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Weird Coolant System Issue

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Old 03-12-2019, 06:55 AM
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Default Weird Coolant System Issue

Hello,

Finished up my AP1 swap after old motor went bad
Wanted to drive the car last weekend, went to start had a very difficult time but it did
This was surprising since started fine weekend before

Anyways I quickly noticed my AP1 temp gauge was bouncing from 1 Bar to 5 Bars back to 1 Bar
I turned it off, put it back in garage and waited to pick up the Code Reader from a friend as I had a code one

Got the code reader from my friend, plugged it in and than started.
Car started perfectly and temp gauge was normal, I let it idle to 3 bars and the reader read coolant temps of 170-180F
The only code I had was for a O2

Everything seemed normal so I went for a drive, drive went fine bout 30mins
I had the OBD reader plugged in the whole drive, and 3Bars stayed constant

I pull into the driveway, check codes again nothing
Temps fine still, so I pull the reader and go to back the car in.

As soon as I pulled the reader my temps again got crazy, and car stalls out.
I open bay, I noticed some coolant sprayed over my block, not much, but I am unsure if it overheated somehow?

Car would not start now, so I decide to plug the reader in before starting and again car started fine
I tested this 3 times, and worked every time
How is that possible? The OBD reader should not have anything to do with it

Air in system?
Coolant Temp Sensor?
Thermostat?

Any help is appreciated

Old 03-12-2019, 07:30 AM
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If your engine overheated, the coolant would include lots of steam, there would be a lot of heat coming off engine, it would probably be ticking a lot, and there would probably be burnt oil smell.

So I suspect you have some coolant leak associated with the swap (something not tight, a hose or fitting damaged during tbe work, etc).

That explains the coolant leak, but not much else. Did you remove the coolant temp sensor during the swap? If its not making a good connection, it could make the temp reading wildly inaccurate. If its making an intermittent connection, it might explain almost all the symptoms. It reports wrong temp, all over the map, making gauge go nuts. But this also makes the fueling go nuts, as ecu is trying to fuel based on temps that are jumping around. This could also cause the o2 sensor to throw a code, as fueling is way wrong.

The only thing a temp sensor doesn't explain is why it likes code reader plugged in.

So was temp sensor touched during swap?
Old 03-12-2019, 09:05 AM
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Originally Posted by Car Analogy
If your engine overheated, the coolant would include lots of steam, there would be a lot of heat coming off engine, it would probably be ticking a lot, and there would probably be burnt oil smell.

So I suspect you have some coolant leak associated with the swap (something not tight, a hose or fitting damaged during tbe work, etc).

That explains the coolant leak, but not much else. Did you remove the coolant temp sensor during the swap? If its not making a good connection, it could make the temp reading wildly inaccurate. If its making an intermittent connection, it might explain almost all the symptoms. It reports wrong temp, all over the map, making gauge go nuts. But this also makes the fueling go nuts, as ecu is trying to fuel based on temps that are jumping around. This could also cause the o2 sensor to throw a code, as fueling is way wrong.

The only thing a temp sensor doesn't explain is why it likes code reader plugged in.

So was temp sensor touched during swap?
Thanks for this info, yes might have been damaged.
I will test with a friends sensor and report back

Based on your description of an overheat, I think you're right there may be a leak
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