The Stovebolt Site Forums The Shop Area Engine Shop Engine problems again

i have a 1949 pick up siezed the 216 because the oil pump broke while i was on the freeway,so i replaced it with a 235.the short block i bought from a friend who had it rebuilt but later decided to go with a v8.head is a 58 model according to the numbers i ran.head has also been rebuilt.put everything together got it fired up with a semi valve adjustment since it was cold let it run for about 30 minutes oil pressure steady in the middle of the gauge temp sensor also showing good and a lil below middle.turned it off did another valve adjustment truck idles great revs nice so i decided to do a lil test drive.it started out smooth and good went around the block and it died.with no warning like if i had turned it off.pulled over tried to crank it and the starter dragged.brand new starter installed and same problem changed the battery 3 times and same problem.tried to turn the motor over with the fan and pressing on the belt and nothing.cant get it to spin.i will remove the lugs to see if i can get it to crank but as of now i want to wait till its cool to see if it will spin when cold.any suggestions fellas?

by the way the truck is 12 volts now using original flywheel and a starter from a 62 impala 235.i have used this combo on all my cars and trucks with no problems.

Hy wirewizards, I know you won't want to read/hear this, but one of the few things that can tighten an engine up like this is a rolled up bearing, this can happen after a rebuild if the bearing clearances or the bearings installed were not correct, I sincerely hope this is not the case, and that something else simple and less expensive to fix is causing the engine to lock up.

i figured as much,but wanted to see if anyone might have a different answer or outcome.

i wanted to build this short block and went against my better judgement.hope its something else.

update went outside to try and crank it over and it did. not fast and it did drag but it spun any ideas?

Drop the oil pan and inspect EVERY bearing- - - -rods and mains. Suddenly getting tight enough to refuse to crank when hot is a HUGE red flag. The engine might be salvageable right now. One more startup and a little tinkering, and you're going to have a boat anchor. I never trust a stale "rebuild", even if it was done by one of the guys I've trained. Until I personally establish that an engine has the proper clearances, I just assume everything has been done just a little bit wrong!
Jerry

thats what im going o do in the morning.going to drop the pan and see if anything looks odd and will re torque and make sure that all tolerances are withing specs.

I'm going to guess you'll find at least one rod bearing with foreign object damage from a "dirty" assembly job, or possibly a scratched crankshaft from letting a connecting rod bolt touch the journal surface during installation of the pistons. One of my former students called me a few weeks ago about a failed engine after just a few miles- - - -he had managed to install one connecting rod cap backwards while assembling the engine. He's incredibly picky about his assembly procedures, and usually does an excellent job, but this time, he got a little distracted. He does have a habit of smoking "alternative" substances, and it's possible he was not giving the engine his full attention!
Jerry

what gets me, is that i know better than to just slap the motor in without first going thru it myself.oh well we will see how much damage has occured in the mornning.

I built a engine and did not follow instructions of the Best rear main seal I used. I packed it in just a little, not like the old seals, but more then I should have. The engine ran fine and sounded good, no problem at all ( on the test stand for break-in). After 25 minutes of run time I shut it down to clean up and rest a bit. Went back out after a break and the motor was locked solid, dad and I about flipped the stand over trying to get it to move. I was upset so we shoved it in the garage till the next day. I would turn over and fire right the next day, so we figured no bearing or crank damage. Using a infrared heat gun, we started checking for trouble spots while it was running. It didn't take long to find, the back of the crank was heating up pretty quickly.
I pulled the pan off and rear main cap, the area of the seal was changing colors which indicated heat. I replaced the seal and follow the directions this time with no other troubles.

Guess I am saying, check everything,

Joe

It is surprising how much heat a rope seal can generate. If the rear main clearance was set on the tight side the heat expansion can lock up that main.

I'm going to pull the motor out today and see what is holding it tight.hope I can reuse the block if not I'm going to be [censored] at myself for not double checking that block.

Update. We pulled the motor out since I want to use the truck on Sunday and have another 235 that I rebuilt myself for my 39 truck.when we pulled the motor out I got my friend to try and turn it over so that I can loosen the pressure plate and the darn thing spins freely.not too loose but it does spin like a rebuilt motor should.im now wondering if the transmission jammed and shut it off? I looked the tranny over and no signs of it being stuck.im going to remove the oil pan and make sure that all is well with the insides.ill keep ya posted.

When you pull the pan, be sure to check out the rear seal. It's beginning to sound like it's tightening up after a few minutes of running time. There should be some discoloration of the seal and/or the crankshaft surface where the seal runs if it's gotten tight enough to seize the engine up.
Jerry

Thanks Jerry. I'm going to start working on it Tuesday. The truck ran beautiful and has some extra power from this 235.i never new it would make this much of a difference. I'm going to put a powerglide rear end on it tmrw and see if it was worth the change.

Well today I started pulling apart the motor and looks like the rear main bearing spun.why? What causes spun bearings. Also noticed no rope seal only the newer style 2 piece rubber type.

Usually a lack of lubrication to that bearing causes them to spin. The oil hole to that one bearing likely became blocked by some sludge that was in the crank.

I would add heat expansion or lack of lubrication.

Update fellas so I pulled the crank out and mic the crank caps and the rear one is way too tight on one side and loose on the other.i called my local machine shop and the guy said that with lunch he would be able to stretch the cap and then shimmy it? Has anyone else heard of this? It would be better to do align boring right

Soo sorry auto correct gets me all the time. I meant with luck he can stretch the cap.

RUN- - - -DO NOT WALK, TO ANOTHER MACHINIST!

This guy is about to make things horribly worse! At this point, line boring is the only reasonable solution. Be sure the machine shop that does the line-bore remembers you've got timing gears, not a chain. If they take too much material out of the block while doing the boring job, you've got a boat anchor- - - -no way to correct timing gears that are bottoming out!
Jerry

I figured as much I went ahead and drove the block to the machinist who does all my work and am waiting on his results. I tried this new guy since he is only 4 blocks away from my new place and well I guess I will have to be driving 100 miles round trip to go to the same person.well worth the drive.

Well I had dropped the motor off at a machine shop close to my friends house and they broke the rear main seal.im soo upset because I 5 old them to hone the mains and these idiots tried to stretch it out just like the last place.i.now have to take apart another block and get the rear main out of it.

PLEASE tell me you don't mean they broke the cast iron rear main cap! Unless you're VERY lucky, they just ruined the engine! Swapping main caps is a problematic, if not impossible job, as finding a cap that can be bored to fit the block is extremely difficult. When the engine was originally manufactured, the block and caps were assembled, then the holes were line-bored. Manufacturing tolerances between blocks make it very hard to use a cap from another block, even if the line-boring is redone. Somebody owes you an engine.
Jerry

Sorry I was soo [censored] when I wrote this.yes they broke the rear main cap right in half.so I guess I have a boat anchor then right.

Don't ruin another block by robbing a main cap off of it. Chances are the shops you're dealing with are too incompetent to fit another cap to the block. Since the stovebolt engine has four different size main bearing bores, most machine shops have no clue how to do a line bore properly. There's a guy about 20 miles from me in Middle Tennessee that I'd trust to do it, but few if any others would get my business. Too bad you're so far away!
Jerry

I wanted to take it to the machine shop that has done all my work in the past but my friend wanted to use his so here we are.i know that the mains are 30 over at least the rear main was.i am going to talk to the man I am use to dealing with and see if he can do something if not then I will rebuild a different block.soo [censored] right now I can't think straight.

It sounds like you'd be better off to use a different base engine. .030" undersize (not over) is as far as most people are willing to regrind a crankshaft, and .010 or .020 is MUCH better. However, that has nothing at all to do with the size of the bearing bores- - - -they're always the same size, regardless of what the inside diameter of the bearing is, and all of them MUST be bored in a straight line. The oddball thing about old Chevy sixes is that each main bearing is a different size- - - -smaller at the front and they get larger as they go toward the rear.

I have block and crankshaft size specifications if you need them- - - -I can copy and email them to you if you need some dimensions to work with.
Jerry

Check the freebies section, someone is giving away main bearing caps. Might work for you.

I can't see anything with the main brg. bores being a problem, this engine ran for years the way it is. sounds like the crank was turned and maybe the rear main didn't get turned to the proper size. just for kicks I would try another cap but be sure to carefully measure the bore all around, measure the crank all around, then measure a new bearing. now you should be able to figure your running clearance.
Jay D.

Just for grins, guys- - - - -those of you who recommend swapping main caps- - - -how many of you have spent 30-something years teaching automotive machining?

Jerry

Everyone should pay attention to Hotrod Lincoln. Ever try putting a rod cap on the wrong way. The inside doesn't line up, or the sides. Same thing happens with the main caps. It will not work.

Joe