Engine Overheating

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Reader Question

Hello Austin,

I have a 2004 Chrysler PT Cruiser non-turbo. The car overheated one day and I immediately began searching for the problem. To make a long story short, I replaced water pump, Timing belt, t-stat, temp sensor, cap, flushed radiator completely and re-filled with HOAT coolant as recommended.

The car still over heats, cooling fans are working with A/C and without A/C thus I am leaning towards a blown head gasket! Will the K&W engine block sealer work on the PT Cruisers? Shop wants well over $1500.00 for the repair. short of replacing the radiator itself, I have done everything else.

HELP!

Michael
Hi Michael,
Thanks for your email.
You have not mentioned any of the typical signs of a blown head gasket (running rough, white smoke out tailpipe, constantly adding coolant, oil in coolant, coolant in oil) so I would not jump to conclusions just yet.

First things first.
#####1. Get a cooling system pressure test, (will also tell you if there is an internal coolant leak inside the engine )
If there are no coolant leaks and you are not having to add coolant on a regular basis.
2. When does the engine overheat?  At freeway speeds or anything really over 35MPH, I would be suspect of a restriction in the radiator or some other coolant restriction….kinked radiator hose, air bubbles trapped in cooling system etc.
Overheating at stops or very slow moving traffic is usually due to an electric cooling fan not coming on when it should. Of course, a radiator restriction can also show up as well if the coolant can’t circulate throughout the engine properly.
Since you have replaced just about all major cooling system components, I can only ASSUME you have a restriction in your radiator. Flushing basically does nothing but remove any floating debris in the system. Replacing the radiator is the only real option to remove a restriction at the bottom that has been accumulating over the years.
Once the engine is at normal operating temperature, feel the upper and lower radiator hoses…they should be pretty close to the same temperature give or take a few degrees. If one is much cooler, than a restriction is probably the cause.
2004 is not really that old, but depending on how many miles you have, how well maintained the coolant was could still put you at risk of needing to replace it.

IF the coolant you flushed out was rusty at all then yes…a restriction is very possible. Those radiators are so thin to start with they plug up very easily.
One last thing to consider. The temperature sending unit and dash gauge accuracy.

The temperature sensor is a computer sensor and not the dash gauge control…that is a temperature sending unit which screws into the engine.
Very rarely these days do you find a sender or gauge issue, but I would make sure the engine is really overheating when the gauge says it is.

I use a thermal heat gun to check, but you can also listen for hissing noises, smell under the hood for a heat smell (ya, you can actually smell it) and feel around with your hands if the engine is obviously hotter than it should be.
Finally, yes the K&W Engine Block sealer will work well on this vehicle, but rule out everything else first. I am not convinced you have a head gasket type of problem.
Keep me posted will ya
Blessings,
Austin Davis

Here is a short video that I made about engine overheating that might be helpful to you.

Reader Follow Up

Mr. Davis,
Thank you for your kind, timely response. I do have white smoke but only when cold, when the car warms up it goes away, doesn’t run rough, I do have to add coolant, but only after it boils out of the reservoir.

I do not have oil in cooling system, (just flushed yesterday) coolant came out clean and clear no “rust color” the top hose does not immediately become charged when the car is started, takes about 7/10 minutes, and no coolant in oil, cap is clean, dipstick is clean. I will have the system pressure tested today to check for leaks, and I plan on replacing the radiator as a precaution.

The overheat occurs during in town, stop and go driving, about ten minutes, or 3 to 4 miles. I have burped the system repeatedly to resolve any air pocket issues, and followed the procedure again when I refilled the system yesterday. Upper and lower hoses do not have much temp difference when hot. I plan on replacing the fan/motor and high speed pressure switch, again as a precaution, since the fan comes on at different temp intervals without the A/C on.

It does stay cool when running the heater, or the A/C, but the fan will come on sometimes at 1/3 and sometimes at 1/2 on the dash gauge, but always at different times, and does not seem to come on at all while driving in town? I will follow your most welcome advise and let you know how it goes. In the mean time, if it helps other owners, please feel free to post this to your blog, as that is how I found you.

 

Hello again Michael,

 

I would assume the exhaust smoke you see on first start up is just normal condensation remaining within the exhaust system.

The upper rad hose will not become firm until the engine heats up and the thermostat opens fully.  not an issue there either.

Overheating at low speeds, and within 10 minutes?  Hummm, that could be the issue.  Next time it overheats jump out, open the hood with the engine still running and see if the electric radiator cooling fan is on.

You have 2 cooling fans up near the radiator? If so, one is the A/C condenser fan for the A/C and the other is the radiator fan, usually closer or on the radiator itself. That fan should be running, and the air that is being drawn from that radiator fan should be hot if you put your hand in that air space. IF the air is cold, then there is not enough coolant in the radiator or there is a restriction in the radiator not allowing enough hot coolant to flow.

You should also turn on the heater inside the cab and use the high speed of the fan. That air coming out of the heater should be very hot and you might be able to bring down the engine temperature by doing so. If that air is cold, then there is not enough coolant in the radiator or there is a restriction.

If the heater is blowing hot air, I would assume that the electric radiator cooling fan is not working for some reason.  Either the fan motor is bad, or it is not getting the proper signal to turn on from the relay or a radiator cooling fan sensor….which I THINK is located at the bottom of the radiator in one of the side tanks on your vehicle.

 

Blessings,

Austin Davis

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