• CA Lessons: Landscaping To Reduce Wildfire Risk
    While there are no ways to fireproof a property, there are strategies to design and maintain landscapes for reduced vulnerability. Click here to learn more.

305 life expectancy


LawnSite Senior Member
how many miles do they average before rebuilding time?
got my truck used 67000 miles i now have 94000 on it.
i had no problems other than water pump and brakes.
dont use or leak any oil.or smoke.
seems like it was tooking care of.
i was told it had new timing gear in it
motor is clean untouched steel looks like factory
this is a 305 are they in 3/4 tons?
why is this motor so bad on gas to much truck?


LawnSite Member
whoa! Rebuild already?!?! Been running it without oil or something? Haven't you ever heard 100,000 is break in on a 305 or 350...it should be fine...if everything looks good and it runs good why touch it...a rebuild will more than likely not help your gas mileage that much...try a good tune up before a rebuild. Gas mileage usually is crap with a 8 305 shouldnt be that bad. What kind of gearing do you have?


LawnSite Senior Member
How long really depends on how you use it and how you take care of it. I had one (a 305) that was probably ready for a rebuild at 120,000. I've also had friends that make it to 150,000 and they still run like new. Sounds like yours is fine, from what you said. I think mine also wore out faster because it had to survive me driving it in my teens when I thought I had a 4x4 race car. Not to mention towing the boat, hauling fire wood, ect. You get the picture. Change the oil, take care of it, sounds like it's got lot's of life left.

mike reeh

LawnSite Member
san diego
regarding mileage, you said it.. too much truck..

had a friend with a 305 in a 79 suburban 4x4, it got terrible mileage.. dont make a whole lot of torque, but that motor should would rev to the moon


John DiMartino

LawnSite Silver Member
Mike the 305 is not a great high revver,due to being a fairly long stroke motor.(as compared to 302 Ford)The 305 is a great engine for a car or 2wd truck,but in a 4x4 it is marginal,especially the 2500.I think if it is EFI,and is mainatined,200K isnt unreasonable to get out of one,they seem to be indestructable as far as durability.I would expect to be adding oil at that mileage along with it getting tired and a little smoke by then.My 350,which is the same engine,but with a 4.00" bore,as opposed to the 3.76 of the 305,has 146 on it now,and it plows and pulls-a lot.The hrs on it are probably similar to a truck with 175-200K on it.It does burn a quart between changes,but runs as good as new,The oil usage hasnt changed ,the valve guides are worn,a common problem with engines built at the flint plant.

[Edited by John DiMartino on 01-18-2001 at 07:46 PM]