BodybyFisher Posted November 8, 2006 Report Share Posted November 8, 2006 That is an interesting idea Johnny. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Bruce Nunnally Posted November 8, 2006 Report Share Posted November 8, 2006 Dexcool should be good up to 100-150K miles IF the cooling system has maintained integrity. If the cooling system is not checked & maintained, then all bets are off. Sorry if there are a variable number of *'s; some were manual and I didn't pay attention to #. We did have one report this year of a timing chain / sprocket that had to be replaced. By carbon rap do you mean early detonation due to build up of carbon on the piston? In which case I agree this can be a cause of headgasket failure. Also an actual build up of a carbon layer in the cylinder head could likewise cause failure I would think. Bruce 2023 Cadillac CT4-V Blackwing Follow me on: Twitter Instagram Youtube Link to comment Share on other sites More sharing options...
Ranger Posted November 8, 2006 Report Share Posted November 8, 2006 By carbon rap do you mean early detonation due to build up of carbon on the piston? No Bruce. Cold Carbon Rap is a build up of carbon on the head from babying it and the piston actually contacts the carbon causing it to rotate on the wrist pin. The skirt then slaps the cylinder wall aka piston slap. Usually only lasts til the cylinder warms up. 60seconds or less from my observations. Link to comment Share on other sites More sharing options...
JohnnyG Posted November 9, 2006 Report Share Posted November 9, 2006 By carbon rap do you mean early detonation due to build up of carbon on the piston? In which case I agree this can be a cause of headgasket failure. Also an actual build up of a carbon layer in the cylinder head could likewise cause failure I would think. I was thinking the latter, as Ranger has said, and more in the "mechanical" force vein. But, I understand your point. That's another interesting possibility, though it really never occured to me. The Northstar combustion chamber design is such that the squish areas might begin to detonate early as combustion pressures rise due to carbon build IN THOSE AREAS. Might the flame front spread to the rest of the cylinder, or stay localized? I don't know. It's not a captive area, so there may be NO detonation at all. I do think however that either scenario is equally bad for the engine and should be avoided with the judicious use of the WOT procedure. Look at it this way, if it's a mechanical noise due to the pistons hitting the head and rocking the piston, it's REALLY bad.....if it's detonation, it's not so bad, but bad enough to do something about it immediately. Letting it go would NOT be a good idea. Especially when the cure is so much fun! Never underestimate the amount of a persons greed. Link to comment Share on other sites More sharing options...
Ranger Posted November 9, 2006 Report Share Posted November 9, 2006 Look at it this way, if it's a mechanical noise due to the pistons hitting the head and rocking the piston, it's REALLY bad.... From what I recall the Guru saying, that is nothing more than an anoyance. Link to comment Share on other sites More sharing options...
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