what should i look out for on a 4.3l Chevy?

[Katmandu]

Originally Posted By: chevyboy14
What are common issues with the 4.3 that I should be aware of? Thanks guys.
SPUN ROD BEARINGS are extremely common on 4.3s over 125k miles. SERIOUSLY!

I've had (2)4.3s go bad after 125k. One spun a bearing and started knocking, the other simply froze up as I was backing out of my driveway (rod/crank bearings locked up).

Go check out the S10 and Blazer forums and you'll see what I mean.

Also, look at how many out on Craigslist are being parted out that have had an engine KNOCKING.

 

[Katmandu]

I've also read somewhere that the 4.3 rod bearing journal diameter is SMALLER than that of V8s.

Also, here's an interesting article on the 4.3s rod bearing failure issue.

http://www.hotrodders.com/forum/4-3l-v6-rod-bearings-124422.html

Quote:
As for 4.3 bearing damage. I was told by a bearing guy. That the reason for all the front rod and main wear is becaose GM went to the large pickup tube on the oil pump.

SBC chevies had no bearing problems since 55. Same with the 229 and many early 4.3's. All had the smaller inlet tube on the pump..

The reason, I was told, for the 4.3 problem, is when the engine is shut down. The oil naturally drains down to the pan.

When the engine restarts. The extra internal volume of the large pickup tube creates a large air pocket that takes just an instant more to overcome and in that time the front rod/main bearings get starved or a weak air/oil combo from the oiling system.

Causing just that little bit of wear. That plus the imbalance harmonics of this engine design really test the bearings.

 

[SteveSRT8]

Originally Posted By: cchase
I think it's a lot less common than the internet makes it out to be. I suspect most engines never have an issue.


This is true. All we have had in our fleet since the late 90's is GM v8 powered trucks. We NEVER replaced any intake gaskets or had any of these issues mentioned here.

Internet Amplification. I've seen that old 4.3 go nearly forever in a van body, and that's with abusive ownership.

 

[hattaresguy]

I have 92k on mine and other than a tune up and oil changes haven't done anything.

Oh wait one T stat, big deal.