450 diesel.....help!

Adrian Billheimer

Well-known Member
First, lets be clear, I DID NOT start diagnosing yet, (look at things other than what it is doing)! My 450 starts and runs fine on gas as usual, when I try to switch to diesel it blows out a bunch of light blue smoke, out the exhaust, and chokes out, or dies, unless I switch back to gas, which then runs fine again.
Is it all injectors sticking, a loose or out of adjustment switch over linkage problem, or ????
Any suggestions on what to look at first are appreciated, Thanks in advance.
 
first... how long are you warming it up on gas? one minute minimum for a good tuned up unit in warm weather, but even 3-4 minutes in cool weather is normal. warm her up good and then switch it over. a good unit will switch over smoothly with hardly any smoke. the ones that smoke and sputter for a while need attention.
 
Had a SMD that sat a long time and would not run on diesel side. Freed up the stuck plunger and started to see smoke not there before but still would die. Ended up finding all four distributor block valves stuck open so when the plunger fed the block fuel went to all injectors instead of the one it should have by the cam. Replaced the block assembly with a known good one and then ran on diesel side OK. Worth a look, run it on the gas side with all block lines off, it should deliver in firing order. The bad block shot fuel out all four at once...
 
I am assuming it has run correctly for you in the past. But With the limited info it sounds like it is not completely switching over to diesel which sets up the higher compression in the head. Based on this I would inpect the linkage and the switchover mechanism on the side of the block. Just guessing
 
I'll answer to the first 3 responders here, Yes was running fine when parked last fall, had close to 10 minutes warm up time by the time I tried to switch over the third time, My dad bought this tractor in the mid 70s, and I personally have been running it since the early 80s, I am very familiar with its' mechanicals, and was thinking/hoping it is in the linkage, as I said earlier, did not start looking yet, hopefully tomorrow.
 
On the right side of the engine about mid way. Check the catch for the switch over kinkage. It is a short notched lever with a spring hooked to it. Will rust up & not move back in place to open hold the manifold butterflies open. A little penetrating oil & move it back & forth should free it up.
 
If checking the linkages out to make sure it is snapping into diesel positon does not solve your problem, just pull the two end spark plugs as they are easy to get out. Leave lever in diesel position , throttle closed and crank it. If you get compression blowing out spark plug holes you know you have stuck decompression valves. You can gently go through the plug holes and attempt to push valve back up and closed. A little spray helps. Getting at the other two if this is the problem, well, much more difficult. Your choice, possibly removal of valve cover or manifold. The blue smoke indicates you are getting fuel but you can also easily check that by opening bleeders on nozzles while running on gasoline cycle and varying the throttle position.
 

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