Overheat shutdown problem I didn't see any water in the oil?

Tiny
JB6870
  • MEMBER
  • 2004 CHRYSLER PT CRUISER
  • 2.4L
  • 4 CYL
  • 2WD
  • 83,000 MILES
So I had my timing belt go out and fixed it with my uncle. Car drove fantastic, on the way home the car shut down. The gauges never showed it running hot but it did. Appears the thermostat stuck and the radiator blew. So I assume the head gasket is probably toast. Tried to crank it and it turns over but wouldn't crank. I didn't see any water in the oil but I figured it still had a blown head gasket. After turning it over a million times I did get it to run. Ran badly tho. So I got the number of a guy who is supposed to know a lot about Chrysler's and he told me the car will shut down if the thermostat doesn't open and I should replace the thermostat and try and crank it again. Now the car has sat for about 7 months now and I was wondering if I change the plugs, oil, thermostat and new radiator if this guy is right and the car will run fine? Or should I just invest in another motor. Car is one of the better looking at cruiser with heated seats and power everything. What is your opinions. Thanks in advance.
Saturday, January 18th, 2020 AT 9:14 PM

6 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Before anything, we need to determine what has happened with your engine. Since you are questioning the head gasket, here is what I suggest. First, lets run a compression test. If the head gasket is out, you will find low compression in one or more of the cylinders.

Here is a link that explains how in general it is done:

https://www.2carpros.com/articles/how-to-test-engine-compression

Compression should not be less than 100 psi and not vary more than 25 % from cylinder to cylinder.

When you perform the test, pull the ASD (auto shut down) relay from the fuse / relay box under the hood. That will shut down both fuel and spark. See pic 1 for location.

Also, take a look through this link. You may find it helpful.

https://www.2carpros.com/articles/head-gasket-blown-test

I have to be honest, I never heard of a stuck thermostat automatically shutting the engine down. The thermostat functions based on coolant temperature and has no electrical connection to shut the engine down.

Try the compression test and let me know what you find.

Joe

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Thursday, July 1st, 2021 AT 1:30 PM
Tiny
JB6870
  • MEMBER
  • 4 POSTS
Thank you. I appreciate you advice. I will watch the videos and try and get that done. If it is the engine and it needs a rebuild is it easier to rebuild it or just replace it with another engine?
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Thursday, July 1st, 2021 AT 1:30 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

If it is only low compression, it may be a head gasket. The head would need removed and checked to make sure nothing is warped, but I feel that would be easier.

Let me know the results. I can help you with the gasket or repairs if that is the case.

Take care,
Joe
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Thursday, July 1st, 2021 AT 1:30 PM
Tiny
JB6870
  • MEMBER
  • 4 POSTS
Hey Joe, thank you.I have been thinking about this and how it happened. I replaced the timing belt, was driving home from across town and the car was running great. The gauge didn't run hot but the car overheated and stopped running. It blew the top of the radiator so I guess the thermostat got stuck. Towed it home and took a lot of turning it over and it did eventually start and run, ran like crap but did run. It did not smoke out the tail pipe tho. If I put a new thermostat and radiator, change the oil and plugs is there any chance it would run correctly? Just throwing this out there for your opinion. I hear these are pretty tough little engines.
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Thursday, July 1st, 2021 AT 1:30 PM
Tiny
JB6870
  • MEMBER
  • 4 POSTS
Also thanks for the information on checking the head gasket for leaks. Very informative.
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Thursday, July 1st, 2021 AT 1:30 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

I have to be honest, the items you indicated won't make it run properly. Something has happened causing it to run bad. Is there any way you could record it cranking so I can hear what it sounds like? Also, it's interesting that the temperature gauge wasn't high. I wonder if the radiator failed and coolant damaged one of the electrical components. That is just a thought. How much coolant got all over the engine and did it soak everything?

If you do a compression test and it checks good, then we can suspect the problem may not be the engine at all, but rather it may be an electrical component such as a crank shaft position sensor. Please understand, this is only a theory, but the compression test would answer a big question.

Let me know.

Joe
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Thursday, July 1st, 2021 AT 1:30 PM

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