Brian,
One good easy test of your bearings is how is the oil pressure at idle?
If low, probably worn. Shows up at moderate RPMs too.
The TRF guy was telling you about Plastigauge. It is the most common
(not most accurate but probably more than adequate for your purposes)
method of determining the clearance in the bearings.
Here's the tricky part. I suggest you get a good manual before starting
this project. There are some very specific procedure to pulling the
bearing caps and these MUST be followed. For example, all bearings, caps
and bolts must be put back in the same place, same orientation. It is a
good idea to throw away bolts and install new. They must be torqued
correctly. There also is more extensive procedure on the reinstallation
of the rear main bearing cap and its seals. It is possible to upgrade,
but requires removing the crankshaft from the car and having some
machining done on it, and it ain't cheap.
The way plastigauge works is it is a precise thickness to begin with.
You take off the bearing cap, put a small piece of the plastigauge on
the bearing surface, put the bearing cap back on and torque it down.
Then disassemble again and compare the plastigauge to a little chart on
the paper package it came in. The width it has "squished" to tells you
the clearance inside the bearing.
The down side is you end up testing one location on the bearing and can
miss out of round problems.
It's a good idea to carefully inspect the bearing surfaces for gouges
and any other damage. You should also check the thrust bearings (for
example, the back & forth movement of the crankshats, lengthwise in the
engine).
If you have trouble finding the specs and procedures for your engine,
let me know off the list and I'll pass them along. I have a manual for
your car and mine.
A good mechanic with a stethascope may be able to help you diagnose the
problem to narrow down how much tear apart and more detailed testing you
really need to do. Again, it would be helpful to take along a manual, if
the mechanic isn't overly familiar with TRs.
Alan Myers
San Jose, Calif.
'62 TR4 #CT17602
anborn@net1plus.com wrote:
> I have solved the advance timing on my TR4... but I beleive that
> problem was just calling attention to a bearing problem. The bearing
> problem could have been caused by years of driving with the detonation
> problem by the PO. Either way... I have an engine that VERY sensitive
> to timing and it makes a very nasty marbles sound before the oil gets
> up to the bearings when it is started cold. Once the oil is up....
> there are no bearing symptoms except the timing advance sensitivity.
>
> Does any know about some standard test procedure for testing whether
> your bearings need replacing? I was on the TRF tech line and the guy
> talked about this but never explained it. He spoke as if you pulled
> the pan and slipped in some sort of plastic shim... I really didn't
> get the jist of it.
>
> Also... does anyone know of a source of advice on TR4 engine rebuild
> procedure. There is an MGB video available but can't find anything in
> the how-to style on TR2/3/4 engines. I know how to do a generic
> rebuild and have direct experience... but each engine has its unique
> quirks. One thing I would love to have is "rebuild Parts List"
>
> Can you guys that have do share your experience.
>
> Brian Sanborn
> 62 TR4 CT16260L Groton,MA
> sanborn@net1plus.com
>
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MZ
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