Hi

My original thread was 11 pages long so this is a quick update...

My 2004 Discovery SE blew its head gasket and being a brave soul, and incredibly naive, I decided to fix it myself... and a few months shy of 70 and not the fitness I may have been decades ago, undoing those head bolts was a task and a half.

I met obstacles on the way, I like grinding and lapping valves myself but had to import a UK made oscillating tool and the coarse/fine paste and, amongst the great advice I've received here, found a decent valve spring compressor at Sears.

So I have valves lapped, valve guide seals and valve springs replaced, and the heads back together (see photo).

I thought, when removing the drivers side head, that a thick cable loom had welded itself onto the back of the head and had to be hacksawed off. Later investigation showed that a metal strap held by a bolt at the rear of the head was in fact retaining the cable and no damage to the cables was involved... but what designer attaches an important wire loom to the rear of a very hot cylinder head? I will strap it to the bulkhead...

On the topic of rear of cylinder head, someone had painted the number 20 on the rear of one head so I presume a prior repair had 20 thou skimmed off it.

I had, after the nightmares of undoing the bolts, given very serious thoughts to replacing them with studs and nuts, but everyone I have spoken to has begged me to keep using the bolts so I will go that direction.

I will replace plug leads and plugs while I can actually reach them and will start the long haul of putting it all back together.

Once that's sorted I have to change the oxygen sensors, squirt some grease into the grease nipple on the front prop shaft and fixed the notorious fault on the ABS modulator.

No rest for the wicked with these cars!

 

Congrats! I was nervous for you, it's not a terrible job, but it's taxing.

Good luck

 

Hi

Thanks!

A silly question.... I have bought a set of Magnecor plug cables and Champion platinum spark plugs.

Given that the long cables go to the front of the engine and the short ones to the rear, they are all different lengths so is there as easy way of figuring which one goes to each cylinder ' s plug?

 

The STI brand I use have numbered rings on them, so not completely sure.

I would venture to guess that each banks wires are the same lengths.

Sort them in 2 sets. As you said longest are 1 and 2 and work back.

 

As I have never pulled the wires all off together and not one by one, I have a feeling it's going to be a case of trial and error, unless they happen to be numbered. Remember that the middle cylinders of each bank cross over to the coil on the opposite bank.

Whenever I go to change my wires, or the head gaskets, I am going to try to remember to number all of the old wires to match lengths with the new ones.

 

you must put that ground cable back onto the head, it is the engine ground.
You will have all kinds of problems like emergency brake handle glowing hot because the truck will try and use the EB handle as a ground.
and if your heads have been milled .20 there is no way I would put it back together with bolts, i would use studs as that is more than LR recommends be removed. IIRC

 

I'm mid sixties and to date have done the HGs on all my clunkers and several orphans that have limped in the shop door, both 4.0 and 4.6. I have always used new stretch bolts as per RAVE, which also has dimensions so you can determine how much head is left and what you can remove. I usually check the head and block for flatness, .002 max in any direction. With that, the part I ready myself for is the final 1/4 turn on the bolts, especially the lower rear on both the driver and passenger sides.

 

Hi

Thanks for the tip but it was not my intention to leave the engine ground cable disconnected.

The loom I mentioned in my prior posts is a bunch of cables in an armored group at the rear of the engine on the driver's side. I did not think it a great idea to bolt a plastic surrounded cable loom to the hot cylinder head.

The ground cable is at the front right of the engine (viewed from the rear) and I will certainly replace that very firmly!

Re the 20 thou.... that was just a guess on my part based on the small number 20 painted on the rear of one of the heads.

I've bought the stretch bolts now and will have to see what happens....

PS The weekend and I am putting the heads back on... I will, as you suggest, also make sure the rear ground bonding strap is connected to the driver's side head!