Help with some 6.2l engine part identification

[5akman]

My son just bought a 1985 C20 with 6.2l/th400. The engine runs but smokes badly (suspect inj pump). He got a deal on a 6.2l out of an airport tug with 16k on the odometer. There was another owner who bought the engine out of the tug at the wrecking yard and drove it for a year. The engine leaked badly so he resealed the entire engine, put head studs in, an upgraded inj pump, new balancer etc. He had also purchased a new Banks turbo kit that came with the engine purchase. All looks good except we're missing the "top hat" for the Banks intake, anyone have one sitting around that they'd be will to sell?

We noticed that the current engine in the truck as an assembly on the passenger side of the inj pump with a few vac lines coming out of it. The tug pull out engine does not have this component. What is it? Something to do with the vac modulator on the 400 trans I'm guessing? Can this part just be swapped from the old engine to the tug engine? And there is a vac line going from it down the th400 dip stick to the trans?

Also, there is a sensor type unit on the rear inside of the cylinder head. On the tug engine, this unit is on the driver head with a 4 lead plug assembly and on the original engine its on the passenger head with only two wires. What is this for?

For performance, is he better off staying with the non egr 6.2l manifold and buying the Banks top hat or just switching to a F code 6.5l manifold.

 

[diesel4me]

That switch on the injector pump is a VRV valve,and yes,its used to control the vacuum signal from the vacuum pump to the TH400's modulator..(that tug engine may not have had a vacuum pump but as far as I know you can just swap your original one onto that engine--they used a shaft to replace the vacuum pump's in applications that didn't need one,and capped off the hole in the block with a freeze plug..)

The other thing sounds like the sending unit switch for the cold start advance in the injector pump--on both of my 6.2's they are on the rear of the passenger side cylinder head right next to the exhaust manifold..
If yours is located on the valley side of the head,it may be a different type of glow plug controller ?...my truck is set up for a manual push button for the glow plugs so I'm not much help there..

 

[5akman]

Diesel4me, thanks for the info on that. I've owned two 6.5's and a dmax but am unfamiliar with some of the stuff on the early GM diesels so appreciate the info.

 

[BadDog]

I've got an extra "top hat" (plenum box? charge adapter? whatever it's called). I had planned to machine it for a different purpose, but not too invested in the idea. I would rather it help someone than satisfy my whimsy.

Agreed as already covered on the vacuum switch/valve

Regarding the glow inhibit/control/etc related sensors, you can find most of what you need (or enough to search for more) in the content or links included in my thread (click here) Not sure what oddities might be found on tug engines, but the various bits off your truck engine should transfer right over without worrying about what the tug had.

 

[5akman]

What top hat do you have? A banks unit or stock? Also, thanks for the link, lots of good info!

 

[BadDog]

Banks Sidewinder. Gen 1 I think.

 

[5akman]

As long as it fits the 6.2 intake profile (round) vs the 6.5 (odd shaped), that would work. How much do you want for it?

 

[BadDog]

Yes, round 6.2. Not much. Headed to lunch, I'll send PM after.

 

[campfire]

If yours is located on the valley side of the head,it may be a different type of glow plug controller

Yes, the "stick" stuck in the port on the valley side of the head is an early glow plug controller ('82-'84). Different years used different controllers. I know by 1986 GM had changed to a 2-wire sensor that's much smaller. Not sure which style an '85 would have had.

Every style is basically a temperature switch connected to a timer circuit. It cycles when cold and doesn't cycle when warm. Plenty of folks have converted to manual switches, and the short cycle times of old controllers isn't very effective when paired with the long cycle times required by newer glow plug styles.

But there are many ways to skin this cat. If your GP controller currently works (and matches your plugs), I'd keep the sensor that matches your wiring harness. No benefit in converting to the older style. The head ports are identical, so swapping side-to-side isn't an issue. If yours doesn't work, and you're already bypassing it with a switch, I'd scrap the controller and install a 1/2" pipe plug in that head port.

 

[campfire]

For performance, is he better off staying with the non egr 6.2l manifold and buying the Banks top hat or just switching to a F code 6.5l manifold.

The non-egr J-code 6.2 manifold comes in both single- and dual-plane varieties. Opinions vary. I'm running a dual-plane J-code intake with my ATS TE-04 turbine. But that's just what I had lying around, it may or may not be better than the single-plane intake.

The 6.5 engines came with at least 3 different intake manifolds.

I think I still have a couple spare intakes if you decide to change yours out.