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Engine Bearings

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David64MGB

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While I have my engine apart should I replace all the bearings? I suspect they are, or were, all fine, but have been sitting idle but oiled for 23 years.

What would you do?
 
Yes...Personally, I would mic the crankshaft and itstall new bearings of the appropriate thinkness unless you know the condition of the engine prior to storage (ie - did it have good oil psi?)


The engine is already apart...if everything is still standard sizing, its money well spent. If the crank is out of standrad, then you would have to be doing some additional work with new bearings anyway.

Kind of like the old Fram commercial....."You can pay me now, or you can pay me later."
 
As I recall, it did not have particularly good oil pressure, at least at idle. I was using 10W30 so that would have some impact. I remember it as being about 15psi warm and less when really hot.
 
You *should* be running 20w50 in an MGB engine (and transmission)...but I doubt if the increase in oil viscosity will increase your oil psi by that much. I'm also guessing you were able to produce *maybe* 40 to 50 psi at speed....right?

I suggest you "bite the bullet" and do the bearings while it's apart now. Check the camshaft bearsing and the camshaft lobes for wear as well as crankshaft and its associated parts for tolerences and repair as required. You may need some machining.

HTH
 
My granddad used to tell me that if you were going to open an engine, redo everything that wears or later you'll regret it...that's been good advice for me all these years.
 
Is there a clever way of removing the main bearing covers without using the special tools? I believe it is a 1/2"UNF thread in the housings.
 
Now more than bearings cost there is absolutly no way I would put it back together with the old bearings.
 
David:

[ QUOTE ]
What would you do?

[/ QUOTE ]

Without ANY doubt, NEW bearings!! Ditto for camshaft!!
Ditto, oil pump!! Ditto Tappets!!

Other things to consider:
Have machine shop checkout cam & crank!! And have con rods checked!!!! Also let THEM tell you about the block!!

Have entire rotating mass balanced!! Have flywheel at least "faced". Lighted same(extra /ubbthreads/images/graemlins/grin.gif)

EVERYTHING MagnaFluxed!!!!!!!

/ubbthreads/images/graemlins/cheers.gif
Ed
 
All of the above at the least.
 
Hello David,

what I would do is check the physical dimensions and if it is in spec then re-use it, if not then replace. I would not bother with crack testing, unless you plan to race it nor would I skim a flywheel if it is in good condition, why remove metal when it's not required?

Alec
 
Hehe, flywheel can afford to go on a diet. Really not much metal is removed at all.
 
Ed, I hope you aren't suggesting I buy a new Camshaft, only camshaft bearings. I definetely need new cam shaft bearings. The Cam shaft looks good, but the bearings are slightly scored. The big end bearings looked good, but I haven't gotten my Main bearings out yet. Still working on building my own 'special tool'. Before I deep six the oil pump I want to see what condition it is in. That is one I can replace later if the oil pressure isn't up to snuff.
 
A CHEAP BEARING PULLER
To "pull" the main bearing caps get a piece of square tubing, 1" sq., long enough to reach across the bottom surface of the block. Drill a clearance hole through the middle so that it lines up with the 1/2-20 tapped holes in the caps. Get a piece of 1/2-20 threaded rod ~ 6" long and a nut. Get two pieces of wood at least 1" thick and clean them (no saw dust/shavings) and coat them with oil (to make the surfaces "squishy", but not splintery).

The blocks rest on each side of the block. Thread the rod into the bearing cap and slide the tubing over the rod, to line sit on the blocks. pin the nut against the square tubing and start turning. The caps will pullout easily.
 
Pulled the main bearings today. Centre bearing was worn to the copper (only have 3). Will check diameters and replace them all: Camshaft, mains, and rods. Thanks for everyone's help.
 
Sounds as though you are on the road to recovery!
 
Well done
 
Were it me, I'd take the crank to a machine shop & have them measure it...I just did that with about a dozen cranks - now I know what they are & whether or not they need to be turned.
 
Well Tony, whether the cranks need turning or not they should be at least polished.--Fwiw---Keoke
 
Absolutely, Keoke....another reason to take it to a machine shop!
 
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