Eightbanger

I took a short video showing the amount of play I found in my bearings from side to side, is this whats causing my low oil presure? or is the movement within tollerances?
Sorry about the lack of light under there.

redoldsman

You have found the problem of the low oil pressure. Unfortunately I think you are in for a total engine rebuild.

Eightbanger

Oh joy! I take it that there should be no play whatsoever?

Glenn, from what I have seen online, I can fit new bearings with the engine still in the car

redoldsman

You can replace the bearings with the engine in the car. However that is a good chance your main bearing are just as bad and the crankshaft likely has some wear in it. Based on this and the condition of your heads, I am afraid your engine is worn out and needs a total rebuild. I think I know where there is one here that is supposed to have been rebuilt. The owner was a member of our club and recently passed away. I have not seen the engine and don't have a price but the freight to the UK would probably be prohibitive.

Charlie Jones

The maximum allowable side to side play on the rods is .011 inch. This can be measured with a feeler guage between the rod side and the crankshaft throw .
The maximum bearing clearance between the bearing and the crankshaft is .003 inch. except for the rear main bearing which is .0035 inch.
This can be measured with plastigage .
It's a good idea to check these bearing clearances before condeming the bearings. Especially if you are on a limited budget.
Here's more on plastigage;
http://www.jegs.com/installationinst.../555-80593.pdf

Eightbanger

Cheers for the link and info Charlie, this is a whole new area for me so I'm learning as I go, the engine runs quiet with no low end or top end noises, but my oil pressure is poor so I have to believe it's wear on the bearings but hoping that the Crankshaft is relatively OK.
I'll measure those areas and report back.

DFitz

Nigel,


You have come so far. Good on you. With your current knowledge of the state of your bearings, it almost gives you some freedom of choice.


Meaning, you really can't hurt the engine much more. Minor concern for additional wear on the crank journals. But as RedOldsman said, the mains are probably in the same shape. If the valve springs are fixed, and it runs smoothly, I'd consider putting off the overhaul till you can arrange it and have the finances/gather parts. In the mean time, you can drive it sparingly. It won't break down, it'll just wear pretty fast till you have no choice but to rebuild. Run some 20w-50 and it will give you enough pressure to at least drive around town. Heads already will need doing--so there you have a total engine rebuild. I'd refrain from long trips though. Change the oil frequently and check for metal.


One caution after the rebuild. A new engine will produce more heat than a worn out one. I think I remember you having some cooling trouble too? Time to fix the radiator too. Although, going through the block could also clean out some passageways and help.


Sorry for you luck. Dave

Tedd Thompson

If mine I would check the rods with plastic gauge before making any major decisions. The crank could be somewhat still round. If there is no knocking going on The mains could last quite a while especially if not pushed hard. You are right there with the pan off and it would only take a few minutes to check it out... Just my thoughts... Tedd

Sugar Bear

X2 Charlie and Tedd...there has to be side-to-side clearance. Measure it with a feeler gauge and measure the bearing clearance with Plastigage. Mark all of the caps before removing them to measure with Plastigage, they must go back in the exact same position.

Let us know what you find...good luck!!!

Eightbanger

Thank you Dave...all good advice.

Thats the thing Tedd, no noises from the lower or top end for that matter since I've had it running and driving...but I do have low oil presure so somethings not right.

Sugar Bear, I took the bearing cap off #5 piston to have a look.


Here are the pics, they look tarnished and some tiny pitting, other than that I can't see much of anything...
To add to my woes, there is a wear ring at the top of the piston chamber that wont let me remove the piston.

Sugar Bear

The bearing looks worn; but, check it with Plastigage. The rod journal on the crank looks excellent. The ridge at the top of the cylinder wall does not look excessive. The ridge should be removed with a ridge reamer before knocking the piston out to prevent breaking a ring land on the piston.

At first glance I think you could freshen it up with a set of rings, bearings and valve grinding. Is it as good as boring, new pistons and major machine work? No. But it would probably run well.

Best of luck and keep us posted!!!

Charlie Jones

Neither the bearings or the crankshaft look THAT bad.
Your next step should be to check the bearing clearance with plastigage.

You mentioned that the oil pressure is low. But , what is the oil pressure ?
Both at idle and at 2500 RPM , with the engine warmed up to operating temperature? Also , what weight and type of oil are you using ?
Was the pressure checked with the guage in the car , or with a known accurate "master" guage ?

There can be many other causes of low oil pressure besides bad crankshaft bearings. Worn cam bearings , worn lifters, worn rocker arms , a leaking pressure relief valve , or even a weak pressure relief valve spring .

Seeing as this car is probably going to be used only occasionally . Unless the oil pressure is REALLY low . you might as well just put it back together and enjoy it.

Tedd Thompson

X2 as stated by Charlie. Back in the day I put bearing shells in engines looking much worse than that. There is a good chance that you will pick up 1/2 of your lost oil pressure. You should be able to replace the bearings without pulling the pistons out of their holes by rotating each piston down some before removing the caps and replacing the shells.... I'd go for it, leave the piston rings as they are till it's at a time when yoy can afford to do it compleatly ... Tedd

MDchanic

My thoughts, in agreement with the others:

1. Do not quit your day job to become a videographer.

2. The con rod bearing side clearance in the video does not look like much more than the specified 0.011". You're rattling them kind of quickly, so it's hard to see.
As suggested, get a feeler gauge in there.

3. Those bearing shells do not look very badly worn, but they are surprisingly pitted.
The crank journals look good.
All in all, that means that a set of bearing shells would probably take care of you, provided your side clearance isn't too bad.

4. Your cylinder walls have a lot of pitting. At the very least, that engine is going to burn oil.
New rings might not hurt, but they won't help much either.
You may be able to hone the cylinders enough to reduce the prominence of the pitting, but I'm not that optimistic - to me it looks like you'll need to have these bored (and pistons and rings replaced, etc. etc.) to make it really "right."
That being said, it should run fine just like it is for an indefinite period, so, finances being what they are, and considering the annoyance of pulling the engine, and the fact that you don't have a ridge reamer, Just Leave Them Alone.
When you're ready, you can have that taken care of.

All in all, you should have a decent, functional engine for the cost of a couple of boxes of bearing shells, so don't sweat it.

- Eric

Tedd Thompson

To me that engine looks as if at sometime it was subjected to quite a bit of moisture/ rust with all the light pitting that has taken place. How are the piston tops, is there one that shows no carbon build up compared to the others. I a'm thinking at sometime in the past that this engine may have had a blowen head gasket and left moisture in there to start the pitting.... Just a thought...... Tedd

Eightbanger

Just a quick update.
Been very busy with work, so no time to get under the Olds, But! I did leave the heads into a machine shop to have the valves and seats reground, plus they suggested having a tiny bit skimmed off the face just to clean them up, that was two weeks ago....unfortunately they're still not done as apparently they've had to order a new part from the States for their machine to do the job correctly.
Eric, running 15/40 Oil, on cold start up the gauge gets up to midway between 30 & 60, then at highway speeds just under 30, but when she's up to temp and idling at stop lights the gauge sits between 0 and quarter (see pics)
Your right Tedd, a lot of moisture in this engine, evidence of water and oil mixing and rust deposits everywhere, a couple of the piston heads on the driver side are quite pitted too (see pic)

I'll report back when the heads are done.

Thank you
Sugar Bear,
Charlie,
Tedd & Eric

MDchanic

Those oil pressures are fine, provided that the gauge is accurate.

As for the pistons, they're usable, but if you've got the thing so far apart, I'd consider removing them and polishing, or at least smoothing out, the crowns, especially of that one that had water sitting on it, as that rough surface could cause pre-ignition.

Since the pistons have been so wet, how're the cylinders?

- Eric

Eightbanger

Cylinders look good IMHO, clean and smooth, as for taking the pistons out im stuffed because of the ridge at the top of the cylinders..needs that ridge reemer tool that Sugar Bear suggested.

MDchanic

Here are a couple from Amazon. I'm sure you could find one locally, too.

https://www.amazon.com/OEMTOOLS-2505...s=ridge+reamer

https://www.amazon.com/Lisle-36500-R...s=ridge+reamer

- Eric

Eightbanger

Watched a YT tutorial as ya do these days, and they seem real straight forward to use, looks like i'm buying one, and at this rate I'll soon have as many Mechanics tools as Carpenters tools. lol

Thanks for the links mate.

redoldsman

Nigel:

If you have the pistons out, you might consider having them knurled. I have never done this but I have heard about it from old timers who I really respected. It is a process that has been around long time. It in essence restores pistons and reduces or eliminates piston slap. I would hone the cylinders with a glaze buster, install new cast iron rings, new rod bearings (inserts), knurl the pistons and put your rebuilt heads back on. It won't be a new engine but no more that you are going to drive the car, it might get you by for several years. Here is a link about knurling pistons.

http://www.pbase.com/stealthfti/image/53355694

Eightbanger

Interesting, I'd never heard of that.

Cheers Glenn.

MDchanic

Yes, Knurling is one of those "oldie but goodie" operations that can be helpful n a wide-tolerance, low-RPM engine such as yours.
Back when your car was new, it was a very standard procedure for prolonging the useful life of the engine without spending a lot of money on new parts and fancy machine work.

As Red points out, with the amount of use that most of these cars see, it would probably take any slop out of the pistons for the remainder of your natural life, and push an actual rebuild into the "afterlife."

- Eric

Eightbanger

Is there anything to take the slop out of me...one can only hope.
And in certain circles Ridge Reaming is an arrestable offence..

redoldsman

You should cut the ridge before you remove the pistons. Otherwise you run the risk of breaking a piston when the rings hit the ridge at the top of the cylinder. Just be careful you don't cut it too much.

Sugar Bear

Do you intend to replace the rings? If not, might as well leave the pistons alone. If you are replacing the rings you will also need to hone the cylinders to remove the glaze so that the new rings will seat. The cost of buying a hone/glaze breaker may be more than having the machine shop hone the cylinders plus the machinists should be familiar with the technique to get the proper "cross-hatch" pattern on the walls. If you are not familiar with honing try to learn on an old block to get the technique.

Knurling the pistons is a good suggestion, measure the clearance first and knurl only if needed.

The ring grooves will also need to be cleaned. Some use a ring groove cleaner for this but they can easily remove piston material. An old broken piston ring will work very well and shouldn't remove piston material from the ring land area.

If re-ringing, let us know for more information than you asked for

Good luck!!!