I'll cover this and cleaning/lapping the valves in the next picture post. I'll make no claim that it's "the best" way, but it's a smart way to do it without removing the pistons, along with everything else that entails.

 

Apologies for the Hiatus! A couple Euro-trips interrupted my regularly scheduled posting. Back to the meat of it.

This post is mostly run-of-the mill cleaning pics, but may be helpful for some to see the difference that a few hours can make while the engine is "opened up."

First, presentation of the exhaust valves after, and before. This was from a cylinder which got coolant in it from the breach.. Lots of hard baked-on carbon all around these valves.


Next, the bottoms of those valves, after and before cleaning. The carbon was cooked on so hard I used a Mill File to remove most of it, and finished up with the wire wheel.


The Intake valves, After and before. These only required a wire wheel to clean up. The small circle on the "before" valve is from the valve spring removal tool.


My Patented valve lapping tool! 1/4" ID fuel line.. featuring the perfect amount of give when attached to a drill, and just enough grip not to tap too hard when pulling to lap each valve. I used fine-grit only to lap, and it was largely only a precaution. It's best to keep each valve in it's original position, and after lapping, it's imperative that they are returned to that same port to get that seal you need to squeak out all 230 hp


The Combustion Chambers all looking much better, and a peek at the freshly lapped valve seats.


So the big change for me during this head gasket replacement was cleaning the pistons with them installed in the block. I found this technique on a 240SX forum.. it made sense to me so I tried it, and the car is still running strong.

The idea is to pack a protective ring of grease above the piston rings to prevent the carbon scrapings from making their way down alongside the piston and scratching up the cylinder walls. Pack in the grease, clean the tops to your heart's content, then draw the piston down- the grease and grit will stick to the cylinder wall and is easily wiped away. Repeat this for all the cylinders.

Cylinders 2 and 5 with the grease rings applied.


Cylinders 3 and 4 after a good in-block cleaning, with the grease ring removed after being drawn down into the block.


Next up is the head surface corrosion fix... officiated by a Jag mechanic.

 

Nice work and tips!

 

interesting, your thread may have pointed to solving an issue; my 1993 XJS4.0 had repeated head gasket failure at 50k km between cyl 2 & 3, similar casting mark turned out to be a cracked block, leaking coolant into cyls 2 & 3 on overrun. Just installed XJ6 block, and now 2k km later valve seals on original head have gone.