Engine not running right, overheating

OK, the car was not idling and was overheating at the drop of a hat at the start of Summer. Why is that? The answer wasn't obvious at all!

Compression test.
Most cylinders showed 135PSI, one at 105, lowest at 100.
I suspected a blown head gasket, so off with her head!
The gasket was OK, but the valves looked a bit the worse for wear: Pitted and with black crap coating the back.
More disturbing was that there were two water holes which were blocked by the gasket. No wonder it was overheating. The new gasket had the same blockages on both sides (front and rear) of the engine. I made holes for it, as you can see:

Engine with new gasket

It's the big one with the big red ring around it. No idea why it was not punched out, it might have been a tooling error.
Jobs to do:
1. Make holes in gasket. Your gasket might already have them if you're lucky. My dad was very surprised this one didn't.
2. Clean the head.
3. Remove then grind in valves.
4. Reassemble

The longest task is #3. Grinding or lapping in the valves is very time consuming. The head was unlikely to have cracked or warped so I didn't get it checked. Cast iron is very rugged.

The gasket was very hard to make holes in. A drill with the round hole attachment is a good choice. It's not like a regular gasket, it has metal in the middle.
The head cleaning just required a wire brush attachment. I did this then removed the valves, which requires a special tool that looks like a big G clamp. I cleaned up the valves and inspected them. They were OK, but pitted and they needed to be lapped in again.
This is the time-consuming bit. It requires valve grinding paste, a little light oil or thinners and a sucker.

Place sucker on valve

paste

Place the sucker on the valve and a small amount of the coarser paste around the valve, where it contacts the head with a drip of something lighter (thinner is ideal) which reduces the friction. Grasp the stick between your palms and rub like you're starting a fire with it. Also, lift the valve every so often. Not sure why but my dad swears it's important. When it feels smooth, remove the paste and inspect the surfaces. If they aren't completely smooth (you can still see the pits) repeat. I had to do this between 6 and 10 times before it was smooth. When it is, finish it with the smooth version at the other end of the tube, just the once. It took me two hours to do 12 valves.

OK, reassembled the head, connected everything and dad told me the valve clearances will need to be set. This is another place where you really need to be careful. The slant six requires the engine to be running and hot to adjust this. The setting is 0.010" (ten thousandths of an inch) on inlet valves and 0.020" in the exhaust valves. Now this is important don't fail to set the valve clearances again when the engine has warmed up.
I did, and had it running on five cylinders until I'd worked it out. The adjuster is 7/16" so get a ring spanner and re-adjust. You'll find the idle speed will change radically if yours was anything like mine.
I'd also bought a tune-up kit at the tip shop and it included a vacuum gauge. This is useful for getting the idle mixture right. Maximise it and your car will love you.
Mine seems to love me now. She idles better than ever (as in has literally never been this good) and is smooth and powerful. Also doesn't overheat as easily. Have to get the radiator sorted out next and I just might get through Summer!

Engine Reassembly

This is pretty easy if you take care. First of all, prepare the bore unless you had it rebored. If you didn't you will see that the bores are very shiny where they have been rubbed for many years by the piston rings. You will need to remove this by honing the bores. This is simple enough, as you can buy a drill attachment. Hone the bores in a criss-cross pattern until there is no perceptible ridge and no glaze. Lubrication with WD40 or light oil is helpful (prevents the stones from overheating). Clean away the oil/grit/filings very thoroughly as anything left will damage the newly rebuilt block.
Oil the rings on the pistons thoroughly and use a ring compressor to get the pistons in the correct way. They should be put in with arrows facing a particular direction, from memory, and will probably be numbered, too. The numbers are less important, but if they're there use them.
Insert new crank shaft bearings and attach. Torque to the correct setting. If you need any of this info, just ask me or Google it, as I'm sure it'd be freely available.
If you have removed the timing case like I did, you will need to align the marks on the pulleys prior to putting the timing chain back on. This is really important: My Dad didn't get it right and it was out by 1 cog. Result was the car had no power and we had to remove the engine again to do it right!
Put the timing case back on with the sump (see below). The engine should be on TDC now.
Put the head back on and torque it up. The engine guy said that even monotorque gaskets should be re-torqued. Schedule this now. If you can't do this because it keeps moving make a note for yourself to do it as soon as the engine is back in the car. If you're a bit absent-minded, put a sticky note over the ignition to remind you.
Lift the engine up with your lifter (or block and tackle) now and put the sump/timing cover on.
The sump should be cleaned and a new gasket with lots of gasket goo will ensure you won't have any dramas with leaks. Use the torque settings again for everything. An oil leak will spoil your pleasure at the end of this and it's extremely difficult to tighten sump bolts with the engine in.
Prior to engine installation I also painted the engine. Couldn't get Chrysler engine blue so did it Ford blue. In retrospect I shouldn't have done this. The paint place in Preston (at the forking of Plenty Road) had the stuff, but I didn't know this.
Putting the engine in was the reverse of removal, with particular attention paid to the alternator and distributor. Torque the head if you couldn't before.
Make sure the distributor goes in with the rotor facing #1. If you didn't mess with the valve timing this should go back in easily and look like the photo you took beforehand. You also should not have to do with the valve clearances if you put the rods back in the same holes, unless you needed to do them anyway. If you do, start the car, warm it up, turn it off, remove the rocker cover, Turn it back on and do it while the engine's going. This is a lot easier and quicker than doing it by turning the engine over by hand.
If you want to (I didn't) you can re-check the compression to make sure it matches that in the book, and that it's consistent between cylinders. The Valiant now runs like it should. It idles much better and is better on fuel (although fuel economy still rubbish on gas for some reason).
Here are some photos of the reassembly.

	If your steering's heavy, lubrication is easy with no engine

Engine Disassembly and Inspection

When it's out, I removed the head. When doing this, my Dad has always told me to keep the push rods in order, so they all go back in the same holes. Here is one way to do this:

Cardboard with holes, marked with corresponding cylinders

Simple and effective. The engine shop guy said it didn't matter how they went back in, but I like to play it safe. Disassembly of the engine is pretty easy but it was unbelievably messy. Make sure you drain the oil very thoroughly and disassemble near basins for excess oil and rags/brooms/turps for clean ups. The garage was in a very dirty state when we finished, even though I thought we were very careful. Also, you will want to clean your engine and engine bay. In retrospect I should have done this prior to starting the job.

The various bits that were removed prior to the engine.

Engine, during disassembly

The aim was to remove the pistons. When this was done, we found that several rings were actually broken. Further good news was that the piston ring grooves were worn, so new ones were needed. An old piston was cleaned up and taken to our local engine shop (C.W. Engines in Beech Street, Vermont). New pistons and rings set me back around $300, which was much better than expected, and a new bottom end gasket set was another $65 (got this from Auto surplus in Mitcham). Obviously new oil and filter are necessary for this job. New pistons and rings mean this will be a "rebuilt" engine. Reconditioning, on the other hand, involves a rebore and doing up the head. I didn't want to rebore it, since the ridges were very small. This means the ridges at the top of the cylinder bore: If they're obvious, a rebore is necessary. The thing about a full recondition is that your engine then has to be treated very carefully as it's run in. This means a set of rules which, frankly, I wouldn't be very good at adhering to. Occasional hard acceleration, but mostly very slow and gentle. If you're old enough, you will recall when people used to do this and they hung a sign on the back of their car which usually said "running in". Ah, better go around them, you would think. I avoided reconditioning mostly for this reason, but also the additional expense, delay (you have to book it in) and that initially the compression is so great that you will nearly always have trouble starting the engine after assembly.

Compression Test

At least it's still November, so this is still "shortly" to me.
Performed a compression test early September to find out if there was anything weak in the engine. If you don't know what this is all about, buy a compression tester from your local auto parts shop.
Compression test
Remove all the spark plugs and screw the tester into #1 spark plug hole. If you didn't buy a screw in one, you will need to hold the tester in place and get someone to help you. Look, just get the screw in one.
With it firmly in place, put your foot on the accelerator and press it to the floor. Now, turn the engine over. You'll hear the compression strokes move the needle of the gauge (sounds like puffing). When you've gone through three engine cycles, check the gauge. Repeat for the other cylinders and write down the results.
As mine is a 160HP slant, compression is expected to be higher then the 155HP version (red motor). I was hoping for 180psi, and got the following:
1 138
2 110
3 155
4 155
5 148
6 152
Urgh! Bloody awful. Definitely something (or things) wrong here. With these results, we look for a couple of things, being firstly the number, which is obviously quite low here and secondly whether the readings are similar to each other, which they are not in my case.
If there's any low numbers at all, you can determine if it's the head or piston that's causing the problem by doing a second test. This time, grab an oil can and squirt some in befrore screwing the compression tester in. The reason that we do this is that squirting oil in will seal any misbehaving rings and bring up the reading significantly if the problem is with piston rings. If the problem is with the head (e.g. valves are damaged or valve stems worn out) the reading will still be low.
With mine, the compression came up significantly as expected, since I had the head resurfaced, bought new valves etc when the LPG buggered it up about two years ago.
So I was going to have to remove the engine. Did this on 6th September.