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Old 01-17-2018, 01:09 AM   #1
Damien
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Spark knock?

I put a used engine in my '92 K1500 a few months ago and the engine had been running great. I think the engine has about 150K on it. Over the last couple weeks my gas mileage has been getting worse, about 10 mpg, but I figured this was because the temps have been below zero. The truck started idling a little rough yesterday and this afternoon I noticed the coolant temp was bouncing around between -32 and 190 degrees. About the time the DTC for the coolant temp sensor was set I noticed the engine knocking. I replaced the coolant temp sensor and the pigtail tonight, but now I have a knock that gets progressively worse while accelerating and during highway driving. If I shift into neutral and rev the engine its not there. I checked the timing and that seems fine. What else should I be looking at? Ignition module? Thank you for the help.
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Old 01-17-2018, 09:59 AM   #2
Mr_Rich
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Re: Spark knock?

You know where the knock sensor is? It's screwed into the middle of the block right by the starter. Check that first.
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Old 01-17-2018, 04:51 PM   #3
Tom
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Re: Spark knock?

Make sure its an engine knock as well. I thought I had one...flexplate was about to come all the way apart via the half way threw crack that had started
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Old 01-17-2018, 08:53 PM   #4
Damien
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Re: Spark knock?

I'm going to try the knock sensor tonight and see if that helps. I put the engine in in August and didn't see any cracks then, but that does mean it hasn't happened since then.
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Old 01-18-2018, 12:14 AM   #5
Damien
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Re: Spark knock?

No luck with the knock sensor. I ran across a thread by Ackattack where he was having similar issues and his problem was a blown head gasket. After the knock sensor I decided to check compression on a couple cylinders be fore spending too much time swapping parts. Checked cyl.3 and got about 150 psi, cyl. 4 not so good. I have about 50 psi so it looks like I'm doing head gaskets this weekend. Thank you for the help guys.
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