While trawling for information about coolants, I made an interesting discovery.

As most know, the Lincoln LS 3.9L V8 is a mechanical twin of the Jaguar V8.

So, off to the biggest Lincoln LS site to discover in their words that
blown head gaskets on the Lincoln LS V8 "are almost unheard of".
And it is confirmed when searching their forum and reading the
individual threads.

That seems to contradict what is found at JF.

The contradiction may have it's roots in the reason I landed there
for this research.

The Ford coolant application chart shows that all Lincoln LS engines
had either the Ford green non-longlife conventional coolant, or the
long life gold coolant specified as factory fill or service fill. The first
two years 2001-2002 were green and the remaining years to 2008
were the gold.

Dexcool or its relatives was never specified as either factory
fill or service fill.

On the other hand, Jaguar went to Dexcool in 1999. Prior to that
it was the Ford green, or gold depending on vin. The Dexcool
long life characteristic depends on the inclusion of 2-EHA. It is a
known plasticizer that attacks and dissolves silicone and
some plastics. See those seal and fire rings on the gaskets?

If the engine is the same and the gaskets are the same, but the
coolant is different it is reasonable to conclude that the coolant
is the deciding factor. Especially if the coolant has characteristics
that compromise gasket integrity.

If some reading this decides to change away from Dexcool as their
coolant, here are some considerations:

a) be very careful of buying green coolant by color. there are some
Dexcool clones out there that are colored green and sold as "universal"
coolant to the unwashed masses. There is no such thing as a universal coolant.
The Ford green, VC-5, is a safe bet. There is also a Ford "specialty" green. It's
a different coolant meant for their Mazda partnership engines. That's not the
right one.

b) the Ford gold is Zerex G-05, this is what I have used for 4 years. i may switch
to Ford green. the only difference is the addition of organic acid technology that
extends the life of the inhibitor package. 4 years is pushing it on the gold since
it is not factory fill, so changing the green every 3 years is not much harder and
gets rid of the organic acid technology.

b) changing coolant types requires a full and thorough flush to get
rid of all traces of the previous coolant. this is more difficult than you might
expect.

If you have had a head gasket failure on a Jaguar V8, it would be nice if
you noted the coolant type that was in service at the time.

Dexcool fanbois: ... it really does not matter that Jaguar points at Dexcool as the
approved coolant. They aren't about to pay for any blown head gaskets out of warranty.

If Jaguar had been able to look ahead in 1998 to today and seen the difference in
results between the Lincoln coolant choice and the Jaguar coolant choice, they might not
have specified Dexcool and stuck with the gold.

We *do* know that they changed to a metal shim gasket in 2001, without any major
changes to the engine. Makes one say hmmmm.

 

That's quite a piece of research plums. I have been using Prestone yellow in both of my cars, but it looks like maybe a change is in order, since I certainly don't know what proprietary additives are involved.

Have been a chemist in a distant past existence I can appreciate the issues, but understand that there is little chance of being able to evaluate the choices. I therefor will probably go to the Ford green also.

 

You mean the jug is yellow? No telling what the formulation might be. Prestone is
extraordinarily vague as to what their products contain. The main site does not
even publish ASTM test results or manufacturer type approvals.

And not all green is the traditional formulation, although the Ford Green is a
traditional formulation.

But before selecting green over gold, this might be of interest:

coolingsys

headgasindex

Happily, there is a 82*C thermostat in the spare parts box

 

I think there would need to be much more analysis of failure mode to come to a conclusion about coolant root cause. My gasket had the metal ring displaced inward towards the cylinder as a failure mode, and at least two others have reported the same failure. I doubt that failure came from coolant. But... your obsevation is certainly significant and interesting.

 

Would that have been the 99 XJR or the 02 XJ8?

And what coolant was in service at the time of failure?

There was a running change to a MLS style gasket in 2001 that replaced
the formerly used convential gasket. So each of those is well on each
side of the changeover date. Knowing why JLR changed the type of
gasket would certainly be interesting.

It is also true that no stock Lincoln LS was equipped with a supercharger
and the additional stresses that it would bring.

They also had something we never got. The LS and Thunderbird have cylinder
head temperature sensors monitored by the PCM that put the vehicle into
limp mode if the heads get too hot.

On first blush, a fire ring displaced inwards can be a couple of things.
Erosion of the surrounding gasket material, erosion of the deck surfaces,
or "wedging" by coolant carried particles.

In any case I am not trying to prove anything. It is more along the lines
of "compelling observation", along the lines of "if I step off the sidewalk
in front of that bus it's going to be worse than if it was a Fiat".

 

As far as I know, the Ford engine used a water pump with metal impellers.

So that needs a coolant with cavitation inhibitors (like silicon, which is present in the green and zerex 05). Dexcool doesn't have these inhibitors, and is not needed for the jaguar setup where plastic impellers are used.

Someone told me once that the shift from nikasil to cast iron sleeves was also accompanied by the switch to mls head gaskets.

 

The apparent direction of a fire ring failure might be misleading.

At some point, the engine will stop. Combustion pressure is then
absent. But, immediately after stopping the cooling system pressure
remains. Usually up to the pressure cap release set point. 15 psi
is pretty normal.

15 psi of liquid can move a lot. If there is a breach between a
coolant filled side and the fire ring, after engine shutdown, there
is no offsetting combustion pressure and lots of time to work.

A search of the big G for:

gasket "fire ring" failure

puts the following at #1

JE Robison Service - Bosch Car Service Specialists ? the blog: Blown Head Gaskets on Land Rover V8 Engines

True, it is the Buick/LR all aluminum V8, but interesting nonetheless.

what Victor-Reinz has to say:

Composite Cylinder-Head Gaskets - Sealing Products Victor Reinz Aftermarket

and a couple more:

HELP- head gasket failure. Was "Multi-layer steel head gaskets?" | The H.A.M.B.

Copper Head Gaskets | AERA Engine Builders Association

 

The changeover years of the two events do not match.

But, it could have a causal relationship:

- switch to sleeves
- do some warranty repairs
- switch gaskets

BTW, the reason that Ford chose to stay with green/gold might very
well be the reason you stated. However, the fact remains those
owners almost never have any concerns about head gasket
failures. In any case, replacing a water pump on these engines
is far more preferable to replacing a head gasket. We should
also note that the early plastic impellers were subject to
erosion from the introduction of Dexcool. Wrong plastic.

Maybe, while Ford owned, Jaguar jumped on the Dexcool
bandwagon to be able to tout yet another "maintenance free"
feature. Just like the gearboxes and differentials. And we all
know what a good idea it is to neglect those fluids.

They do obsess over secondary tensioners though.

 

It’s true about the very early water pumps (i.e. 98 and older), after that I am not aware anymore of failures (other then effects after overheatings), and it was only after that that dexcool came into place.

I don’t have any figures of failures per year, other than it is rare to see one with a mls gaskets

As far as I thought, it was also around the same time as the nikasil switch, so starting from engines build from September 2000 (which is when the 2001MY started). The earliest 2001MY I have seen had an engine build in May 2001, and already had the MLS gaskets.

Which cut over date do you have for MLS gaskets?

 

I think between the AJ26/AJ27 there have been three waterpump versions issued
by Jaguar.

The MLS switchover was announced as a US 2001 model year change as opposed
to a running change. Although, it could be earlier given that it might have come
about before the actual announcement.

I had thought the nikasil to liner change was pre 2000 US model year which would
have started September 1999 according to US convention. Could be wrong, since
I don't have one.

 

The Nikasil changeover started from engines build from September 2000 which was also the start of the 2001MY. I am not aware of a different start date for a 2001MY, so thanks for the info that adds to what the mechanic told me.

With regards to the water pump, there have been 4 bad versions all labelled 96JV-8501-CA, CB, CC or CD used until 98 need to be replaced.

Here some more info from a TSB:

For information, listed below are the details of coolant pump changes and the introduction VIN.

• A black Nylon 66 impeller was fitted from VIN 001036 to 028000 (XK series) and 812256 to 843500 (V8 XJ series).
• A black PPS (Poly Phenlyene Sulphide) impeller was fitted from VIN 028001 to 040100 (XK series) and 843501 to 873499 (V8 XJ series).
• A white PPS impeller was fitted from 040101 onwards (XK series) and 873500 onwards (V8 XJ series).

The white PPS version is the good one.

Jaguar had raised a TSB (303-11) with regards to the green/yellow coolants used until the 99MY, as there could be bad heater performance due to clogged heater core (maybe due to the silicon content?). They advised to flush and go to the dexcool with that one, so before switching away from the dexcool variants, I would think twice (as my 2 cents).

 

Plums:
My MY 99 XJR was running Dexcool when the failure occurred, so that is consistent with your hypothesis, but I think you will agree it does not appear that the water path was involved in the burn, although it certainly leaked water into the cylinder after the failure.

I began using Dexcool on my X-300 and X-308s (three of them) after I had two cases of the heater matrix plugging with a white material I believed was some aluminum precipitant, but after reading Avos' post, I think it might very well have been silicon.

Added - Notice what looks like a mark that would follow the arc of the cylinder wall. That would sure seem to me to indicate the initial crush of the gasket during assembly is when this problem started.

 

As others have indicated the metal makeup of the cooling system determines ... or should determine the coolant and the additive pack.

I don't think the Fords got the same heads .. I think Land Rover did. While we hear about the head gaskets ... wonder what the actual percentage is?

Most of the ones talked about are early cars with unknown history ... I always advise people buying to stay away from the early cars due to the cooling system issues and the engine being very susceptible to problems if run hot. I personally don't know of anyone with the issue ... although my X300 S6 had one replaced under warranty.

The introduction of the long life fluids has been a great success IMO ... Years ago when fluids were changed often .. all manner of problems occurred from poor service work.

 

Yes, in your case, it could have been a bad initial install. I didn't stop reading the links
after posting a few. In further links, there was mention for example of aftermarket
cylinder heads or over bored cylinders used with standard bore head gaskets. In those
cases, the gasket could let go almost at installation time. In one case, the installer
changed a complete set of lifters on a 16V Saab before discovering that the fire ring
interfered just enough with the piston to sound like all lifters were defective.

Where silicates are involved, it is easy to extrapolate to crystals being formed from
precipated silicates. But, I have them, and after many searches over the months, have
finally found a name mentioned. It is aluminum "something or other" pictured in a
research paper published by scientists at Los Alamos Nuclear Laboratory. The paper
was studying the effects on aluminum post "coolant loss events" in reactors.

On the other hand, silicates are known to form a white gel in the presence of
heat when the coolant is used at high percentages. 70/30 which is maximum
limit recommended by coolant manufacturers is pretty much the threshold where
this behaviour is guaranteed. That may be why their main recommendations
center around 50/50 to 60/40.

Around here, 50/50 will almost guarantee at least one "slushy coolant" event in
any given winter. 60/40 is what I have generally run in all vehicles. The current
Zerex G-05 has been in for 4 years and there is plenty of heat.

 

None of the generally accepted categories automotive grade coolants is contraindicated
for aluminum alone with the caveat that the conventional green be low silicate. That
is defined as < 250 ppm. In fact the silicate is required as a aluminum corrosion inhibitor
in the absence of a suitable substitute.

Aside from perhaps the most recent years which I would not know about, the BASF
Glysantin G5 formula has been the recommended fill for all Mercedes engines including
all aluminum engines. The US equivalent is Zerex G-05. In fact Ashland(Zerex) supplies
the Mercedes, Chrysler and Ford labelled coolants in the North American market.

The sole impetus behind Dexcool when initiated by GM was extended life. The cost
is that it requires meticulous preparation and maintenance. Wrong materials in
the engine? Guaranteed failure. Air entrainment? Guaranteed failure.

Since I do all my own work, avoiding sloppy work through having a "no touch"
policy is not a concern of mine.

The Ford engines received the same head or almost the same head.

The head bolts, head gasket, secondary tensioners, are all known to be the same.
Plenty of Jaguars have been repaired using part numbers that cross to both makes.

Even the valve covers and related gaskets are the same.

The difference is they seem to experience a much lower incidence of head gasket
failure. In their words, "almost unheard of".

If it isn't the coolant, then there are other less flattering possibilities such as Ford owners
being more diligent or the Lima, Ohio plant turning out a better product.

Come to think of it, they don't moan about clogged heater matrixes either.

The matrixes could be a X300/X308 design problem since S-Type owners don't seem
to experience the same problem at any exceptional level and their vehicles have
many more systems in common with the Lincoln LS.

 

The heater issues would probaby be indeed a combination of heater core and coolant.

It’s very uncommon for the mls head gasket fitted engines to have a failure as noted (which use the dexcool), though the early AJ27 (so pre 2001) and AJ26 with the composite gaskets are much more common. Just like sparkenzaps one, the picture shows a composite version.
The Lincoln ls version also uses the mls type gaskets.

I don’t know the content of the coolants (so green and yellow ones) used on the pre 2000 cars, but here you may find a lead if there could be an issue with the composite gaskets and different coolants.

 

While it was all Ford ownership at the time -- the Lincoln motor was technically a licensed motor .. I don't think it ever had the VVT .. and the heads were made in the USA -- I don't believe you can bolt any of this stuff on a Jaguar motor. I believed the whole motor for those cars were USA manufactured. I believe this is the case with he chains -- the LS are labeled as USA and the Jaguars are GB.

I have never used anything other then the Jaguar coolant .. never an issue ... We never had any issues with Dexcool -- in our fleet cars.

While MB always published a minimum specification -- like almost all makes they use this as a base line. G-05 being the baseline .. MB coolant was always manufactured with additional additives.

Can't just make blanket statements about some of this .. because its not always off the shelf like some believe.

My only business directly related to the automotive business currently is in specially headliner material ... I used to live and work in Munich and had a good fiend that worked for MB worldwide fluids.

I don't have the part number for the matrix - but I would be surprised if they changed much of the Denso system from the x300 under the dash. The coolant is an issue with the valves and pump.

 

The X-300 and X-308 matrix units are identical.

 

Just by coincidence I may have found another reason why you don’t see many head gasket failures with the Lincoln ls engines.

Am in the progress of installing cht sensors on my heads, and while I was looking for generic temperature figures, I came across sites that mentioned that Ford is using a CHT sensor on these blocks (other engines as well). The CHT sensor is located on the RH side between cylinder 3 and 4 on the early 3.9 blocks from 2000-2002. This is then also a difference in heads between the Jaguar and Ford version.

But the importance is in the fact that the Ford ECU has a failsafe mechanism when it detects a higher cylinder temperature then allowed (contrary to Jaguars). Not sure in detail how it works, but it seems that at 1st will avoid spraying fuel on some cycles (to aid cooling via the fresh air) and at a certain point will block fuelling for all cycles to avoid further serious damage.

As far as I know, overheating has been one of the main causes for the rare cases where engines equipped with the MLS gaskets would also fail (so I am not speaking for the pre 2001MY failures).

 

It does about the same (overheat seen by CHT so cuts fuel) on the 3.0 petrol S-Type,

I suspect they ran out of CPU power/memory and/or pins for the 4.2 S-Type PCM so removed the feature.