fire:
And behold, they were all bound, I saw, and they all stood before Him. And the judgment was held... and they were judged and found guilty, and went to the place of condemnation, and they were cast into an abyss, full of fire and flaming, full of pillars of fire. And those seventy shepherds were judged and found guilty, and they were cast into that fiery abyss. And I saw at that time how a like fire of abyss was opened in the midst of the earth, full of fire, and they were judged and found guilty and cast into this fiery abyss, and they burned.... (1 Enoch 90:23-26)"
above from:
Raphael, Simcha Paull; Raphael, Simcha Paull (6/15/2009). Jewish Views of the Afterlife (p. 43). Rowman & Littlefield Publishers. Kindle Edition.
now, granted sheol, gehennah was only a prison for 12 months according to jewish tradition,
some people got eternal hell:
"However, rabbinic literature does assert that certain classes of sinners are eternally condemned to Gehenna. In particular, heretics, informers, and scoffers (Hebrew: epikorsim), as well as people who have rejected the words of Torah and denied the belief in the resurrection, are sentenced to Gehenna “for all generations” (Rosh Ha-Shanah 17a). Another tradition maintains that only “one who commits adultery with a married woman, publicly shames his neighbor, or fastens an evil epithet upon his neighbor” descends to Gehenna and never reascends (Baba Metzia 58b)."
above from:
Raphael, Simcha Paull; Raphael, Simcha Paull (6/15/2009). Jewish Views of the Afterlife. Rowman & Littlefield Publishers. Kindle Edition.
THE JEWISH ENCYCLOPEDIA acknowledges the 12 month max but at the same time also talks of eternal gehenna for heretics, adulterers etc:
"after twelve months their bodies are destroyed, their souls are burned, and the wind strews the ashes under the feet of the pious. But as regards the heretics, etc., and Jeroboam, Nebat's son, hell shall pass away, but they shall not pass away" (R. H. 17a; comp. Shab. 33b). All that descend into Gehenna shall come up again, with the exception of three classes of men: those who have committed adultery, or shamed their neighbors, or vilified them (B. M. 58b).
…The Book of Enoch also says that it is chiefly the heathen who are to be cast into the fiery pool on the Day of Judgment (x. 6, xci. 9,
et al.). "The Lord, the Almighty, will punish them on the Day of Judgment by putting fire and worms into their flesh, so that they cry out with pain unto all eternity" (Judith xvi. 17).
Above from :
GEHENNA - JewishEncyclopedia.com
so it was this context of rabbinical settings that Jesus came and said, "hey you know gehennah? The one the scribes talk about? It is that place that even liars will go to, and it's duration will be forever!