New to me 720

[that-son]

hello everyone. new to trucking and dirt roading but not new to tinkering.

i just bought an '81 720 4x4 and was wondering if i could get some advice. the truck has a lot of issues but i'm willing to do some of the work. so far i've replaced a brake master cylinder, differential gear oil and cleaned out and killed a couple of rust spots.

before i changed the engine oil the truck would get 26 mpg- some city but mostly highway. after i changed the change oil, i now get about 11mpg and hear a lot of backfiring when let go of the accelarator. a compression test revealed 3 cylinders at about 120psi and one at 80psi. what do you guys think about lucas stabilizer and anti foul for the spark plugs. or should i just go with heavier oil? i am getting either a rebuilt engine or getting this one rebuilt in august. would it be better to do a swap-like a totally different motor?

last week i topped off the coolant reservoir, filled it to the max level and the next day it leaked and is now down to the min level. could not pinpoint the exact location of the leak so i topped it off again and have been driving it for 4 days without any coolant leaking. what gives? anyway, i borrowed a pressure tester from autozone so we'll see what happens tomorrow.

my main issue with the truck though is that sometimes it will not start. i found this:

http://dlarson.hubpages.com/hub/The-Dat ... t-Tell-You

i have not followed all the steps he recommended to do before replacing the relay however, i looked under there since the knee guard has already been removed by the previous owner. there is no fuel pump relay. there is another relay but it does not look like the one posted on the blog. also, i think i hear the fuel pump running even when the engine won't turn. the battery and starter are both new and the alternator has no issues. i'm getting tired of pushing the truck so i could pop it in gear and start it!

i really like the truck and enjoy driving her. however, i think she looks a little tall and skinny. i don't mind the height but i was wondering what your thoughts were on wheel spacers. i think i would like to push the wheels out about 2 inches but do not know how that would affect alignment, suspension, ride and tire wear. has anyone done this?

i meant to post pics but could not transfer them to my computer. sorry.

also, there aren't too many videos on youtube that show what this truck is capable of so please share your experience/s in whatever terrain you've been in.

thanks!

[that-son]

so i borrowed a pressure tester from autozone and found the leak where the lower radiator hose connects to the radiator. i think i'll just keep topping it off and wait till august when they rebuild the motor.

i see people reading but so far no inputs? any advice is welcome!

[Superflyers]

I wish I had something to add. Just got my first 720, and I have non of the listed issues, but what kind of oil are you currently using. I just changed all fluids in mine. I hope you find a answer for your questions

[that-son]

whoa! sorry i did not see this but thank you for replying. i am using 10w30 but just recently added lucas stabilizer.

anyway today i finished redoing all vacuum lines. will have to get an ab valve though.