The Stovebolt Site Forums The Shop Area Engine Shop Ruined fresh rebuild-oil pressure issue.

Pushed my truck into the shop today and spent 45 minutes carefully removeing the pan.

There was the slightest sparkle of metal in the botttom of the pan. Not much, had to look to find it.

Rod bearings seem fine but I didn't pull 'em to see, just moved them for and aft. They feel likr they did when I installed them.

Main bearings look like they've been oil starved. Slight scoreing down in the 'seat' of the bearing with a little copper starting to show. No bearings were spun. Could just feel the scoreing in the crank with my finger nail.

Rear main seal looked good in the bearing cap.

I still have no idea why I have no/low oil pressure. My friend has convinced me to pull the engine and deal with it later, which makes the most sence, but if I could figure out the oil pressure problem I'd be tempted to put new beaings in and run it.

Also, all main caps as well as everything else was stamped before removal and assembled as removed. So the 2nd and 3rd caps were not swapped.

DO NOT take a chance on anything short of a complete teardown and a detailed cleanup- - - - -including removing all the oil gallery plugs and running a rifle brush through every oil passageway! Even tiny deposits of debris in the block or crankshaft will get washed into the bearings the next time oil is circulated through the engine. While the engine is down, have a machine shop polish the crankshaft. A few score marks won't hurt, but any raised areas will chew on new bearings like a meat grinder. There's no such thing as a "too clean" assembly job. Check every bearing clearance with Plastigauge or a small piece of shim stock between the crankshaft and the bearing, and anything over a .002" clearance should be regarded as very suspicious. Also check out the condition and the internal clearances of the oil pump. Install a new, high-volume pump if one is available. Good luck!
Jerry

Hotrod is absolutely right. Take it out, take it apart and clean it better than the dishes you eat on. Remove any block plugs so you can clean the passage ways. If you see sparklys in the pan, they are else where.

The rod bearings get their oil after the main bearings (Hotrod will correct me if I'm wrong) so if the mains look starved, then the rods will have been starved too.

You're right on with that advice, Roy. Drilled passageways in the crankshaft carry oil from the mains to the rod bearings, so everything downstream from a worn or damaged bearing must be considered to be failed already, or will fail soon. Time to do a full breakdown and start all over, unfortunately!
Jerry

I am really surprised that the engine was actually starved for oil. After hearing of what you found, I agree that with what you found, a complete cleaning will be necessary, and then you haven't figured out what went wrong. Did you look to see that you had a float on the oil pump and that there was no restriction in the pickup. There has to be a reason that you lost oil pressure and its almost got to be something wrong at the oil pump. The tang on the distributor is actually the shaft itself so if the motor runs, the tang turns. Are you sure you shvoved the oil pump all the way in so that the set screw went into the hole? I suppose I have guessed this whole thing wrong, but, I would really suspect that something went wrong coupling the distributor to the oil pump. This is why I am not a big fan of turning the pump with a drill. There is always a possibility of not getting the distributor stabbed correctly. And there is really no way of telling if a GMC distributor is stabbed all the way by just looking at it. I usually remove the plugs and spin the engine with the starter until I get oil at the rockers. One more thought, I think there is an upper and a lower bearing shell at the rear main. The upper one has a hole and if you don;t have the hole you starve for oil. But you would still show oil pressure on the gauge.

I recently blew a turbo on a Cummins and the driver didn't know to kill the engine. We didn't even bother to inspect the engine. Its going through an auction as a core on Wednesday.

http://berryhillauctioneers.com/detailview.php?itemnum=536793

Cleaning up an engine that was starved for oil is an expensive ordeal. My Cummins will probably wind up in some country where they have cheap labor.

Wearing away the babbit down to the insert could have been a result of improper crank grind or out of spec bearing insert. Once the oil comes up the pump its main oil galley->main bearings->cam bearings.

If your cam bearings are good then oil got to the main bearings.

Here is a photo of the oil flow.

Even if you ran the motor for a couple minutes(yeah I know, its not something you WANT to do, but running a motor for a bit with no oil is not a huge deal, and I know the 'po-fessional makaniks' are going to howl.. but it really isn't going to destroy a motor in seconds) as long as there was no real load not much would happen. The bearings were lubed (from your previous priming).

Since you scarred up a bearing, I'm going to bet that the motor had other issues. Machine shops screw up all the time, wrong parts get installed etc etc etc.

No Pfarber.. Machine shops DONT screw up all the time. Saying that is not fair to say. your giving the good Machine shops out there a bad name, so stop with your BS. If you are going to say that then Name the shops so everybody knows them. Dan

Benny, I think you're trying something like this:

http://i1225.photobucket.com/albums/ee388/Fred4949/Beating-a-dead-horse.gif

Give it up!
Jerry

LMAO! Thanks Jerry!

Bad link, don

Most likely **** is not the file name of the jpg?

The links work they just don't open private or hidden photo's...

Crenwelge, the float was properly installed and the pickup was clear and the set screw was in the hole like it should have been.

As far as the distributer engaging the oil pump; I have two dizzies, both from 1959 270s, the one I used has vacuum advance, the other does not. I used the mounting bracket on the non vacuum dizzy to double check the depth of my vacuum unit. Also, when I used a third dizzy shaft to pre oil the engine, I marked the depth on the shaft before I removed it from the block and used that to TRIPLE check the depth. I think I can rule out an improperly installed dizzy. That does'nt make it any easier, I still failed the rebuild some how.

I'm going to pull the engine back out and tear it down over the next few months. See if I can learn something about what went wrong. And as money allows, I will have evrything remachined as needed.

I appreciate everyones help on this. When I learn anything new I will update.

Now to post a want ad

What about the oil pump? Was it new, rebuilt or did you use the old one? This month marks 50 years ago that I bought my first semi and I now run over a dozen. I have had to diagnose a lot of strange things over the years. I don't think I ever had a mechanical failure that i couldn't figure out what caused it. If it was new or rebuilt, I would begin suspect new defective. There were always some new defective parts but they are becoming more and more common. Probably less than a month ago we replaced a Cummins ISM water pump just because we saw a little oil at the weep hole at a 15,000 service. The new pump went less than a thousand miles and we had to have it towed. Years ago Cummins paid for the part as well as progressive damage. Now I had to argue to get a replacement water pump. It was a Cummins Recon which is supposed to be rebuilt. However, it turned out to be brand new fresh out of China. And it cost me 6 hours shop labor and a $700 tow. I am very anxious to see how this thing unfolds.

Did the same thing one time on a Dodge pkup. Put a water pump on and it didn't last 100 miles. Had to put another one on. So though with the oil pump it being defective might be rare, it's still in the possibility range.

Oil pump was a rebuilt from NAPA. Of the last three waterpumps that I've replaced, two of them were bad out of the box, so a bad rebuilt oil pump wouldn't surprize me.

Here is something I need a second opinion on; When I dropped the main caps the bearings were soaked in oil but there was evident scoreing in the seat of the bearing with the rest of the bearing almost untouched. My friend says that's obvious oil starvation. Now I don't know what kind of gap should be evident between the bearing and crank but I see a gap between the end of the upper bearing and the crank big enough I could stick a matchbox cover in it. My gut says that's wrong. I know, I know, My gut is no substitute for plastigauge.

That sounds like a standard-diameter bearing running against an undersize crankshaft. Did you measure the crank and then plastigauge the assembly as it went together? It sounds you need to reevaluate the capabilities of your mentor if he missed something that obvious.
Jerry

Did you save any of the bearings that you took out of your engine? If so you can look at the back side and see what they are marked?

HotRod Lincoln speaks the truth!

Plasti-gage all the rod and main bearings as part of the "post mortem" &
Record all clearances.

When you clean & re-build make sure you do it all over again….. & don't button it up till they are all within spec.

It seems to me that some mismatch has occurred between between machine work and bearing size selection……
Most importantly, Keep the Faith …. crap like this happens more often than you might think!
mike

If in fact you have the wrong size bearings, that would explain the oil problem. Your pump was working correctly, thats why oil is everywhere, it just wasn't holding the crank up off the bearing surface. You also wouldn't have much oil pressure.

jjoe

I don't have the original bearings but they were marked as standard. The boxes the new bearings came in were marked standard, but that's no guaranty. Because everything looked like new and we were replacing standard bearings with standard bearings, I was assured plastigauging wasn't necessary. You don't have to explain the error in that. It's an expensive and embarrassing lesson I've learned all by my self.

As for the capabilities of my mentor, when I rebuild this engine, I will rely not on the knowledge (or opinion) of one person, but the collected knowledge of the Stovebolt community. You'ld be amazed at what I've learned from all of you over the past week.

I will plastigauge during the 'post-mortem'.

When you rebuild your motor, don't ask what kind of oil to use. It would drive you crazy trying to gather a consensus from that!
I am trying to share a little humour in this dark hour of yours.

Hey man, I appreciate the humour. This is a terrible setback for me, but I realize that I have an opportunity to rebuild. The engine's bad, that's all. Nothing the right lottery ticket can't fix

The only sure thing at this point is the engine oil I'm going to use.

Seven pages of info! I hope this serves to help someone else out in their rebuild.

Plastigauge for sure. Learn to use a micrometer is the best. And some arithmetic skills. But I never learned from my successes, just my screw ups. The very first engine I rebuilt was an Olds V-8. Everything was good until the one rod cap nut I did not put a torque wrench on let go. But that is how I learned to sleeve a cylinder and use a torque wrench. Also got better at stuffing money into my project jar..:) Best of luck as you go.

You may have misinterpreted 'all the time' to mean 'everything they touch', no, of course not. But they do screw up. Names? UCF Machine shop, Mechanicsville PA installed my cam bearings and the oil holed were not lined up... 2nd bearing obstructed the oil feed hole by 50%+. I was able to fix it myself (had a spare set from the overhaul kit) plus its an hour+ drive each way. So yeah... wanna see a receipt?

To err is human, to claim they/you don't is Internet Machismo.

The insert should have a part number that ends in the size stamped on the outer shell. Check to make sure they are all the same. If the crank was ground polished there should be a record of it somewhere (invoice usually has the work performed).

Even if you have a set of Harbor Freight calipers you should be able to get a good diameter reading (to a thou or so) and verify the journal to the bearing and any paperwork.

Plastigauge is like $5 a tube. That and about an hours time is the best insurance you have against any mix-ups.

Sure hope twotone comes back with the final results so we can see what the culprit was. Nothing worse than having a failure and feeling the pressure (pun not intended) to fix it and get it back on the road...especially with limited funds.

One lesson I am learning from this: If possible, take the time to put a rebuilt motor on a break in stand and dial it in before installing on the truck.

Just a little update. Picked up the engine from the machine shop last week. Yes, my friend/helper installed the wrong bearings. The crank had already been turned and to rebuild this engine I will need another crank. The machinest told me that the engine wouldn't have lasted too long anyway because it needs line bored and the cylinders need bored as well. My friend(?)/helper(?) was way off on many counts

What I've learned; Just pay the professionals to do the job right the first time. It'll cost less in the long run.