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As a pump engineer I calculate thermodynamic loads in the wine industry through refrigeration and ferment control almost every day. It is a complicated topic as fluid dynamics and fermentation has a multitude of variables which can be a headache for correct component design.
In an engine and once the engine is warm and the stats have opened, the water pump design is set as per maximum flow of the impeller at said RPM. This is obviously set by Jaguar engineers and would have been designed with the correct temperature differential split (flow rate) for the required temperature transfer required through the radiator once the engine has warmed up to operating temperature. The faster the flow the lower the temperature differential split meaning that the coolant is cooling the block at its highest rate.
A high flow rate with faulty Tstats or Tstats removed with a cold engine is obviously not good as the block will take too long to warm up.
Once engine is warm, It is not possible to flow too fast due to the pump design, however if flow rate is too low due to faulty pump or loose belt etc, pockets of coolant may get too hot before it reaches the radiator causing damage to certain parts of engine block etc.
In a nutshell the pump can never run too fast when warmed up but can damage stuff if too slow.
Last edited by Crackerbuzz; 08-24-2018 at 11:40 PM.
I replaced my thermostat housing years ago with a metal one due to chronic leaks and I have not had a problem since. While you're in there it makes sense to change the thermostat. It's not a difficult task and well worth the time and money invested.
I have two Stant thermostats #45398
Measuring them closed is 33mm to the outer face closed and 43mm when fully open, water boiling.
Also is this the correct place to drill the bleed hole?
Drill a 3/32" hole in the disc of the stats and fit them with that hole at 12 o'clock, also never had issues with bleeding etc, ever.
2.30mm so I can assume 2.5mm will be ok.
So these will be OK based on the above?
if you view this thermostat, notice the little brass piece is sticking up,,,thats the area to drill for the bleed hole. also make sure the bleed hole is located in the upright position
Im ready to attack my thermostats tomorrow. Drilled the bleed hole and will mount at 12 o’clock with new gaskets. The more I use this car the more I’m convinced this is my problem. Cool day today and it still ran on the hot side of normal. I tested the extension of these Stant units and the measures up to prior posts.
The other thing to check is the radiator and condenser. Often there can be a huge amount of debris in the space between those two and they block the airflow. On my car the PO must have liked the beach, as the fins of my radiator were completely plugged with sand. I must have knocked at least 2 lbs of sand out of the fins, and prior to doing that I held the radiator up to the sky and couldn't see the sun through the fins, there was so much sand in there.
After I cleaned everything out, I could stand beside the car while it was idling and feel a nice breeze coming out the passengers side from under the car.
Jagboi.
In another post I described how I cleaned in between the heat exchangers. Found a bunch of debris but no change in performance. This is one reason why I believe my problem is not in the radiator efficiency but in the control (thermostat). We will see tomorrow hopefully.
Thanks,
greg
Hmmm. Those gaskets look like paper, and that tube of permatex says ‘yep, paper’.
I’d order proper rubber-clad metal ones and wait for them. No comparison. Stick it in place and tighten down. No mess, no leaks and a clean painless swap next time too. I’m sounding like a late night tv ad.
Well I got the thermostats changed today and while it was a cool 77 in Miami the car idled in the driveway with the ac running and the gauge stayed comfortably on the center mark. Same for driving around town afterward. One original thermostat was in the car and was not in great shape. One replacement which did not have the bleed hole. So I should be good for that part. Unfortunately, one screw on the driver side stripped and is not holding. I made it worse by forgetting to mount the bracket for the air filter box initially and had to remove it one too many times. I have a helicoil job in my future but it held fluid for the first test drive. I’m expecting that to fail and will work on the helicoil repair preparation. One more thing...
Hmmm. Those gaskets look like paper, and that tube of permatex says ‘yep, paper’.
I’d order proper rubber-clad metal ones and wait for them. No comparison. Stick it in place and tighten down. No mess, no leaks and a clean painless swap next time too. I’m sounding like a late night tv ad.
Am I assuming that if I order Jag original gaskets the will be rubber - clad metal versions?
08-24-2018, 11:26 PM
