| Author | Message | ||
     John Beech Prolific User Username: jbeech Post Number: 142 Registered: 10-2016 |
Verifying function of the thermostat is important. It's easy to check via use of an IR non-contact thermometer by monitoring two locations, the thermostat housing where water exits the engine and the upper radiator hose where the water enters the radiator. The goal is to note the time it takes the thermostat to begin and fully open.  I recorded the following data for Tootsie (SRX6816) this morning after first, on a notepad, creating two column headings; one for the Thermostat Housing (TH) temperature, the other and where the Upper Radiator Hose (URH) enters the radiator. After recording both initial temperatures, I started the engine and jotted down new temperature readings every 30 seconds (in °F). Here's the data. Time - TH - URH 0:00 - 78° - 78° 0:30 - 78° - 78° 1:00 - 79° - 78° 1:30 - 82° - 78° 2:00 - 85° - 78° 2:30 - 91° - 78° 3:00 - 94° - 78° 3:30 - 98° - 79° 4:00 - 103° - 79° 4:30 - 109° - 80° (Note 1) 5:00 - 156° - 85° 5:30 - 170° - 118° Note 2) 6:00 - 180° - 137° 6:30 - 182° - 151° 7:00 - 184° - 160° 7:30 - 188° - 166° 8:00 - 190° - 171° (Note 3) 8:30 - 192° - 172° 9:00 - 192° - 173° 9:30 - 193° - 174° 10:00 -190° - 175° To begin, the desired outcome is to record a sudden inrush of hot water to the radiator as the thermostat opens. This, versus a slow rise in temperature at the radiator upper hose, which would indicate a failed thermostat operating on bypass. Notes: 1. 4:30 the Thermostat Housing (TH) temperature began rising very fast and while I wrote it down as 109°, had I waited a mere 10 seconds, I could have noted it as 130°. 2. 5:00, the temperature at the thermostat housing has spiked very quickly. However, the temperature at the upper radiator hose had only just begun rising (and continued quite steadily for the next two minutes). This indicates the approximate time it took the thermostat to fully open. 3. 8:00 minutes both temperatures had stabilized and while there were minor fluctuations of a degree or so for the remainder of the test run the pattern was set. 4. The engine was at fast idle the entire time and the instant I got in the car and touched the accelerator pedal it idled down to a normal idle speed. 5. While I didn't note it down, the temperature at the upper radiator hose would cool a degree or three, then warm again in a slow steady cycle of about 15 seconds, which I attribute to the thermostat opening and closing a little bit as cool water from the radiator entered the engine via the lower hose, circulated, then reached the thermostat, which closed minutely to vary the flow. Conclusion: the thermostat is functioning normally. | ||
| Patrick Ryan Grand Master Username: patrick_r Post Number: 825 Registered: 4-2016 |
That is a really good and comprehensive test and report John. Text book operation mate. Great result for a great car. You are a definite Rolls Royce convert John  | ||
| Brian Vogel Grand Master Username: guyslp Post Number: 2168 Registered: 6-2009 |
I agree that the verification technique is indeed thorough, but what it doesn't do is identify whether you have an original UE36600 thermostat or something else (whether functionally correct in terms of being able to close off the bypass entirely or not). If you're uncertain about what's in there I'd check at least once per year unless something else indicates a thermostat failure. For myself, I will never have a UE36600 in one of my cars ever again. (For the reasons for that, if you haven't already read it, see Thermostat Issues and Selection. Disclaimer: I am the third author of this article. Brian | ||
| John Beech Prolific User Username: jbeech Post Number: 144 Registered: 10-2016 |
Brian, I am utterly convinced by the research on thermostats . . . and reading your results with the Stant 13558 with the jiggle pin modification results in mey being a convert. Thus, my plan is to replace the existing thermostat with the Stant. Frankly, in my opinion the evidence against the UE thermostat is overwhelming so believe me, this is ON the agenda because in my lifetime I have suffered the loss of an engine due to a failed thermostat (and that was a costly and troublesome experience despite a Chevy V-8 being common as dirt and costing nowhere near what the RR engine represents). | ||
| Robert Noel Reddington Grand Master Username: bob_uk Post Number: 1242 Registered: 5-2015 |
I test stats with a thermometer and boiling water. To test installed measure the temp of the stat elbow and the bottom hose to water pump. When the stat opens the temp should increase at the water pump. Stats tend to work or not work and ideally should fail open which is safe. So if a stat opens and closes its probably OK but because in general stats are cheap I tend to just fit a new one and look elsewhere for the fault. The stat should start to lift at around the stated temperature and be fully open say a couple of degrees centigrade after that the system is reliant wholly on the radiator to keep the from overheating. On the MG site there is a very detail explanation of what thermostats actually do and their limitations. One of my friends on this esteemed site posted about this but I cant remember who. The cooling system also includes the cabin heater of course. The water capacity of the heater can be used to cool the engine by turning off air con and turning heater to max and opening all the windows should ones engine get a bit hot. The water tap is under the brake fluid tank and is either fully off or fully on. The temperature of the air is controlled by a flap which is variable and blends cold air with hot air. I understand the concern over thermostats. but dont get to concerned because there are many thermostats that last for years. In the UK our average temperatures are cool enough that if the stat does go wrong that running with out a stat will work and enough of the coolant will circulate through the radiator to cool the engine but in cold weather the engine may never heat up enough despite the by-pass being open. However if the by pass is blocked off with a piece of dowel then even in very hot places the engine can be run with out a stat. Thus a stat failure need not be a dire emergency. Part of my service schedule is on a warm engine is to loosen the bolts that hold the stat elbow off one at a time because they can seize in the inlet manifold. At the side of the road is not the place for seized threads. The genuine stat with lead plugs is not good and expensive it tends to fail shut, not safe. Modern stats have stainless steel bits unfortunately Crewe ones have Stainless running on Stainless which tends to gall and seize. Stainless is a bugger for this and be careful in general where stainless nuts and bolts are used. | ||
| Patrick Ryan Grand Master Username: patrick_r Post Number: 838 Registered: 4-2016 |
This subject is always a very popular, well commented & sometimes contentious issue. It's like any posting on engine oils & fluids. I'm keen to read everyone's thoughts and opinions. |
