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98 chevy k1500 gas to diesel conversion

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liftedchevymotocross

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Hey guys im new to the forum and i need some help,i have a 98 chevy extended cab 1500 4x4 5 speed ,but its gas and im really really wanting to convert her to diesel ,based on my research a gm 6.5 should bolt up but im not sure if she will bolt up to the 5 speed ,so basically i would like to know the easiest route on this project and i dont want to get a new truck,im highly skilled in mechanics,so please tell me what kinda engine would be easiest to bolt up and anything else i need to change,and im not worried about the front suspension cause i will get new heavy duty off road shocks
 
Another option would be a propane conversion on your gasser. Here I buy fuel for $1.39/gal Just thowing the idea out there. I love my conversion. Its hard for me to want to drive the diesel because its $3.70ish/gal.

Anyway a diesel into your truck is straight forward. You'll want to go mechanical IP and you have a 5 speed so no TCM. Your 5 speed is probably not the same as behind the 6.5. Fuel tank sender and LP might need changed?? Bigger radiator....ect
 
Burning oil said:
Another option would be a propane conversion on your gasser. Here I buy fuel for $1.39/gal Just thowing the idea out there. I love my conversion. Its hard for me to want to drive the diesel because its $3.70ish/gal.

Anyway a diesel into your truck is straight forward. You'll want to go mechanical IP and you have a 5 speed so no TCM. Your 5 speed is probably not the same as behind the 6.5. Fuel tank sender and LP might need changed?? Bigger radiator....ect
Click to expand...

i would love to pay $1.39 a gallon but im just dieing for a diesel cause everyone around here has one and they sound amazing,anyway im nut sure what you meant by "your 5 speed is probably not the same as behind the 6.5" do you mean that if i change the fuel tank sender and lp it will work or do i have to get a new transmission and change those also ,and i alreaady have a big radiator due to my lift kit and tires
 
most of the gasser 1/2tons had a light duty 5 speed. need to verify your rad is the correct one as the 6.5 idi engines run quite a bit hotter than a gas engine.
 
Welcome to TTS.
Need heavier springs not just shocks.
what 5 speed is it? Yes the 6.5 bolts up inplace of other gm v8
Read the forum notes for a "Ted's take out." pick up a db2-4911 ip to eliminate electronics. Other than that, lay out your budget so the best recommendations can be made for your money. Heck you might choose a new p400 if you have the cash.
 
ak diesel driver said:
most of the gasser 1/2tons had a light duty 5 speed. need to verify your rad is the correct one as the 6.5 idi engines run quite a bit hotter than a gas engine.
Click to expand...

yes i have been told about them being light duty im just gonna try it and hope it holds up if not ill try a diffrent route and im not sure on the radiator as i got it for a gift i know its a flex a lite and its aluminum ,my buddy said it was made for trucks with big tires due to the engine struggling more than usual to pull them,when i do this conversion ill buy more gauges to check for overheating and if its a problem ill try diffrent radiators,thanks for the concern ,but do you think the engine will bolt up?
 
Will L. said:
Welcome to TTS.
Need heavier springs not just shocks.
what 5 speed is it? Yes the 6.5 bolts up inplace of other gm v8
Read the forum notes for a "Ted's take out." pick up a db2-4911 ip to eliminate electronics. Other than that, lay out your budget so the best recommendations can be made for your money. Heck you might choose a new p400 if you have the cash.
Click to expand...

yea i meant springs too ,and yes i was gonna get that ip,i wanna do it for the cheapest i can yet i dont wanna cut corners,i didnt know they had diffrent 5 speeds in the 98s so im not sure on that? so what do you think now
 
If you are that set on a diesel, and I don't know much about conversions, you may want to think Duramax... I do know that would be considerably more $$$. Just sayin'

Art
 
The radiator opening in the core support for a diesel is physically larger. If you are in the habit of browsing through pick-n-pulls very carefully compare the diesel and gasser core supports in these vehicles. My pickup was a rebuilder I purchased and I still have the core support I replaced. Here's some pics of it, and the differences I have noticed.

PIC 1: This pic shows an overall shot of the bumper side of the core support. Look at the D shaped ends of the radiator opening, ignore the horizontal notch on the left side as that was to make it easier to remove the AC hoses. One, or both, of these D shaped areas are filled in for gassers, depending on the radiator size.

PIC 2: This is of the motor side of the core support. This shows the rubber cup that holds the bottom of the radiator in place. The pen is pointing to alternate locations for the rubber cup when smaller radiators are used.

PIC 3: This is where the other end of the radiator sets, and the alternate locations for the rubber cup for smaller radiators.

PIC 4: This pic shows welded in nuts that are used for bolting in the removable upper radiator mounts. There are several of these nuts. I have no actual evidence, but I think that different shaped upper mounts are required for different size radiators, and by choosing different nut locations you then capture and support the upper radiator.

If you do this diesel swap, and end up needing to increase the radiator size even larger than your current one, you should be able to use these pics and modify your current radiator support for the diesel radiator.

Don
 

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handcannon said:
The radiator opening in the core support for a diesel is physically larger. If you are in the habit of browsing through pick-n-pulls very carefully compare the diesel and gasser core supports in these vehicles. My pickup was a rebuilder I purchased and I still have the core support I replaced. Here's some pics of it, and the differences I have noticed.

PIC 1: This pic shows an overall shot of the bumper side of the core support. Look at the D shaped ends of the radiator opening, ignore the horizontal notch on the left side as that was to make it easier to remove the AC hoses. One, or both, of these D shaped areas are filled in for gassers, depending on the radiator size.

PIC 2: This is of the motor side of the core support. This shows the rubber cup that holds the bottom of the radiator in place. The pen is pointing to alternate locations for the rubber cup when smaller radiators are used.

PIC 3: This is where the other end of the radiator sets, and the alternate locations for the rubber cup for smaller radiators.

PIC 4: This pic shows welded in nuts that are used for bolting in the removable upper radiator mounts. There are several of these nuts. I have no actual evidence, but I think that different shaped upper mounts are required for different size radiators, and by choosing different nut locations you then capture and support the upper radiator.

If you do this diesel swap, and end up needing to increase the radiator size even larger than your current one, you should be able to use these pics and modify your current radiator support for the diesel radiator.

Don
Click to expand...

thank you for all the info and pictures,im really hoping my radiator will work tho
 
The 6.5 will bolt right up to your trans. The gearing of it may not be right though. What RPM do you cruise around at 70 MPH now?
 
liftedchevymotocross said:
yes I have thought about the gearing,and I would take a guess of 2500 or 3000 rpm im not sure,I think the guy before me geared it high
Click to expand...
The diesel likes to cruise at 1800-2200 you should be OK but your MPG will suffer.
liftedchevymotocross said:
Do you have any suggestions on the starter?
Click to expand...
If diesel starter wont fit try a high performance one made for high compression gasser?? Not sure if flywheel is same tooth # as a gasser but I think it would be.

Something else I just thought of, you could use a bed mount fuel tank (or get a tank from a diesel or both)
 
Burning oil said:
The diesel likes to cruise at 1800-2200 you should be OK but your MPG will suffer.

If diesel starter wont fit try a high performance one made for high compression gasser?? Not sure if flywheel is same tooth # as a gasser but I think it would be.

Something else I just thought of, you could use a bed mount fuel tank (or get a tank from a diesel or both)
Click to expand...
I just test drove it and it was about 2400 rpm ,and yes the flywheel should be the same,and im just gonna try for a high compression starter for a gasser,and i cant use a bed mounted tank,not enough room cause I motocross and haul hay,but I'll definitely figure something out,thanks
 
Really consider regearing the axles, my Hummer has the gearing that keeps the rpm high and it brings mileage WAY down. There is also the problem of when on the highway and deciding you want to keep the engine cool while climbing a hill. You already said you want to try to run the smaller radiator. These 2are not going to add up well. Count on the cooling mods : dmax fan, modded fanclutch, and balanced waterpump. Swap your bumper for the diesel bumper for the airflow.

You should also consider turbo choice. Free flowing turbo like ATT over the GM turbos helps drop egt/iat and will help a lower temp as well. 4" exhaust also.

For the fuel tank, does anyone know will the diesel pickup assy have same dimensions as the gas? If not, look loosing the in tank pump assembly, at modifing for a pickup tube, make sure the return line goes down just as far, and get the metering rod from Leroy. All this unless you can just find a diesel tank from a junkyard like Leroy said. Also the filler neck that mounts to the bed needs swapping, larger hole for the diesel nozzle at the pump.
 
His 5 speed trans in his truck will be an NV3500, it is lighter duty and will bolt up to the 6.5. But i would get an NV4500 if doing this swap.
 
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