Spark Knock

[tomj22]

1995 Windstar 3.8. Can anyone describe what spark knock sounds like? I have a lound tinny sounding rattling noise when the engine gets a lot of rpm's. Kind of sounds like a paint can rattle when you first start shaking it. Doesn't matter if in park ( I rev engine uo), neutral or driving. It kind of sounds like a push rod hitting the valve cover put I know it's not that. Also sounds a bit like a bad berring but the van doesn't smoke and the compression is great. If I give the gas gradually I don't hear it. Is there a spark sensor on these things? I have read ( on this site) the recommeded procedure for getting rid of the carbon i(spark knock) If need be I will do that but first would like to know if that is what I am hearing. Sugesstions and opinions welcomed. Also - I do not have a CEL on. I know that works due to recent codes for tranny and it still lights as it should when I start car but goes away when engine running.Thanks

[wiswind]

I am not sure if the '95 has a knock sensor.....I think that it does. I DO know that the '96 and newer ones do.
I would try running to succesive tanks gasoline with fuel system cleaner. I would use either Redline Complete Fuel System Cleaner (1 bottle) or Chevron Techron (2 bottles). You have either a 20 gallon tank, or the optional 25 gallon tank. The cleaner will clean your injectors and valves.....It will help with carbon build up....but not much, if you have much buildup.

Also, look for anything loose, such as catalytic converter heat shields. I had the insides of one of my converters come loose and rattle. If the rattle happens at idle.....a careful listen around may help....but only at higher rpms.....kinda hard to track down.

Hopefully you have not had the coolant level dropping in the overflow bottle....which would lead you to suspect internal engine items...such as bearings, etc. (coolant in the oil).

[tomj22]

Thanks for the sugegestions. I will try the cleaner. Fortunetly my cooent level is fine. Thanks again