Mechanics

99 AWD LOWER END KNOCK

1999 Chevrolet Astro

I have just purchased a 1999 Astro AWD with 165,000 4.3 VIN W. He took the van into a repair shop and had then change the lower intake gasket (dex-cool caused it to start leaking) Once he got the van back he drove it for 2 days with lower than normal but tolerable oil pressure. Instead of the normal 40-idle 60-driving it was 20idle 40 driving. On the third day he was getting on the the highway and noticed it lowering towards zero so he pulled over and as soon as he stopped it started the engine started to knock. The engine only ran for about 4 seconds knocking. He then had it towed home and a few days later started it and it came up to full oil pressure and was not knocking. He then drove it from his house to the shop that did the lower intake gasket which was 1.5 miles from his house. It drove there fine but as soon as he pulled into the lot it lost pressure and started to knock and he turned it off immediately. He then accused the shop of getting debris into the pan and made them pull the oil pan. They showed him the oil pickup tube that was not clogged and said it wasn't their fault. I plan on purchasing a reground crank and matching bearing set and a new oil pump. One of the rod bearings did spin but it doesn't look bad at all, I have seen much worse bearings. But if I need to replace a rod is it possible to pull the heads and pull the piston and rod out of an Astro van with the engine still in the van? Do you have any idea what could have happened to the oil pressure after we got the van back from the shop? Thank you in advance!
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Jacobburch
October 9, 2007.



Your problem is not as descriptive as I would like to see and I have questions. You said that dexcool leaked. Did the raiator drain or leak in to the oil crankcase? Was there Dexcool coolant mixed with the oil? If there was, you could probably buy a junkyard 80,000 mile engine cheaper than fixing this one and have better confidence in it. If the coolant did not leak and flood your oil crankcase, there are other cheaper to fix possible causes for the knocking.[/Quote: f0e421f708]

The lower intake leak was very minor and no mixing of fluids had occured. I would add about a cup of antifreeze per week. Sometimes you could smell antifreeze when finished driving it but rarely saw drips because the leak was so minor. As of right now the oil pan is off and a couple of the rod bearings are shot, one being spun. Today im going to measure the rod journal to check for round or loss of material. If this rod is not reusable do you know if it is possible to remove the piston and rod with the engine in the van. Also do you have any suggestions why the oil pressure was lost to begin with? I dont want to go through all of this work and fire it up and not have pressure. I want to make sure im not overlooking some kind of internal pressure loss problem. Thanks in advance!

Tiny
Jacobburch
Oct 11, 2007.