Exciting 720

[jagman]

Mike ,  I got the new thermostat from Nissan and it has a 63 c on it .  I take it to mean 63 degree Celsius  or 140 farenheit temp setting and if that is the case I have been running a  180 or 190 farenheit.  If it is supposed to run at the lower temp why do the parts stores only carry the higher temp thermostats?  Is the temperature setting on the nissan part correct?

[datzenmike]

I have no idea what that could possibly be used for on a Nissan. Today engines run at about 100C or boiling. The Z24 would run just under 190F and will give the best engine life, mileage and performance.  The TVV thermal vacuum valve opens or closes at 140F so this is impossible to have. Take it back and tell them you want a 180F or 185F or just get your money and go to NAPA for it. Maybe someone threw it in the wrong box. It's still wrong.

 

These are for Z24 wengine but I imaging same as others just upgraded part numbers.

 

You want an 21200-80W00 is 82C or 179F this is for temperate applications you want

 

21200-80W10 is 76.5 C or 169F for tropical use

21200-80W05 is 88C or 189F for arctic use

[Charlie69]

ST Sport Truck model.  More bells and whistles!  LOL

 

I run a 180 In the desert.

[datzenmike]

The thermostat sets the minimum engine temperature. Generally 180 - 185F is normal. Metal parts expand from the heat and close up loose tolerances, compression is higher, oil lubricates better when warmed up properly. On the way to the combustion chamber gas droplets absorb heat in order to vaporize. Gas by itself won't burn.... it has to vaporize first. A cold running engine will fail to do this as well and give poorer mileage. A cold engine will absorb more heat around the combustion chamber, pistons and cylinder walls. There will be markedly less heat available to expand the air and push on the pistons. Surely you've noticed a cold engine is sluggish until fully warmed up.

[jagman]

Hi Guys,  I put in the Nissan thermostat  and readjusted the timing to 3 degrees before top TDC then ran the truck for about 30 mins and the temp guage showed the needle in the lower quarter of the range scale. On monday I will again use the truck for deliveries and see if under load conditions it no longer hits boiling.  I am running water only in the system now but once the overheating is under control I will switch back to antifreeze.

[datzenmike]

Should be in the middle of the 'run' range or a needle width above this.

[jagman]

The temp is running at  1/3 of the normal range   On a hard pull with load it rises to just above the center of the guage.  I like it but I don't like the noise I am getting from the driveshaft when I first take off.  The donut thing seems to need replacement.  I have checked Rockauto and they have them but what do you folks recommend as a proper replacement for the carrier?

Edited September 21, 2020 by jagman

[datzenmike]

Temp sounds better now. On long down hills mine will over cool slightly but it likes to run just over 1/2 and this would be about 185F. I have electric fans now so if the engine is pushed hard enough or idled long enough it will go to 3/4 when the fans come on. I have an IR gun and should shoot the sender and the sensor switch for the fans and see what they are set for compared to the stock gauge.

 

Carrier isolater...

Well first off the bearing inside rarely fails but the rubber surrounds always rot away. I did the following as a temporary fix but it worked so well I left it.

 

I found some 3/8 or 1/4 inch conveyor belt but any similar rubber floor mat will do. Cut a long strip a couple of inches wide that will wrap around the driveshaft 5-6 times. (depends on thickness) You might try using zap straps around it to hold in place. Adjust length to suite. When the bolt down support fits but holds it snugly when tightened down, you're done.

[jagman]

Do you have to cut off the old rubber donut thing or does your fix go on the outside of that?

[datzenmike]

 

 

I would remove any rubber down to the metal sleeve that turns on the bearing... actually it stays still and the drive shaft turns. I seem to remember wrapping the rubber on like a jelly roll and tying it on with black wire to hold it and then clamping it in place.

[Charlie69]

Take the drive line a part.  There is a large staked nut that you remove with an impact wrench.   Then you simply tap off the old bearing and rubber.  Not the direction it is on there.  Buy a new one and install it in reverse order.  Be sure to restake the nut.

 

Edited September 22, 2020 by Charlie69

[bottomwatcher]

On your overheating issue the thermostat was definitely the main culprit. The fact that the temp continues to climb indicates your radiator is not operating at a 100%. You can probably get by just watching the temp. But with a new radiator and a functioning thermostat you should be able to drive as hard as you want without any temp climb. It's cooling of this time of year but if you notice it getting hot next summer time for a real flush or new radiator.

[jagman]

Yes I believe the thermostat was the major culprit.  I have pulled the trailer with a load on it and as you would expect on a long uphill pull the temp goes up but now it also goes down and does not get to the boiling point.  The radiator is being cleaned as I drive since it is full of CLR.  I will drain the system this weekend and fill with the antifreeze mix. also have to fix the carrier bearing and plug an exhaust leak.  Then home free!

I don't have any spare rubberized flooring I can cut up so I will go with Charlie's advice and buy the part I need for now but I will keep Mike's fix in mind for the future.

Edited September 22, 2020 by jagman
add

[jagman]

I checked the number of the thermostat Nissan sent me. It is a 21200-80w00 and is working fine.  I did check my timing and reset it from 12 degrees BTC to 3 degrees and the truck seems to perform better. It was in the 40''s here yesterday morning so I got to find out if the heater works ---- it do!

[jagman]

Today a friend and I picked up some rough sawn oak that I had stored at another friends place. I had forgotten that we were cutting  the logs at 16 feet but we got it all loaded to the top of the bed and gently took off for my place.  The rear springs were 1 in off the bump stops with the front wheels in bare contact with the road surface.  To turn I had to gently apply brakes. It was a good test of the carrying capacity of the 720 and the smoothness of the drive train.  We couldn't avoid all the potholes and those we hit caused the front of the truck to rise and break contact with the road surface for a second or two but the lower boards in the bed saved the day with 8 feet of them sticking out the back.

Tommorrow I will get the truck on the lift and change the drive shaft support and fix the exhaust leak and she should be 100 %

Mike I was wondering if that flex seal stuff advertised on tv could be used to fill the rubber piece as well since it seems to be a rubber like compound.

[datzenmike]

No idea. You mean fix to old rubber isolater for the carrier bearing? RTV would work if you take it off the truck and position it so it doesn't drip all over.

[jagman]

I got the center carrier bearing in the truck today without removing the drive shaft. I didn't want to piss the 90 wt all over the floor of the shop like last time when I didn't know that would happen.  I put new belts on too.  The exhaust sounds loud but there are no leaks that I can find ahead of the muffler (new) and when I put my fingers beside the header connector there is no hot exhaust escaping.  My inspection station insists the noise must be a leak.  I will take it in again this week and see if they are willing to pass it.  Does anyone know of a tire with an aggressive tread for the 720.  I will be looking for rears for the winter. 

[Charlie69]

I have run BFG All Terrain Radials on several of my trucks.  I do not believe they make these 14" anymore so you would hav to go to  15" wheel.

Edited September 30, 2020 by Charlie69

[jagman]

To those of you who suggested a tow hitch from either a n s10 or a ranger from the mid eighties, I have scoured the local yards for a used one and the only thing that turned up was a mangled s10.  I don't think a mouse could have survived that wreck.  So I have ordered a new hitch for an 86 s10 from e-trailer. I will let you know how that installation goes.

[Charlie69]

Buy one off any truck/van, a little time with a torch and a welder and any hitch will fit. 

[jagman]

Too little time to search.   Have drill and welders all I need is a steady hand and glasses.

[jagman]

Charlie69 et al,  I have completed the installation of the tow hitch with the help of a friend.  The S10 hitch is 3/4 of an inch too wide to simply bolt up so I used 1/2 plate on the right side drilled to fit and 1/4 plate on the left.  It is held to the frame by two bolts per side. The bumper brackets are offset by 3/4 and 1/2 inches with washers for spacers.  I will need to raise the hitch ball by at least 5".   The hitch I currently have sits too low for my trailer.  I shall remedy this tomorrow.  I will also recheck my valve clearances and flush the radiator and fill with antifreeze mix.

[Charlie69]

Mine is welded to my bumper brackets.  This way it comes off with the brackets.  No extra holes in the frame.

 

Jagman sounds like you used factory frame holes also.

[jagman]

Yes Charlie, I used the factory frame holes for the mount.  I just couldn't see why I would need to make more.  I didn't weld because at some point someone may wish to dismount the tow bar and go back to the original bumper mounting.  I did have to cut about 1 3/4" from the front of the tow bar frame attachment to get the angle right.

[jagman]

Well, the truck is still running hot.  I have retarded the timing once more and it sounds better and is running cooler?  I may have to retard it yet again I'll see.  The drive shaft carrier bearing introduced a noise when the truck is pulling that goes away on coasting.  I had checked the ujoints when I assembled it and found no play.  Has anyone had a similar experience?