The Stovebolt Site Forums The Shop Area Engine Shop 235 engine frozen

Hopefully someone here can give me some advice been working on an old 54 with a 235 straight six. When I bought the engine someone had already gone through it and so I installed it. The engine has turned freely with no issues. Put oil in and spun oil up to the rocker arms which looked great. Then turning only with starter the engine bound up. Not immediately but after several days of turning slowly turning the engine to adjust all the rockers and I was about to close it up. I did spin the oil to the top consistently over those several days just to make sure there were no oiling issues. The transmission is currently not in so I was able to put a breaker bar on the fly will and it is boundup pretty good. I didn't want to force anything so I thought I would start asking questions. What the oil Pan off I could see that everything looks oiled well and I can't see anything out of the ordinary.. I pulled the rocker assembly and all the lifters and rods move freely. At this point does anyone have any suggestions as to what I could try next to figure out where the problem is.

Welcome to the Bolt

Are the plugs out?

Have you checked each valve to see that they aren't stuck? Put a block of wood squarely on top of the valve stem and give it a medium sized hammer blow with a no-bounce hammer, you should feel the spring rebound with each hit.

Mike B

Start diagnosing the problem by loosening the connecting rod nuts a couple of turns, one rod at a time, and see if one of them might have spun a bearing. Do the same with the main bearings. If loosening the rods and mains doesn't free things up, there's a remote possibility of a seized-up cam bearing, but that's highly unlikely. If loosening the rear main bearing frees up the crank, look into the possibility that the rear main oil seal might have tightened up. An incorrectly installed rope seal can lock up a crankshaft on occasion, particularly if the new Best Gasket seal isn't installed according to their directions.

Don't force anything! it's possible to bend a connecting rod if something has a piston seized up where it can't move. A little patience and a methodical approach to the situation beats brute force any time! Good luck!
Jerry

A little more background. This is a 54 vette which does havea high pressure oiling system. Brand new oil pump with good pressure using a drill. Good flow out of all rockers. I pulled the rocker assembly off of the head to check all the hydraulic lifters Which are well oiled and move smoothly. Rods are all fine. I did put some Marvel Mystery oil in the cylinders about 3 months ago. Thinking its possible that oil has dissipated and it now needs more so I just added some ATF. No spark plugs are in and all of the valves seem fine with none of them sticking. I am assuming this has to be a lack of oil situation so possibly the cylinder walls are dry after several months. Very confusing since it turned so freely just a few days ago. Seems like it was fine and the quickly bound up. Also, So far I've only turned the engine a one revolution at a time while spinning the oil pump with a drill to check the rocker oiling. I won't be ready to start the engine for a couple more months. If oiling the cylinders again doesn't do it I'll move to loosening the connecting rods. I truly appreciate your comments.

RC

RC -- Thanks for stopping in and joining us here at Stovebolt.com! You've asked a really good question and the ultimate answer will be of interest/use to a number of our gang here. So ordinarily, because you've divulged that this isn't actually a truck application, we would be inclined to move your post to our off-topic discussion forum -- The "Greasy Spoon" ... wherein one finds bad jokes, questionable anecdotes, pet stories, marital advice ... and questions about cars ...

However comma two things mitigate in your favor:

1. You've asked a really good question with broad application.
2. It's not just any car, it's *the* car (as Stovebolts go, anyway.... personally, I'd rather have a Schwimmwagen or a Hebmüller ... but that's just me )

So here's the deal:

Your question stays right here in the Engine Forum but you must do two things:

1. PLEASE circle back and tell us what you found to be the issue and what you did to correct it.
2. Include a picture or two of the car.

And listen to Jerry (Hotrod Lincoln) -- he really knows what he is talking about. Personally, I have truly saved thousands of dollars following his direction and advice.

Regards and welcome,
John

Is it possible something fell into one of the open spark plug holes? Did you try turning the engine by hand the other direction?

A little more background is that the engine was rebuilt about 5 years ago and has only been turned until recently. I would rotate about every 6 months 1 turn but a couple weeks ago put oil into it iand started turning with the starter. I always kept spark plugs in it until recently when I took them out in order to turn easier with the starter. Later today I'm going to check the rods and rear main. I'm thinking it is the rear main and possibly something with the seal after it soaked up oil and expanded.. I'll post what I find.

Can you access the flex plate from under the car? If you can, Try taking the starter out and see if you can turn it using the flex plate and a flywheel turning tool.

That is exactly what I did since the transmission is not in the car. It was not wanting to turning in either direction and I didn't want to force it. I did noticed the connecting rods didn't seem have much play to move horizontally on the crank. So I started at the rear of the engine and loosened the bearing cap to the first connecting rod. It now turns freely. The bearing was getting oiled and the cream main looks fine. The bearing is obviously new and is marked 020 so the crank has been milled at some point. I'm thinking of adding a .002 shim on the bearing cap to provide additional clearance. Does this make sense and any suggestions.

Just to catch up here I've loosened up the clamshell to the rear cylinder connecting rod bearing and the engine now spins fine. The other cylinders rod bearings seem fine so I've left them alone for now.. This rear rod bearing did seem to have plenty of oil on on it so I don't think that is the issue. The bearing is oversized at .020 So I'm wondering if the journal was not machine correctly and the fit is to tight. I'm thinking of adding a .002 shim to ease the fit. Anyone have a suggestion.

Plastic gauge it, and see what you have for clearance.

Measure the OD of the crank with a micrometer to compare when you plastigauge it.

Ed

Good suggestion. Will see about doing that.

The post I made last night didn't show up for some reason. Absolutely DO NOT try to shim the rod for a better fit. That is only done on Babbit bearing engines, and no 261 was ever made with Babbit rods. Remove the cap and bearing shells from the tight rod and inspect the crankshaft and bearings for debris, scoring, or other causes of the sudden lockup. I'm going to guess a piece of debris left over from an oil passage has found its way to the rod journal and jammed the works. Measure the diameter of the rod journal with a micrometer, NOT a dial or digital caliper. A properly ground .020" undersize journal should measure 2.2925" +/- less than .001". There should be no scratches or score marks on the crankshaft and no debris imbedded in the bearing shells. I have an idea that the engine builder might have been a little careless about assembling the engine in a clean environment or he did not clean the oil passages properly. Oil clearances are less than the thickness of a strand of hair, and a dirty buildup has wrecked untold numbers of engines. Good luck!
Jerry

Last year I bought a complete 235 off craigs list claimed it was newly machined and assembled but would not turn had zero miles on it. I got the thing dirt cheap almost free because the owner was done with it and hated looking at it and reminded him of how much money he spent on it. It was bound up more that a 90 year old on morphine. Upon disassembly found that the crank was turned .020 under and they had .030 under bearings in it. Advise to start measuring but first would look at a poor installation on the rope seal.

Steve

Mic'ed the crank at 2.285
Plastigauge was at .0015 at cylinder #6 which was binding

Not sure whether to add a shim to get min. .002 clearance or put it back together and assume it was 5 year old assembly lube that locked it up. That seems to be flushed out by the oil frim spinning the oil pump. So I'm thinking about pulling the individual bearings and cleaning them and checking all the clearances with plastigauge. If it checks out I put it back together and continue to prepare to start it up for the first time.

I welcome any ideas and thoughts?

I agree with Steve. My 235 was newly machined and rebuilt before I bought my truck and the previous owner had nothing but issues. After wrangling this engine for more than a year, I disassembled it and the clearances were all over the place to the point I had to get it totally remachined by a reputable machine shop. There is allot of shops that do shoddy work.

My point being you really should disassemble, clean and check the clearances and other to satisfy yourself that you have a good engine.

2.285" is not a correct undersize, no matter what the Plastigauge says. Here's a few correct measurements:

STD.- - - - -2.311-2.312
.010" undersize- - - -2,301- - - -2.302
.020" undersize- - - -2.291- - - -2.292
.030" undersize- - - -2.281- - - -2.282

A 20 under bearing will be sloppy loose, and a 30 under will lock it up.
Jerry

The original measurements I made with a digital calliper which wasn't accurate enough. My micrometer doesn't go over 2" so I am borrowing one from a friend and will get back with the real measurement.

In your previous post you queried about installing a .002 shim on the rod to gain a little clearance. It’s the second time you mentioned it. Hot rod Lincoln previously advised you that the rods in your motor should never be shimmed. If that wasn’t enough warning, let me warn you a second time, no shims on the rods. Those are precision bearings that require the proper crush, clearance and clamping force to be round, stay in the rod and work as they should. Installing a shim is just an invitation to a rod bearing failure. So scratch that one off your list of possible solutions. Believe me, having that kind of catastrophic failure is no fun at all.

Re measure the journal. If it comes up to specification, clean everything up, then coat the bearing with lubriplate’s white engine assembly lube.

https://www.movingupgaragedoors.com...msclkid=fb5669cc71b710217e8509f76540e0ec

Then see if it turns, by hand, not using the starter. If it does, you are good to go.

Why borrow a micrometer? There are literally dozens of 2-3 inch mikes on Ebay, some for as little as $15.00!
Jerry

I get the concern about shimming so I won't go that direction. I will re-measure the journals again and if they're within tolerance I'll lube it up as you recommend. Turning the engine by hand is really difficult without the use of a hand crank on the flywheel. By hand I can only move it an inch at a time. I've never worked on a 235 engine before so is that normal or should it turn easier to turn.

Can you access the flex plate from under the car? If so, this is the tool you want to purchase to turn the motor over by hand. Also, to make it easier, remove all the spark plugs so you are not fighting compression.

https://www.walmart.com/ip/JEGS-Per...m&affcmpid=2777022492&tmode=0000

The adapter ring for the Powerglide transmission makes it impossible to use that type of tool on the ring gear. It's a narrow casting about 1 1/2" wide that completely encircles the flex plate ring gear. I believe there is a sheet metal cover over the lower part of the adapter ring that will allow a long box end wrench to be used on the torque converter to flex plate bolts to turn the engine. If the crankshaft front damper is accessible, most of them have a square hole in the front that a 3/4" drive ratchet or extension will engage to turn the crankshaft.
Jerry

Rcnicholl Why dont you begin by looking at that rod to be sure its not bent,look for dirt under the bearing halves,look for a shiny spot on the bearing (tight spot) mike the rod throw for size,I wouldnt shim a precision rod cap-it might spin the bearing. If that turns up nothing tighten it up a little at atime to see if it locks it up. If the crank is too big you could emery cloth it (which I would hate to dofor losing precision reasons) however in the olden days they almost all done it !! Not impassible its not the right cap ,may be on backwords/ If you get past all that check clearance with a little square of a.001 feeler gauge deburred with emery cloth. Dont roll it thru just see if it will move then a .002 same way just move it . Good Luck !

Were the rods reconditioned when the engine was assembled? A round crankshaft journal and an egg-shaped big end on a rod don't play well together, but the result is usually too much clearance, not a tight fit. Rods usually get stretched top to bottom. I recondition the rods on everything I build. It's just part of a good overhaul.
Jerry

Sorry for the delay in response. The crank was definitely machined and it has new bearings. I've noticed that number 6 has a different type of bearing which is strange. There is a groove down the centre of both bearing shells on the inside against the crank. All of the other bearings do not have that groove. Regarding the rods and reconditioning I would guess that they have been since the engine has brand new aluminum pistons. It only makes sense they would go that far since they've done everything else correctly.

At this point I believe they wish just grime in number 6 since there is a slight scratch on the backside of the bottom bearing in in the cap. Ireann a pipe clear up into the rod with gasoline on it to clean it out in then put a pan of oil over the oil pump intake. Then I spun the oil pump with a drill and ran a couple cups of oil through to flush out the passageway in number 6. Hopefully it was that simple. The scratch is very small like a grain of sand got in there. All cleaned out and touched up with Emory cloth. At this point I think I put it all back together and continue preparing to start the engine

That "groove" is probably the path the piece of debris from the oil passage took when it locked up the engine. Is it in line with the oil hole in the crankshaft? If you're a gambling man, maybe you think that was the only piece of trash in there. Personally, I would disassemble everything and do a thorough cleanup of every oil gallery in the engine block and the crankshaft with rifle cleaning brushes. Good luck!
Jerry

Jerry and Mike are the final say on this situation. In the past I have bought newly rebuilt engines. If I didn't know who rebuilt it I would tear it down, paying close attention to the bottom end and once going so far as pulling the pistons. This was because of rod bearing problems. It is a good thing you got it cheep. Doc.

I just want to thank all of you who helped me out especially Jerry. I have taken your advice and pulled the engine and begun to clean and inspect everything. I've never been much of a gambling man. It is good that I got the car cheap. I could sell the individual parts and make a lot of money but this is about recreating a part of Corvette history and I appreciate you guys helping me move forward. When I finally get to starting the engine I let you know powered comes out. Thanks again.

Back when I was building round track racing engines, it was not uncommon to assemble/disassemble an engine multiple times in the process of checking the fit of critical parts. One of my competitors used to kid me about "wearing out the bolt holes". Of course, the view he got of my car most frequently was following it into the turns! "When the green flag drops, the B. S. stops!
Jerry