QuestionI have a 1988 Chevy G20 with 305/TH400 that I would like to convert to a 6.2L or 6.5L diesel. I realize the older 6.2L diesel engines would be more simplistic, but still... Is this project too large to consider realisticly? Thanks,
Brian
AnswerBrian,
Unless you can get the engine for free (or have a donor vehicle to parts from), the conversion is not likely to be cost efficient.
Yes, it can be done. If you are mechanically inclined, the conversion is relatively simple. But there are a lot of details to consider:
The 1994 and newer 6.5 diesels are computer-controlled and are troublesome due to poor design of the computer system. An older style, mechanical injection system will fit these diesels (my 1983 G-20 has a 1992-1993 6.2 block and 2000 year model 6.5 heads on it) but the parts can be costly if you cannot obtain them as a set off a running diesel.
The fuel tank requires supply and return lines and the fuel filtering is much more critical on a diesel than a gas engine. Aftermarket fuel filter systems may cost $200.00 or more.
Your TH400 will work, but it will need a diesel torque converter (my 84 K-2500 has a TH400). You will also need a vacuum modulator switch that mounts on the side of the injection pump and which can be hard to find.
The installation of the engine is very tight in a G van. The entire front of the vehicle has to be diassembled and the diesel cannot be installed with its intake manifold or harmonic balancer installed. You may need a heavier-duty radiator, as well, that has an engine oil cooler as well as the transmission cooler (unless you install external coolers).
Power braking is provided by a Hydroboost unit that runs off the power steering system. That will require a different pump and hose set (if your vehicle does not already use Hydroboost).
G vans with diesels use different lower ball joints and may require higher load-rated front springs than the gas versions.
A second start battery is required. Not hard to add to a C/K pickup, but the G van has it under the driver's seat and accessed from under the vehicle. There is no place under the hood for a second battery.
Lastly, you may run into problems with emissions testing, if such tests are required in your area. An exemption may or may not be possible to obtain in order to license the vehicle for road use.
Yes, your G-20 can be converted. But if cost is a deciding factor, it cannot be justified or expected to return the investment required for conversion.
