I got my engine running again last night after changing the timing cover and chain. No oil leaks so far but had to retorque the water pump after a couple heat cycles. Had a drip so hope that is gone.

No progress on the exhaust leak and the best thing I did today was stop working. Spent too long fighting the front u joint. Pulling the clips made this much easier. Broke my reading glasses so couldn't see the clips at first.

 

The aggravating thing is that I just changed the gaskets maybe 20k miles ago... oh well...

At least I know what I'm getting into this time? lol

 

How did you make out with the intake gaskets? Any idea why new ones would fail in only 20k? What brand of gaskets did you use? Did you follow the tightening torque pattern on assembly?

 

I honestly have no idea. They were Felpro brand gaskets that I installed. It's been so long ago, but I'm pretty sure I followed the torque sequence...

 

It’s odd that your gaskets went bad, but **** happens I guess. I suppose you could look at it as a good excuse for a new thermostat, and fresh flush/fill of antifreeze.
When I had mine apart, I also replaced the oil pressure sensor and knock sensor with new GM parts. Both inexpensive items, and much easier to do it now as preventative maintenance while you’re in there; especially if you’ve still got the original 16 year old parts on your engine.

 

This vintage of 4.3L are known for this failure. As soon as heard about this I replaced mine and found that they were beginning to go.

There are stories of these gaskets fsiling catastrophically dumping coolant into the lifter valley ruining the bearings when it is pumped through oiling system.

 

You missed some of the thread, he already said he had done the job with Fel Pro gaskets only 20k ago

 

I believe there are two different Fel-Pro part numbers. One is the improved rubber on metal style, and the other is the OEM type. I wonder which one he used.

BTW, that's one of several reasons I use propylene glycol coolant. It's not nearly as damaging to bearings if a little gets in the crankcase.

 

Indeed, there are two types of Fel Pro gaskets, and the more expensive metal backed gasket is always recommend.

Changing the gasket and using green antifreeze has been a suggested repair. Dex-Cool was known for causing premature failure of OEM intake gaskets by dissolving the gasket material. Supposedly the formula was changed to prevent this.

However, Dex-Cool is a superior antifreeze in many ways. If the upgraded metal backed gaskets are used, and the intake is tightened in the three step torquing procedure as indicated in the GM service manual, there is absolutely no reason not to use Dex-Cool.

As an aside, years ago I had replaced the intake gaskets on one of my first s-series trucks with the less expensive plastic Fel Pro’s. I flushed and filled the dex-cool, and drove the truck another 100,000 miles without a problem before I sold it.

Edit: PS, I’ve made a habit of having a Blackstone oil analysis completed after each oil change of all my vehicles. This is the easiest way to keep track of oil performance and engine wear, in addition to staying advised if any contaminants such as antifreeze makes its way into the oil.

 

You know I've heard of the "upgraded" gaskets, never knew what the difference was though... Never thought to ask for them at the parts store, and was never offered anything different...

The ones I installed back then were the plastic gaskets, and the new ones I have now, are plastic...

That being said, I dove in today after I managed to get off work a little early and actually got further than I thought I would. At this time, the new lower intake is installed and torqued down to spec, with the plastic style gaskets... so that's what it's getting lol. I did plan on flushing and using green antifreeze though, so maybe that'll help keep these gaskets alive a little longer?

Pretty sure I found my gasket blow out that caused the loss of coolant. The very rear of the passenger side looked the same, but it tore apart when I pulled the manifold off.






Can see my trusty 'ol faithful C-clamp that's held the thermostat housing together since the last time I changed the thermostat and the lower intake cracked at the forward most mounting location, that was about 4 or 4 1/2 years ago. Never leaked a drop there lol






So everything got cleaned up really good, ready for new gaskets and the manifold installation







And as it sits now. Torqued down and letting the gasket maker at the front and rear cure, and tomorrow it's just reassembly of everything else!