At long last, I have started to replace the cylinder head gasket on my 1976 4.2 series 2 Jaguar. After a fight, I now have the head off and have ordered a new set of head studs, since there were signs of stretching and corrosion to them. I could not see any reason for the failure!! Now I have a new Payen gasket, but my problem is "which way up is correct?" There is no "TOP" marked as I expected. There are a series of holes coinciding with the water channels. On one side the holes in the gasket are much smaller than the other side- so it will make a difference to the water flow. Also, one face has a continual run of metal from one end of the gasket to the other along the cylinder bores, whereas the other side has "interruptions at each bore" I hope that makes sense! So which way is up?

 

When I say that I could see no reason for failure, I should qualify that. There are small cracks between adjacent bores, but, all the bores have bad liners in place - thus no cracks extend into the cylinder bores!

 

OK, you're not going to like what I have to say to you, but you've got the rather bad syndrome of cracking between the bores. It is this that has caused your HGF. Sorting this out properly is expensive, hence why so many XJ saloons are 'lumped' with reliable Ford or GM V8 engines ! If you just replace the head gasket it will not last long, you'll struggle to get 10k miles out of it.

The long stud version of the XK engine is, frankly, a dreadful piece of design work that was later modified slightly in the early 80s to deal with the problem. Jaguar engineers should be hanging their heads in shame at this woeful design, but I suspect it was forced on them by the bean counters, as Jaguar was run on an absolute shoe string at the time.

The 4.2 long-stud engine was cast with siamesed bores 1-2, 2-3, and 4-5 and 5-6, so to make sure coolant could move across the block, two horizontal slots were machined between these bores to make water passages. The bores then looked like 2-stroke engine bores. To cover these passages, thin-wall liners were then inserted. Over time with heating and cooling of the engine, cracks would start at the top of the top passages, and gradually work their way up until they reached the top of the block. Now cracked, the metal between the bores lost its bridge strength and subsided very slightly taking pressure off the head gasket. Combustion gases soon found their way into the cracks and pressurised the coolant forcing it out and overheating the engine. The liners themselves are too thin to allow the head gasket to withstand combustion pressure for long,

How do I know all this ? Yes, that's right ! I fixed my engine with another uncracked block.Not all blocks cracked. The cure for you is to strip the engine down to a bare block, remove the liners, and then machine recesses in the top of the block to take new liners of the lipped type, (top hat liners). This is an expensive operation hence why so many US owners have lumped their cars. Later engines from about 1981 or 1982 had narrow vertical slots machined between the bores and no liners were used, (the so-called "slotted block"). No cracks occur with these engines but head gaskets, although lasting longer, still struggle to get past 80-85k miles, but then replacement is fairly simple and straightforward.

Even the later aluminium AJ6 engines can suffer HGF, but in this case repair is a simple matter unless the block face has been eroded by combustion gases !!

Have a read here: -

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

However it doesn't go into much detail on the cracks, but it is definitely NOT good practice to just ignore them if you want a long-lived engine.

 

Oh, yeah, a cracked block has been bad news to many in many critters. At times, enough to send the entire car to the "junk yard".


But, in my past, I've lived with or "fixed" a couple. Inelegant in each case
but, effective.


The almost elegant method is to "stitch" the crack. A product is available. It's brand name escapes me. Iron screws with break away heads. Drill and tap the hole. Run in the screw. Break off the head, file smooth. Drill again over lapping the first screw. Tap ands run in an other screw. Repeat all along the crack. If the space is tight, it might be difficult to do or impractical.


A less elegant method is to use a sharp punch and ***** long the crack to tighten the gap by expanding the metal. File smooth, so as to fit tightly against the gasket.


I used the latter on a 312 Ford. To raise a flame damaged area between bores. It worked !!!!


Carl

 

This vehicle is infrequently used - probably less than 1000 miles per year! I have been using the car for some two years in its "gasket blowing state" - generally covering up to 100 miles per run to Classic car shows only. I cannot justify any major expense and I have two other Jaguar/Daimlers. I think that I will re-assemble it with new studs and gaskets - already acquired, and see the result. 10,000 MILES WOULD BE GOOD!!!

 

Many thanks for your replies. Fraser Mitchell - do you have any idea of the cost of machining and fitting top hat bore liners, or the cost of a later slotted blocks?

 

I've never had it done, so can't answer, but most of the cost will be in labour of removing the engine from the car, stripping the engine down to a bare block, then reassembling the engine after block work, and re-installing the engine back into the car. So if you do all the stages bar the liner replacement, the cost would be reasonable, I would think.

This UK-based engine rebuilder has a price for these, but it's not clear if the price includes machining or not. Note also their recommendation on an update for the rear main oil seal.

Rob Beere-Engine Components

 

So, after much thinking and searching, I have come upon another engine of similar vintage with less miles on it than my engine. It appears to be fuel injected, not carburetted. How difficult would it be to remove the intake manifold and substitute mine with associated carbs? I do not know if the "new" engine came from an automatic or manual shift car. Again, are they easily interchangeable?

 

There shouldn't be too much trouble, my Series 1 came with Series 3 engine. All the series 1 bits bolt straight on.

 

It should be OK. The EFI engines had larger inlet valves, (actually those that went in the D-type engines), and hence a bit more power.

Do you know the year of production of this engine ? Some very late Series 2 cars had EFI, but they were almost all Series 3 cars with the slotted block coming in the early 80s but I don't know the exact year. You'll have to transfer over your engine breather plumbing, as it is different on the EFI engines.

When I had cracking on my 8L block, the one I got to replace it was a 7L off a carburetted car. My car was a 1980 Series 3, and very badly made, Jaguar people of the time should have hung their heads in shame at selling these cars to people who expected, (and should have got) better.

wish you well in getting your car fixed.

 

The replacement engine is also an 8 series and from 1976 or 1975.

 

This engine may also have a cracked block.The chap who sold me my un-cracked block way back in the late 80s told me that 6-7 out of 10 7L blocks cracked, and 8 out of 10 8L blocks. Only way to find out is to lift the head and look.

Jaguar was a disaster area in the 70s, and not much better in the 80s. It took Ford to sort them out and they had to spend the equivalent of the US defence budget to do so !

 

+1. Very true Fraser . . . and even more so of the paint department during those latter years. First thing Egan did on arrival was order an entire new paint plant. Reputed cost (then) was 16M Pounds and it still took some years to get it sorted. Hard luck for all those whingeing customers who were less than happy when paint faded or, worse, top coats started peeling off.

Some colours have endured better than others, but it's no wonder that one of the kindest upgrades that many Series II & III and XJ40 cars deserve, is a serious full body repaint.

Cheers,

Ken

 

A lot of good reading in here in between the we fun had, being two guys who have been mates since we were about 7 years old.

https://www.jaguarforums.com/forum/x...157830/page11/

 

I failed to buy the replacement engine! Looking for another.

 

Hey, put the fuel injection in too! Not too much trouble I'd think. Great starts when cold, proper fuel metering etc...

 

There shouldn't be too much trouble, my Series 1 came with Series 3 engine. All the series 1 bits bolt straight on.
__________________
Clarke

There is one "gotcha".

On a S3, the back of the head, in the area where the cover meets the head, there are no holes drilled and tapped to accept the throttle cable bracket the S1 uses.
With the advent of injection, the bracket was no longer used, and the holes no longer drilled and tapped. This has to be done while the engine's out, as there's no room with engine installed. I had to fab up an ugly bracket off a head stud when I found out, after installing an engine.

Cheers,

Rob

 

The bracket I have which I assume is original bolts to the back two studs for the intake manifold.

 

Ah, right.

S1's have the issue I described. Sorry.

Rob

 

So I am nearing the end of my saga!! I have replaced the series 2 engine with a series 3 engine - but have retained the carbs. I used different carb needles and after very much tinkering it runs quite well now. balancing the carbs was tricky. I have a small issue with the auto gearbox - I suspect that there s a very slight difference in the position of the gearbox relative to the selector cable and this causes a malfunction when drive is selected. It is fine when selecting 2, or 3 or reverse.