Coolant - Engine block drain plug

[MikeB]

Hi,

Plan to change the coolant soon on my 1994 4.0 Coupe. I understand that there is a radiator drain tap so will look for that!

Can anyone tell me where I will find the drain plug for the engine block please?

Thanks,


Mike.

[ptjs1]

Mike,

You haven't mentioned if you've got an AJ6 or AJ16-engined car.

On an AJ16 engine, the block drain plug is on the right-hand side, just aft of the twin down pipes and just below the manifold to down-pipe studs. It's a standard hex head. Torque setting is 68-75 Nm.

Drop a post back if you've got an AJ6 engine. It might be the same. If no-one else posts and gives the answer, I'll look it up for you.

Paul

[ptjs1]

Mike,

I think it's the same on all 4.0 litre cars.

Good luck,

Paul

[ballme1]

Not sure if anyone can help regarding the previous threads but I have located the Drain plug but it has 2 pipes going straight across the plug with a saddle clamp held with a phillips screw to the centre of the plug.
Any idea how this saddle clamp can be removed as access is virtually impossible to undo the screw ?

[MichaelSB]

If there is a drain tap on the radiator can anyone tell me where to find it please? I have a 1995 AJ16 XJS
Michael

[ptjs1]

Michael,

Our cars have engine block taps but not radiator taps.

If you're draining the coolant, remove the lower hose attachment at the bottom left hand corner of the rad. You might also need to syphon any residual coolant from the header tank.

Cheers

Paul

[MichaelSB]

Hi Paul
Thanks for that, I thought it maybe a bottom hose job, unfortunately the bottom hose when the car is on my ramp is directly above the ramp treads so I can’t easily collect the old coolant, it’s going to be a messy job.
I am draining it so that I can replace the heater control valve which is playing up, I will explore the possibility of undoing the valve and just drain what comes from there
Michael

[ptjs1]

Michael,

I changed my valve a few years ago but did it whilst I had the coolant drained. However, the valve is so high up at the back of the engine, that I suspect that just syphoning the header tank should mean that you could remove and change the heater valve without losing much coolant.

I would also change the short rubber pipes on the valve as they are prone to swelling up and deteriorating over the years I found.

Good luck

Paul

[PaulGover]

I've one of those electric drill mini pumps attached to a length of PVC hose that fits neatly into the hole where the RH banjo bolt goes through the top of the radiator. That lets me suck the water out down to the level of the bottom of the radiator.

That leaves a fair bit, so if you want to refill with clean water to flush out all the old stuff, I'd recommend four goes, running the engine between each to stir the water around.

[stephenstoelinga14122]

The basic steps to flush a car engine block are:

1. Remove the lower radiator hose and catch the draining coolant in a bucket.
2. Remove the top radiator hose and flush the system out with a normal hose.
3. Continue until the water runs clear out of the bottom of the engine.
4. Refill with coolant and reattach the radiator hoses.

[ng4xjs]

I have to admit to being a bit lax on the coolant changing side, My car has now done about 90K and despite the warning sticker, "do not drain" on the header tank think it's about due (been more years than I can remember although coolant still a reasonably good yellow). My main consideration is do I bite the bullet and put a new radiator hose on at the same time. The AJ16 item is a bit exaggerated more like an octopus with all it's various connections. I would add that the original still looks and feels good. Straw poll. How long have you left between coolant changes?

Nick

[ng4xjs]

I've bitten the bullet and decided to change the coolant. Ordered a new (octopus) bottom hose but admit to going for the aftermarket one at some £200.00 less money. My rationale being that the one on the car is some 24 years old ad it may be problematic in/if how it comes apart cleanly, if it does okay then it's a useful spare. I've always topped up with JLM204042 Jaguar Antifreeze (yellow). I'm guessing that I need a good quality phosphate free variant to do the job but please let me know what you use.

Am I the worst and not having completed a change within living memory. In my defence the coolant in the header tank remains yellow and seemingly free of debris. Temp runs at just below mid-way never falters.

I would also comment (off tangent) that I happened to notice the cost of a new header tank at some £300.00 plus. I remember some 20 years ago having to undertake a temporary (solder) repair to a tank which worked well and which I still have in my shed but the new replacement from Jaguar was circa £40.00. Should have bought more at the time so still working after normal retirement age although maybe decision jaundiced by the working from home option.

Happy days
Nick

[ptjs1]

Nick,

A couple of thoughts:

I'm slightly confused by your "yellow" coolant. Although there are lots of confusing colours of coolant around nowadays, yellow coolant was traditionally Ford's Hybrid Organic Additive Technology (HOAT) coolant. I thought that came out around 2000? Are you sure your coolant isn't a weak green colour? My understanding is that AJ16 XJSs originally had Inorganic Additive Technology (IAT) coolant, typically ethylene glycol and blue or green in colour. And HOAT is not generally recommended for older engines as it can damage some seals and older-type hoses.

The difficulty is you have HOAT currently in the system is that you really need a very good flush to clear it out of everything. If I were you I would drain the system and then run with just filtered water, drain, run again with filtered water, etc etc. I'm not near my car, but I think there's a plug on the top right of the rad. With the header tank open as well, You can then insert a thin tube to the bottom of the rad and siphon out a lot of the coolant. (Hopefully I'm not thinking of another of my cars!!)

Only when you've run a few changes, would I then remove any of the hoses and then do your hosepipe flushing of rad. Great idea to save your old lower hose. They are long-lived and I'm not sure of the quality of the after-market items. If it's stuck on the rad or water-pump, carefully try and twist it or insert a thin but very rigid piece of plastic between the hose and stub and run it around to free it.

On the "whilst you're in there" approach, with all the hoses off, I would probably replace the thermostat with a good quality one. The Jaguar one isn't that expensive.

I use a Bluecol ethylene glycol IAT that is blue, in my AJ16 and change it every 24 months.

Now, here's the bit you don't want to hear! The weakest part of an AJ16 coolant system is the radiator which deteriorates over time. Debris gets blown through the rad destroying the vanes and significantly reducing the cooling capacity, particularly at idle. And because there are rubber flaps on the rad outside the fan shroud, you can't easily see the deterioration. So, lift the rubber flaps on the right-hand side or look through the fan shroud on the left-hand lower side, and check the state of the rad. This would be a great time to change it, if less than perfect. See my pic when I changed my rad.

Cheers Nick

Paul

[ng4xjs]

Hi Paul - I'm even more confused than I thought I was. This is what I have been using in all three XJSs I 've had over the last 24 years or so and my current for something like 14. I had my first experience using this variant back in 1997 and have continued. I'm going to regret saying this I know but in all that time I've not had a hose or water pump fail (sods law). Whilst my current AJ16 has yet to pass 100K my previous 1992 Facelift had almost 200K before being acquired by and exported to France.

As I think I mentioned earlier, the "header tank" clearly states "Do Not Drain", whilst the "Service manual says that it is a maintenance item. That said very interested by your comments and observations and will investigate further.

Many thanks
Nick

[ptjs1]

Hi Nick,

Yes, that's confused me. However, I think I might have the answer!


Late XJSs originally used D985 coolant which was blue / green.

Jaguar then moved to D542 coolant in 1997 which is yellow and the one in your photo.

Jaguar then moved to long life coolant in 2000, which is red.

That seems to indicate that at some point, your coolant MUST have been changed from the original blue /green Jaguar D985 to the yellow Jaguar D542 fluid.

D985 is definitely an IAT coolant.
Jaguar "converted" early XK8 cars to D542 as per a Service Bulletin. Part of that bulletin states:

HISTORIC BACKGROUND:
D985 coolant was used in production on the following vehicles:
(i) XJS vehicles until 1996 Model Year
(ii) XJ6 and XJ12 Sedan models prior to VIN 803241 (February 1997)
(iii) XK8 models up to VIN 010341
Note: The majority of XK8 vehicles in the VIN range 001036 - 010341 will have been converted
to D542 coolant under Service Action S813. These converted vehicles should be recognized
by yellow coolant and a corresponding label affixed to the cooling system header tank. Full
details are in Bulletin 303-09 dated 6/97, and Service Action S813.

D985 coolant is blue/green in color. Jaguar part numbers JLM 11979/1 - JLM 11979/5 apply.

D542 coolant was used in production on the following vehicles:
(i) XJ6, XJ12 from VIN 803242 (1997 Model Year) to VIN 812255
(ii) XK8 from VIN 010342 (1997 Model Year) to July 1999
(iii) V8 XJ Series Saloons from VIN 812256 to July 1999

D542 coolant is yellow in color. Jaguar part numbers JLM 20404/1 - JLM 20404/5 apply.

EXTENDED LIFE COOLANT applies to the following vehicles:
(i) S-TYPE from 1999.25 Model Year Introductory VIN: L00600 (and from L25201 2000 MY)
(ii) XK8 from August 1999 Introductory VIN: 042635 (and from A00083 2000 MY)
(iii) V8 XJ Series from August 1999 Introductory VIN: 878274 (and from F00103 2000 MY)

Extended Life Coolant is orange in color.



So, I'm GUESSING that D542 is also an IAT, but it just MIGHT be an OAT! On an US website, I found this analysis by someone:


Here's the disclosed chemistry of Jaguar D542 / DOW 542:

Ethane-1, 2-diol (another name for Ethylene glycol) (CAS 107-21-1) 90% - 100%
Sodium hydroxide (CAS 1310-73-2) 0.5% - <1.0%
Disodium tetraborate pentahydrate (CAS 11130-12-4) 0.3% - <1.0%

Sodium hydroxide (NaOH) is commonly known as Lye, widely used in soaps, drain cleaners, anti-freeze and many other products.
Disodium tetraborate pentahydrate (BH13NaO8) is commonly known as Boric Acid or Borax pentahydrate, widely used in detergents, paints, anti-freeze, and many other products.

Note that neither of the above contains carbon, so they are considered inorganic compounds.

We can not tell definitively if D542 is an IAT, OAT or HOAT coolant because we do not know if all of its ingredients are disclosed on the MSDS.



Interestingly D542 was originally used in the 1997 X300 cars including the ones fitted with AJ16 engines. So that might imply that it should be safe in an AJ16 XJS, as I don't believe there were any material changes in AJ16 engine gasket composition or water hose composition in 1997.

So, as I said, I THINK D542 is an IAT!

Whether you refill with the yellow Jaguar liquid, or a more readily available Blue/Green Ethylene glycol IAT, I would still flush the system through a number of times with a warm engine, not least just to remove as much sediment from the engine and rad before refill.

Hope that helps a bit and doesn't make it more confusing.

Cheers

Paul