Sunday, June 7, 2020

Pressing F5

In the computer world, F5 means 'refresh'.  After pulling the engine out of Gidget, I figured I should take a quick look inside both to find that oil leak and see how the engine was holding up.

I'm glad I did.  I had problems.

First, I had a head gasket failure-in-progress between cylinders 2 and 3.  I could see the gray crusty residue of coolant being burned. It turns out the brass plug between 2 and 3 had receded enough to open the gap.  So a trip to the machine shop (Morrison Auto Machine, awesome!) fixed things right up by threading a new brass plug into the head and planing it off flush.

I also had lots of carbon buildup in all cylinders, and it wasn't until I pulled the head apart that I found out why.  This is embarrassing to write, but I had installed the oil seals on the exhaust valves and not the intake valves, so it was just sucking oil into the cylinders.  I hadn't noticed significant oil consumption, but I did see a couple of puffs of smoke every so often... now I see why they were happening.

The valves and guides are in fine shape after a bit of wire brush to remove the carbon.

After all that, I now have a rebuilt cylinder head with properly installed Viton valve stem seals on the intake valves.  I left the seals on the exhaust too--while not absolutely required, I have not found anything that says it is bad to leave them.  And if they degrade, no big deal.

With the cylinder head sorted, I looked over the remainder of the engine.  I mean, why not?  It's apart... and I had to pull the rear plate and rear main seal (Gerard's) to install the Rivergate plate.  Again, I am glad I did... I had some less-serious problems.

I pulled the pistons and rods.  The bearings were worn more than I liked, but the journals were clean.  These were the bi-metal bearings.  I have tri-metal King bearings to Vandervell specs waiting to go in.  The main bearings looked pretty good, but I replaced them (again, tri-metal) since it's a "false economy" to leave them alone.

The camshaft didn't turn smoothly, either.  I had noticed this when I first assembled the engine, and got things lined up pretty well.  It seems that the middle bearing was eating itself up.  These were 'split' bearings, which apparently weren't honed for fit.  The camshaft itself is fine; the bearing surfaces are clean and none of the lobes show unusual wear, all specing out within .001" of each other.  Dan took care of the bearing problem for me by sourcing 'solid' bearings and installing them, and checking the fit.  The cam now turns smoothly and easily.  I replaced the lifters with lighter ones that have an oiling hole as I wanted to eliminate any possibility that the lifters were the cause of my tapping noise.  Everything is clean, smooth and moves easily.

The rest looked ok.  The cylinder bores were not worn, so they got a light hone to allow the new piston rings I have on order to seat properly.  The block is clean inside and there's no metal residue in the pan.

I could not trace down the root cause of my oil leak, though.  Everything seemed tight, though there was a light trace of oil at the oil pump cover (but not enough to cause me to suspect it).  The rear main seal was clean with no signs of a leak.  I suppose it is possible that a slight gap at the cover could have pushed a little oil out, but that was a lot of oil I saw under the car after a short run.  Something was pushing it out under pressure.  Maybe the seal at the block side of the rear main was faulty, but I don't think so.  Anyhow, it will all get sealed up tightly again when I install the new rear plate.  Since I am converting to the Rivergate seal, I installed the original rear scroll seal cap with a new gasket and a light coat of silicone sealant.

Having gotten the block back from Morrison Auto, I installed the crank, lifters, cam, and oil pump.  I had the rotating assembly balanced, and it was indeed a bit off, which could explain the light vibration at 3500RPM.  The pistons and rod assemblies were all within a few grams.

The front plate, timing gears, oil thrower and timing cover went back on with new gaskets (that I happened to have, thankfully).  I checked the timing cover for straightness and made it nice and flat.  I installed a new front seal as well, though the one that was there was still ok.  Finally, the water pump went on with a new gasket.  Everything is nice and clean and properly torqued.

This is apparently a 'refresh', though to me it's a 'rebuild' since I replaced pretty much everything.


I also made new timing marks at a location that I could actually get to with a timing light.  It's accurate enough.  I didn't need all the marks, but it was simple to do.

I'll get this back on the stand (it's all I can do to deadlift it off the bench as it is) and install the pistons with new rings and bearings, and the head.  Then it's on to what I originally set out to do--install the new transmission!

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