Datsun 720 SD22 new owner

[mikecaleb]

I figured it out. All of the wires from the GP relay were slipping out of there connectors. Put some new ones on them and it works great. Now that i have that out of the way on too the next obstacle. The exhaust manifold is falling apart where it attaches to the down pipe. Is there anything you can do to fix this or do you have to find another?

 

[wayno]

Good job, you figured that out, I would never have thought of that.

The exhaust manifold itself is falling apart, or is it the down pipe/flange that is the issue?

Are both studs holding the down pipe on still there?

[mikecaleb]

The down pipe/flange. Only one of the studs are left. 

 

I'm also looking into getting an electric fan. I know its going to need to be slim. But i wasnt certain wether it needs to be a pusher or puller? And how strong/big of a fan would it take to keep it cool? 

[Charlie69]

I prefer the puller then there is still room for an AC condenser.

[mikecaleb]

Theres no ac on the truck. Or power steering lol. Its got heat but thats it. 

[620slodat]

Use a stock Nissan fan as stock fans seem to hold up better than aftermarket fans from everything I've read. A 2000-2001 Sentra fan seems to be about the best size for a stock SD-22 radiator, it has two fans (a five blade fan and seven blade fan) and it appears to have four speeds available. The big questions are, did I try the correct wire combinations for the fan, and how best to fit the fan to the SD-22 radiator as I have yet to do that part. 

 

The biggest problem that I have yet to get an answer for is that the upper right fan mount and the coolant return to the upper right tank of the stock SD-22 radiator occupy the same place. A possible solution that I am currently looking for information on is a radiator for 2000-2001 Nissan Sentra along with the cooling fan. The fan and radiator would work together correctly, but would the Sentra radiator be adequate to cool the SD-22. Also, I don't have any answers yet about mounting the Sentra radiator. The Sentra radiator (aluminum) is thinner than the stock SD-22 radiator which leaves more space for an AC condenser, but does thinner work with the SD-22.

 

Don

[wayno]

I had to cut off a 1/2" of the ends of my stock fan blades to clear the upper radiator return hose in my 521 kingcab diesel truck with a stock 2 core L16 radiator, it still cooled my SD25 engine until I turbocharged it, I now use a Volvo wagon radiator and it runs cooler than it ever has before, but I had to make a little room on each side(reshaped with a hammer).

I am a huge fan of stock fans, they never have issues, electric fan equipped vehicles have left me on foot in the past(not my car), I had to walk the last couple miles up the mountain to retrieve my vehicle in the middle of the night after a long cross country hanggliding flight, but that was better than having to walk the whole way up, he told me that the fuse blew the next day, I was very happy to get a ride even part of the way up.

Maybe you can find something in a wrecking yard the right size to replace your down pipe, and you can remove the exhaust manifold and either heat it up with a torch till it is glowing and use vice grips on what is left of the stud to turn it out, if it sheared off flush drill it out with the proper sized drill bit and clean out the threads with a tap.

Edited April 20, 2019 by wayno

[620slodat]

I can understand where you are coming from Wayno. I have read too many bad reports about aftermarket fans that have gone bad.Sometimes it is the fan, and sometimes it has been because of the wiring components/way they were installed (questionable components). Because of these kind of reports I have decided that if I go to an electric fan it will be a stock electric fan (better quality). The car companies put much more effort into making sure that the quality in the fan, and the wiring/switches are the best because their warranty and reputation around the world is on the line. It's not just amazon pushing the sales, it's the reputation of the auto manufacturer. Do the auto manufacturers make mistakes? Sure, but they stand behind the products better.

 

Don

[Charlie69]

3 hours ago, mikecaleb said:

Theres no ac on the truck. Or power steering lol. Its got heat but thats it. 

There is alway an upgrade to make the truck more user friendly in the hot months.  If you use a pusher fan this eliminates the AC unless you redo the fan.  Just a suggestion.

[mikecaleb]

Ill probably end up biting the bullet and buying an original. 

 

After starting it up and letting it warm up is it still supposed to put out white smoke?

[wayno]

Does it have a weird smell also?

Does it look like this in the photos below, pay attention to the exact color.

 

 

This above happened to me when my truck overheated on the freeway one night, and that was the night the dash lights quit working also, it somewhat cleared up when I drove it, but I still got comments in parking lots said loud enough so I would hear, it didn't start so good either when it was cold, right before I pulled the engine and replaced it I put new glow plugs in it and that was the only time it ever started clean when cold, but that was the last time them glow plugs worked because they were the wrong type and the ends of them blew up like balloons, I was very lucky to get them out of there without pulling the head apart, them glow plugs only worked that one time, they never worked again as they were ruined, they were a fast warm up type and are engines use a slow warm up type, 20 seconds was enough to ruin them.

I don't know where you got this truck, but they sit in one spot for a reason, I have a friend that picked up a truck that smoked like a steam locomotive, we towed the thing to his home and he tinkered with it, adjusted, and replaced things like injectors, and the diaphragm I believe and he got it running good after quite a bit of time and it didn't smoke, I really don't know all of what he did, but it did eventually blow a headgasket and they fixed it and they sold the truck less than a year later.

I still have the overheated engine in storage, it still runs but it is gutless for an SD25, I believe that something bad happened inside that engine like the head cracked or it lost compression somehow, soon I am going to pull it apart to see what happened as it overheated likely 4 years ago and has been sitting since.

 

[mikecaleb]

Yes it does have a weird smell. And those pictures are pretty spot on. It only does it when ive got the rpms up though. When its sitting there idling it dont smoke at all

 

[mikecaleb]

Yes it does have a weird smell. And those pictures are pretty spot on. It only does it when ive got the rpms up though. When its sitting there idling it dont smoke at all

 

[wayno]

Well if it doesn't smoke like mine in the photos as that is just above an idle your likely better off than my engine was.

Maybe your injectors are wore out and the fuel is not atomizing like it is supposed to, white is un-burnt fuel, does it blow white smoke when your actually driving it?

When you turn it over to start the engine dies it turn over evenly, wow-wow-wow-wow, or does it sound more like wow-wow-wow-woosh-wow-wow-wow-woosh-wow............

Woosh is it turning faster on that cylinder.

[mikecaleb]

I havent been able to actually drive it yet so im not sure about that. Ive got to figure out what wrong with the clutch. I replaced the master cylinder the other day as i had a new one laying around from a hardbody. That and i need to figure out the cooling fan situation. 

 

And it sounds normal to me. I will get out there and actually listen for it tomorrow though 

 

[wayno]

I asked because you and another guy have had issues with the engine starting, your issue was glow plugs not warming up, I suspect he has/had the same issue, the point being you listened to your engine turning over when it didn't start for a while, so I thought you might remember.

You should try to keep your costs to a minimum till you figure out the smoking issue, you can dump a lot of money into it and still not be able to save it without rebuilding something.

How many miles are on it?

I got real lucky finding my SD25 engine for my 521 kingcab, I just happen to stop and talk to a guy with a 4wd 720 in front of one of my customers houses, I listened to him talk about is truck and when he finished I told him I was into 720 diesels, he looked at me and said he had a diesel engine for sale, so I went and looked at it and for just over $300.00 I bought a diesel engine, transmission, gauges, turbo, he kept hauling stuff out and putting it in the back of my truck, what I was so lucky about was because it was a SD25 diesel engine/transmission with likely less than 50,000 miles on it, the thing runs great and it has since I bought it, I was so freaking lucky I stopped and talked to that guy, so very lucky.

I will make a smaller box for that fan assembly and get another shipping quote from the regular post office instead of that small place I went to the first time where I got someone that didn't know what they were doing.

[mikecaleb]

It only has 187k. And alright id greatly appreciate that.

 

[wayno]

187K is good but really doesn't matter if it was not taken care of before you bought it or if it was overheated, you need to check everything, check to make sure the valves are adjusted right, if they are too tight or very loose that will cause issues.

I don't really know a lot about this subject, one guy I know had this issue and he bought a used injection pump from me and he said it was way better after that, I would have more suggestions if it were blowing black smoke as I know what causes that, also no smoke/no power I have had before, but smoking like my truck in the photos, I replaced the engine with a completely rebuilt SD22, but that was only in there for a little while because I found another SD25.

[mikecaleb]

Yeah i thought that was pretty low for one of these.

 

The oil and water look fine and there is no leaks so the head gasket is fine. None of the original hoses leaked besides a couple fuel hoses. I went ahead and replaced the fuel hoses and a couple other coolant hoses that were looking awful. After replacing the fuel lines i went ahead and bled the injectors. Dont know if itd have anything to do with it but figured id mention it. 

 

I have read somewhere on a different forum that the air filter could contribute to a white smoke under throttle. The air filter on it is beyond needing replacing 

 

[wayno]

187K is not that many miles for the SD22 diesel engine with an inline injection pump, if it had a VE type injection pump the IP would be close to needing it's 3rd rebuild, at least that is what I have heard, 60,000 miles is all the VE type pump lasts.

When you replaced them fuel hoses if you didn't prime/bleed the lines before tightening the clamps or even connecting the hose to the fitting, it can make it a major hassle to get it started and keep it running, when bleeding everything you need to loosen and bleed almost all the banjo fittings except the ones on the lift pump, especially the one banjo fitting on the front of the injection pump, air in that feed line is a major pain in the butt, you can wear your battery down to nothing trying to get the air out of that line.

Also when you replace the spin on fuel filter you need to fill it with diesel fuel first, all the way to the top, then when you prime/bleed the system you loosen each banjo fitting on top of the fuel filter housing and pump the primer till no air comes out, every stinking one of them, any air and the engine can die and be a hassle to get it started and running again.

I have a turbocharger on both my SD series powered trucks, I had to add a support screen inside the filter as my filter was being sucked flat/collapsing on itself, a dirty air filter could cause an issue I suppose, but none of mine ever smoked white smoke because of a dirty air filter, I could see it causing black smoke.

The air filters are available at the local parts stores around here.