Check engine light on and white smoke from exhaust

Tiny
SSHERRILL1978
  • MEMBER
  • 2013 RAM 1500
  • 5.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 225,000 MILES
My check engine light came on. I had a test run on vehicle from AutoZone and it came back with misfire on cylinder 8. I had replaced spark plugs 6 months ago. I had checked the connection of coil wire plug. Removed coil pack, spark plugs and cleaned them. Reinstalled components. Light still on and now white smoke is coming from exhaust.
Thursday, July 30th, 2020 AT 2:20 PM

7 Replies

Tiny
KASEKENNY
  • MECHANIC
  • 18,907 POSTS
Unfortunately, this points to a head gasket issue. So we need to rule that out before you move much further. Here is a guide on how to test this:

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

You can also run a compression test but this is not as definitive as a chemical test on the cooling system but should be run as well.

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

Let us know if you have questions but let us know what this info is and we can go from there. Thanks
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Thursday, July 30th, 2020 AT 2:32 PM
Tiny
SSHERRILL1978
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I used the blue devil product and followed the directions. Drive vehicle down the road about 1.5 miles. Vehicle still running rough and on way back vehicle started to overheat. It blew smoke out the exhaust at first but I didn't notice it on the way back just overheating.
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Saturday, August 1st, 2020 AT 4:27 PM
Tiny
KASEKENNY
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So that is most likely misleadingly positive news. The fact that it is not smoking is good but now that it is overheating, I suspect you have a blockage in the cooling system causing minimal coolant to get to the possible issue in the head gasket which means it is not getting coolant to the place of the leak.

We need to use a laser temperature meter to find if there is a hot spot when this is overheating. If we can find a place that is hotter then an adjacent place that would be the blockage. Usually it is the radiator.

https://www.2carpros.com/articles/how-to-use-an-infrared-temperature-meter
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Sunday, August 2nd, 2020 AT 6:37 PM
Tiny
SSHERRILL1978
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Okay, I'll get laser temperature reader to use. Just curious though LLPif the vehicle didn't overheat at normal idle for 50 minutes per blue devil instructions. Why would it on a test drive a few miles down the road?
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Sunday, August 2nd, 2020 AT 10:49 PM
Tiny
KASEKENNY
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Good question. It is most likely restricted and not fully blocked. So there is just enough coolant passing the restriction to keep the engine from overheating when it is just idling. Then when you add the load to it and increase the RPM there is more heat and it can't keep up so it overheats. This actually supports the idea of a restriction so I bet you will find it. I think it will be the radiator but it could be something else.
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Monday, August 3rd, 2020 AT 6:21 PM
Tiny
SSHERRILL1978
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Oh okay. Sounds reasonable. I'll let ya know what I find out with. Thank you!
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Monday, August 3rd, 2020 AT 8:24 PM
Tiny
KASEKENNY
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Sounds great. We will wait to hear some good news. Thanks for the update.
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Tuesday, August 4th, 2020 AT 4:33 PM

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