All Small Six Head Bolt re-tightening after Break-in period

[tonyduc]

All
Is there a need to re-torque head bolts after breaking in a rebuilt engine (proper sequence was done a/t manual)? I put about 3,000 miles on my 170 Bronco, there a slight oil leak around the head gasket, can live with that, but just wondering if certain bolts need tightening after break in.

 

[aussie7mains]

NO, this was never in the service manuals, and is unnecessary.

 

[alwill923]

I always retorque. There is a procedure to do this. I just loosen each bolt slightly to break the friction and then torque to spec.

 

[Cox Custom Mechanical]

No they do not.

With a quality composite gasket and 2 machined surfaces you should not have any trouble. Most people don't bother maching the deck surface to save a few bucks and it leads to this issue. Loosening and tightening a composite gasket is like ripping off tape and trying to stick it back down, a recipe for a premature failure.

MLS or Copper is a different story when running high cylinder pressures, but its not relevant here.

 

[tonyduc]

Thanks, I'll then leave it alone. It's more sweating from the gasket area, but no oil really drips to the floor.

 

[bmbm40]

How did your 170 rebuild turn out? Running well I hope. Did you get a new exhaust manifold with 2" outlet?

 

[ActionYobbo]

I always retest the torque on the head bolts after first long heat and cool. Don’t disturb the bolt just put the torque wrench on and slow pull to clicks. If you have a bad bolt you will know when it turns. If you find a suspect bolt then check them again after another hot run.
I have a motor in the stand now that was “professionally rebuilt” that has just over 6k on it and it’s blown the head gasket between 3 and 4 which was most likely from lose head bolts. When I was taking the head off the bolts between 3 and 4 were hand tight and 2 others were only just firm. I have never blown a head gasket on an engine I have retorqued after the first run (proper operating temp for 5 or more minutes) lose bolts are from block deck or head warp/stress relief so just because you hit the mark with your torque wrench on assembly won’t take into account heat stress or warp. The deck is flexible that’s why a top engine builder uses a torque plate to keep the cylinders trued up for boring and honing.

Bottom line is retorque won’t hurt and it has benefit’s