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Rebuilding of '99 Northstar Engine


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My 99 Seville STS blown head gasket and started to take coolant into the combustion chamber. There ins't that many shops that rebuild Northstar engines. Some insist on installing block inserts (coil or solid type) to prevent treads stripping.

I found Accurate Engines in Grandville, MI quoting full rebuilt for $3K with 3 year unlimited mileage warranty. They don't use inserts but supposingly stay behind their work. Have anybody used them? What comments do you have on rebuilding with vs. w/o block inserts?

Thanks, Marucha

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For a long lasting repair, the Timeserts (a solid threaded bushings) must be used. Heilicoils will pull right out. I would be afraid that the Accurate engine's threads would pull when it was just outside the warranty period. Even if it failed within the warranty period, the warranty would not cover the R&R of the engine.

There is not much that would need attention on that engine - just get the head gaskets fixed properly and it will be good for 200,000 more miles.

'93 Fleetwood Brougham
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I agree with Kevin and Jim.

The short answer is, I recommend that the Northstar engine head bolt holes be time serted any time the heads are off, including for rebuild or gasket repair.

The book answer is that the bolt holes only have to be time serted if the threads pull. It is a repair procedure.

Time serting the holes does add expense in labor, and minor expense in the timesert parts.

The problem is one of economics however. As Kevin points out, if you have to R&R the engine a second time 12-14 months from now because a head bolt thread pulls, you will have another large expense. The powertrain will have to get taken out of the car again, and the heads off, and the holes timeserted, new gaskets, new head bolts.

It is simpler to just time sert the head bolt holes the first time the heads are off and have some surety that they won't pull out later.

Timeserts are the only approved head bolt hole repair procedure for this engine. Heli-coils can not be used.

With regard to Accurate Engines, http://www.myengine.org/ if they are local to you and the 3y/unlimited warranty would include future repair costs if the head gasket blows, or the threads pull, then that seems like a good deal, and let them keep the risk.


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Do it right the first time or regret it later. Nothing can cover your lost time with a car down for repair. You only live once.

Eph 5:15 See then that ye walk circumspectly, not as fools, but as wise,

Eph 5:16 Redeeming the time, because the days are evil.


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Take it from those of us who have been down this path.

The Time-serts are needed to make sure the bolts don't pull after all the work has been done and the engine is back in the car. As stated, the Heli-coils won't take the force.

Sure, you could take the risk, but paying $300 for a Time-sert kit versus pulling the engine again and then having to Time-sert it anyway to get it back on the road was enough incentive for me.

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