Head back on 454 Vortec 1997

[trop-a-cal]

The heads back with no cracks and on the block. This engine had two cylinders getting antifreeze in from a head gasket leak in between them. Now the rest of the top of the engine has to be installed and fluids added before we start it up. It was ticking then knocking and had a sweet smell of antifreeze as it was being burnt in the two cylinders. The sweet smell and very minor consumption of antifreeze had been present for 3 years before the leak got so bad it flooded the cylinders when shut off and still hot. Upon restart it pinged and dogged until the engine reheated and the leak slowed down. The ticking started first then the knock as it got bad. Then we think the distributor gear chewed up as the one bank was under more compression than the other so it shut down only to restart with new distributor worm gear. Then the engine shut down again, perhaps with a crank shaft sensor signal due to uneven banks compression. It's only 46K miles and no indication yet of any other problem.

[MEXICOWANDERER]

Way back in the days of pterodactyls and stegosaurus, I learned factory engines had horrid machine work quality of the block and cylinder head mating surfaces.

A machinist would jig the BRAND NEW cylinder block in the milling machine and the first pass cutting "decking" the block .010 made my jaw drop. Same thing for milling the "heads". The factory machining quality control sucked!

Even with a compression ratio of THIRTEEN TO ONE using LPG propane motor fuel in a heavily loaded R.V. I never ever had coolant leakage or combustion gas leakage. For many years.

So this may be something to think about...

[mchero]

Sounds to me like it's time to pull the engine.

[byronlj]

Did you check for bent connecting rods. If you hydro-locked those two cylinders it could cause bent rods and knocking.
Dave

[trail-explorer]

trop-a-cal wrote:
... the leak got so bad it flooded the cylinders when shut off and still hot. Upon restart it pinged and dogged until the engine reheated and the leak slowed down. ...

Was there evidence of antifreeze in the oil?

If the leak was so bad that it filled up two cylinders, I'd be really concerned that AF was leaking past the piston rings and down in to the crankcase.

[trop-a-cal]

Full compression in left bank so not pulled. Nothing redone to leaky head as it came back as it went out as nothing was found. Since it never overheated, no damage was done to it. Two cylinders were the interior ones that had leak in the middle at closest point.

[j-d]

Took me awhile to remember this case, since now you're in a different thread.
Glad it doesn't seem like major damage, but I have a question...

... Did you pull the other head and re-work both? Change both head gaskets?

[ScottG]

A little surprise I had after installing a Mr. Goodwrench engine was that apparently anytime an eng digests antifreeze, it murders the 02 sensor!
I learned this the hard way after driving it and feeling like it just didn't have the power it once did. A new sensor solved the problem but it took a while to figure it out. An old mechanic that knew about this enlightened me.

I think you use the same sensor and it was cheap - less than $30.