Hi everybody!
After four weeks of idleness, DAVZCAT is back on the road, feeling fine. (I
got the license plates too, it’s a kick seeing PATZCAT and DAVZCAT
side-by-side in the garage with the plates on). You may remember how this
all started - in trying to perform a valve adjustment to eliminate excessive
tappet noise, one of the head bolts snapped off as I loosened it, way down at
the block level. I tried to drill a hole in it and get it out without
removing the head, but that didn’t work, so the head had to come off.
I put on the fender covers that Patsy got me for my birthday, without these
the job would have messed up the paint for sure. I disconnected the intake
manifold, the heater hose at the rear of the head, the thermostat housing,
the fuel rail, the EGR pipe and valve, removed the distributor, chain
tensioner, and intake elbow, loosened the exhaust joint where the header
pipes connect to the exhaust next to the transmission, took off the exhaust
heat shield, removed the nuts holding the header pipes to the head, removed
the cam cover, took out the camshafts, followers and shims, the bolts at the
front of the head where it attaches to the front cover, (no more head bolts
broke, thank goodness) and the head was ready to lift off.
With some strong rope and a couple of pulleys, I rigged a hoist with a 2:1
mechanical advantage hanging from a rafter in the garage right above the
engine compartment, and moved the car so the hoist rope would clear the rear
edge of the bonnet - that way I didn’t have to remove the bonnet, a good
thing since I had nowhere to put it, and I doubt I could have got it back in
the right alignment anyway. The head weighs about 55 pounds, but with this
arrangement (and Patsy (wo)manning the hoist rope) it was easy to remove,
swing clear of the car and lower to the floor.
I had to drill several holes in the broken bolt end and then fish out the
pieces, which took all day one Saturday - even with the head off, it could
not be removed with EZ-outs.
With a rented valve compressor and a short piece of PVC pipe I removed all
twenty-four valves (this seems like a lot of valves to deal with, getting
them
out, cleaning them up, and putting them in) and then took the head to a
machine shop to get de-greased, which they kindly did for free - this is the
same place that did an extensive rehabilitation of my XK140 head - I think
they felt guilty for spending six months to do that job). Next it was
de-carbonization time, lots of cleaning with wooden sticks and a wire wheel
for the valves. There was a lot of varnish on some of the valve stems, which
was responsible for the occasional “chuff-chuff” noise from the exhaust pipes
that I had noticed - this noise is gone now, since the valves no longer
stick. There’s just a single spring per valve on this engine, not like the
dual springs on the XK head, so it doesn’t take much to make them stick.
I filled a few areas of minor corrosion on the head sealing surface with JB
Weld and scraped the areas flush with the surface. All the valves (24 again)
were lapped with fine grinding paste, this did not change the clearances at
all. A final cleaning with detergent and water , a film of oil on the bearing
surfaces, guides and seats, and then the head was reassembled. Assembly lube
on the followers, on the tops of the valves stems and the adjusting pads, and
the bearing surfaces, but just oil on the valve stems inside the guides -
didn’t want any molly or graphite particles in there, especially since with
the
valve guide seals on both intake and exhaust there won’t be much oil going
through to flush that area out. I measured all of the clearances again and
adjusted to obtain 0.0130" clearance on each valve. The pads come in sizes to
the nearest 0.0005", and I have a metric micrometer, so I was able to do this
with the help of a calculator. The clearances close up just a bit (about
0.001") when the head is torqued, probably because the head bolts pull the
camshaft bearing caps down just a bit relative to where they are with just
the bearing cap bolts installed and torqued. I was aiming for perfection,
after all this work it should be good for a long time, right?
At this point the work was interrupted by a trip to Minnesota for the 75th
Lokensgard family reunion, held near St. Peter on my grandfather’s home
place. We had a wonderful time, and found that several family members had
happened across the archives while doing searches for the family name on the
internet. I got a lot of comments about my posts! If you guys are still
watching (when the archives open up again) thanks for the great hospitality!
Next it was time to prepare the block for the rebuilt head - I used a
long-handled scraper to clean up the block surface, and also used it and a
razor blade to clean up the piston tops, with a vacuum cleaner nozzle right
next to the scraper to suck up all the debris. This worked very well, I’m
sure that none of the scrapings got down between the pistons and the cylinder
bores. There was no ridge on the cylinders, just a layer of carbon at the
top above the level where the compression ring scrapes, and this came right
off with a razor blade. The head and block looked just beautiful when they
were cleaned up; Patsy took some pictures.
I also removed the block coolant drain plug that’s located behind the exhaust
down pipes, and drained the coolant from the rear half of the block. There’s
about a gallon of coolant in there that doesn’t come out when the radiator is
drained.
Next I changed all of the coolant hoses - that was hard enough with the head
off, it would be next to impossible with the head and intake manifold
attached! Removing the air pump was necessary to get at the clamps for the
hoses attached to the water pump and the thermostat housing. I double
checked all of these connections afterwards.
Then on to reassembly, using the hoist again to get the head back in there.
I didn’t use a sealant on the head gasket, but did put anti-seize on all
threaded fasteners (new head bolts, of course) and used a sealant called
Hylomar HPF on the intake gasket - this is some blue stuff that stays tacky
forever and should assure a long-lasting seal at this critical joint.
Positioning the cams was easy, since I had marked the position of the notch
on each cam relative to its bearing cap with paint and just reoriented to the
mark. I did not separate the inner and outer portions of the cam chain
sprockets, either, and it was easy to get them back in the original position
since varnish patterns showed how they should be oriented relative to the cam
spocket mounting flange cut-outs.
It took about six hours to get everything back together, the most troublesome
part was getting the heater hose back onto the head at the rear, under the
intake manifold. I thought my wrist would break before the hose would go on,
but with me underneath the car and Patsy tightening the clamp it finally went
back on.
Filled it up with coolant and some Castrol 5W-50 synthetic oil (now that the
head gasket now longer leaks oil, I can use the synthetic stuff). At 1:30 in
the morning, Patsy started it up after I connected the ground at the battery
(Sorry neighbors, we forgot for a little while how to silence the alarm). It
ran perfectly right from the start, and the only noises are the injectors
clicking and the power steering pump and so forth. It drives great, and I am
very happy to be back in my car.
Dave Lokensgard
'55 XK140 OTS
'86 Volvo 740 Turbo
'90 Burgundy Sovereign 4.0L (PATZCAT)
'90 Majestic (DAVZCAT)
Poway, California