Pounding Rox Truck Shop Posted March 14 Report Share Posted March 14 I bought a 720 last summer dirt cheap and have been fixing it up slowly. It won't be pretty but it runs good. It's been Weber carb swapped and overall not bad for a $700 truck. I made some YT videos about it. I'll post the links. I owned an 81 720 King Cab 2wd 25 years ago when I was in college so this one is like stepping into a time machine for me so I named it TimeMachine720. 1 Quote Link to comment
datzenmike Posted March 14 Report Share Posted March 14 Should be a 180/185F thermostat. Your Z24 is designed to give best performance and mileage when it's hot and all engine components warmed and expanded. Engine oil works best when hot. If you need something lower to keep it cool then something else is wrong. Running hot low speeds... missing fan shroud. shroud increases fan efficiency high speed... soft lower radiator hose collapses under pump suction heater hoses are joined because heater core leaks... always block flow if doing this The rusty thermostat indicates that a previous owner did not look after your truck properly. Never run tap water, it's full of dissolved minerals, use distilled water and always always always use a 50/50 antifreeze/coolant mix to prevent rust. 1 Quote Link to comment
Pounding Rox Truck Shop Posted March 14 Author Report Share Posted March 14 2 hours ago, datzenmike said: Should be a 180/185F thermostat. Your Z24 is designed to give best performance and mileage when it's hot and all engine components warmed and expanded. Engine oil works best when hot. If you need something lower to keep it cool then something else is wrong. Running hot low speeds... missing fan shroud. shroud increases fan efficiency high speed... soft lower radiator hose collapses under pump suction heater hoses are joined because heater core leaks... always block flow if doing this The rusty thermostat indicates that a previous owner did not look after your truck properly. Never run tap water, it's full of dissolved minerals, use distilled water and always always always use a 50/50 antifreeze/coolant mix to prevent rust. Fan drive hub was completely shot and spun freely so that probably had most to do with temps being higher than desired. It was missing the fan shroud which I did add recently. It would run temps 3/4s of the way up at times. I dialed back the timing a hair, that helped but based on what I saw when I replaced the pump itself, it was due. Not sure why the PO would go through the trouble of doing a head gasket, sending the head out and then skip the water pump... the whole system is new now. 170 should be fine for summer driving since it will get up to temp regardless. I use only 50/50 with distilled water. I won't drive it in winter, she gets parked and mothballed. Quote Link to comment
datzenmike Posted March 14 Report Share Posted March 14 You shouldn't have problems now. The silicone oil in the clutch fan leaks out. Years ago someone replaced with grease. It works a little too well and fans turns too fast and sounds like a jet taking off. Engine oil might have been better. Quote Link to comment
Pounding Rox Truck Shop Posted March 14 Author Report Share Posted March 14 Yeh, overall the truck isn't bad. For a junkyard and household handy truck I think it does well. Replaced my 91 D21 with it after the frame on that truck rotted away. I don't plan to abuse this one, I want to keep it for a long time. It was overdue on many items and the guy I bought it from had other trucks ahead of it. So it came home with me and I have been checking items off the list. It will need a clutch and carrier soon. I want to do both at the same time but it's still very driveable as it sits. It's also extremely nice for being a NY truck, I've looked at others to buy and they were roached with NY rust. I feel I got lucky on this one and I will drop some money into it. Quote Link to comment
Pounding Rox Truck Shop Posted March 15 Author Report Share Posted March 15 Had to reseal the water pump over the last couple days, working on it off and on. I thought I had cleared off all the old paper gasket but a little piece remained and caused a leak. I did a good clean up and reinstalled everything last night. Topped off the coolant and fired it up for the first time since last November when I stored it. Got it running and left the cap off to get some air out. Fan sounds good and I can feel it moving some major air in front of the grille now. Next is the oil change and then wait while the rains wash the salt off the roads over the next couple weeks. I'll have a vid up on YT soon. Felt great to fire that truck up again, I get sick of my commuter car by the end of every Winter. Quote Link to comment
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