Thread: Overheating issue - absolutely stumped (Done almost everything)

Did LIM full job a few months back including new tep sensor in LIM
New Water pump
Rad looks brand new
New rad cap
Tried 2 thermostats now
Coolant flushed

About a week ago car was overheating fairly quickly once it go up to temp, no idea why so I pulled the t-stat right out and voila no overheating in fact car barely registered on needle during long drives & idling. I figured a bad t-stat.... got another 195 degree stocker again today and boom car overheating!

Upper rad hose feels hot but not tons of pressure. If I crack the bleeder at idle RPM coolant will stream out then stop (this is when the car is already at 212 deg). To help facilitate the air bleed I rev up the engine to 2K and hold. I expect coolant to come flying out as it passes the t-stat but I get absolutely nothing. However, when t-stat gone coolant flows out like a champ.

Need help here folks!

Im kinda stumped aswell.

But the thermo aint in upside down is it?

Thermostat in properly, coolant elbows replaced too.. Perhaps it is such a huge air pocket that it is preventing the flow of coolant past the thermostat? still stumps me how removing the t stat made it all better. I will fill manifold at thermostat housing and try.

bad coolant temp sensor ?

Coolant sensor i suspect is ok because it was low during the time i had no t stat. Plus didnt seem far off when electric fans went on. I filled the LIM directly to top and no difference. I am no engine guru but cant make sense of why when i hold revs at 2000 and crack the bleeder i get zero flow?

If clogged rad... How to proceed? I did get a coolant flush and figured rad would have been unclogged then.

Originally Posted by matt5112

no flow.

So there is no coolant flowing there or the level is too low to hit the bleeder.

How can i explain that things seem perfectly fine when i get rid of t stat?

If it is defective it will be the second one in a row that has performed the same. The first t stat actually opened up in boiling water. They are not fail safes..

Once it gets anywhere close to operating temp, the temp starts going up fast. Went around block and was up to about 220. But while no t stat no problem.

No i figured a stocker should work just fine

Moto**** from psource

No lights come on assuming they work. Will try Napa I guess. What kind of an effect does drilling a small hole have if this remains an unsolved mystery?