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How to fix my 2005 PT Cruiser?


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In my driveaway business and personal use, I have been building and working on my own PT Cruisers (on #5 currently) as tow cars for 2 decades and never stumped the pros until this one...

First, let's establish the patient: 2005 bottom baseline with 5 speed manual... 2.4L... non turbo.

Problem: This sweetheart wants to build pressure in the cooling system to consistently gain pressure over 18-20 lbs past 1500 rpm and will force antifreeze to the overflow bottle and continues forcing until the engine level is low enough to genuinely overheat ( No, I am EXTREMELY observant and this engine has never been overheated ).

Slow the rpm down to 900 idle and the pressure returns to under 16# (normal) and the overflow bottle doesn't change... no more fluid

Current mileage: 161,000 /  Timing belt and water pump 130,000 /  New Radiator less than 500 mile as an experiment with new hoses, worm gear clamps, etc.

Here's the kicker - please do not say heads, gaskets etc., as I have (and others in repair have independently ) fully tested for CO2 aspiration at the radiator and the Blessed Test Fluid STAYS BLUE! All cylinders pressure test to within 10% of original specs. No engine water leaks. No oil consumption. period. I change oil (Mobil1 10-40 HM) every 5,000 miles, needed or not - and virtually each of my cruisers have gone over 300,000 on the engine - cruiser #3 went over a documented 750,000 total rolling miles with over 400,000 on the original motor - IRS has my proof.

The golden question: At what other point can you induce pressurized air into the cooling system without showing any sign of leak when it cools off after shut-down?

Changed caps 3-4 times... also 4 thermostats (@195) using NAPA and dealer parts.

Water bottle is a crap shoot as to whether it will be vacuumed back or not.





2 Answers

Why I don't care what kind of protest does the pressure builds up like that your head gaskets starting to blow you don't necessarily have to get exhaust gas into the coolant to have had gas cuz it's starting to blow they can blow many different ways

Thank You!

I installed an LKQ engine from a previous PT that I had in my garage. Works beautifully and I thank you for pushing me over the edge. Thanks.


Properly burp the air out of the system.