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I have a 4.6 L northstar that overheated breifly and I cooled down as fast as possible. The plastic ac compressor pulley / ac compressor belt / and the smaller idler pulley were overexposed to heat and were damaged beyond salvage. Is this an easier repair for a do-it-yr-selfer? Is there a timing issue if I run the vehical with this drive system removed. It has been driven slightly before I discovered this problem. Ordoes this belt solely run the ac compressor and no other critical systems i.e.- timing/oil pump/ ? I have heard that this engine will advance the timing electronically when subjected to exceedingly high temps. I have solved the original overheating issue and am now in need of professonl advice. Please Help, and thankyou for your time. My, name is William.

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Hi William, The belt that you describe is not timing related or oil pump related, these items are controlled by a timing chain, which is not exposed.
The damage that you describe sounds like the unit got quite hot.
The things that your electrinics do in an overheat is stop firing some cylinders, to lower the temperature.

The nortstar has head bolt issues relating to overheat. In essence the headbolts are screwed into the aluminum block, and those threads pull out. The repair is extremely expensive to do correctly. Just changing head gaskets is a very short term bandaid.... The damaged threads need a threadsert installed, and you have to put a bare block on a machinists bench for that job....just plain ugly....To test for this issue, check for exhaust fumes in the cooling system....Compression gasses push coolant out, heater stops, and eventual overheat, top up with coolant, everything okay until next compression leak event.....

Posted on Mar 11, 2011


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