Subject: How to keep TR4A engine turning?
Peter et al.:
Its great that you can turn your engine over manually, some resistance is
appropriate even with the plugs out. Adding engine oil into the cylinders
by the plug holes is probably a good idea, as is draining the water from
the engine for longer term storage.
In retrospect I was asking alot for the engine to be "just fine" after so
much sitting. The head contained alot of carbon deposits and as you see
if you read on there were other problems. At the very least it is
probably a good idea to pull the head to inspect the cylinders and bores
before getting your car back on the road. Since I am planning to build
from scratch a more performance-minded engine as the next stage of the
restoration I went into this with the idea to keep the stock engine with
matching numbers fairly original in case I want to sell the car. That
doesn't mean I want to do a cheapo cut rate rebuild on it, just that I
want to save my money for building a high compression engine with the
spare parts I am accumulating for ultimate use in autocrossing the car. So
keeping all of this in mind I went about getting the original engine to
function as original without putting excessive money into it. Keep in
mind that this is my very first time delving into the innards of the
internal combustion engine.
In my case, after removing the head and identifying the bad cylinder
filled with rust and debris, I was able to turn the engine again. More
specifically after some more soaking in penetrating oil and "Marvels
Mystery Oil" and then some gentle heating and a few raps with a hammer and
a wooden driver I was able to break it free.
Needless to say the teardown continued to check on the piston rings after
removing the pistons and conrods. (This can all be done readily by
removing the sump and the oil pump, with the engine still in the car and
the car on jackstands.) The piston rings were found to be stuck on two
out of four pistons, and then the pistons were cleaned by soaking them in
gasoline and then wirebrushing them. After removing the rings, the
pistons were set back in their corresponding liners in the block and
feeler guages were used to check for wear on the cylinder bores. None of
the bores showed significant wear (.005 inch) when clearances were
measured between the piston and the bore, with the piston 3/4 inch from
the top of the bore, vs. at the bottom of the stroke. This was good news,
and I decided that a ring job would probably get me through this rebuild
instead of a new set of pistons and liners. Of course I will also clean
up the head and grind the valves while I have the head off, and mill it if
necessary due to warpage. I need to replace one of the head studs which
was stretched to the point of failure. In other bad news I checked
the clearance of the thrust washers on the crankshaft from beneath
the car. This was .012 inches, or twice the allowable clearance. I then
removed the center main bearing cap to inspect the bearing and found it to
be both pitted and scored. I was able to remove the old bearing and
thrust washers and replace them without removing the crankshaft from the
block. Of course I now suspect that I need to replace the front and rear main
bearings. Which leads me to a question ....
-Can these bearings be replaced with the crank in the block and the block
in the car? Or must one remove the crank to replace all threee main
bearings?
The big end bearings in contrast appear fairly good, although replacing
them is rather trivial once you have things torn down this far.
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