That's all good info. Have you tried running/idling without a thermostat in? This would prove pump flow. The other thing I'm thinking of is the distance between the block and the current thermostat, it's long enough to cause some cooling. In a simple setup obviously the thermostat is mounted to block where the coolant is at it's highest temp. Being so far from the block I could see a 20* drop in temp by the time it reaches the remote housing. Lets say the block temp sensor is a little high and the inline probe is accurate, what if the thermostat never saw 180* until after heat soak when you felt warmth on the other side of the remote Tstat. One more thing would be blockage somewhere that occurred during the rebuild that isn't allowing coolant flow within the block or through the pump, like RTV in quantity. That would require removing the pump....... Mercruiser inboards use a 140* Tstat, $19 bucks. I'd test with a stat at that low temp, again just to check flow. Impellers can come loose too...... just thinking aloud and passing my thoughts on.

 

With the OEM setup I ran a gutted stat, and temps were on the low site. With that setup I can manipulate the temps by camping the bypass hose. I could loosen or tighten that clamp to adjust the temperature. The new temp sensor is about 12" from the sensor in the manifold. I can't see the being a nearly 70* difference in a 12" span of hose, but I've been wrong before. I'm fairly certain there's no blockage in the engine or any other component of the cooling system. We had this professionally flushed, and we did it on our own when these issues started.

I need to get some readings with the IR scanner. I plan on making a time table to document the temps on the UltraGuage an inline gauge in 60 second intervals, and see what comes up. I also plan on using the IR scanner to get readings from the hose leaving the plenum, going to the radiator, going from the radiator to the water pump, the oevrflow tank, radiator itself, and the steel elbow leaving the manifold. I also plan on testing the sensor that's located in the manifold to see what comes of that.

Worse case, we have a great Rover shop in town that I plan on talking to about this.

Mike

 

Look forward to what you find.

 

Hopefully I have some answers tonight.

Mike

 

I was able to get some testing done last night, and below is what I found out after running the Rover for 10 minutes.



Then I waited I pulled some IR reading after we shut the engine off, and again after about 8 minutes.



After this I let it set for an hour or so, and came back out to look things over. Then I noticed the viscus fan had little to no residence against it when I turned it. I broke it loose from the water pump, and removed it. I was so loose that I couldn't free spin it off, and had to use a wrench on it until it was completely off the threads. Next I installed the slightly used Astro Van fan/clutch assembly that I removed after buying a new OEM. Then we started the Rover back up, and I instantly noticed the temp dropped with the new fan, but that was short lived.

Below are the temps after installing the new fan, and after about 2 hours of sitting.



I didn't bother taking any additional reading after that. Next I'm going to pull the t-stat, and running it wide open to see what happens. Before I do that I'm also going to flush the radiator just to make sure it's flowing good.

Mike

 

I pulled the 180* stat last night, and ran the Rover wide open with no stat in the housing. I also re-positioned the sensor for the new temp gauge into another housing for better positioning of the probe. This time around both the computer temp and gauge temp were just about the same, and matched the readings I was getting from the IR scanner.

This is after roughly 10 minutes at idle.


This is after roughly 16 minutes at idle.


After last night I was able to verify the radiator wasn't blocked, and that the computer sensors are reading correctly. Now the question is why does my Rover not like have a t-stat in?

Mike

 

A Tstat is a restriction for one. The current location is too far to ever achieve opening temp is another. You would have to experiment with lower Tstat temps.

 

I personally don't feel the t-stat location is the issue considering we had the exact same issues with a 180* OEM stat in the OEM location. To recap, we have had 3 OEM stats in the OEM location all cause high temps. We had 1 gutted OEM stat in the OEM location that kept temps around 150*. We have 1 inline 180* stat pre-radiator that caused high temps, and now a gutted in-line stat that kept temps around 150*.

Since the inline stat has works for many in this location I don't feel that's the issue. The only difference from others to mine is that others have drilled an 1/8" at 6 o'clock to allow coolant to pass through prior to the stat opening. I did not drill that 1/8" hole in my inline stat.

Mike

 

Drill it.

 

I had almost the same issue post HG install. Got a new temp sensor and it solved the problem