So, I've gotten the '85 Marquis LTS on the road, but have been dealing with a mild "over-heating" issue. It hasn't gotten over 225-230*, but with new cooling system components on a stock 5.0 with a 180* stat, it shouldn't be working hard.
New radiator, stat (180*), water pump, etc. Installed an aftermarket gauge (Stewart-Warner) to monitor the engine temps.
When sitting in the drive, idling/light rev (650-1500 rpm) it'll hold steady at 180-185*. I had it running at 1500rpm in the driveway for 20-30 minutues after swapping the radiator. Stayed right at 180*.
Driving, it does fine for a bit, then it starts to creep up. Coming to a stop and putting it on P or N allows it to stabilize or VERY, VERY, VERY slowly drop.
The car sat for a LONG time before I got it running, and I initially suspected a clogged radiator, but the new one only gave a but more leeway on how long until it starts to warm up.
After checking a few more things (lower rad hose collapsing? Timing off?) and ruling them out, I'm left with a couple other possible culprits. 1. Crud in the engine block or 2. the AOD is running warm and thus heating the engine up.
I'm discounting #1, as after running the car for a bit with the old and new radiators, there is no crud or debris in the coolant. All the stuff I drained for the swap was still bright green and no signs of rust or other junk.
I've been needing to swap out the pan on the AOD, as it had been nicked by a previous owner when they were hacking off the exhaust and has a small hole that is closed with RTV. It's not leaking now, but I have the parts to replace the pan and filter. Just need to take the tie to tackle that nasty job. The transmission doesn't appear to be shifting weird, but it is an AOD and I hate automatics and think they all shift poorly. (Gotta keep this one auto for the wife, though). No slipping or anything when changing gears, though. The level of the fluid looked good and doesn't look terrible. No idea how old it is though.
Seeing as it's heating up while the trans is engaged, I'm thinking the AOD isn't super happy, even though it's not showing any odd behavior. Probably worth a shot to do that filter/fluid service and add an aux cooler to it while I'm in there?
I can't think of anything I'm missing in regards to the cooling system of the engine itself. They're not that complicated...
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