I wanted to see what the core looked like inside, I took a saw's all and cut it open.

Look what I found! Looks like sand.

I can now drive around in my T-shirt, however, it's not that hot, but still a lot better then before.

 

Thanks for cutting away and showing what many have susspected as one of the major causes of loss of heat.

To try to help understand what may be causing this:

Is the plugged side of the heater core what we would consider to be on the drivers side? This can explain the climate control flap open on the drivers side but little heat coming out of the far drive side face vent?

Do you know if someone ever put green antifreeze into your car, some suspect this causes such sludge? Not sure if Orange antifreeze since new will also develop this sludge issue?

You mention sand, some have suspected sand from the engine casting but a Jaguar Mechanic once said no way? Does the sludge have grit in it like sand?

My car is a 2008 VDP and am thinking about doing a full flush now that may aid in preventing this issue if this problem simply happens in all XJ8's. This tells me that the origional Jaguar antifreeze is not optimal, another brand using orange antifreeze may be a better choice for a full flush.

My 1988 Jaguar XJ6 over the last 18 years never came close to developing this type of issue.

Thanks for the pictures,
LCMJAGUAR
2008 XJ8
1988 XJ6

 

If we knew what it was, a chemical flush might be possible. Limescale can be dissolved by (I think) citric acid.

 

Is that some jelly like substance on the right end of pictures two and three?

 

To answer some questions,

It does feel like it has grit in it, how ever, it's a little bit jelly like. My Tech said maybe bar leak was added. I have all the dealer service records and there is nothing about coolant leak.

Yes, the clogged side is the drives side, (left side) What I don't understand is even my right-side was weak getting hot.

I don't think at any point green coolant was added, But i can't be sure.

Chemical flush might be possible. It might take a long time.

Cheers,
Kevin

 

Per my 2008 XJ8 Jaguar Owners Manual: Use anti-freeze to specification WSS M97B44, coloured orange, Extended Life Coolant. This 50/50% mixture gives frost protection for temperatures down to –40°C (–40°F).

Jaguar specs WSS-M97B44-D which is based on organic acid technology (OAT). It's DexCool. WSS-M97B44-D is also a Ford part number. If you want to stay original to the Jaguar coolant, then check the bottle label of any orange coolant and if the referenced coolant specification (WSS-M97B44-D) is not on the bottle don't use it.

Per Jaguar, only Jaguar antifreeze Havoline XLC Extended Life Coolant (specification: WSS M 97B44-D) should be used on V8 XJ series vehicles that use the orange coolant. Antifreeze to this specification has been used in all 2000+ Model Year V8 XJ Series vehicles and may be recognized by its orange color.

To find Havoline XLC coolant search for “Chevron Texaco Anti-Freeze Coolant”, it is sold for instance at Sears online, Amazon, but usually in pack of 6 unfortunately. However some forum discussions have mentioned that the Havoline US version is a little different then the European Havoline version making the US version a DexCool type. Confusing indeed but no facts if it is different so far. One would need to match the ingrediates label of both.

Now searching other forums of non Jaguar cars, there is much evidance that the Orange DexCool Coolant has caused issues in clogging the heater cores. The "recommended" service intervals of DexCool coolant is 5 years 100K miles and in some cases 150K miles. These extended service intervals have not proven to be any thing but trouble for the consumer. In some cars, the coolant tends to turn to a thick, gooey, sticky, muddy, gritty, orange corrosive gel that fouls the radiator, heater, plugs coolant passages in the intake manifold and heads, and many times starves the water pump, resulting in overheating, and leaking. Mounting evidence suggests that DexCool reacts with plastic sealing surfaces, allowing leakage at the intake manifold gaskets. The best thing to do is to probably change your coolant every two years with the recommended coolant to refesh all of the additives that tend to deteriorate over time and become acidic thus causing the issues.

LCMJAGUAR
2008 XJ8 VDP
1988 XJ6

 

Looking at this material, it appears to me that the coolant has jelled out due to a foreign additive of some sort. Cooling system neglect could be a cause. Dexcool is not good with any additives, it will jell in a heartbeat. Never put anything else in there. I maintain both my Jags cooling systems by simply draining the radiators and refilling with fresh Prestone Dexcool every few years. I don't wait 5 years. Old longlife coolant will develop hard particles in it that feel like sand. They are not, they are minerals. There is no casting sand left in Jag engines.

 

Wow, Reading this does make sense. The dealer serived this car since new.
I would think that they used Jag Coolant.

I did and still do use Dex-cool coolant in the Jag. After reading this, I may flush the system and refill with Jag coolant!

Thanks,

Kevin

 

thats normal sludge buildup without any additives or anything else added. It is primarily why many time we recommend a cooling system flush, but many owners dont think its important or a gimic. Problemis, when you let it go too long the flush chemicals wont penatrate a sludge buildup because it has to FLOW to remove the sedimant before it really buildsup

 

Wow, Who would have guessed the inside of a heater core could get so jello clogged. Mines coming out shortly in prep for the winter. No flushing, just a straight swap for a new one.

 

While you are at it, might I suggest you verify that the auxiliary coolant pump is working properly? My sense is that the pump failure goes largely unnoticed and contributes to sediment (or whatever) building up in the core.

 

I will look into that as well. Thanks for reminding me.