Time to start cleaning and preparing for assembly.
I cannot stress cleaning all dirt, sand and machine shavings out of all components. It only takes one grain of crud to get into the wrong spot to destroy the engine. Whether it is stuck on the block deck and causes the head gasket to leak again or get onto the cam bearing or lobes which will destroy the cam and fill your sump with metal shavings that will travel further and cause more damage.
Prepare the block deck surface first.
The old gasket residue will be stuck on hard. You must take care not to drop rubbish into the water passages as you can block water flow, or into the bores which can scratch and damage the bore and pistons on start up, into the bolt holes which can bugger up your torque wrench settings, into the oil drain back passages which will drive the dirt into your sump and into the oil passages which could block them or drive dirt up into the cam and rocker assembly destroying everything.
The method I use is to firstly run all the old and clean head bolts back into the block to stop rubbish falling back into them.
Rags and/or paper towels are pushed into the bores and oil drain back passages.
A Phillips head screw driver with a rag over the tip is placed into the oil supply holes to protect them from dirt falling into them.
The water passages are not as important, but you want to avoid pieces of gasket falling inside and blocking the water flow. When cleaning around any hole I prefer to scrape the gasket away from the area I am trying to protect.
My favourite tool for cleaning is a sharp blade.
Once you have the entire gasket off the deck you will notice some reside still left behind and the deck still looks dirty. The best way to finish of the deck and bring it up new and shiny is to use some 180 grit wet and dry emery paper on a rubbing block. Avoid doing it against your fingers as you want a straight and true (level) deck surface, only use your fingers in hard to reach areas and go gently. When done the deck should look like near new.
Carefully remove all rags and paper towels from the bore, oil drain back holes and the Phillips head from the oil supply passages taking care to remove as much rubbish that may have fallen inside with them.
Remove all the old head bolts.
If you have a thread cutter its good practice to run it down each head bolt hole to clean any dirt out.
If you don’t, blow some compressed air down the bolt holes to get any crap out. It’s important that the thread holes are clean so the head bolts don’t bind and give a bad torque wrench reading when assembling.
Get a vacuum cleaner and vacuum out the bores, water passages and oil drain back holes to remove any large bits that may have fallen in when removing the rags and paper towels.
Get a clean rag, put some fresh motor oil on it and wipe the bores, this helps the rubbish stick to it and easier to remove.
The last thing is to clean all oil reside off the deck with methylated spirits or petrol and a rag. Keep changing the rag until no stains are on it after rubbing and cleaning the block deck.
It should look spotless. Here you can see the thread cutter being run one more time after the deck had been cleaned just in case, .better be safe than sorry.
Now cover the block to protect it from dirt with a large garbage bag.
Don’t forget to clean the intake and exhaust manifold gasket surface while your there.
Next step is to clean the head, remember its been to a machine shop and the water passages and intake and exhaust ports may have metal shavings inside.
I use an industrial strength degreaser, brush it on and let it sit wet for 5 to 10 minutes, then blast it off with a high pressure water cleaner or the jet of a garden hose.
Stand the head upright on its end and start blasting water into the water jackets and watch all the metal flakes and shavings pour out the bottom. Blast all the ports, head bolt holes and valve guides to make sure all the rubbish is out. The most important thing is to make sure is that you blast the oil passages clean, very, very important.
Dry with an air hose and place in a clean garbage bag to keep dust and rubbish getting onto it.
Degrease the rocker gear; valve springs, retainers, camshaft and rocker cover while you’re playing with the degreaser, water and air hose to get it all out of the way. Put everything into separate clean garbage bags.
Now its time to assemble the cylinder head, but before you do that the valves should be lapped in first for a perfect seal.
Its good practice to coat the valve faces with engineer’s blue, fit them into the head and give them a spin with a lapping tool. Where the blue has been removed will show high spots, low spots will be a darker blue.
A lapping paste is available with 2 grades (course and fine) in one tube; in this case the valves and seats have been resurfaced so a simple fine lap is all that’s needed to get a perfect seal.
Coat the sealing surface of the valve and place it in the cylinder head, taking care to place it into the cylinder it came out of originally.
Fit the lapping tool (a suction cap on a stick) to the valve and start rubbing your hands together, around the stick, like your trying to start a fire with 2 sticks.
Every now and then stop, remove the valve and wipe it and the seat to inspect the progress.
In this picture you can see a stripe appearing on the sealing face. If you look carefully, you will notice shiny points that are low spots and need more lapping till the whole surface is one even finish.
This is what the sealing surface should look like when done.
Bookmarks