Lq4 swap, then truck won't warm up.any ideas?

Lq4 swap into 04 Sierra 1500. Everything works fine other than a check engine light and truck won't warm up. Ran it for bout 10 minutes and never mover over 160. Is my thermostat stuck or what?

Have you checked to see if the hose running to the radiator is warm or not?

Yep, it's just not warming up at all, but like I said, only drove up the road to make sure everything was running fine, but still should h e gotten above 160

Not necessarily gonna warm up in that distance(takes about 10 mins and 10 miles for mine to warm up on a cold morning), but if the hose isn't warm at all you might have a thermostat stuck open or a bad water pump. My money is on the first, but I may be way off.

I was thinking thermostat too. Water pump is new. I've also read that it could be air in my system cause I didn't follow proper filling procedures. Guess thats a possibility lol

Is the head hot? did you do the initial start up with the reservoir open to get all air out? does the heater blow warm? bad gauge?

Haven't checked the head, I didn't do initial start up like you said. Guess I should have. Heater doesn't blow warm at all. I think the gauge is correct. Thanks for the replies. Hope I can figure this out.

Not sure if that is the gm way, but it is how I have done all my installs and have had no issues.

Leave cap off until every thing starts to get warm and top off as necessary.

I'll probably drain the fluid tomorrow then refill like that amd see what happens. I appreciate the help

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