farout squarecat
Member
The other day we noticed that the engine in our stock '04 ST has a spark knock, but only when the A/C is on. We noticed this last year too. Any ideas what the problem might be? We always use 87 octane gas. Thanks.
spark knock only when A/C is on
- Thread starter farout squarecat
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Jeff C
Well-Known Member
You're positive it's not just the a/c compressor clicking?
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I had this only after getting a tune for my Xcal, Timing was too high..LOL
But as Jeff said, It could be the ac noise, OR the serp belt tensioner rattling that sounds like spark knock...
Todd Z
But as Jeff said, It could be the ac noise, OR the serp belt tensioner rattling that sounds like spark knock...
Todd Z
farout squarecat
Member
I am certain it's not the compressor clicking, (I can hear that loud and clear also!)
I don't know what the belt tensioner rattle would sound like. The noise only happens when driving with the AC on - and when the AC compressor is "engaged", so the belt tensioner rattle idea is worth pursuing.
I'm assuming that when the AC kicks in the belt gets a little tighter?
I don't know what the belt tensioner rattle would sound like. The noise only happens when driving with the AC on - and when the AC compressor is "engaged", so the belt tensioner rattle idea is worth pursuing.
I'm assuming that when the AC kicks in the belt gets a little tighter?
- Joined
- Sep 21, 2003
- Messages
- 22,458
- Reaction score
- 796
- Location
- Long Island, NY
- What engine do you have?
- V8 engine
- What year is your Sport Trac?
- 2010
- What Generation is your Sport Trac?
- 2n Gen Owner
Parts of the belt get tighter an other parts get slack, then the tensioner has to take up the slack and thats where it can get noisy...
Todd Z
Todd Z
