I have had my 4.2 in my series 3 xj6 rebuilt. Have not got it started yet. Coolant is wicking up one head bolt at a huge rate. Have been told third Dodd happen on 1 out of 10 newly overhauled engines but will take up once run for a while. Anyone else had this experience

 

Yep.

Not sure on the take up.

Some weeping prior to start is OK????, but a flow is NO GO, That thick hardened washer may have a deformity on the face/s, or the top face of the head where it sits may be grooved.

I would remove that dome nut, inspect what I mentioned, then "smear" that washer on both side with #3 Permatex, and refit that nut.

I smear them all when doing an engine, even on the V12.

 

No direct wok on the DOHC. But more than a little on old Fords that relied on studs to fasten the heads, said to be superior to bolts.


1. On my old Fords, a normal nut was used, not the "neater" acorn as on Jaguars!
For adornment, used a cap in acorn form over conventional nut.


But on occasion, a "weeper" occurred in the "stud to head" space. Fixed by adding a crystalline solution.


2. There is no way that I could or would quarrel with Grant's solution.


3. But, I would suggest a way to check on how the acorn nut clamps down!!
Measure the exposed stud threads above the head surface. Measure depth of threads
in the acorn nut. Include copper washer squished thickness.


Enough squeeze ?? Critical in my view !!


Carl


2.














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I would check and make sure the dome nut is not bottoming out on the top of the stud prior to reaching the clamping force required. Did you have the studs out of the block? If so,..did you clean out the holes where they screw into deep inside the block? Just a guess ... but if some crud is trapped inside the screw hole down in the block ,..the stud will stand taller and may not allow the dome nut to tighten down enough to achieve the necessary clamping force between the head and block, and leak around the stud bolt.
Again just a guess but you have to start somewhere...

 

Yup, that is my guess from long afar...


Carl

 

Yes, my guess too !! When I rebuilt my 4.2 in the late 80s, I had a bare block on the engine stand, so took out all the core plugs, flushed the block out then installed new studs but vacuumed out the threaded holes then put a tap down. Belt and braces stuff !! I had no trouble with the sealing where the head nuts fit, but Jaguar at that time recommended a bottle of Barrs Leaks when replacing coolant.

 

While I probably will **** a lot of people off, but my opinion is that the 4.2 Jaguar 6 is the biggest piece of junk ever put in any car. Not even good for a boat anchor. When I finally pulled mine in favor of GM 350 I could not give the damn thing away.. Finally found a sucker.. was happy to see the butt end of it heading away from my property on a flat bed truck. The guy got it for free as long as he agreed he would never bring it back Good riddance to rubbish

 

Yes, yawn, we all know you're opinion of the Jag engine. You've made it abundantly clear on many occasions.

Yours is *exactly* the sort of commentary helps the fuel the anti-lump sentiment. Congratulations on that.

If that's your desired outcome then, by all means, carry on. If you're interested in *less* anti-lump sentiment then be part of the solution rather than part of the problem. That is, put your best foot forward and ease-up a bit on bashing Jaguar engines.

Maybe the anti-lump crowd will ease-up as well.

No cheers
DD

 

Or, back in my day. Dumb flat head Ford guys. Who would want to deal with an engine that had exhaust passages trough the coolant passages??? Or had valves that could only be adjusted by the removal of material from the block seat or the valve stem!!!


And, au contraire, who would deal with an engine put together with stove bots and had Babbitt bearings and "splash and hope" oiling system. And a fiber timing geat that would eventually shuck it's teeth, if it didn't toss a rod or two first.




Worse yet, a side valve Plymouth 6. Adjusting or grinding valves in situ only for the guy with a knack of working in a contorted position. Well, if the thing didn't spin all it's rod inserts first. Known for the spaghetti crank shaft.


Oh, oddly each survived decades of use in many applications. Gee.


Alyn, I was glad to see my busted DOHC go. Free. But, a bit sad. Cheered me that cleaning the driveway of it pleased dear departed wifey. Happy wife = happy life.


And, shew did love her Jaguar.


I've always had an infinity for in line engines. 4's.6's and 8's. The DOHC is just flat out good looking. Only the clunky Bosch Jetronic EFI "dirties" the look. A brace of Webbers, oh yeah... Or about three down draft old 97's, leaky float bowls and all.


Carl

 

I do see where Alynmurray is coming from with my own experience of the 4.2 XK in a 1980 XJ6.

The plain fact is that the 3.4 XK was definitely the best engine and that was the first one that was fitted to the XK120 of 1948. The later 3.8 was almost as good, and the 2.4 was a little turbine, although not all that powerful. The early 4.2s from 1964 were OK, but when Jaguar engineers decided to locate the head studs in the bottom of the block inside the coolant jacket then the troubles began.

I bought my 4.2 XJ in 1988, so it was 8 years old. Not long after this, I started to have serious trouble with my engine suffering head gasket failures. I managed to purchase an uncracked block from a chap whose business was rebuilding XK engines, and only then did I find things out. He told me that with long-stud 7L engines, on stripping down, out of 10 blocks about 7 suffered cracking between the bores, and with the "strengthened" 8L blocks it was about 8 in 10. The only cure was an expensive process of inserting lipped liners to cover the cracks.

The essential problem, as pointed out by Roger Bywater of AJ6 Engineering is that the engine was in front of all others for about a decade or two, and then started to become progressively old-fashioned and was well past its sell-by date when the 80s came along. There was a period in the 70s when every engine suffered bearing failures due to a minor engineering change. Sometimes the cars didn't leave the factory before they failed.

Things were seriously wrong at Jaguar in the 70s but of course the whole of Great Britain was in a seriously bad state then, so maybe I'm being too harsh.

The Jaguar XK Engine / AJ6 Engineering

 

Ben,

You said you had the head rebuilt, was it resurfaced? If so, the acorn nut bosses sit lower by the amount of material removed during resurfacing. If you had .030 removed, the acorn boss will be .030 lower. Which makes the studs sit .030 further above the acorn bosses if the studs were not touched. So I would agree with the other members notions that the acorn nut may not be fully clamping down. Ask the rebuilder if they resurfaced and by how much. Ask them if they can supply shims of the same thickness that you can place on top of the original washers. This will guarantee the head is clamped properly. If one is leaking there may be others that are not completely clamping down.

Steve

 

Thank you Fraser Mitchel !!
Happiness comes from dealing with facts. Junk is junk.
There are simply too many problems to have to contend with,.. with that old antique engine. And as a side note to Doug "denial is not just some river in Egypt"
Why beat the dead horse ? At this point we all know you get about 100,000 low power miles then the thing craps out with something or other, And when it is running for that short while; it's nothing to write home about . Heavy leaky and too many moving parts. The only thing that is attractive about these old Jags is the body styling,, and while it is nice , it is quaint and a wee bit long in the tooth, some of the newer stuff is more attractive. Its time has come and gone and now they are just collector's curiosities and some are fancy resto mods with GM V8s. And run as they should have in the first place smooth and strong with reliable GM V8 power.
Recently saw a 67 E -type on Mecom Auto Auction, It went for big bucks and the commentator happened to say "yeah we had one we raced ,..looked great but we could never get it running right for very long" I thought "AMEN"

 

There are many paths to happiness....And opinions are not the same as facts


I've never denied any of the faults with Jaguar engines. Some people can deal with 'em, others can't.

In any case, I stand by the remarks in my earlier posting.

Good question....why ARE you beating it? We know how you feel. Continually....and gratuitously... bashing Jag engines adds nothing of value to the discussions but it DOES help keep the lump-versus-original engine animosity going. I can only assume that's you're goal. It's nothing to pat yourself on the back about.


We know

We know

We know

Why do you even own one? I hard pressed to remember you mentioning *anything* you like about the car, ever.

Anyhow, since these old Jags are merely collector curiosities it should be very easy to understand why many are willing to deal with the original engines.

Agreed. And constant bashing of Jag engines, although obviously pleasurable to you, does absolutely nothing to make your V8 conversion even more smooth, reliable, or more powerful.

Doug

 

Good on ya Carl.

I remember those 2 engines very well.

The V8 with the mushroon valves was something special indeed.

The Flat Top 6 was just plain different.

My family had many of each, and they went forever that I remember, and yes, Dad and I spent thousands of hours under many bonnets (hoods), and it was just what we did in those days.

Changing engines was never on the lips, why???, "the one we got does what it does, and needs what it needs, now shut up and get on with it".


This one was a recent "get going" at my place, Overhead Inlet, and Side Exhaust, and they MUST be set HOT, which for the exhaust is real fun with that manifold blocking 80% access.

 

My path to happiness? Dr Phill & I considered the lump for less than 1/2 a beer.
Each to their own.

 

Sorry, but beyond the engine from the 70s onward, I am not with you on the style aspects. I still don't think Jaguar has yet captured the zeitgeist of auto styling in the 21st century. However, if they sell lots of cars then I'm wrong. At the moment, the SUV sweeps all before it.

 

He, he, I spent time with my son and his SO on Christmas day. About 30 minutes from here. Drove the Jaguar. Care, as "nuts" are on the road. Taching at about 1750 to 2000 rpm. Speedo nuts, but that equates to 65 to 70 MPH. Wowee, all others blasting by!!!


Joelin, Tom's gal, "Wow, you brought the Jaguar". A bit scruffy, could stand a bath!!
But, oh so different from the other cars on the street. They have two a bit nutty inside cats. Both black. On the back shelf of my Jaguar is a bobble head. Given to mew by daughter. A black cat... Joelin: "Tom, get me one...."


Ouch, the Jaguar misbehaved just a tad on the way there and back. Temp at 100C instead of usual; 90C. Warm air from heater erratic.


Since checked out. Added about a quart of premix coolant. All systems go. No sign of weeps or leaks. Why, only the Jaguar gods know !!!


Carl

 

How sad to be ending the year with such grossly opinionated vitriol parading as "fact" from [alynmurray] at posts #7 and #14. I defend your right to your personal opinion . . . whatever misfortunes in your Jaguar experience, they are yours . . . but they are that, OPINIONS, and no amount of forceful invective will ever make them universal facts.

To keep on bashing your opinions at all the rest of us, suggests you fail to understand some key issues that ARE facts -

1. You are clearly in the minority - while forums are awash with members' problems, this is normal among enthusiasts who love their cars enough to invest time and money into fixing and maintaining (not bashing) them - and there is no shortage of positive feedback to that effect;
2. This forum has been built on friendship and the generous sharing of many years of experience (both commercial and DIY) by a vast number of tech gurus as well as ordinary "new to Jaguar" members - but, instead of seeking to build on that platform, your self-interest is vested in tearing down;
3. Your sweeping generalities of Jaguar as "crud" have most of us here questioning your inherent motives - I mean, why DOES a self-ordained rubbisher spend so much time on a Forum dedicated to all that he hates in both styling and engineering? Who do you REALLY think your negativity will influence?

Please leave us to enjoy! The XK engine in my avatar was pulled down at 120K miles, found crankshaft still to be within FACTORY TOLERANCES bar half a thou ovality on pins and with bores 1-2 thou taper. Rebuilt with all new STANDARD bearings and rings, head re-torqued and valve clearances re-adjusted after 1K miles, that XK (your "crud") ran for another 250K miles in my hands over the next 5 years. Do I then trumpet that ALL such XK units will happily outlast 350K miles? No! Not everyone has access to a Small Arms Factory engineering department and its boffins. Not everyone has the patience to rebuild an XK to such precision. So, how can you generalize as you do from purely the basis of your personal experience? Weird!


For the rest of us . . . 2017 promises better than "kicking the s**t our of Santa Claus" and I look forward to that well oiled friendship and sharing that keeps me coming back. The aggro . . . I don't need!


Ken

 

Well said Ken.

I am sometimes called lots of things, mostly not printable here, but:

I like originality, but sometimes other things work well for some, and not so well for others.

Many years ago, a mate arrived with a 1980 XJ-S with a 350 SB fitted, and a S3 XJ12 rust bucket. The 350 was as sad as yesterday's Dingo's breakfast, and he wanted the V12 back in the XJ-S, so we did as asked.

The 350 sat in my shed under my bench until about 18months ago. One of the neighbours asked about it, and I said to "come and get it", which he did. The conversation got around to the next life of that 350, with me thinking for one of his Street Rods, BUT his reply had me smiling. "I am going to use it as a mooring for my new boat, I got one, but need 2 to make it work proper", and a fitting end to a SB350 took place.

Another mate has a 1977 XJ-S, and he has a 351 Cleveland in it, and loves it, so my jollies are different to his jollies, but neither of us is right OR wrong.

Like Ken, all my 4.2 XK engines worked hard, went long distances without fuss, and never left me stranded, and stranded is OZ will see you in serious sh*^ very quickly, coz help is usually thousands of kms away.

Our PreHE V12 is at 550000kms, and untouched, OK, it weeps oil, DRINKS the fuel, and loves the RED line on the Tacho, what more could a mere mortal want?????

 

The old "Boat anchor" story. applies to all specie!!! Got a good laugh pout of that tale!!!!


Going to the store later. Rain predicted. If so, I'll drive the Jeep. If not, I'll drive the Jaguar. Why? Well, my "little" dog Coco gets into the Jaguar easily. Needs a boost from me to get in to the Jeep. Guess which he prefers???


Odd logic. The car born in the rainy fog has wimpy wind shield wipers. Jeep's larger and faster.


I just aadm