The Stovebolt Site Forums The Shop Area General Truck Talk Rebuild

When is it time for a rebuild?

My truck engine (235) has probably 200,000 plus miles on it. I keep it tuned up. I’ve replaced some minor things and rebuilt the carburetor. It runs OK but I don’t drive it too far from home.

It only gets around 11mpg (city) but it doesn’t burn oil and I don’t see any leaks. The compression could be better but it always starts up every weekend. The engine seems tired after its run for an hour or so, which is understandable after 50 years.

Just wondering what others would do in this case.

Thanks.
Mark

Wow. 200K is a lot on that era of engine. Having said that, if it isn't using oil, starts & runs good and does everything you need it to do, I don't see a reason to mess with it. Your mileage isn't that bad for around town.

If the compression is low or unbalanced I would start with a valve job. When you pull the head you can inspect the cylinder walls for wear and go from there.

I agree. I was leaning towards pulling the head. I've heard stories of some of these engines never running exactly right after a major rebuild.

Just a suggestion...I'd run a compression test first.....get a baseline reading and then add a little oil to each cylinder. A boost in compression will indicate ring wear....adding a fresh valve job will just create additional blowby.

As I see it you have three options.....leave it as it is....rebuild....or replace the engine with a decent running used engine.

A professional rebuild is going to run 2K and you know that you'll add additional bucks for upgrades.....finding a good used engine that has been replaced by a small block shouldn't be that tough in So. Cal. Or you can just drive it as it is....if it starts and runs and you just use it on the weekends it may be tough to justify the expense. Your call!

Dave

Thanks Dave. I'll do some tests before I decide.

Mark

With some sweat and alittle work the rebuild kits are only at or below 900. Have fun with it. She has lasted you this long. Look into it and if a rebuild is warranted think about doing yourself. It can be complicated but the satisfaction of doing it yourself can't be beat. Good luck

i'd leave her alone for now, add a little of that "engine restore" it comes in 4-6-8 cylinder cans, it helped alot on my 94 chevy with 196,000 miles.

you can put new rings and bearins in the truck without pulling the motor drop the pan and see if the bearings are loose they make a 1000 over size i had two rods knocking once put oversize just on those two jernals and new on the rest took care of it these motores are so easy to work on if you do it your self it dosent cost much

The engines that don't run right are the ones that get a shade tree overhaul. Unless you're willing to do an out-of-the-frame major rebuild, don't mess with it!
Jerry

I'd do a couple things that will make life a little easier for the old mill. Like, electronic ignition, some taller gears so it doesn't have to rev to high, maybe 30 wt oil. Plus the compression test, tune up and valve adjust.
My old 47 coupe had a sweet running motor that I finally replaced but it ran great with low compression in one cylinder, drove it everywhere. Biggest help was going to 3:55 gears.

I got a pretty old 235 as a daily driver.
This engine was rebuilt about 20 years ago, at least.
All I did was a head rebuilt and new lifters 3 years ago and it runs like new again with no oil loss and 20 mpg on the freeways.

A stock 235 block if kept under 3000 rpm should last several decades, especially if not driven daily and with frequent oil changes.

Well, I don't run that well myself but hope no one decides I am too old to function. I am not old, just mature.

It sounds like maybe you are running it a bit on the rich side if it gets 11mpg. Is your power valve working?

I think if I commit to anything it will be pulling the head. I have two cylinders with fairly low compression in comparison to the other four.

As far as the mileage goes, my carb (Rochester B) has always functioned best a little on the rich side. I don't know if I want to rebuild it again. I may switch to the Carter YF if I can find one for the 235.