Datsun 83 720 project sd 2.2

[Fly Dawg]

Hi ratsunners

 

I thought i would start a project thread on my young fellas 720, This thing has been sitting for a very long time and when he got it the old owner put a battery in it and she kick over but was only running on 3 cylinders,, We haven't given it much time lately so i thought i would look at things this weekend and found when i tried to start it it sounded like the starter motor had died and would not turn over the engine, coincidentally i was also going to check the injectors to see if they were damaged or dirty causing the running on  3 cylinder thing, what i found was number 2 cylinder full of water which i found out last night after extensive research on here causes hydrolock, So i took the rocker cover off this morning and found a rocker above 2 cylinder was in 2 bits (snapped), I really don't know were to go from here but my thought was to remove the head and look further into this engine, Any info or tricks or things i should be careful with would be much appreciated, I have never worked on a diesel before:) I will post photos of the rocker and car shortly. 

 

The young fella is going to be PISSED at this issue as he is working doing dishes to pay for this reno,, Luckily we picked up a 1983 hilux extra cab SR5 that could be his first drive car but he will never sell the datto

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[haubstr]

Nice 720 project...

 

What wheels are those? 

[Fly Dawg]

Nice 720 project...

 

What wheels are those? 

The wheels on the 720 are PG PDW Horizon 17x8 with 235x45 treads

[datzenmike]

Don't take the head off unless indicated. (don't fix what ain't broke) Get another rocker. #13258-36W00 only $30 and get it running. Evaluate after you get it running.

 

Needs oil and filter change(s) to clean it up inside.

[Fly Dawg]

Don't take the head off unless indicated. (don't fix what ain't broke) Get another rocker. #13258-36W00 only $30 and get it running. Evaluate after you get it running.

 

Needs oil and filter change(s) to clean it up inside.

Thanks Mike , I will try and source a rocker here in AUS,

[wayno]

My first question would be how did the water get in that cylinder?

The broken rocker could have been the miss, so I would find a rocker and install it, but make sure that valve does move down somehow before installing the rocker, then start it again and see if your hitting on all 4 cylinders.

But first I would try to figure out how the cylinder got water in it in the first place, did the engine set out in the weather where rain could have got in the intake?

[Fly Dawg]

My first question would be how did the water get in that cylinder?

The broken rocker could have been the miss, so I would find a rocker and install it, but make sure that valve does move down somehow before installing the rocker, then start it again and see if your hitting on all 4 cylinders.

But first I would try to figure out how the cylinder got water in it in the first place, did the engine set out in the weather where rain could have got in the intake?

Thanks Wayno

 

I thought it was a mystery that it had water in the cylinder my self as last time we looked at it and started it was a couple of months ago. My boy put water in the radiator the other day and when we started to look at it this weekend the water level had dropped lots (NO leaks under car ), we did pressure clean the engine a few months back ?.It did seem to have a watery look on the rockers when I took the rocker cover off this morning. I have taken the injectors out and can turn the engine by hand to a certain spot were it stops and cant turn it any further like it is jammed on something. there seems to be no water in the sump when I take the dip stick out

[wayno]

Is the valve that had the broken rocker arm any higher or lower than the others?

I would focus on the valve first, make sure it functions properly before you break another rocker arm.

Turn the engine by hand the other way and see if it stops again in one turn of the crank, also watch that all the valves move up and down like they are supposed to.

It kinda sounds like something is in the way like a piece of the valve seat holding a valve open, or something got into the cylinder, these are high compression engines, so there is not a lot of room between the piston and the head when the piston is at the top.

If you cannot get it to turn over 2 complete turns or more, your likely going to have to remove the head, I would get it to turn freely before ordering the rocker, something might have let loose, you need to figure it out before spending much money on the engine.

These engines have an issue of getting cracks between the valves in the head, I think it is hilarious that Nissan says that if the crack don't leak water, then the crack isn't to big, maybe you have to big of a crack and a seat came out of position.

[Fly Dawg]

Is the valve that had the broken rocker arm any higher or lower than the others?

I would focus on the valve first, make sure it functions properly before you break another rocker arm.

Turn the engine by hand the other way and see if it stops again in one turn of the crank, also watch that all the valves move up and down like they are supposed to.

It kinda sounds like something is in the way like a piece of the valve seat holding a valve open, or something got into the cylinder, these are high compression engines, so there is not a lot of room between the piston and the head when the piston is at the top.

If you cannot get it to turn over 2 complete turns or more, your likely going to have to remove the head, I would get it to turn freely before ordering the rocker, something might have let loose, you need to figure it out before spending much money on the engine.

These engines have an issue of getting cracks between the valves in the head, I think it is hilarious that Nissan says that if the crack don't leak water, then the crack isn't to big, maybe you have to big of a crack and a seat came out of position.

Thanks wayno

The valve does seem to be the same height as the others in the same stroke and I am able to push it down on the spring a little

if I turn the engine the other way it also comes to a stop, the valves all seem to be moving except the one with out the rocker

If it is a cracked head can they be repaired as in welding or something

[wayno]

Thanks wayno

The valve does seem to be the same height as the others in the same stroke and I am able to push it down on the spring a little

if I turn the engine the other way it also comes to a stop, the valves all seem to be moving except the one with out the rocker

If it is a cracked head can they be repaired as in welding or something

Something is stopping the rotation of the crank assembly, if a valve seat fell out, then the valve end where the rocker is would likely be higher, if the valve seat got stuck in between the valve and the head at an angle, then the valve end would likely be lower.

If the cam broke then not all the valves would move, so unless you have a scope that you can look into each cylinder if that is possible to do in one of these little diesels to figure out what is stopping the crank rotation, you will likely have to remove the head.

Head gaskets are expensive for these diesels, there is also a little rubber ring that goes where the oil supply is to the head, remember where that goes when the head is put back on.

I have no idea if the head can be repaired if cracked, but Australia has diesel 720s in the wrecking yards over there, as I have seen them on the gumtree Australia site over there(it's like are craigslist) parting out Nissan 720 diesels, I have messaged them more than once looking for a RHD 720 power steering gear, but none of them have responded to my inquiry so far, they figure out I am in the USA and don't want to deal with it I suspect.

[Fly Dawg]

thanks wayno , your wealth of info is appreciated,

after looking again I would say the valve could be slightly higher than the others but only slightly nothing dramatic, anything could have found its way into this engine after sitting for so many years and may have found its way into a valve .

I gotta tell you its not much easier to get replies from the wreakers in Aus  when you live in Aus but we live at the top of Queensland in the tropics so the nearest big city is about 1600klm away , they still don't want to reply knowing we live up here , We don't have a forum like this in AUS so that's why I ask my questions on here

I think I will remove the head next weekend and keep you posted on what I find

Cheers Peter

 

Anything other than the rubber o ring I need to watch out for

[wayno]

I have a few Nissan SD series diesel engines around, been driving them for maybe 10 years now, not very powerful, but they get good mileage.

[Fly Dawg]

I have a few Nissan SD series diesel engines around, been driving them for maybe 10 years now, not very powerful, but they get good mileage.

growing up in AUS in the late 60's and 70's we were very much into Holden (GMH) and ford v8's so I am on the thought that the slowest my sons first car is the better so bring on the slow diesel Datsun,:) He is also into sk8 park BMX so a mini truck is what he wants with a little influence from the old school dad I hope

[finney]

growing up in AUS in the late 60's and 70's we were very much into Holden (GMH) and ford v8's so I am on the thought that the slowest my sons first car is the better so bring on the slow diesel Datsun, :) He is also into sk8 park BMX so a mini truck is what he wants with a little influence from the old school dad I hope

 Until he wants to notch it, bag it, engine conversion, drive it, pull it off the road to body drop it and it continues to spiral out of control from there….. 

[Fly Dawg]

Hi finney

The funny thing is I have heard all those things from him already,,, great to see another aussie on here:):)

[Fly Dawg]

Something is stopping the rotation of the crank assembly, if a valve seat fell out, then the valve end where the rocker is would likely be higher, if the valve seat got stuck in between the valve and the head at an angle, then the valve end would likely be lower.

If the cam broke then not all the valves would move, so unless you have a scope that you can look into each cylinder if that is possible to do in one of these little diesels to figure out what is stopping the crank rotation, you will likely have to remove the head.

Head gaskets are expensive for these diesels, there is also a little rubber ring that goes where the oil supply is to the head, remember where that goes when the head is put back on.

I have no idea if the head can be repaired if cracked, but Australia has diesel 720s in the wrecking yards over there, as I have seen them on the gumtree Australia site over there(it's like are craigslist) parting out Nissan 720 diesels, I have messaged them more than once looking for a RHD 720 power steering gear, but none of them have responded to my inquiry so far, they figure out I am in the USA and don't want to deal with it I suspect.

Hi Wayno

I removed the head off today and this is what i found

 

And as you predicted the valve in question was sitting higher

 

I have put up some photos of the piston in question and also the haead , I cant see any holes in the cylinder or head but the piston top in number 2 has had a flogging 

Is there anyway from this point that i can check the rings ect

[wayno]

That head looks repaired, is that welding in between the valves in each cylinder, or are my eyes just old and seeing things?

The intake valve should have been higher than all the other valves, and that is likely why the rocker broke, it ran out of adjustment, it had tension on it all the time and was not entirely closed and a piece of the seat must have got between the piston and the valve and it broke the rocker forcing it to a seated position.

You should take it to a machine shop and ask them what they can do with a guarantee.

It looks like that piston took a beating, I personally could not tell you if it is good or bad from a photo, you need to have someone that knows what they are doing look at it, or take a chance and have a seat installed and throw it back together and hope for the best.

[Fly Dawg]

That head looks repaired, is that welding in between the valves in each cylinder, or are my eyes just old and seeing things?

The intake valve should have been higher than all the other valves, and that is likely why the rocker broke, it ran out of adjustment, it had tension on it all the time and was not entirely closed and a piece of the seat must have got between the piston and the valve and it broke the rocker forcing it to a seated position.

You should take it to a machine shop and ask them what they can do with a guarantee.

It looks like that piston took a beating, I personally could not tell you if it is good or bad from a photo, you need to have someone that knows what they are doing look at it, or take a chance and have a seat installed and throw it back together and hope for the best.

I have to agree with you with the piston , it has had a beating but it looks like i could be alright still after a little clean up.

it looks like the head has fine cracks between the valves so I will take the head to a shop to get fixed if it can be. It probably is the photo , i dont think it has been welded by the look of it

I was thinking while the head is off is there any way of telling if the piston rings are good or not? if i was to pour some fuel or something in the pots should it disappear or not if the rings are good or bad

 

Thanks for your time wayne

[wayno]

I don't know a lot about checking rings that way or any other way for that matter, it seems to me that the fuel would get past the rings as they all have gaps.

When you had it running it likely was blowing white smoke out the tail pipe, this would have been raw fuel that didn't ignite in the bad cylinder, no compression, no fire means white smoke that smells funny, black smoke would mean it was rich, I don't know what color smoke would mean bad rings in a diesel.

I don't know what to say about the cracks in between the valves, my machinist rejected the one I had so I had to find another one, I do know that Nissan put out an advisory about crack size, they determined that if it didn't leak coolant into the block/cylinder, the crack wasn't to big, they even had a depth gauge, they were basically saying use it till it is causing a problem, give me a break.

[Fly Dawg]

I don't know a lot about checking rings that way or any other way for that matter, it seems to me that the fuel would get past the rings as they all have gaps.

When you had it running it likely was blowing white smoke out the tail pipe, this would have been raw fuel that didn't ignite in the bad cylinder, no compression, no fire means white smoke that smells funny, black smoke would mean it was rich, I don't know what color smoke would mean bad rings in a diesel.

I don't know what to say about the cracks in between the valves, my machinist rejected the one I had so I had to find another one, I do know that Nissan put out an advisory about crack size, they determined that if it didn't leak coolant into the block/cylinder, the crack wasn't to big, they even had a depth gauge, they were basically saying use it till it is causing a problem, give me a break.

When it was running wayno it was blowing white smoke,I put the same amount of fuel on top of each piston today and it did get past the rings a the same rate on each piston, I think I am at the point where i will try to get the head fixed and put it back on and see how we go , Thanks from Aus

[wayno]

That is what I would do, I would not spend a lot of money though.

When it was running wayno it was blowing white smoke,I put the same amount of fuel on top of each piston today and it did get past the rings a the same rate on each piston, I think I am at the point where i will try to get the head fixed and put it back on and see how we go , Thanks from Aus

[Fly Dawg]

 

The back gaurds arrived today ready for me to build a tray around

[bananahamuck]

The inside of your engine looks like the time my friend thought it would be just fine to not account for two of the carburetor lock washers ... Ouch

[Fly Dawg]

The doner D21 3ltr v6 which we are going to attempt, sorry we are going to put it in the 720

[Fly Dawg]

I did a bit of work on the 720 tray today,, 30 years since I have welded anything even though I did a trade as a fitter and turner it still took a bit to get it again

 

Still have to do the head board and timber,, Fitting 3 bmx bike clamps and 4 concelled tie down points 

 

Have to unbolt it and turn it over for welding on the bottom side