slight overheating w/ new cooling parts - what next?

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substars

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2005 V8, 95K miles, was running fine (other than occasional coolant smell), but car started overheating and I found a crack in the thermostat housing.

So with LVC's guidance, I replaced every plastic part except the degas (bought a URO bottle to put in in spring) and most of the hoses.

But...it's still overheating! Notes:
  • Bled twice with the car facing downhill
  • Coolant pours out of bleed hose steadily, maybe a sputter if I let it bleed for a few minutes
  • Coolant is not boiling, even at 240F engine temp
  • Coolant level doesn't seem to be going down to max fill level ever
  • Not sure I trust that Gates therm, thinking about pulling it and putting a Motorcraft one in the Gates housing.
Anything else I should try before replacing the thermostat, like bleeding more? I used to think people asking about this were just bad at reading directions since I've bled my V6 no problem multiple times, but this is driving me nuts.

Thanks!
 
After doing some searching, I'm going to buy a new thermostat and see if that fixes it. Gates CO34838 is the assembled thermostat kit in question, can't find any other references to it but sure looking like it's not worth the $60 I saved.
 
Agree, I put in an aftermarket thermostat that was a disaster!!! The Motorcraft Tstat is the way to go. Mine will get up to 230 pulling a grade or sitting in 100 degree LA traffic. The temp drops once I am cruising along.
 
Thanks Roger, hope this does the trick.

Did you put the t-stat into an aftermarket housing? Was thinking I'd leave the plastic as-is since it seems fine.
 
It's your money, but I would worry that the plastic may be restricting the flow.

Take the thermostat out, refill/rebleed, and drive around monitoring temperatures. If it stays below normal, then you could be okay to just replace the thermostat. Don't go too many days without a thermostat though.
 
LOL

joegr, I dunno how i got so lucky on my 02. 290,000kms on it, never overheated. Tho it stopped blowing heat in the cabin. Was luke warm at best. What cause that? I never did fix it so I dunno
 
lincoln_zero said:
LOL

joegr, I dunno how i got so lucky on my 02. 290,000kms on it, never overheated. Tho it stopped blowing heat in the cabin. Was luke warm at best. What cause that? I never did fix it so I dunno
Click to expand...

aux pump maybe?
 
My experience with my 2005 V8 says its air in the cooling system. I know you said you bled it but.....using that little bleeding valve is tricky. Instead I bought one of those yellow buckets that sit on the radiator opening. With that installed I ran the engine for at least 30 minutes while I watched it 'burp' air. That did the trick for me. I learned the hard way when I replaced a leaking plastic part like you did. It would run hot and the cooling fans would come on and it would sound very loud. Burping the cooling system cured all that.
 
substars said:
Thanks Roger, hope this does the trick.

Did you put the t-stat into an aftermarket housing? Was thinking I'd leave the plastic as-is since it seems fine.
Click to expand...

I had purchased a non-Motorcraft Tstat and housing that came together as a set. It did NOT work, so I put the "old" ones back as they had been changed a few years ago. Hope that answers your question.
 
Michaelait said:
y. Instead I bought one of those yellow buckets that sit on the radiator opening. With that installed I ran the engine for at least 30 minutes while I watched it 'burp' air.
Click to expand...

What's the "yellow bucket"? Does it sit on the Tstat housing? How does that work? Or does it sit on the degas bottle?
 
rgorke said:
I had purchased a non-Motorcraft Tstat and housing that came together as a set. It did NOT work, so I put the "old" ones back as they had been changed a few years ago. Hope that answers your question.
Click to expand...

Yes, basically was wondering if the housings were interchangeable, or even meant to be taken apart at all.

I swapped in the Motorcraft thermostat today and it appears to have fixed the problem, temps ranged from 195-210 stop-and-go driving on a beautiful 50F Minneapolis day. The Gates t-stat looks a bit different, fit much looser in the housing than the Motorcraft, but I think it once the spring was loaded, the Motorcraft was seated in there okay.

I didn't mention before that the temp would steady out at ~238 with the heat off and ~228 with it on (it blew hot). Combined with the coolant level not going down, that was what made me suspect the t-stat wasn't opening all the way.

Anyway, doesn't inspire much confidence in the Gates plastic that's still in there, but that's what I'm going with for now. For future reference, someone is selling a kit with all OEM therm + housing parts + seals you need for $129 on ebay right now, just do that.
 
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rgorke said:
What's the "yellow bucket"? Does it sit on the Tstat housing? How does that work? Or does it sit on the degas bottle?
Click to expand...
It fits on the radiator opening. It’s called “Lisle spill free funnel”. It allows you to fill cooling system and burp it at same time. Sold at Amazon. BTW. I live in Oxnard.
 
Michaelait said:
It fits on the radiator opening. It’s called “Lisle spill free funnel”. It allows you to fill cooling system and burp it at same time. Sold at Amazon. BTW. I live in Oxnard.
Click to expand...
I sees it now....

Oxnard!!! Awesome!!! We'll have to meet up and obsess over each other's car...LOL!!! Nice to know there is someone near by. I have seen half a dozen or so LSes in Camarillo...or it could be the same car several times...
 
I just wanted to add confirmation that the Motorcraft thermostat and housing are the only way to go. After some cracks in the plastic parts I ended up with a Gates t-stat housing and T-stat and it started to run hotter and the rad fan ran steady once it got up to temp. The ended up getting a new rad, water pump and tank with no change in the temp or fan running all the time. Along the way a different non-Motorcraft t-stat and housing was swapped in.

After months of driving and getting annoyed I saw a post to only use Motorcraft. I put them in and it now runs normal, 190~ish idle and normal driving and 210~ish under load. The fan hasn't turned on yet.

The opening on the Motorcraft thermostat must be about 3/8" larger than the other 2 I installed.

This was the most expensive thermostat swap ever.....

I should note mine is '05 3.9L V8 with approx 220,000 km's
 
Stevep-05LS said:
I just wanted to add confirmation that the Motorcraft thermostat and housing are the only way to go ...
Click to expand...

It's written a thousand times all over this LS forum to use OEM part only and replace all plastics all at once when restoring/refreshing/repairing this Cooling system.
 
Stevep-05LS said:
If only I had found these forums before going through the pain. The good thing is it's working great now...
Click to expand...

At least you don't have to worry about the radiator's inevitable demise now!

I think the replace-every-plastic-everything-at-once-with-OEM advice is generally good, but there is still a time and a place for troubleshooting. Granted, in our cases the need for troubleshooting is because of an non-OEM part...
 
substars said:
At least you don't have to worry about the radiator's inevitable demise now!

I think the replace-every-plastic-everything-at-once-with-OEM advice is generally good, but there is still a time and a place for troubleshooting. Granted, in our cases the need for troubleshooting is because of an non-OEM part...
Click to expand...

I'm all for diagnosis and troubleshooting. The thing here is that once you find one plastic cooling system part that is failed or failing, the rest of the plastic parts will be in similar condition and likely to fail within a couple of months or sooner. (The parts on the cooler side of the system will last a bit longer than the ones on the hot side.)
 
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