Thermostats and Thermostat Housings

[Dynomite]

Here is How My Day Went

After a New Fluidyne Radiator Install I thought I should go all the way and put in a New 180 deg Thermostat. Marc answered a question I had in that regard. The thermostat for all LT5's is the same. The temperature rating is 180 degs F. In detail, the thermostat begins to open at 175 and is fully open at 185 degrees. A thermostat with over 50k miles generally opens 5 degrees later and opens about 80%.

So.....why not. I checked my New 180 deg Thermostat in Hot Water and it started to open at approximately 175 deg. Ready to go...and I had my Post on LT5 Thermostats on hand

Post 7 - LT5 Thermostats
Post 237 - Blocking TB Coolant, Fluidyne Radiator and Thermostats

Well......the New Fluidyne Radiator Drain Port worked perfectly. Now to separate the Thermostat Housing Halves. OOPS!!!!!

It all went down hill from there on.....

1. Bottom Bolt on Thermostat Housing was frozen Solid. Broke it off.
2. Had to remove Belt Tensioner, to get my hands in to move AC Dryer and to get to Lift Thermostat Housing.
3. Also removing Belt Tensioner gives access to the Spring Clamps on both ends of the Radiator Hose connected to Water Pump.
4. The Hose from Water Pump to Thermostat Housing is the only Coolant Hose I have yet to replace.
5. Disconnected Passenger Side hose to Heater Nipples on Thermostat and got it free (what a corroded mess).
6. Cut the Coolant Hose going over rail to Thermostat Housing.
7. Finally got Thermostat Housing up and out after moving the Top Coolant Hoses connecting Each Injector Housing.
8. Once the Thermostat was lifted up so I could get to the Drivers Side Heater Nipple....Disconnected that Heater Hose.
9. The Water Pump Spring Clamp was completely turned impossible to get a pliers on it so I used an Air Grinder.
10. Oh...ya.....Got the Hose Clamp cut but all I did was cut a piece out that allows you to compress the ends together. Now what a mess
11. After a couple hours with a razer blade and screw drivers finally got that hose off the water pump.
12. OOPS.....forgot about the frozen Bolt in Thermostat Housing which I had to use Acetylene Heat.
13. After heating finally got the stud showing to move back and forth and 30 minutes later got the stud out of the Thermostat Housing.
14. Chased the Threads in the Thermostat Housing.
15. The Drivers Side Heater Nipple on the Thermostat Housing has an "O" ring and the inside where the "O" ring resides was corroded.
16. Thanks to Jerry having much more foresight than myself I ordered a New and Improved Thermostat Housing Heater Nipple.

THIS ALL STARTED THIS MORNING AT 9:00AM AND ENDED AT 5:00PM THIS AFTERNOON !!!!!!!!!

This should be titled "You think you got Problems"

Oh......Checked that Stock Thermostat (must have been stock since the bolts in the Thermostat Housing were frozen solid) for Function.

I suspect it be a 180 deg Thermostat. It started to open at 195 deg and never opened all the way as far as I could tell.

So....what started off a great day with great idea had some tuff spots but ended up solving several issues including Corroded Thermostat Housing, Old Water Pump Hose that needed replacement, Corroded Heater Nipple on Thermostat Housng, and finally found out that what Marc had suggested about Thermostats was exactly what I found with the poor condition of my Stock 180 deg thermostat.

Installed the NEW Jerry's Thermostat Heater Nipple on the Thermostat Housing. After Cleaning up both Heater Nipples and with the New Heater Nipple installed I popped on the Heater Hoses. I acutally used just a tad of Permatex on the nipples for ease of insertion and a bit of additional leak protection. I also installed one new Water Pump to Thermostat Housing Coolant Hose. Fired up the LT5 after filling with Coolant and took it for a spin. No Leaks and Coolant Temperature stayed about 15 deg cooler than with the worn out Thermostat that actually opened at 195 deg (the New 180 deg Thermostat opened at 175 deg).

Just a Heads Up......if you ever have to remove the Thermostat Housing for any reason, have on hand one of Jerry's New Heater Nipples to replaced the old Heater Nipple on the Thermostat Housing. Jerry's New Heater Nipple

As an aside See Item #9 Post 237 - Blocking TB Coolant, Fluidyne Radiator and Thermostats..........My thinking is that the whole purpose of the Dual Opening Thermostat Housing (Thermostat can open at the Temperature side or on the other end at the Pressure side) is to keep Radiator Pressure to acceptable limits. In other words the Thermostat functions when the engine is cool and when the engine is at high rpm.

When the engine is at high RPM, the Bypass on the thermostat will be open completely do to the water pump developed coolant pressure on the bottom of the Thermostat. This Higher pressure being developed at the bypass end of the thermostat because the Thermostat is closed on the Temperature end or because the high water pump RPM is developing too much pressure on the radiator on the Bypass end of the thermostat.

In other words the Thermostat can open on either end (one end temperature controlled and the other end differential pressure controlled). And even if the Temperature End of the Thermostat is fully open, HIGH water pump RPMs may develop greater pressure than the radiator can stand on the Bypass End and the Thermostat would then open on both ends to allow more coolant to recirculate rather than ALL of the coolant flow being forced through the Radiator . 7,000 Engine RPM does that to you