2008 SLT 4x4 5.7L 125,000 miles.

Dealership replaced water pump & radiator. Did not replace thermostat. (At least paperwork does not indicate so)

Now temp gauge, which use to rest at about 3/8 of the way up, sits more like at 1/2 mark, but increases up to about 7/8 of the way, then will drop back to 1/2 mark over 2-3 seconds. Heater is plenty warm, works fine. Any thoughts? Maybe they didn't burp it well enough?

Thanks.

 

That's what I was thinkin'. Air pocket in there somewhere. Take it back, make 'em fix it.

 

Arrgh. That's probably another week it sits there. If I get it on an incline with a no-spill funnel in the radiator neck, let it idle and squeeze the top hose will that burp it? I checked and the radiator was full but the overflow bottle was below the "min" line. Added fluid to the bottle and drove around, still doing the same thing.

 

It's worth a shot. Sure can't hurt anything.

 

Make sure heater is on full blast. Last time I burped mine, took a while.

 

Could be an air bubble, could be the thermostat. I rec replace the thermostat and see if it fixes the problem.
Hemi engine typically does not have a problem with air bubbles. 4.7 does, but not hemi.
More background would be helpful. Why was radiator replaced? Did they flush the cooling system and replace with all new coolant?

 

The radiator was replaced because the dealership notes said: "found radiator was leaking coolant from core. Drained coolant, removed/replaced radiator. Refilled coolant, bled system, road tested and performed leak check. Verified no leaks present and topped off coolant" It does NOT say "coolant flush" there or in the description of replacing the water pump. The coolant was flushed by the dealership at around 105,000. I'm surprised they didn't replace the thermostat when they did the water pump & radiator.

In any case, I did try to burp it with a no spill funnel. Heater on full blast at hot. Let it idle for quite a while, squeezing upper hose. Temp gauge got up to about 1/2, upper hose was not even warm and air being blown back off the fan was not hot. Revved it up to about 2000-2500, held it there for a little bit, and all of the coolant boiled/exploded out of the funnel. Luckily I was inside the truck.

Turned it off, let it cool down, refilled the radiator with new coolant. Bled (no revving) and took it back to the dealer. I know, the thermostat is only a 10 minute job to do it myself but it's covered under my lifetime warranty so let them deal with it or figure out if that's the issue. I'll update the thread when I hear back from them.

 

Here's the update. The dealer said the truck was "operating normally". I don't tend to think the temp gauge moving all over the place is normal and I asked them to please replace the thermostat under the lifetime warranty but they refused. It's really frustrating when I've driven this truck almost every day for 14 years and I know what the temp gauge does but a guy there can't find a code and drives it for 5 minutes and wants to tell me everything is normal. The temp gauge was erratic on the drive home from the dealer, so nothing had changed.

In any case, I replaced the thermostat myself with an OEM one and it seems to have fixed the problem. The temp gauge now sits just below the 1/2 mark and doesn't move any more than the width of the pointer. The old one came out in 2 pieces. Picture attached. The loose piece will pop back in and stay in place but I don't know if it's supposed to be able to come apart like that.

I'm going to ask the dealer to refund my money for the thermostat, that should have been on them. I imagine they'll balk, but it's worth an ask.

 

See if thermostat is included in the warranty before you bother with it.

 

Well, they certainly won't pay if you DON'T ask.