hi everyone. I have a 79 monte with the 200 metric 3 speed trans. I put a new front seal and pan gasket and speedo oring. It still leaks around the front. It only does it when warm. I have layed under the car on heavy duty ramps and have sprayed the area clean with carb cleaner and have watched where it comes from. I have even tightened up the bolts alittle but wont cure it. I have been told that it is almost never the front seal but the pump seal. I have and eploded view of this trans and am wondering if i can just pull the front pump out and put in a new what ever type of seal it has. I think it could be and o-ring or gasket. I am not a trans mechanic but have had a few apart to learn from in the past. Help needed as i have it almost back out. thanks
200 metric trans 79
Jul 16, 2005
3 Replies
think
I strongly recommand that you just scrape the 200 and find a THM 350 in a bone yard and put it in its place. It is a bolt in. The THM 200 was a joke of a tranny that GM quietly slipped in cars around that time that had no bussiness using them and there were a lot of failures. It is a light weight tranny that was never meant for use behing a V8 in a mid sized to full sized car though a lot of them made it there for GM profit.
Check your tourque converter fo a crack aroun the endf that goes into the pump end they sometime crack there and only leak when they heat up hope this helps
Have to agree with SnoMan, I had a '77 Impala with the same tranny, never made it to 100K miles. Shop told me it was a lightweight transmission and not durable and replaced it with a rebuilt T350. Drove that for 175K more miles with zero service. I seem to recall they had to run a vacuum line to it, as the 200 had a detent cable but the 350 worked on vac, or maybe it was the other way around.
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