Hey guys - brand new to the forum here. I bought my daughter, who just turned 16, a 2007 H3 back in April. It has 71k miles, 2 owners and is in really good shape. She called today and said it was driving 'funny'. Once she gets to about 30mph, the engine will rev a bit and then finally catch. I drove and experienced the same thing, fine at lower mph but will act up as we approach 30 or 40. I assume this is a transmission issue? Sorry, not very mechanically inclined and would like to have some sort of idea before taking in to a local shop. Any suggestions would be greatly appreciated.

I'll post some pics of the ride in the new members area in just a bit.

 

I assume you are correct in your assumption that you have a Trans issue. While parked on a level surface, pull the Trans dipstick and check level and quality. If the fluid is pink all is good, if it is dark and smells burnt, not good. If the fluid is low, then that itself can cause issues and premature wear.

Leads to the obvious question. When was the last time the Transmission fluid and filter were changed? When was the last time the Transfer Case, Front & Rear Diff fluids were changed?

71K miles is a bit early for the trans to need a rebuild, but it depends on what the prior owners were doing with it. Might get away with a fluid & filter change to see if the issue is crud + age of fluid as apposed to wear?

Rule of thumb with any used vehicle is if you do not know when fluid changes were last done, change them all out after your purchase.

 

All good points.
I'd hope like h@ll you don't have the pink milkshake though.
I removed that from the equation years ago by bypassing the internal trans cooler entirely.
I have a B&M plate stack cooler for transmissions with built in bypass for cold WI. nights.

 

3-2 control solenoid. Check fluid level/condition, and open a can of trans tune

 

If the transmission fluid appears to be good, and maybe you've had a chance to have a local auto parts store hook up the OBD tool to see if any codes are present, you may want to replace the speed sensor in the transfer case. It's an inexpensive part... about $20-30 and it can be replaced easily in about 5-10 minutes.

YouTube video showing location: