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The GM 5.7 Olds 350 Diesel Thread
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Oh yes and the biggest thing of all I can't forget
is Vacuum.

Brakes, Vacume for indash HVAC controls if any on that old of a car,etc.

Does the 6.2 have a good vacuum pump?

Also I need some input on Internal EGR vs External EGR set ups on the 6.2

What will be the best year for me to try to find for the donor truck?

Thanks again
I owe you guys a million bucks.

If I won the lottery I'd buy up all the LF9 diesels I could find. I'd
have a shop that worked full time fabricating diesel conversion into big old classic 80's GM boats.

This would be the life.
 
Location: Springdale, AR | Registered: November 11, 2011Reply With QuoteReport This Post
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Oil pan modifications if any

You will have to remove the first 4 inches forward of the sump and re-weld a shallower section. They put an extension onto the sump that hits the cross member

Engine/Trans mounts tips

The front mount was the same in all of the "B" body cars, The Olds conversion was on the engine side. The tranny mount will be different depending on the transmission used. Typically the 700R4 was used for the 4 speed trucks while the 400 was the 3 speed. You may have to move the rear cross member.

Drive line cost to shorten/lengh fabrications$$

about $100 to shorten, $300 to lengthen (new drive shaft)

Can I buy a Chevy C20 diesel 2WD(say 1986-1987ish) and drop the whole engine and transmission into the car- if not what will I have to do about a torque converter

That is probably your best option. Will have all the bits you need. Torque convertor is specific to the transmission. If the original tranny was behind a diesel than your good to go. Remember, the Olds diesel had the BOC type bellhousing and the 6.2 used the Chevy mounting so normally you can't bolt up the Olds transmission to the Chevy configuration (note here. Some of the Olds transmissions, especially in the 80s, had the universal bellhousing that worked on both types of engines)

Radiator/cooling concerns

Use the Caddy rad tanks but have your local rad shop install a 4 core onto the original tanks (about $200)

Glow plug wiring to ingition key

Follow wiring diagram for the truck

Water seperator

use the Delco square filter assembly that was used on the truck

Adding electric fuel pump

yes

Exhaust challanges/modifications/Cost- shoud I go dual or 3-inch single?? I want quiet exhaust- I want to hear the Diesel clatter- not the exhaust.

Duals is better for power and economy. 80s B bodies did not have the cutout on the drivers side tranny crossmember for the left pipe so fabrication is needed. Good high flow mufflers are needed with at least 2 1/2 inch pipe. Quiet mufflers are restrictive so your mileage and power will suffer. Your call

Extra weight on the front end of the car/changes in braking/emergeny handeling

Not sifnificant. Buick only dropped about 1/2 inch with the 6.2. Handling actually improved and the ride was smoother

Ultra low Sulfur Diesel fuel use in an older diesel fuel system/any concerns

Always, always use additive

Possible rear end gear modification to allow even lower RPM at higher speeds for improved mpg.
My 1981 Oldsmobile Diesel has a rear axle that helps mpg a lot per the prev owner. Power isn't that important to me, as long as the car is somewhat responsive at higher speeds.

3.23 gears with 15 inch tires willl give you the ideal 1,800 RPM for best efficiency at highway speeds

Engine/transmission mounting issues that may lead to noise/vibration/harshness into the car's cabin.

I used the poly urethane mounts fron and rea with no noticible vibration

6.2L diesel Harmonic balancer concerns

Change it out ($75) just to be sure

Battery concerns, will one work- or is two the only way to go? Should I put the batteries in the trunk of the car for better weight ratio?

Speedometer concerns- will it still read somewhat correct/or at all?

speedo gears are available for these cars for any rear end gears available

Will having 2-batteries in a gas car cause electrical problems once the car becomes dieslized with 2-batteries vs one?

You will need 2 batteries for sure. Will have no affect on the rest of the system. Buy a new high output alternator

And any other topic of concern that you guys can think of.

Try to find a 2,500 or bigger truck with the "J" code engine (no EGR)

I plan to buy a whole running truck- so I will have all the mounting brackets for things like the alternator/ac compressor.

Special note: My state has no vehicle emissions or inspections of any type- so no concerns in this dept.

I feel I can get a good running rough bodied truck for $1000-$1500
I feel I can get the Fleetwood Brougham/or 98 Brougham for $1000- they pop up on craigslist now and then and are usually in decent shape-maybe a slipping trans or knocking engine.

Other cost
Custom drive line?
Exhaust??
Adding electric cooling fans??or keep belt driven??$$$$
Front suspension upgrades- if any needed- but I read that the 6.2 is only 150 popunds heavier than a 350gas.

Thanks for your input.
Any talk/input would be of great interest and help.
What do you think my MPG would be?
Preformance?
Durability?
Cabin noise?


Good luck and keep us posted on the conversion

Bill


91 Buick Roadmaster wagon, GM 6.2 diesel conversion (gone but not forgotten
89 GMC 6.2 (Just got rid of the last pieces)
84 Mercedes 300D (gone to the great autobahn in the sky)
94 Cadillac Fleetwood (Sold before I could convert it)
 
Location: Manotick, Ontario Canada | Registered: July 02, 2002Reply With QuoteReport This Post
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quote:
Originally posted by fastrace01:
Oh yes and the biggest thing of all I can't forget
is Vacuum.

Brakes, Vacume for indash HVAC controls if any on that old of a car,etc.

Does the 6.2 have a good vacuum pump?

Also I need some input on Internal EGR vs External EGR set ups on the 6.2

What will be the best year for me to try to find for the donor truck?

Thanks again
I owe you guys a million bucks.

If I won the lottery I'd buy up all the LF9 diesels I could find. I'd
have a shop that worked full time fabricating diesel conversion into big old classic 80's GM boats.

This would be the life.


As I said above, no EGR.

Bill


91 Buick Roadmaster wagon, GM 6.2 diesel conversion (gone but not forgotten
89 GMC 6.2 (Just got rid of the last pieces)
84 Mercedes 300D (gone to the great autobahn in the sky)
94 Cadillac Fleetwood (Sold before I could convert it)
 
Location: Manotick, Ontario Canada | Registered: July 02, 2002Reply With QuoteReport This Post
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Wow Bill McD

You are amazing.

I am really excited about all this.

I plan to of bought the donor truck and the Car by this spring and start this spring on the conversion.

I have driven Lincoln Town Cars for 17-years and I am spoiled with the keypad entry on the driver's door. I will also place a keyless keypad module into the diesel car and cut a hole in the door on the diesel and wire it all up to work as if it was on a Lincoln. All I care about is if it will unlock the driver's door.

I love my Town Cars, but they don't drive or ride nearly as good as a mid 80's big GM car.
Like I said, my number one choice is a 1984 Oldsmobile 98 Brougham with pillow top cloth seats, #2 would be a RWD Fleetwood Brougham, #3 Buick, #4 Pontiac

I will for sure update and make a youtube video as well.

Thanks again, you guys are worth your weight in gold.

Thanks
Freddy in Arkansas.
 
Location: Springdale, AR | Registered: November 11, 2011Reply With QuoteReport This Post
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Here is a new one for ya. I am restoring an 81 trans am that is in need of an engine. I could drop in a poncho 400 like every other ta out there but thought a diesel would be different and cool. I was thinking the 5.7 but not sure it would meet my needs so would the 6.2 or 6.5 fit? I had an olds 455 in it at one time and it fit no problem. Thanks for the help.

Dave
 
Registered: March 30, 2013Reply With QuoteReport This Post
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The 5.7/350 Olds will drop in place of the 455. The 6.2 is based on Chevrolet mountings and bellhousing pattern so changes will have to be made. It's also a little heavier and has a longer oil pan.

In your case, the Olds engine will be easier.


And on the eigth day the LORD created the turbocharger
 
Location: Watertown, NY/Ocala, FL | Registered: August 14, 2002Reply With QuoteReport This Post



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Got an 80 Caddy diesel that has been well kept. 67K on the clock.

So far it runs fine, but what should I be doing to prolong my good luck?

New oil and fuel filters, Stanadyne elixir, ok, what is next?

If it breaks, I will then worry about copper gaslets, DX blocks, etc.

What is this about dual hoses to the heads, or somesuch?


Charles
 
Location: ocala, fla | Registered: August 25, 2013Reply With QuoteReport This Post
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I am new to this site. I have a 84 olds regency broughm diesel, that I am considering selling. It starts and runs well. Has had new head gasket installed. Body is in good condition. hardly any rust. I can get pics. if I get any interest in this car. Just wanting to know what interest level is out there.... thanks.
 
Registered: September 14, 2013Reply With QuoteReport This Post
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Me again... forgot to give email its reimnitzlarry@hur.midco.net
 
Registered: September 14, 2013Reply With QuoteReport This Post
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I have an 81 Seville with the 5.7, 72K Original miles

Runs pretty good.

I am hearing what sounds like one lifter tapping. This goes away after about twenty miles or after a hard pull. I have been wrenching on diesels for years, CAT, Mitsubishi, Mercedes. Ford, International and Cummins, so I love a challenge and bought a 5.7

Best way to describe this knock or tap, is that it sounds just like my 3208 did, it also went away after a hard pull. ran for years. Pulled that motor completely apart and never found the source of the noise and ended up putting over 100K miles on it

So I am very interested in what ever opinions might be offered, seems like a lot of wisdom in this group.

I will be doing ARP studs as soon as I get the car back from the body shop.

I don't think it is an injector, exhaust is clean, blowby minimal and power even and smooth.

Any thoughts?
 
Location: Mendocino Coast | Registered: June 11, 2014Reply With QuoteReport This Post
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The noise you hear is the WHOLE problem with the 5.7 The quality control of the piston pin to the top of the pistons varied. That is the noise you hear, VERY high compression on that cylinder and I think pre ignition. The heads need to be removed, the height of the piston over the top of the block varies. The tops of the pistons have to be machined to the lowest one so they are all the same. This is why the thicker head gasket works. This busted crank shafts, tore hunks out of the block and busted head bolts. This and the flexible plastic drive disk in the injector pump were the main problems and could have been corrected for $2 or $3.00. I had a block that the lowest piston was .013 + .045 for the crushed head gasket above the block and the highest was .029 + .045 This worked out to 3/8" cube on the low one and 1/2" on the high one. We marked the height and numbered each piston and machined the pistons down to the match the lowest one. This was in 1980 when I bought a disassembled engine on a skid for $150.00. I only wanted the heads and pump for spares. I drove to a friends diesel shop and he said listen to this, a Cadi was pulled off I-75 with a broken crankshaft and would run on the front half of the engine. It broke at about the middle and tore big hunks of block out still bolted to the main cap. I sold the shaft and block for $150.00 This was the one we did the piston work described above one. When the owner picked the car up she said the engine never sounded that good or ran that smooth. I have had 4 new 78 to 81 olds and Cadi diesels and then went to Mercedes and also a Duramax. I still have the 78 GMC 5.7 P/U and a couple 6.2 suburbans. I bought the GM P/U new April 3rd 1978. Just put a crate 81 engine in it last year and only had pump flex washer problems about every 25,000 miles on it. I welded the two pump halves together 25 years ago and no problems since. There was never a loud rap in this engine. This is not a converted gas engine as many say. GM really screwed up the diesel car for $3.00 but it looks like the diesel cars are on the come back. G.M.
 
Registered: July 31, 2014Reply With QuoteReport This Post
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Hey y'all, I'm obviously new to this site, and I hope I'm putting this in the right spot. I can't find any information at all for what in searching for, and I really hate to bump an old topic.

Long story short, I have an 81 Cadillac Fleetwood with the 5.7 diesel. Bought it from an old lady who didn't want it anymore for $600 (I felt pretty bad for taking it at such a low dollar) anyhow, it ran fine for a long time. Then one day, when momma bear was driving it to work, it just died. After weeks of trying to figure out what happened, I deduced the IP went bad. And after almost a year, my local dealership finally tracked one down for me via my vin. And you would think that by running the vin, I would've gotten the correct part, but apparently I didn't.

The model number was incorrect. And besides that, the only other difference (besides the look of it) is that the old IP from the Cadillac had 2 wires, one for the altitude/cold start I assume, and the other for a fuel cut off.

I was told by numerous people, including a few respectable mechanics in my town, that the part should work. I did a little research and found out the new IP I got was apparently from an Oldsmobile.

Any help, of ANY kind, would be greatly appreciated!

I know these old diesels weren't necessarily the absolute best idea of GM, but I have one, and I want to preserve a little piece of history and not let this one die off.
 
Registered: July 10, 2015Reply With QuoteReport This Post



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