6.2 install into 89 (NBS) 1/2 ton truck?

[Russell]

Hey guys!

I had a 350 in my 89 that was knocking pretty bad due to worn out bearings, so I just recently pulled it out, so I am looking for a new a new engine so I can either start driving the truck again, or sell it.

However, a buddy of mine just came across a 6.2 / 700r4 / 208 powered truck that he is considering purchasing for 4x4 parts, and is willing to sell the diesel engine to me.

I'm very tempted to pick it up, and run diesel in the truck, both for the milage, and the potential for bio-diesel in the future.

I know the engine will physically bolt straight into the old 350 mounts, that I will have to clean the fuel tank out for filling it with diesel, run the new lines, and other various smaller things, but what else will I have trouble with?

 

[diesel4me]

get more than just the motor...

If you are serious about swapping,I'd get the whole truck for parts!..it would make the swap child's play in many ways..you could simply swap in the glow plug wiring harness VS making a manual setup,and you'll need the Hydroboost power brake setup,the diesel radiator and its support,and you could use the sending unit and wiring harness from the diesel's fuel tank in your gas tank..also the dash cluster ,if you want to retain the water in fuel light,etc..

Not sure if the diesel torque converter is a must have,or if a gas engine one would work--the stall speed is lower on a diesel,and the flex plate might have 6 bolts instead of three..never tried to see if a gas one with 3 holes lines up with 3 of the diesels flex plate holes..others I know say they do,but I don't know for certain..

At any rate,its nice to just walk over to the "donor" truck when you need that elusive "diesel only" part..saves time searching boneyards,and wasting money on expensive dealer only parts..but its worth doing,for reasons you stated,plus the fact the diesel is more capeable off road when its on a hill, or bouncing ,than a carbed truck is..

 

[Russell]

I would likley have the parts truck out at my place, so that shouldn't be a concern. The donor is an 86 1/2 ton, while the 89 is a new body style truck. Not sure if the rad or anything would even fit...

How major is it to install the 4 core rad?

 

[diesel4me]

not sure..

I havent fooled with any 88 and newer trucks yet..swapping a diesel radiator in a 82-87 truck requires the radiator,its support,and the shroud..might need "tweaking" too...not sure if any parts will interchange from the new body style to the 73-87 style..

I've only put 4 core "gas" motor radiators in many older trucks..never did a "gas to diesel "radiator swap,but have seen others do it to their trucks..to fit the 4 core "gas" style radiator in my 74 K20 truck, I had to move the bottom rubber pads on the radiator support to the outer set of holes,(not all 4 cores are wider though,some are just thicker)...and used the top support from the truck originally equipped with it....I think the upper hose was a different size outlet too,but that was easily corrected by using the right hose off the donor truck...

 

[Russell]

Lookin pretty likely that I'll do this swap now

One question with regards to the brakes. Would a cam run vac pump make enough vaccum to operate the brake booster? The 89 doesn't need vac for anything else like the heater or whatever.

How about my transmission modulator? Planning on using a TH350 with a govenor set at 3500 rpm, and a low stall converter, unless I can come up with a 700r4...

 

[diesel4me]

Vaccuum pump...

Most 6.2's with an automatic tranny with a modulator,or have A/C,have a vacuum pump where a distibutor would normally go in a gas motor,to supply vaccum for the tranny modulator,and EGR plumbing,and A/C controls..

I'm unsure if that pump would be big enough to power the brake booster--it might be,my VW Jetta Diesel had a tiny vacuum pump for its vacuum brake booster,but it was a VW too,not a huge full sized 4x4...I've seen guys use some other vehicles vacuum pump adapted to the engine to avoid swapping in the hydroboost...you could swap in a manual brake master cyl,but then you'd have no power brakes anymore..not a hot setup if you tow!..

Belt driven vacuum pumps off another vehicle will work..but if the belt fails,so does your power brakes..(but so will a stock GM hydroboost setup !)..same if the pump fails..

The tranny modulator in my truck with a TH400 uses a "VRV" valve to make the vacuum from the pump,a constant steady vacuum source,mimic the vacuum you'd get from a gas motor during its various throttle openings..highest at idle,and gradually tapering off to zero as the throttle opens wider to full throttle...that switch was FUARED on mine,and I had no luck getting another one,(discontinued by GM,and no junkyards want to let me rob one off a "complete motor")..so I asked a local tranny rebuilder I trust what he would do..

He said to run the vacuum directly from the pump to the modulator,and turn the adjusting screw inside the modulator's nipple IN all the way until it gently bottoms out..I did as he instructed,so far my truck shifts at low speeds like it should,rather than having to wind it up to 50 mph and have it slam into 2nd and 3rd,like before,which couldn't be any good for the tranny or motor!--..but it shifts rather "soft"now,and I dont like the "early" shifts..I often use the colum shifter to hold it in lower gears a bit longer than it would if left to shift on its own..I hope to find a new switch someday,I fear this might shorten the life of the clutches..but I plowed a good many storms with it,and the tranny seems fine..

They also make a cable operated modulator for TH350 and TH400 trannys,used on drag cars with a blower..the blower makes pressure during acceleration,and it goes to the modulator instead of vacuum,and holds the tranny in low gear!..so they had to come up with a cable operated version..last one I priced was over 100 bucks,I think TCI makes one..it would be one way to end the vacuum modulator dilema permanently..

 

[Russell]

Hmm... Buddy of mine tried the stock 6.2 vac pump on his powerbrakes with no go, so I'm gonna need to switch to hydroboost. Will a 73-87 unit bolt up?

 

[diesel4me]

Dunno...

Someone else will have to answer that one!--I have little to no experience with 88 and newer trucks,and don't know what,if any,parts will interchange between them and the "old" 73-87 year trucks..

 

[Russell]

Me neither, LOL