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If I remember correctly, the GM 3.4L engine built in 2002 and early 2003 had the bad intake gaskets. Especially if Dexcool was NOT changed every 3 years. If Dexcool changed every 3 years, it dramatically lowers the risk of problems with weaker factory intake gaskets (in 2002, 2003 3.4L engines). Was told that intake gaskets often "let go" when above 60,000 miles (for normal city miles) and above 80,000 (for less stop/go hiway miles). For intake gasket replacement (in my area), its approx $1,800 (including planed heads / intake - to remove warps).
If my memory is correct, the early versions of Uplander/Montana had front brake rotor problems. The rotors are too under sized, they over heat and "can" warp. Not all rotors warp but if replacing, do replace with thicker 3rd party brake rotors. Some GM mini-vans in harsh turning conditions tend to blow more front wheel bearings as well. In my area, approx $400 to replace each wheel bearing (or, under $900 for both fronts).
I've read that many GM mini-vans have problems with their power sliding doors. Thus, why I bought a 2009 Montana with only "manual" sliding doors. Hopefully, the 2003 van has manual sliding door as well.
Before buying my 2009 Montana, I also read a high number of GM vans have problems with their factory "load leveling" air suspension (air shocks). Shock problems, compressor problems. Very expensive GM repairs. If replacing, go with 3rd party air shock replacement - at 1/4 the cost of GM. If wondering, my van has normal suspension and I installed Timbrens (at 1/4 the cost of factory "load leveling" system). If wondering, Timbren SES are rubber blocks that fit into rear coil springs. Think "air bag" without presurized air inside them. Love them since day one.
Was told the 3.4L engine is really "good on gas" (especially compared to my new van's 3.9L) but it lacks torque for towing and larger then average internal cargo. If planning to "load her down" with passengers or internal rear cargo or towing a little utility trailer, then the larger 3.9L engine will better. More "loading / hauling" stress also means more stress on its transmission / engine parts as well.
If the 4T65E transmisison is used on the 2003 van, do surf all contents within:
http://www.tripleedgeperformance.com...sion_Info.html Lots of known transmission problems. Do "double check" transmission number before buying as well.
These are the items that come to mind (when I did my GM mini-van or not? research)... In the end, I still bought a GM mini-van (with larger brake rotors, 3.9L engine and other design improvements - compared to previous years).
Hoping I made a good choice for the long run as well....
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