The Imperial has been running hot ever since the engine rebuild. It isn’t overheating, but running on the Interstate it goes to the top of the normal range – sometimes just a bit above. Running on back roads at slower speeds it runs cooler. In cold weather it runs cooler.
Potentially related, the last time I had the AC worked on, the shop told me that the fan clutch wasn’t working – the fan was just freewheeling. While this shouldn’t have any impact on the Interstate it was another data point.
OK, check parts. Hmm, there is an option of a heavy duty fan clutch that applies more torque to the fan. Looks like I should try one of those.
While I’m looking, I’ve been a bit suspicious of the water pump. Interesting – they have standard volume water pumps as well as high volume/pressure water pumps. Might as well do that while replacing the fan clutch, so add a high volume/pressure water pump to the order.
While I’ve already replaced the thermostat once, might as well see what else is available. Would you look at that – there are high flow thermostats available! Add one of those to the order.
Replacing the water pump and fan clutch isn’t that bad of a job, but it still took a couple of hours. The thermostat is a different story – it is buried under the AC compressor and tightly protected by the 5 braces supporting the compressor. One of the bolts can be reached with a swivel socket, but the only access to the other bolt is with a wrench that can only make 1/8th of a turn at a time. Both removing and installing the bolt…
By exercising the full capabilities of my patience the high flow thermostat was finally installed with no collateral damage. Top off the coolant and time for a test drive!
Initial results weren’t encouraging. Once I got on the highway temperature headed up toward the hot line. Crud! Another dead end!
But after 10 or 15 minutes of driving the temperature started dropping, ending up on the normal temperature line. And it stayed there! Odd, what is going on here?
After a few minutes of thought, it looks like this behavior could happen as air was purged out of the system. The cooling system had to be drained to replace the water pump and thermostat, so introducing air into the system was a concern. Air locks in the cooling system are a common cause of overheating.
Did I manage to get lucky? While encouraging, this was a 60 degree day, so still not definitive. Need to try it on a hot day to be sure.
Today was in the mid-80’s so fire up the Imperial and head out. It quickly warmed up to normal operating temperature – so far, so good.
Head to the Interstate and start cruising with traffic at 70-75 mph. The temp gauge moved about a needle width above the normal line. And stayed there! I put in close to 50 miles of high speed driving with the temp gauge holding steady. Even better, the air conditioner was running the whole time, putting additional stress on the cooling system.
Getting off the Interstate the temp dropped slightly to right on top of the normal mark. Perfect! This is exactly what you would expect if the cooling system is working correctly. I need to test it on a 95 degree day, but it should still be OK.
And, needless to say, there was much rejoicing!