I spent a little time in the garage today and cleaned up the block a little. I took pictures of what looks disturbingly like cracks between each cylinder. Might be a bit difficult to see.
Is my block toast?

 

Sorry to be the bringer of bad news, but Pics 2 & 3 seem to show a crack. I'm not sure on the others; only a visit to your place could I be sure. You can test by putting a drop of kerosene on there, wipe off well, then dust with talcum powder. You should see the crack appear as the talc absorbs kerosene in the crack. This is a primitive crack detection test.

The only certain cure is to fit lipped liners so the lips cover the cracks. This would be a big job involving engine strip, machining out the old un-lipped liners, machining grooves for the lipped liners to fit into when pressed in, and then facing off the deck of the block.

I think a later engine with the slotted waterways would be better and cheaper, frankly. See if you can find one. It really needs to be an 82 or later.

However, wait and see what Doug Dwyer says.

 

Thanks Fraser, I will wait for Doug's input too. It was tough to capture in the photos but I can see the cracks with the naked eye here. So, an '82 or later block? Would that be an 8L or a different stamping? I'll have a closer look at my spare block.

This just means I shift my focus to one of my other cars for now...

 

Hi
You can see why so many people fit a US-made V8 engine ! The later blocls were all 8L, I think, but from about '81 the water passage arrangements were changed to be a vertical slot in the deck of the block, and this needed different cylinder head drillings too. So if you can find a complete 82 engine, then it would slot straight in. I say '82 to be sure of getting the latest block.

 

Wow, you guys have really good eyes! I had to do a lot of altitude and azimuth adjusting before my bifocals picked up what you were seeing

Yeah, looks like cracks.

A known-good used engine seems like a plausible alternative

Cheers
DD

 

Well, just to make sure, I pulled out my copy of "Jaguar XJ The Complete Companion" by Nigel Thorley, dated 1991. (ISBN 1-870979-22-2). He is still editor of the magazine of the Jaguar Enthusiasts CLub here in the UK. This book is a mine of information. He states in the book that in 1979 the block water passages were changed to the slotted type, but I had a 1980 car with the old water passages, and (of course), a cracked block !! He also states that if fitting an earlier head to the later blocks then drilling of new waterways must be done to the head to match the waterways in the block.

No VIN or engine number is given for this changeover unfortunately, so if buying an engine earlier than '82, I would want to see the head off so the block can be checked for the later waterways.

 

NO! :-)

Thanks Doug, Fraser. I know people that may have spares and I do have a spare block I can have a look at. Perhaps Doug I will see you at the PNW ABFM and the Portland ABFM next year...
Do you ever make it up to the show here at VanDusen Gardens?

 

I try to make both the Seattle and Portland ABFMs each year, and one or two other shows if possible. I used to hit 6-7 shows/year....got a little burned out and, frankly, expensive. Hotels, gas, meals.....

Van Dusen? Haven't been in several years but attended many times in the past. Wonderful show and venue. Love the Abercorn Inn. Wonderful restaurant and a great little pub. I spent a week there one night.

Cheers
DD

 

I found this article on the Jaguar Club of Tasmania website: -

Fighting the Flaw in the 4.2 Engine Block | Jaguar Car Club of Tasmania

As I read it, it looked familiar and it actually appeared here in the UK in the Jaguar Enthusiasts CLub magazine, and was written by a chap named Brian Read, who who sold me an uncracked '7L' block in 1990 so that I could rebuild my XJ6 engine around it. Brian is not quite right about certain things, for instance there is no "supercooled coolant" it is just "cold" coolant.

For those wanting to know the detail, the '7L' long stud engines had cooling passages machined across the block between bores 1-2, 2-3, and 4-5 and 5-6. This was done using the bore to position the cutting tool, so afterwards, steel liners were pressed in to cover the slots. As the passages are only about 1" below the deck of the block, the temperature gradients across the block cause cracks to start at the top of the cooling passages, and these work their way up until they reach the deck of the block.

Having now got a continuous crack, the bridge strength of the 1" deep "bridge" between the bores and which "connects" left and right sides of the block is now gone, so over time the metal sinks, thus easing the pressure on the head gasket. The thin steel liner is insufficient to stop combustion chamber gas at high pressure from forcing its way into the crack, into the water jacket, and then to blow the coolant out via the pressure cap. This is because the pressures generated in the coolant gallery is such as to force the pressure cap open to relieve the gas pressure.

The '8L' blocks were supposed to improve on things but actually cracked more than the 7L blocks until around 1980 or thereabouts, the slotted waterways were introduced, and the liners eliminated. However, engines with these later blocks can still suffer HGF, and it is important to repair this at the earliest opportunity.

Brian Read told me back in 1990, that 70% of 7L blocks cracked, and 80% of the 8Ls. His opinion was that lipped liners were the only permanent cure, and he had a lot of experience as his business was rebuilding XK engines in Hinckley, Leicestershire.

I finally managed to find a picture of the slotted block. You can see how narrow they are and the metal available to seal the bores is still minimal !

 

This is my 86 slotted block that is currently in the rebuild process, am i to believe that this has new liners/sleeves as the slots do not connect? until seeing the photo above i thought mine was a normal slotted block

 

Just read the article. Thanks for the link, it was extremely helpful. So my next question is top hat liners or ceramic coating? If I wanted to go ceramic, what else needs to be done? Do I still need to fill anything or will the coating just close up the gaps? I assume I will need to remove the liners.

 

Hi Hooter

Looks like somebody has linered your block, the original had no liners. They could be, (probably are), lipped liners, so the water passage is there underneath, so nothing to worry about. However, worth a check with a feeler gauge to see if the slot is there underneath. The liners were probably necessary due to block burning following a HGF and it being ignored for some time. Once you get a burn across as this point, the block will probably not stand re-facing, (depending on depth of the burning), so liners is the only option to recover the block. You should be OK with yours, it's the first I have seen with these liners.

 

Well, if it was me, I'd look for another engine either to supply an uncracked block, or as a swap.

If you're going to do a full rebuild, make sure you clear out the sludge traps in the crankshaft unless you know the engine hasn't done too many miles. Anybody "lumping" an XJ6 will have an XK engine available.

And BTW, I would go for lipped liners if you have to. They work. I don't think this ceramic process does, and I think the article says so, basically

 

Fraser:

I, too was fortunate. I stayed married to the same woman for 54 years. Only her passing in 2009 ended the association in this world. We still communicate, but in a different fashion. Probably sooner than later, I'll join her in paradise.

As to more power. An engine is an air pump. The more air one can get it to pump plus fuel, the more BTU's "power' it will deliver.

Now, the basic architecture of the engine has a lot to do with how to get the most out of it.

The XK engine is a marvel. But, an enigma as well !! Hemi head, cross flw oHC, etc lend to great breathing capability at higher RPM"s But, for political reasons, it sia stroker, Ie, under square. Not as good for the higher RPM's. Piston speeds can be alarming and the changeover from up to down is dynamic up the rev scale. it will not be happy as a "screamer" as an oversquare engine would be. You can wring it's tail and it will perforem for a while, then booooom!!!

So, in spite of that wonderul head, go for torque at the rpm where the engine will be driven most of the time. And, tall gears that the torque can pull.

Here, a supercharger would be a better choice than a turbocharger. At least, in my way of thinking.

My 4.0 Jeep Grand Cherokee is very lively as it is cammed as max torque around 2000 to 2500. Old engine design with a head breathing system that is far inferior to the XK.
But, engineered to the most driven condition. The Jeep is still tight, shiny and strong at 200+ miles.

Carl

 

That is my plan, probably a centrifugal supercharger. I have already designed my own intake system and now is my opportunity to have it fabricated and start test fitting stuff. I'm almost glad my engine grenaded....

 

It may not be well known as to why the XK engine had such an unfashionably long stroke. In the design stages during and just after WW2 the engine was to be a 3 litre. ( BTW engineering evaluation 4-cylinder engines were built as well, so that Jaguar could carry on just like pre-war with a "cooking" 4 cylinder saloon, (it was a 1.7 litre), with the profits being made in the higher capacity six cylinder saloons, (of 2.5 and 3.5 capacity)).

However, the engine as a 3 litre had very poor torque and it was considered totally unsuitable for the market. However all the machinery had been installed to make the engines, the block design and moulds were ready in anticipation. A redesign at this late stage was impossible as finance was very short. So the stroke was lengthened to 106mm to give a capacity of 3.4 litres and the torque at lower revs was restored !

Apparently, at the time of this engineering "cobble", the Chief Engineer, William Haynes said, "we'll have that stroke around our necks for the next 10 years". Yes, a very prescient comment, except that it was a little bit longer than 10 years. The XK engine went from 1948 into 1988 with that 106 mm stroke. Only exception was the 2.4 litre "stroker" but I don't recall the dimension, but that engine could really rev its heart out. I know because I had one !