My engine's running very cool, takes forever to warm up. Just noticed this as the weather's getting cooler outside, I'm thinking it's a bad thermostat. Couple questions:

Does that sound like the right diagnosis?

Sounds like the 2003's thermostat is a huge pain to replace from other posts. Is that right?

Anybody know a good guide to do it? At least where it is? I've replaced the thermostat on my truck before but it was right on top of the engine and easy to get to. Just want to do this job right.

Thanks!

 

I assume you have the 3400 from the way you say it is difficult to do.

There's a good chance that it is stuck open. Just follow the upper radiator hose and you'll find it. Throttle Body is probably in the way.

 

Thanks. Will do.

 

Will I need a 180 degree tstat? or 195? Any particular brand that's good? I figure if I'm going to replace it might as well put a good one in there.

 

if you have cold winters and like your heater, put a 195 back in. I dont' think there are any bad brands, I usually try to replace with ACDelco or OEM equivalents.

 

I had similar issue, in my 03 ss 3800. It was running at 160 degrees after a 40 minute commute at 75mph, it actually threw the code and check engine light. I picked up a new thermostat and in less than 10 mins after watching a short youtube video, had it installed and it was running at the normal temp (approx 195) with much better gas mileage and idle.

 

happen to remember the link?

 

This video was pretty informative. The bottom bolt uses a slot on the housing. You may or may not need to remove this bolt completely to get the housing off.

 

Just the stock temp tstat and you'll be fine. Changing it on a 3400 is not super hard. There are two methods to do it, I've only used one of the two....
Method 1 - Remove the throttle body to gain access to the t-stat housing and bolts. It's still a bit tight because of the exhaust cross over pipe, but it works. Takes about and hour to do.
Method 2 - Remove the exhaust cross over pipe. I've never done this (only heard of others doing it). Exhaust bolts tend to become brittle and snap. I don't like messing with them unless I need to.

 

Nice video, thanks for the link! The people on this forum are great