1984 chevy 6.2 diesel with oil in the intake

[Paul3880]

I am looking at a 1984 chevy truck with a 6.2 diesel. it has an oil leak running into the valley of the motor. it looks like it is coming from the runners for the intake. the valve covers are dry above the intake runners. I looked inside the intake and see oil, is it common for them to have oil in the intake? if so then does it, after some time, start leaking out and running into the valley? if I remember right I read somewhere that the 6.2 vents the crank case pressure into the intake. is this a common issue or is there something I can do to fix it or at least make it better? I plan to replace the intake gaskets, I am just wondering if there is anything else I can do to prevent it from happening again.

 

[Wayne M.]

Welcome to the TDR. There are plenty of Diesel guys here, but mainly we're into Cummins engines. However, you may get a guy who used to own a 6.2 who will have input. I used to work on a few many years ago. I don't recall this problem, but your theory sounds good- that the crankcase vents into the intake, and this could be the source of the oil. If there's oil deep down in the valley, perhaps the injector pump is leaking?

Good luck with the truck. Sounds like a good candidate for a Cummins swap!

 

[jgillott]

I had an '85 Chevy with the 6.2L many, many years ago. I don't recall excess oil in the intake, but I don't remember needing to look for it either.

 

[Freebore]

I owned two GMCs, one 6.2 and another 6.5 TD, and have over 350,000 miles of experience with them. With the oil problem in the intake of the 6.2, you probably need to replace the crankcase depression regulator valve located on the right hand side of the intake. I could check some service manuals I still have from factory training that might lend some insight, but that is where I would start. I believe the CDR valve's job was to regulate crankcase vapor pressure in place of having a breather. While it might be possible you have a lot of blowby, the CDR valves could cause problems. Cleaning them is not the best route to go - get a new one from GM. The 6.2 and 6.5 were no powerhouses, but I managed to find most of the fixes they required to keep them reliable. They are very fussy on fuel, the 6.5 electronic injector pump driver was a nightmare at first, but solutions became available. The 4L80E automatic on the 6.5 was light years ahead of the 700R4 I had behind the 6.2 (replaced/rebuilt it 7 times). Powermaster starter (available for both) ended cranking problems, both started very well down to -10F without preheaters.