The Stovebolt Site Forums The Shop Area Engine Shop My 250 uses a lot of oil. What shall I expect?

Id expect to see some degree of smoke like you're seeing on a 'free' engine like that... I ran a qt of MMO through a Studebaker 289 both in the oil and the gas and was amazed how much cleaner it ran. It had sat for years like yours and was close to 1K miles on odometer.
It went from mozzy fogger to misting tailgaters like your describing. It might clean yours up enough to get you in the 1qt/tank range... for free I'd live with that and be glad I had a built in tailgater 'back off' tool to to use on unwelcome commuters riding my bumper.

I can't be certain but I think it was the MMO in the gas that made the real difference.

That long block price is about half of what my machine shop bill was for my 270 FYI. (and I had to reassemble everything)

Try adding a couple of quarts of kerosene or Diesel fuel to the oil, enough to bring the oil level about 2" above the full mark. Then run the engine at a fast idle (1200-1500 RPM) for about 15 minutes, with no load on the engine. Drain the crankcase and change the filter while the engine is hot, and refill with straight HD-30 oil. It can't hurt, and you just might de-carbon the ring grooves enough to get a better seal against the cylinder walls.
Jerry

I guess one could think of the carbon in the ring grooves as the dirt hiding under fingernails?

Is this in the cylinder walls or on the rings themselves? I can't picture it.

In the piston groove where the rings live. Keeps them from rotating and flexing properly. Cheap and will do no harm, if done as HRL suggests. Will also dissolve any dirt in the oil system so a plus for that.

Ahhhhh! Light bulb just came on in my head. Thanks. New terminology for me. Haha! Isn't it fun having a total newb as a student? I know just enough about engines to get myself in trouble and waste a lot of money. Thanks.

Lugnutz, you think we were all born knowing this stuff? Down the road you'll be sharing what you learned to other people also.

And hopefully you will be able to share it in an artful, kind, polite, heart-warming and diplomatic manner as HRL does!
Truthfully I wish there was a place on this site where you could go to and see all of the priceless tips which he shares. Especially the quick hitting ones that make you say, "Why didn't I think of that?"
Carl

Yep. He taught me how to put my harmonic balancer back on. The kind without a bolt where you heat the center of the balancer, grease the snout and tap it on.

Overfilling the crankcase turns the crankshaft into a very efficient washing machine agitator. Just don't try to drive the vehicle, as the solvent destroys a lot of the lubricating and load-bearing properties of the oil. It's OK to run the engine as long as no driving load goes on the bearings.

Carl, being able to be a blunt, insensitive, and just a bit irritating old geezer is one of the few perks I can think of after spending 50-something years wrenching on these old rigs! The aches, pains, and scars of half a century of doing dumb stuff, not so much!
LOL!
Jerry

Valve seals leaking? Very common on oldergm v8 and 6's. Another method of cleaning out a block is to drain the oil and refill with atf and a couple qts of engine oil. Warm the engine up,run it for a couple blocks, and drain the oil. Do the filter too. Atf has a high detergent agent in it and works well for cleaning out the engine. The nice thing is that it is safe to drivefor a short time.used this method lots in in the past and is real effective in cleaning up hydraulic lifters.however if doing this and the solvent treatment doesn't work then the rings are done and that's it.! I'm not discrediting the solvent treatment....never tried it as the atf worked so wellong for me. Also have seen but never used is a additive for engine oil that works the same as atf,I don't recall what it is called.

Valve seals are all new. Only seal I didn't replaced was head gasket and freeze plugs. I will wash it out in the next 2 weeks and update everyone.

Plugs look good, not to sooty or oily. Have you had it on a long highway trip? A 50 mile trip each way at a steady rpm and decent speed may just loosen up the rings and get the oil usage down. Get the engine good and hot. The muffler could have excess oil in it thats just burning out from the old valve seals so it could take awhile to clean out.

Joe

Thanks Joe. Entire exhaust is new. Manifolds were clean when I installed them with a new gasket. Longest trip has been 20 miles one way. I am puzzled to say the least but a novice so I need to run everything by folks who know. That way I won't waste money with the wrong diagnosis.

Video of exhaust 30 seconds after cold start. Choke still on and RPMs range 1500 - 4000 in video. White and black smoke. Looks pretty grim.



Jay

You say unknown miles on this engine and it burns to much oil... but the plugs look ok and the compression is workable...
I think you need to drive that sucker a good couple of gas tanks, (keep the MMO in the gas tank too) and give it a chance to settle down.
If that's all the worse it smokes on warm up what's the problem? You live in a snooty community or something?
Show us a video looking out the back window as you run it up through the gears on the road, then maybe that will show something scary or more indicative of the problem.

Haha! No snooty neighborhood here. People on my block know me as the guy always messing with something on the truck or one of my cars.

Three more videos.
First is after a 5 minute drive.


Second is holding RPMs steady at normal driving RPMs.


Just a few seconds under the hood.


Jay

If it's running rich (the black smoke) it could be washing down the cyl walls I guess. Its an old engine that's why someone quit using it... Just buy oil by the gallon and remind yourself 'this is what it was really like in the old days'
DO the other stuff you mention in your first post and see what this does (after you adjust the carb) over the winter.
Is it a DD? how many miles a week does it see?

Doing a cold compression test is not accurate,when components are cold they are in a contracted state,thus giving lower compression readings. Warm the engine up to operating temperature. Pistons etc will expand and give you more accurate readings.compare your hot and cold to see the difference it makes.the hot readings are what you have driving,which is the true picture. Would be interesting to see the difference on #3. If you do have new valve seals then I suspect rings are the issue. Check your pcv system and make sure it's not plugged or the valve isn't gummed up.

I say valve guides are worn, need to have the guides knurled or replaced. Just pull the head and have a competent machine shop do a valve job on the head.

Guides are possible,although with new seals it shouldn't be to much of an issue.biggest indication of seals or bad guides being bad is a cloud of smoke on start up that clears up quickly.when engine is shut off oil seeps past seals and ends up pooling on backside of the valves. Now if guides are completely thrashed then valve stems could flop around oil could get by the sears. But for them to be worn out enough to leave a constant trail of smoke out the tail pipe? I don't know about that,I've never run across that being the issue. But you never know right?!!

I ran one of these in a 68 Nova for ever(250,000 miles) It never smoked, but did have a ton of blow by. Would vent out the cap on the valve cover. Biggest issue was the PCV valve. It would get sticky and push oil into the intake. Cheap part and easy to change. Caused all sorts of running issues when it would go bad. It could be just that easy. Compression was good, but a lot of wear and loose pistons were my real problem. By 1978 it was done. Ball joints were the reason I got rid of it. Back then the car was worth about 800.00 and the parts alone were more than that. Try the PCV valve and see what happens.

Jay, hey, you've did everything else you can build that engine. I know you can do it. Any problems there is a great bunch of guys here to help you through it.

Should you decide not to do it, or have someone else do it maybe give this folks a call and chat with them. They are in Johnston, S.C.
http://www.cmengines.com/Home/tabid/36/Default.aspx

My nephew has sent probably a half dozen to them and each one has been "jam up" and actually saved some money. I may end up letting them do my 4.8

Well...you did a pretty good job of diving into the old t5 and figured that out. Rebuilding an engine is not that hard. Really the biggest part of it is the machine work. My approach is as follows. Strip it down,head gets rebuilt,block cylinders get measured so I know if it can stay standard or go with a rebore. Crank gets measured and either gets a polish and new bags or get ground to what ever size it needs to. New cam bags if needed and cam checked out. You can go with a regrind or spec.a mild cam,or what ever you want. Get that all done. Bring it home and get a good shop manual and put it all back together. Warranty...you.unlimited milage. Experience. ..priceless.you may or may not save any money doing it your self. Check engine rebuild shop for prices on their machine services,and compare,also compare prices on parts. If I were to go with a rebuild, I would go with the best warranty I could get. By comparison. ..I've got a 5.9 Cummins out of a 06 dodge that dropped an exhaust seat and damaged head and #1 piston and broke the crank. 6600.00 to rebuild,and only a low cost rebuild.that's only boring out #1 cylinder and replacing 1 piston. A complete long block is 7400.00. If I were to rebore all 6 holes in the old block it would be more than the rebuilt long block. There is a big back story to the engine that failed,I won't go into that except to say it was a badly rebuilt engine.PO had engine rebuilt before he sold it. All that to say that which ever way you go...do it right the first time.

I love my 250. It's a nice size for the '65 C10 with a 4-speed & 3.73 rear end. I did a rebuild in my home garage almost 20 years ago...it was very tired and using lots of oil. I don't remember the numbers, but it wasn't that much for machining and parts.

Wish I had known about using 307 pistons to bump the compression.

cm

I would rebuild what you have. Parts are not that expensive, it's the machine work, so shop around. Do as Starfire4 mentions, and add 307 Chevrolet V8 true flat top pistons. They are a true bolt in and will raise the compression 1 point, to about 9.0 to 1. You will still be able to run regular gas but the added compression will help in the power department. Do as much of the nasty work as you can and save some money. Shop manuals will tell you how to assemble or take apart.

Joe

Alvin,
I've talked to them already and yes they have a good reputation. Unless a good engine falls into my lap I'll probably take my 230ci to them and have them do the long block. Sounds like 307 pistons and roller bearing rockers would be the only upgrades I'd want. I plan to run the stock intake and a progressive 2 barrel Weber carb. Headers are not out of the question but I'm trying to keep the cost down and I can always add those later. Sounds like I need to sell some T5s to find this. Haha!

I hope the "230" was a typo- - - -the 307 pistons won't work in that one, only the 250. The big block V8 rocker arms work on a 250, but you lose a slight amount of valve lift in the process from 1.75% to 1.7%. Have the machine shop install pushrod guide plates and screw-in rocker studs while they're reworking the head. If you install a cam with slightly better timing and lift, the .05% drop in rocker ratio isn't noticeable.
Jerry

The difference in the 230 and the 250 is the stroke. You would need to use a different crankshaft and turn it into a 250. The 230 has a 3.25" stroke; the 250 has a 3.531" stroke. The 307 piston would stop about 1/4" short of the top of the block, and the compression would be about 6:1. Performance would be a bit below par!
Jerry

Ok, so it can be done. Just need to get the right parts. I have no problem spending money to get the right parts. Thanks. That simplifies life a lot. Drive the 250 until the 230 is done. Then swap.

Here's a standard diameter 250 crankshaft:

http://www.ebay.com/itm/6516-Cranks...12743927?hash=item5d46615af7&vxp=mtr

These are available pretty often, usually at reasonable prices. If not this one, there will be others. Just search "Chevy 250 L-6 crankshaft".
Jerry