First time caller here... I got a Cruiser for my kid who graduates HS today. 2001 Base, 72K, 5spd (for some reason, he like other teens want a stick - they have not learned yet!) and a killer price at auction. It went thru my typical new (to me) checkout and seemed fine, but one issue was noted it had no thermostat and on the day I patriated it from the auction, it was a chilly ride. Once I drained the water and used antifreeze and installed an over priced thermostat, it seemed fine. Until a highway trip last monday it overheated. I showed the age old 'heater on high' trick and it kept the needle out of the red, so I tore into it and found a TON of sludge in the filler/thermostat neck. WTH? Further investigation and testing has found the following, and hence my post. It should be noted that overheating is by far the LARGEST issue reported with the cruiser. Everything I likely will state here may be stated elsewhere and on other forums, but when I went thru a google search, the data is random and haphazard. Since I search first, buy parts later, this may assist someone in the future. Part 1: The problem as it were 1) The cooling system on the PT is way undersized. Period. Radiator size is dictated primarily by HP generated by the motor and can be mitigated *somewhat* by airflow over the core. 1A) the cruiser has a stylish front end that impedes airflow at low speeds 1B) typical traffic in the US nowadays guarantees congestion near any population 1C) the cruiser makes near 150hp which is pretty sporty for a core the size of the tranny cooler on my Suburban *all* engines are aircooled. Most of the cooling at speed occurs from airflow (auto engineering 101) and liquid cooling is essentially for the heads due to other issues. A combination of factors (square area, airflow, airflow speed, effective channeling) are all compromised on the Cruiser design. 2) the PT uses the newer OAT based silicon free coolant which is a mistake - plain and simple. 20 years of actual data has shown us that this coolant is only acceptable when *zero* fresh oxygen is available. Otherwise it forms a sludge that looks like oatmeal and diarrhea. Most vehicles using this have a radiator fill that doubles as the overflow tank and is sealed to the outside, any oxygen in the tank is incidental. On the Cruiser the tank is very remove and is vented to the outside, the cold vs hot volume of the tank varies by about a pint - typical, but each movement flushes and refills the tank with fresh oxygen. This is a different looking, but identically operating system used for example, by the W-motor S/T GM vehicles, which was a disaster using dexcool. 3) No larger radiator seems to exist. Reserve cooling capacity is extremely small. For example, in the early/mid 80's ford used on the manual trans, ac-delete, I-6 motor F-series a small radiator (larger than the PT by 50%) with a direct drive fan. Capacity was so limited that replacing the direct fan with a clutch fan would result in overheat at low speeds, and this is on a bull-nose vehicle. From looking at it, there is no reason the radiator cannot have 2 cores, but none are OTS available. I did not look at the turbo model radiator, I figured where would be other fitment issues on a non-turbo due to the likely use of an intercooler - Mopar tends to get the Turbo 4's right. So, next post!