Blown head gasket V12
 

Hi all

I don't usually post here, but as the title suggests this is a V12 specific problem, and one I don't wish on anyone, the title says it all... :icon_violin:

Anyways, got to have a bit of a story right? So she's been up for about 2 weeks, I ordered and fitted a new alternator and replaced the viscous fan clutch, got the tranny bush and spring seats too, all smiles so far, loving it. Shes had a sticky ring on B1 since I got her, ATF did wonders to improve her, so I figured I'd let it soak in ATF while I waited. Got everything fitted, made mods to fit the Bosch alternator and pieced her back together, took the main HT lead off and cranked just to check. Then fired her up, purred beautifully. she seemed to start missing suddenly, felt the pipes and she'd dropped a cylinder, then I noticed coolant had started leaking everywhere... Switched off and looked for the leak, couldn't for the life of me find it. Anyways I assumed the worst and pulled the main HT lead again, luckily, as when I cranked she locked up... So, she's popped a head :(

Now what I'd really appreciate is if anyone with tricks to pulling a head, especially regarding the cam chain tensioner, would be so kind as to forward them to me. As always, ANY advice is really appreciated, especially with this one, I've never pulled a head on anything with more than one cylinder.

Many thanks in advance.

So sorry to hear this! It could have been worse, at least you cranked it to test it first and it locked up there. You're right, it's nothing I would wish on anyone.

I hope you get her fixed!

Yes, it could have been worse, let's be grateful it wasn't. Gotta stay positive ya know :icon_rain:

The Great Palm's Book has loads of stuff on this topic. Although you may not really want to, I strongly recommend removing the engine from the car. Once out it is SO much easier to work on it, remove ancillaries, exhausts, etc. etc. Also, you can go over the entire engine changing gaskets and generally oil-tightening it. As long as you have a covered space, it is not that bad getting it out, once you master your fear of the unknown, that is!.
Greg

Engine removal is rather straight forward. I did so just to clean the bugger up...

You'll be wanting a head puller tool. Either made up for you or rented...

Bugga Nathan.

Very observant, and that HT lead out was really smart, and probably saved that engine somewhat.

As Greg has said, "Experience in a a Book" by Kirby Palm is FREE from the link on here. It is 800+ pages, and well worth the read.

Also, engine OUT is now a must in my opinion.

That plastic chain tensoiner is probably worth replacing, as at the age, will probably "snap" when attempting to straighten. NOT what you want to hear, but they are brittle.

I would be taking both heads off. Also new Viton o/rings on the oil pipes inside the sump would be a very smart move. Clamp the liners when the heads are off, and leave the pistons etc in place.

Removal is not that hard, and my first one took me a full day, the others have been out in around 4 hours.

You know where to find me if you need some assistance. Same rule as before, keep the post updated to help others as we go, hahaha.

Thank you all, mmm, engine removal, won't I need a hoist of sorts? The only working space I have is my grandpa's garage, I take after him, he's pulled many cylinder heads in his youth, the V12 is something else though. We don't have any access to a hoist though. I've had her down to the head before though, nothing too hard. Wondering if I've blown the gasket or cracked the head?

The current symptoms are; good supply of coolant reaching the cylinder, especially under pressure from the pumping cylinder.
First thing I did was clean the cylinder out, plug out HT off and crank to clear her.

Then plug in for a little pressure and start for a QUICK run (no HT lead or injector clip on affected cylinder) pressure in the coolant system builds up fast, I'm seeing the work that the radiator shop DIDN'T DO on the expansion tank. No leaks on top, but a drop from under the exhaust manifold. Sound like a gasket?

Thank you very much Grant, I really appreciate your assistance, I'll be keeping everyone up to date for sure.

Cheers

If there is coolant inside a cylinder, 99% the head gasket has failed.

The V12 is a wet liner engine, and they are sandwiched between the head and the block landing at the bottom, and simply cannot move.

Cracked V12 heads?, I have never seen one.

I use an engine crane (one armed bandit) to remove these engines. Lots of places hire them out.

I would have the car nose first into the workspace, engine out, car backed out, plenty of room. Take the engine and trans out as a unit. It can stay as a unit if the heads are all you are going to attend to.

Wet liners, I read they were so somewhere, great help. Got down to the exhaust to see if I could see any cracks as the top of the manifold was stained with coolant and found nothing. As usual Grant, you would be correct.

Next is the induction manifold and rockerbox.

Oh, me????


Lots of ways to R&R an engine. But, that one and it's transmission
is a big "lump"!!!


1. Grand pa's garage offers two options. Doubled 2 x 4's across the wall top sills. Or just over the beam at the door. Chain fall aka block and tackle. I've done few other critters that way. Or a geared or o'wise "come along". Either from a tool rental.


2. A "cherry picker". Base and a long lifting arm leveraged by a bottle jack. Tool rental source. bulky, though, even in the "knock down" version, so transport is an issue. Rent the truck to transport and return??? Day rate not bad, it is the miles that get one!!
Been there, done that.


3. Buy the "cherry picker". In the USA, not all that bad. Use and sell, or keep as a "toy".


4. Borrow one??? I used my son's to pull the 4.2 and set in the LT1.


Carl

odd, that it would blow into one cylinder while not overheated or stressed!!!


Carl

Indeed Carl, unless the starter has the power to do damage with a hydro-lock...

Anyways, I've gotten down to the rocker-box without breaking anything.

Now to figure out how to rest the cam-wheel on the little fork that Jaguar thoughtfully provided, how does one go about securing it to this fork? I would imagine a washer of just the right side to fit over the shaft along with some locking wire? Or is there a better way?

Doesn't look like this exhaust manifold can make it out of the bay... Where about should I place the jack to lean the motor to one side?

I trust I don't need any fancy tools to relieve this tensioner? Just a little of movement would be sufficient.

These head bolts, what's the best tool? I can't budge them with a spanner, do I need to try obtain a crow-foot spanner, or am I missing something?

Thanks again, I'm very grateful for all the help.

A strip of about 1mm sheet steel with slot cut. Can be rough and ready with simple slot or fancy hole merging to slot. Slot same measurement as minor diameter of groove on cam sprocket stub.
I have in the distant past moved the sprockets from cam to holder without retracting the tensioner. It is a play it by ear sort of thing but does avoid stretching the tensioner back to flat which more often than not is when they seem to fail. No need to bother trying if you intend to replace with new part which l would recommend.

If you have to remove the engine its much easier to remove the trans first. You can do this on ramps, you will need a very long 1/2 drive extension to get the bellhouse bolts.

Right, got her down to the rockerbox, just waiting for gaskets, decided to do all the other graft while I wait. Might do the windscreen, myself this time, as it leaks. Gonna fit the new tranny bush and spring seats plus get some new window weather strips.

Just incase I have to pull the rockerbox off to get to those head bolts properly, what can I expect under there? Is it easy to put back on? Or will I be fighting spring tension etc?

Hi all

Sorry for the delay, computer refuses to go online at home, must have a Lucas wire or two...

Jokes aside I've replaced the head gasket, all went well, used a head puller, cheap to make. For the record I didn't have to touch the timing chain tensioner, the sprocket slipped off and slipped back on, no issues. Thank you to everyone that helped me with that one, I really appreciate it. Now if someone can tell me all the reasons a Jaguar has to run lean and misfire...

quick pic of engine without heads, notice cam sprockets on mounts with small metal strip to hold them while doing work,clean up etc.

its patience and time, observe everything.