AZBLACKSMOKE
no truck payment
I wanted to try to document my S-series gas to diesel swap Ive been working on. The truck im working with is a 1979 IH 1724 dump truck with a 446 gas engine and IH 5speed direct. The 446 had been rebuilt around 5 years ago and finally spun a bearing. This truck sees use almost everyday of the week.
I found very little info on the web concerning this swap, so a lot of stuff was learn as I go. I knew the International MV gas motors were a direct bolt in as far as the transmission/accessories go, and my main issues were exhaust manifolds and the oil cooler. The 7.3idi came in many IH medium duty trucks in the late 80's and early 90's.. but these trucks are getting difficult to find out here in the west..many are still in use. Uhaul had lots of these trucks. I got a pretty smoking deal on my 6.9 at the local wrecking yard. I definatly would have rather had a 7.3, but couldn't pass the deal up I got on the 6.9.
The 6.9/7.3idi's have at least 2 different style oil coolers...possibly a 3rd. Im still not sure what the applications are. The problem with the F250 truck exhaust manifolds are the outlets are pointed directly into the large 5 speed bellhousing and there was no way to make them work. Note: the oil cooler tube are all the same...its the mounting heads that are angled differently. I did much research on van oil coolers and manifolds because I was told they would work. from what I found, they were different, but still wouldn't work. But I cant confirm that 100%. What I ended up doing was finding a vin number from a later model International 1654 from 1988. After locating a few used sets that fell thru, I finally found a NOS set in Chicago and had tem shipped to AZ. The oil cooler was found the same way with the same vin number. I used the vin number to figure out the oil cooler heads I needed, then got the oil cooler head part number and found a set on Ebay. They looked right, but what I did not notice was the forward cooler head is a 3 bolt style, and I needed the 4 bolt style. Im still not sure what application is what. But I couldn't easily find the non angled 4 bolt design I needed, so I made some then 3/16th thick aluminum adapter plates and so far seem to be working. Im disappointed I failed to get pictures of this part.
The exhaust was easy. It did not line up, but the flanges were the same. On the truck, the exhaust pipes join back at the muffler, then have a short single exit near the muffler. I simply cut one side and shortened it, and cut and extended the drivers side. Bolted up like factory.
I had a small issue with the starter. Since I am using the "gas" bellhousing...I have to use the gas MT10 style delco starter. The diesel 2 bolt starter is bigger bolt pattern, therefore a bigger starter. From my research it is a MT37 style starter which is would be great. I had to pull all the glowplugs to get the engine to spin over fast enough to prime all the injectors. The entire fuel sytem is new/rebuilt, so it took a lot of priming. Actually went pretty quick once I figured out to do that. The starter seems to be fine. The engine spins over fast enough and fires off on the first kick after about 10 seconds of GP time. I also upgraded from a single group 78 battery, to a single group 31 battery. We'll see how she does out in the field. I may have to find another spot to put a second battery. Would I prefer a diesel bellhousing? Absolutley. But I think it will be fine as long as it doesn't equire extended cranking. I will, and am currently keeping my eyes peeled for a factory 7.3/ HD 5 speed bellhousing.
Both saddle tanks were drained and filled with diesel. I mounted a aftermarket fuel filter water separator on the passenger outside frame. I simply plummed the return into the saddle tank crossover, so the return wlll dump into both tanks. I did have to move the ports on the sending units as the factory ones had check valves in them. Im assuming for proper syphoning of the fuel for proper distribution.
Today Im finishing up the glow plug harness. Im simply using the factory F250 GP relay with a push button. I have a maxi fuse coming for protection since Im not using Fusable link wire. Ill post pics of this today. Also, I'll be mocking up my radiator and air brake compressor lines. Im pretty sure I can make the original radiator work since the water outlets don't appear to have moved a whole lot, but im not sure. My original radiator is toast and need to be replaced anyway. so im making sure it will work before I order a new one.
Im sure there is much Im forgetting or skipped over. But its still a work in progress even though Im getting close to the finish line. Feel free to ask me any questions. I will continue to update until the project is finished.
I found very little info on the web concerning this swap, so a lot of stuff was learn as I go. I knew the International MV gas motors were a direct bolt in as far as the transmission/accessories go, and my main issues were exhaust manifolds and the oil cooler. The 7.3idi came in many IH medium duty trucks in the late 80's and early 90's.. but these trucks are getting difficult to find out here in the west..many are still in use. Uhaul had lots of these trucks. I got a pretty smoking deal on my 6.9 at the local wrecking yard. I definatly would have rather had a 7.3, but couldn't pass the deal up I got on the 6.9.
The 6.9/7.3idi's have at least 2 different style oil coolers...possibly a 3rd. Im still not sure what the applications are. The problem with the F250 truck exhaust manifolds are the outlets are pointed directly into the large 5 speed bellhousing and there was no way to make them work. Note: the oil cooler tube are all the same...its the mounting heads that are angled differently. I did much research on van oil coolers and manifolds because I was told they would work. from what I found, they were different, but still wouldn't work. But I cant confirm that 100%. What I ended up doing was finding a vin number from a later model International 1654 from 1988. After locating a few used sets that fell thru, I finally found a NOS set in Chicago and had tem shipped to AZ. The oil cooler was found the same way with the same vin number. I used the vin number to figure out the oil cooler heads I needed, then got the oil cooler head part number and found a set on Ebay. They looked right, but what I did not notice was the forward cooler head is a 3 bolt style, and I needed the 4 bolt style. Im still not sure what application is what. But I couldn't easily find the non angled 4 bolt design I needed, so I made some then 3/16th thick aluminum adapter plates and so far seem to be working. Im disappointed I failed to get pictures of this part.
The exhaust was easy. It did not line up, but the flanges were the same. On the truck, the exhaust pipes join back at the muffler, then have a short single exit near the muffler. I simply cut one side and shortened it, and cut and extended the drivers side. Bolted up like factory.
I had a small issue with the starter. Since I am using the "gas" bellhousing...I have to use the gas MT10 style delco starter. The diesel 2 bolt starter is bigger bolt pattern, therefore a bigger starter. From my research it is a MT37 style starter which is would be great. I had to pull all the glowplugs to get the engine to spin over fast enough to prime all the injectors. The entire fuel sytem is new/rebuilt, so it took a lot of priming. Actually went pretty quick once I figured out to do that. The starter seems to be fine. The engine spins over fast enough and fires off on the first kick after about 10 seconds of GP time. I also upgraded from a single group 78 battery, to a single group 31 battery. We'll see how she does out in the field. I may have to find another spot to put a second battery. Would I prefer a diesel bellhousing? Absolutley. But I think it will be fine as long as it doesn't equire extended cranking. I will, and am currently keeping my eyes peeled for a factory 7.3/ HD 5 speed bellhousing.
Both saddle tanks were drained and filled with diesel. I mounted a aftermarket fuel filter water separator on the passenger outside frame. I simply plummed the return into the saddle tank crossover, so the return wlll dump into both tanks. I did have to move the ports on the sending units as the factory ones had check valves in them. Im assuming for proper syphoning of the fuel for proper distribution.
Today Im finishing up the glow plug harness. Im simply using the factory F250 GP relay with a push button. I have a maxi fuse coming for protection since Im not using Fusable link wire. Ill post pics of this today. Also, I'll be mocking up my radiator and air brake compressor lines. Im pretty sure I can make the original radiator work since the water outlets don't appear to have moved a whole lot, but im not sure. My original radiator is toast and need to be replaced anyway. so im making sure it will work before I order a new one.
Im sure there is much Im forgetting or skipped over. But its still a work in progress even though Im getting close to the finish line. Feel free to ask me any questions. I will continue to update until the project is finished.
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