rattling from engine/bad ideling/gears slip when going up hills sometimes

**jordonr** · 09-06-2010

i have a 2000 GrandPrix GT 3.8 and about 2 months ago my car statred to make a bad ratling noise in the engine and it is loud. it also makes my idle very speratic. then the other day when i was drivin i had my car on cruise and i was going up a hill and it felt like my car was trying to shift gears but it started slipping gears.....i am no mechanic but i am doing my best to describe it but idk what it is and i really need help with it.

idk if this helps but right before it started happening i was coming over a hill on a gravel road and there was a huge truck comin over the hill and i either had to go head on, take the ditch, or go half way off the road and start riding over big gravel clumps. needless to say i hit the clumps and it put a huge dent in my radiator but nothing was leaking so idk if that would have anything to do with whats going on with my car...

**cerick08GP** · 09-07-2010

Well, IMHO you have at least two separate problems. Your first problem is the transmission 4th gear hub is probably toasted. Are you sure it actually still goes into 4th gear? I’d bet you have tiny scraps of metal your tranny pan.

The rattling might be from hitting that rock. Could been a damaged exhaust heat shield.

Your idle issues could be a bunch of items a little more detail would help. Another thing is when you have multiple issues a time line is useful, I don’t have a clue what happened when reading your post.

If the gear “slipping” occurs mostly/wholly between 3rd-4th then I’m 99% confident is the hub. If that is so, the tranny might last another 1-6 months. But rest assured you will need a transmission rebuild, I’d get it looked at before winter.

**jordonr** · 09-07-2010

ok thanks man! ill give you more of a time line and sorry its confusing this is the first one ive done

2 months ago i hit those rocks..sinse then my car has rattled and the idle seems kinda wierd.

Then about 2 to 3 weeks ago my gears felt like they were slipping going about 55 mph on cruise up a hill.

i dont know which gears are which or how to tell which ones im in at any givin time but it does seem like it doesnt want to shift gears when i am on the interstate past 55mph.

and with the idle. its hard to explain! my car kind of shakes and when im ideling is when i hear the rattle and when it shakes the worse!

thanks for helping me man!

**cerick08GP** · 09-07-2010

Originally Posted by jordonr

Then about 2 to 3 weeks ago my gears felt like they were slipping going about 55 mph on cruise up a hill.

Now I have very little doubt your 4th gear hub is bad, it is almost completely stripped. What you are feeling is the tranny falling back into 3rd gear, but it wants to be in 4th.
Some people let the tranny eat itself alive before repairing it. I however recommend fixing it ASAP, unless you intend to replace it with a (different) rebuilt tranny. If the tranny lasts until spring the Vatican might send a team to your house to confirm the miracle.

Now back to your other issues. One problem that could explain both the weird idling and shaking is a broken motor/tranny mount. This is just a guess, but broken lower mounts on 10 year old GPs are fairly common.

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