Author Topic: 84 k30 Project  (Read 188 times)

Offline KamperBob

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84 k30 Project
« on: March 23, 2024, 05:06:47 PM »
I recently got into an 84 Chevy k30 6.2 diesel. To my knowledge it hadn't been started since the mid 90s but it was garaged since then. I was shocked how it started on ~30 year old fuel but there are definitely some issues to sort out. The previous (not original) owner died and I'm dealing with his widow so history is limited.

1. When first started the oil pressure gauge starts increasing as expected but doesn't stop. The needle pegs high. There is also some old leak indications under the truck. I suspect some cause and effect there. Once I get a good service manual and workshop access I plan to drop the pan and check the pump. Someone on another forum suggested maybe there's a stuck relief valve. Seems plausible enough and changing dirty old oil can't hurt.

2. It has a turbo with ROTO-MASTER cast on the housing. Does that clue ring a bell with anyone? It also has a "Dyno-Tune" sticker on the air cleaner housing but that company seems to have disappeared ~25 years ago according to Uncle Google. He kept a paper file on the truck including the ad clipping how he found it which stated "new 6.2 turbo, trans. and transfer case." What exactly "new" really meant is anybody's guess. Could that turbo be a later 6.5 parts mod since factory 6.2 was NA only? What casting marks can I find to confirm which block is really under the hood?

3. The truck was stolen and recovered ~1 week later but some parts were stripped. The dash definitely has issues with lights and controls that need attention. Assuming the power train gets a clean bill of health that is...

4. I've read online that harmonic balancer rot was a problem with these 6.2 Detroit Diesels that if not fixed could cause web cracks and/or broken crankshaft. Hopefully a good service manual will walk me through that procedure. I also read that glow plugs were another problem area. Any other known issues to check out?

5. The truck was recovered with junker wheels. Before he died new mags and tires were sourced which I just installed. The wheels are not small at 33, 16.5 and 12.5 inches. I also don't have the right lug nuts yet but that seems solvable. The front wheels barely clear the fender corners when turning the steering wheel. In fact one rubbed slightly so I gently hammered a bit more clearance from maybe 1/4 to 3/8 inch. Not much I know but at least it can move under it's own power which delights me at this point. The truck already sits high so further lifting doesn't interest me. I'm hoping to carry a slide-in camper in the bed so the higher the less stable handling clearly. It'd be a shame to not use otherwise perfectly good wheels. So I'm curious what fender mods others have done for big tire clearance.

Looking forward to input from others. Thanks a bunch in advance!

Offline bd

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Re: 84 k30 Project
« Reply #1 on: March 23, 2024, 07:43:01 PM »
A few routine problems with the 6.2 include glow plug swelling and burnout due to excessive pulse width, injection pump elastomer ring disintegration, leaking head gaskets, fuel system air intrusion, cracked main webbing, and shattered pistons.  Rotating assembly damage often resulted from numbskulls using starting fluid.

The oil gauge symptoms could be caused by a faulty or incorrect sensor.  IMSM, 6.2 equipped vehicles used 80 PSI oil pressure sensors (OPS).  V8 gas powered engines typically used 60 PSI sensors.  All of the GM "gauge" OPS appeared indistinguishable save for the pressure calibration number stamped into the threaded hex nut at the base of the sensors.  If an incorrect sensor was installed at some point it would yield a false pressure indication.  A poor internal connection between the signal wire terminal and ground also can produce an open circuit that would peg the gauge high.
Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)

Offline Mr Diesel

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Re: 84 k30 Project
« Reply #2 on: March 23, 2024, 07:56:43 PM »
2. It has a turbo with ROTO-MASTER cast on the housing. Does that clue ring a bell with anyone? It also has a "Dyno-Tune" sticker on the air cleaner housing but that company seems to have disappeared ~25 years ago according to Uncle Google. He kept a paper file on the truck including the ad clipping how he found it which stated "new 6.2 turbo, trans. and transfer case." What exactly "new" really meant is anybody's guess. Could that turbo be a later 6.5 parts mod since factory 6.2 was NA only? What casting marks can I find to confirm which block is really under the hood?

4. I've read online that harmonic balancer rot was a problem with these 6.2 Detroit Diesels that if not fixed could cause web cracks and/or broken crankshaft.

The Rotomaster is some aftermarket concoction. Probably a 6.5 hodge podge of parts. It it works, keep it.

There is a theory that failed harmonic balancers caused broken cranks in these engines. I'm not convinced it is true, but it's fairly cheap insurance to just replace it. Not too hard either.
1976 C20 Crewcab, 6.2L/SM465
1982 K30 Crewcab , 427TD/TH400
1983 C30, 6.2L/TH400
1983 K30 Crewcab 454/700R4
1986 K10 350/400. 1989 K30 cab/chassis 454/SM465

Offline KamperBob

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Re: 84 k30 Project
« Reply #3 on: March 23, 2024, 11:27:47 PM »
Thanks for the replies.

I need a good service manual. Any go-to favorites or recommendations?

Offline bd

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Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
87 R10 Silverado Fleetside 355 MPFI 700R4 3.42 Locker (aka Rusty, aka Mater)