Hi there,names Erik. I've been a huge GRM fan for years, first finding the site and magazine in my very early teens. Now I know that GRM is a community that prides itself in knowing about very obscure vehicles and is very mechanically inclined so I decided to ask for some help. I recently picked up a very beat up 1981 Datsun 720 diesel with the SD22 motor commonly found in forklifts. After some fiddling and digging up the pneumatic governor (which seems to be discontinued), I got it to run pretty good. Now the issue is that after it ran good, I decided to turbo it. Donor is a CT26 from Toyota. Fabricated everything needed (I have access to mills,welders, hand tools out the yahoo and pride myself in knowing how to use it all) and installed it. Now the problem is that the truck is very hard to start with the turbo installed, needing ether (bad, I know) to turn over and when it is on it bellows white smoke. I have a feeling that the intake/exhaust manifold gasket that I reinstalled used is the problem, leading to an air leak of some sort and that the smoke is just unburnt diesel. I am at my wits end and even tried to join a Nissan diesel specific message board but that didn't work because no administrator will approve me.
Please help me save this gem
PS not sure how to post pictures from instagram but I will throw a couple up as soon as I figure it out.
Welcome Erik.
I have no personal experience with your Datsun diesel but I do find it interesting and unique.
As for pictures, this recent thread is a tutorial on posting pictures and may help.
John Welsh wrote:
Welcome Erik.
I have no personal experience with your Datsun diesel but I do find it interesting and unique.
As for pictures, this recent thread is a tutorial on posting pictures and may help.
Unfortunately it being unique seems to be it's main problem. The damn governor is made out of leather! So yea, I'm sad to say I might be SOL. I appreciate the link, here's a couple photos.
You are probably way ahead of me on this if you have been researching, but Nissan made larger diesel engines that are turboed. The think the 2.5 and 2.6 or 2.7. I was very sad they never sent a diesel hardbody to the US.
In reply to spitfirebill:
Not much to research unfortunately but I was looking for a hard body when I found this beast. I hate new cars and had a plan to buy a hard body and one of the diesels you mentioned (from a patrol) and make me a nice little rig.
The IHC scout was offered in the early 80's with the big brother to this engine, the Sd33. Now that is a unicorn haha.
Although your setup is certainly unique, troubleshooting it won't be.. It worked correctly before turbo, therefore it's either something you hooked up or something that needs tuned. Assuming you're correct there's an air leak of some sort, do you believe that it's internal or external to the gasket? If you think it's internal (from the intake to the exhaust), then I'd start by pulling the turbo and doing a smoke test on the intake. If it's external, then spraying ether around the mating surfaces while the truck is running should reveal a change in idle/smoke amount.
In reply to WonkoTheSane:
That is the same thing I thought, but I can't get it to run long enough. I think the intake side is leaking to the atmosphere, I will probably just start with making the gasket and giving it a try. Problem is that the intake/exhaust gasket is one piece and it makes it difficult in picking a gasket material. I have a tube of copper rtv I could try.
At idle, the intake side is still vacuum, so spraying ether around with ether should work to verify that..
I'll deactivate my glow plugs and give that a try. Don't wanna burn those out haha
Just to clarify, how long will the truck run when it's idling? You said that it's hard to start and billows white smoke while on:
eplas92 wrote:
Now the problem is that the truck is very hard to start with the turbo installed, needing ether (bad, I know) to turn over and when it is on it bellows white smoke.
How long will it stay "on"?
I'm confused how an intake leak on a diesel would keep it from running, on a gas engine sure, it will screw up the AF ratio. But a 4 stroke diesel engine intake just feeds the engine unlimited air full time, you'd get boost leak issues but that wouldn't keep it from running.
You mentioned governor troubles, are you sure it's still injecting fuel? Maybe try cracking a fuel fitting loose on an injector and see what happens when you crank it.
BrokenYugo wrote:
I'm confused how an intake leak on a diesel would keep it from running, on a gas engine sure, it will screw up the AF ratio. But a 4 stroke diesel engine intake just feeds the engine unlimited air full time, you'd get boost leak issues but that wouldn't keep it from running.
You mentioned governor troubles, are you sure it's still injecting fuel? Maybe try cracking a fuel fitting loose on an injector and see what happens when you crank it.
Not with this one, this one actually has a throttle body controlled by the governor. But on another note, you may be right. At first I thought I knew enough to fix it but there are always little things that escape you when you gotta fix it yourself. Ill give that a try, the priming valve for the pump does have a leak but apparently they all did even when new.
WonkoTheSane wrote:
Just to clarify, how long will the truck run when it's idling? You said that it's hard to start and billows white smoke while on:
eplas92 wrote:
Now the problem is that the truck is very hard to start with the turbo installed, needing ether (bad, I know) to turn over and when it is on it bellows white smoke.
How long will it stay "on"?
About 30 seconds, its not it turns off. I typed that after a long shift, its that if there is no wind you get smoked out and can't really do much in the engine bay. Now I feel dumb that you guys are recommending things that escaped me but totally make sense. This is why I love GRM haha.
BrokenYugo wrote:
I'm confused how an intake leak on a diesel would keep it from running, on a gas engine sure, it will screw up the AF ratio. But a 4 stroke diesel engine intake just feeds the engine unlimited air full time, you'd get boost leak issues but that wouldn't keep it from running.
You mentioned governor troubles, are you sure it's still injecting fuel? Maybe try cracking a fuel fitting loose on an injector and see what happens when you crank it.
Good point..
I don't know nothin' about old diesels, so I was going with the assumption that there some sort of air metering kinda thing going on and it was running really lean, but thinking about how diesels operate, my thinking was probably about 20 years too advanced for this thing.
In reply to eplas92:
Ok, but is this "throttle body" actually regulating airflow, or is just supposed to be an emergency stop valve (which I have heard of on a diesel)? I wouldn't expect the former on an engine from 1981, though I should admit that most of my hands on diesel knowledge comes from a single cylinder Yanmar sailboat engine that was about as primitive as possible. A factory service manual may be of assistance here.
from the amount of smoke you are talking about it sounds like its just dumping way to much fuel, is that something you adjusted at all?
