Tefba filters finale, a unexpected result

It’s interesting that casting sand/silica in the cooling system is not just a classic vehicle problem. There are many reports on the web of this being also a recent problem and in particular Chrysler is alleged to be facing a class action re it’s Jeep Wranglers (2012-2017) problems with casting sand compromising the cooling system.
I spoke to a local radiator specialist and he claimed that the problem with retained casting sand was a bigger problem in Australia from the mid 90’s and before. He also confirmed that the granules from my XJS were indeed casting sand/silica.
Added to this I found a couple of web articles that say the clay also used in the casting process has also been clogging up the cooling system in some cars. The pictures I have seen resemble the brown sludge seen in our filters.
In short I think we know what we are dealing with but it’s how to handle it the problem.

Current findings.

Pre track work preparation. (last Friday night)

I was taking the XJS to the race track for some sprint work last Saturday so I cleaned her coolant filters on Friday night. Below is what I collected (Pic 1) which is since December 21018 until July 2019. (about 7 months). The previous collection have been posted earlier.
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Pic 1. Seven months of collection in both filters (about 3K klm)

After the track work.
I noted a temp rise (not great …) on the A side but not the B side post-race so I suspected that the vigorous work out she got at the track had dislodged some material and the A filter was compromised (Pic 2, 3) . The comparison of the filter cleaned (Pic 4).
The collection from A and B from just the Saturday (Pic 5).
The filter plungers from just the Saturday, A (Pic 6.a) and B (Pic 6.b).
The filters and plungers from the Saturday (Pic 7). An interesting observation is that one side of filter B is all but clear.
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Pic 2 ……………………………………. Pic 3
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Pic 4 Clean filter …………………. Pic 5 Collection from A and B sides
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Pic 6.a Plunger A (Saturday only) ……Pic 6.b Plunger B (Saturday only)

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Fig 7. XJS filters and plungers after 1 day track work.

As we a discussing the function of filters I’m including a picture of the Tefba filter from my XJ6 last week that hadn’t been cleaned for about 18 months. This car however does little work and not energetically (Pic 8). But it does show the casting sand/silica. I suspect that many these cars will have this problem.

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Pic 8. Xj6 Tefba filter after 18 months.

Conclusion.

My XJS engine components were presumably flushed post casting. Also the PO had the radiator redone and the cooling system flushed about 15 years ago… added to which I had it flushed less than two years ago and still the sand and muck keep coming.

It appears my XJS has/had a reasonably high residue of casting sand/silica and possibly clay in its engine. I could do another flush but this has, by precedent, not been completely successful. As she is not suffering any cooling problems while the filters are serviced regularly I don’t feel there is an immediate problem. I suspect that eventually there will be less and less for the filters to do.

Trev

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Good to know Trev.

Although… I knew already…
The first time, in my hands at least, that my XJ went up to 150 km/h it, soon after, started overheating… both coolant filters filled with debris…
These filters can be a double edge sword… you must keep an eye on them.

Aristides

Hmmmm, installed mine three weeks ago, have only done about 80 miles city driving. I check weekly and have only pulled out three tiny bits. How does more spirited driving push more junk? Is it simply high rpm = water pump pushing harder?

…yes.

Is it high rpm and water flow or hard cornering that dislodges this debris?

The local radiator man says that bursts of a higher speed water flow while the engine is hot is the dislodgement process. However he may just be fitting into the story and It was a coincidence.Then again maybe he is right.
Lets jus say that the in-cabin digital temp read outs from both thermostats in conjunction with the filters sits nicely with my driving.

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Wow, that’s quite a pile of crud. Still not entirely convinced it’s casting sand for two reasons: 1) I’d expect casting sand to be tinier and more uniform; and 2) I’ve seen minerals from hard water form deposits that look remarkably similar. The distinction is perhaps academic, as either one would plug up a radiator core big time. The only significant difference is that once casting sand is gone it’s gone, whereas you could keep producing hard water deposits as long as you keep using hard water to fill the cooling circuit.

As I believe I’ve mentioned before: I decided to install my Tefbas backwards, and to fold the screen into a crisp V shape instead of that gentle curve. With the gentle curve and the flow into the concave side, it’s possible to blow the screen up against the outlet port in the Tefba housing. This effectively reduces the filter area by 90%, the flow is now entirely through the area of the screen over the port itself. Once that’s plugged up, there’s no flow. With the flow reversed, the flow would be against the point of that creased V and you could nearly fill the chamber outside it with junk before it’d start to impact flow. Of course, that magnet would end up on the wrong side of the screen, but I didn’t have one of those.

Your screen looks remarkably coarse. IIRC, mine was much finer than that.

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If this is true, then I think it proves ONLY MIX DISTILLED WATER with your coolant. You could have had PO who did not do this.

Everyone here should ponder what would have happened had you not had the filters, or had removed them after a while because you weren’t getting much more crud in them. You’d at least be in for a radiator R&R. You might even be in for valve seat repair. And the dual temp readouts really made it clear what was going on and in a timely manner.

The latest Tefba filters come with a coarse and fine mesh, and are shaped like a V. It says to use the coarse mesh for a while until it doesn’t plug anymore, and then switch to the fine.

It’s certainly a lot coarser than the sand I remember when I did my 3 months in a foundry. What we used was only a bit coarser than playsand.

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Two things Kirbert, firstly the modern SS filters on the Tefbas are rigid…not flow distortion. Secondly, the radiator man warned me that mixing different coolants “WILL” produce solid products in the form of that clay like substance. Sort of making our own problem. As for the granules, what ever they are they will compromise a radiator in short time.

We need a chemist to take a look

Yeah, like five minutes.

That’s nuts. So you’re supposed to let the fine stuff through for a while to plug up your rad?

There’s not really any good place for such crud to hide in a V12 block casting. If this stuff is casting sand, it’s most likely been hiding inside the heads – and since the banks have separate coolant filters, we know which head.

I think it gives us more to ponder, though. If crud of this sort is hiding in the coolant passages inside a head, what implications might that have for dropped valve seats? Is it possible that the occasional dropped valve seat might have a more direct cause than the standard explanation of obstructed coolant flow? Could it be that a collection of this crud could be parked directly on top of a valve seat and preventing coolant from cooling it properly? Is there a way to get a borescope camera in there to inspect the cooling jacket? If one has the heads off, is there some way to have them flushed to ensure all this crud is removed? Is there anything a mere mortal can do about it without pulling the heads and sending them somewhere to be flushed?

When I removed all my cylinder liners I was amazed how much “crud” had accumulated at the rear of the engine block behind and beside the rear liners. This area probably suffers from low flow because of the shortcut available to the coolant to stay in the front of the engine. This stuff would keep coming out after heating and cooling and increased flow…so possibly a repository for the ongoing “crud” in the filters. It was hard as hell and had to be removed with a sharp object and a persuasion stick. I wonder if it could be chemically persuaded to leave the premises…???

Interesting you say this Matt… my radiator guy said even professional flushes won’t get everything back there.

hmmm, I just switched thermostats from 190F to 180F on my V12. Now my car runs around 180-190 instead of 190-200 like it did before. I wonder if the hotter temperatures are better for helping get the crud out of there…

I recently completed an engine swap in my 1984 XJ6 Vanden Plas. I was very familiar with the crud deposits in the water jacket due to casting sand, Bar’s Stop Leak, tap water, and other stuff.


Here are before and after pictures of the debris around the head studs with the core plugs removed in the replacement Jaguar 4.2L I6 XK engine . I have removed and replaced the core plugs in this type of engine a few times and this is how things usually look.

Paul