Coolant Filters

The Jaguar crew is experimenting with radiator filters (pics below). Food for thought and discussion...


http://www.jag-lovers.org/xj-s/book/CoolantFilters.html


Having suffered the effects of a blocked radiator (overheating, dropped valve seat), Kirby Palm was understandably interested in avoiding a repeat. While his engine was apart, he posted a message to the [email protected] discussion list suggesting that it might be a good idea to put some temporary filter screens in the upper radiator hoses somehow to stop any leftover crud from the rebuild from getting into his freshly-rodded radiator and plugging it up again. Lo and behold, Brian Schultetus pointed out that such filters exist. One source is:
Gano Filter Company
1205 Sandalwood Lane
Los Altos, California 94024
+1 (650) 968-7017
So, Palm purchased a pair (the Jaguar XJ-S V12 has two upper radiator hoses) of filters with clear plastic housings from Gano and installed them. Meanwhile, a discussion ensued on the list about whether the filters should be removed shortly after the rebuild and most of the debris has been removed, or whether they should be left in the system permanently. Gano apparently intends for its filters to be left in place permanently, and if they are not plugged up it's not immediately apparent what benefit would result from removing them.
Gano also offers a smaller filter assembly for a heater hose. This is a good idea, since such a filter could get totally plugged up and the only result would be a loss of heat, but it might be very effective at removing suspended particles from the entire system. It might even serve many owner's interests to have only a heater hose filter, which would not positively prevent radiator clogging but would reduce the number of suspended solids in the entire cooling system and therefore hopefully postpone the need for a radiator rodding or replacement by a few years.

Unfortunately, Gano's heater hose filters are brass rather than clear so you cannot readily see when they are full of crud. Hence, rather than buying the Gano item, Palm opted to save money and simply purchased a set of solid brass 5/8" garden hose fittings and a screened hose washer at the local hardware store. The screened washers are commonly used in the hoses that connect to a washing machine, and the careful shopper will note that they can actually be purchased in a variety of screen grids. What's more, the XJ-S owner is thereby provided one more option: he can use a screened washer in the summer when a loss of heat would be no big deal, and then he could install a normal garden hose washer in the winter to allow full coolant flow to the heater.

Palm also revised his radiator drain scheme, since he would need to use it regularly to keep these screens clean. The '83 XJ-S comes with an overdesigned drain valve that dumps coolant all over the front suspension when opened. He replaced this with a simple fitting (not easy to find, since it is BSPP thread -- see the book), connected a short length of hose and plugged the end of the hose. When draining coolant, he just unwraps this length of hose out the bottom of the car, pinches it with a pair of Vice Grips, removes the plug, puts the hose into a suitable container, and releases the Vice Grips.

After the head rebuild, the car was driven once and the Gano filters were clearly already in need of cleaning, as expected. The heater hose filter was found to be 100% plugged as well. All three were cleaned and reinstalled, and a report was made to the list -- whereupon someone asked the obvious question: What did the crud that came out look like? Too late, the crud had been hosed out into the yard somewhere.

A few hundred miles later, and the Gano filters were cleaned a second time. This time the crud was collected and photographed.



Despite many more hours of operation, the filters were nowhere near as fouled as they had been after the first few minutes after rebuild. Hence, as long as no new crud is being introduced into the system (being refilled with coolant and distilled water only, etc.), perhaps it would be acceptable to remove the filters after a while.

The larger chunks were all in the left side filter; the right side filter contained only small particles. This is in contrast to the first cleanout after rebuild, when both filters were pretty well choked up.

The large solid black chunks appear to be a dried, crumbling seal -- possibly the old "top hat" seal (C37990) on the water
rail connecting pipe. This would make sense, since Palm had rebuilt the right bank some time ago with new seals, but this was the first time the left bank had come apart -- and these seals were correspondingly dry and crumbly on the left side only. Sure, every attempt was made to get all the chunks out while apart, but when you're actually doing this kind of rebuild it becomes all too apparent that leaving pieces inside is likely gonna happen.

The large brown chunks appear to be pieces of wood. No idea how those got in there.

The smaller particles appear to be large grains of sand or tiny pebbles. The only apparent source would seem to be leftover stuff from the original sand casting of the engine block. This engine has over 90,000 miles on it, so one might question that such grains would still be in there from casting; however, when the heads are off, you can see some excellent little pockets in the block around the liners that hold heavy stuff like this indefinitely. During this rebuild, Palm endeavored to clean these pockets out, and it's understandable that a few grains were left behind but loosened enough to start circulating around.

There was one other thing of note that doesn't appear in this photo. The filters also seemed to have collected some "goo" that was circulating around in the system. Best guess: excess Hylomar that squeezed out of joints as the bolts were tightened down. It's not clear if this stuff does any harm in the cooling system -- it washes off the filters fairly easily -- but it certainly doesn't do any good. It might be expected to coat surfaces inside the radiator and impede heat transfer, and it might even crud up tubes and impede coolant flow. Mechanics might want to note that being generous with this gasket sealant may not be a good idea.

It should be noted that neither of the Gano filters were significantly plugged this time. Despite the collection of large chunks in the left side filter, the car was running cool. This is because large chunks don't plug the screens very effectively. The screens are more likely to be seriously obstructed by smaller particles, just the right size to get stuck in each opening in the screen.

The heater hose filter was only about 50% plugged this time.



While it caught a couple of large pieces as well, this screen had a collection of "mud" in it; the small grit shown is merely what is left after the mud dries up and the remains are scraped together for the picture. The screen in the heater hose is considerably finer than the screens in the Gano filters; this mud would have gone right through the Gano filters.

After reassembly, Palm drove the car only a couple of times and large chunks were visible in the left side Gano filter again. So, that filter was cleaned out once again. This time, not only wasn't the heater hose filter opened up, but the right side Gano filter was not disturbed.



This time, the Gano filter itself was disassembled for the picture. The second screen at the right, with the big gaping hole in it, is intended to allow junk to get into the filter assembly but to prevent it from falling back into the thermostat housing at shutdown.

The two large chunks appear to be more of the old top hat seal. Hopefully, there can't be much more of that stuff in there!

Some of those smaller particles actually look like thin flakes. Perhaps some of the scale from years of refilling with bad water is coming loose.

Again, the car was keeping its cool just fine; these particles did not impede coolant flow through the filter significantly.

One bit of bad news to report: The clear plastic housings on the Gano filters are showing signs of stress fracture. This might be due to overtightening of the hose clamps, or it might be due to dynamic stresses caused by the engine moving around on its rubber mounts and pulling on the radiator hoses. Note that these filters are supposed to be installed with the hose clamps only moderately tightened and a length of steel wire wrapped from clamp to clamp to prevent the hoses blowing off. Tightening the hose clamps hard enough to prevent the hoses blowing off without the wire would evidently be a mistake.


Regardless of the cause, it provides one good reason not to leave these filters in place permanently. Tentative plan is to buy a pair of 1" copper piping couplings (1-1/4" OD) and reconnect the radiator hoses with these tubes and the screen assemblies from the Gano filters. Won't be able to see the crud collecting in the screens, but once the system is largely clean and the rate of collection falls off this shouldn't be a big deal -- just check the screens whenever the coolant is changed. Gano sells replacement plastic tubes, which might be a good idea if the engine is rebuilt again -- or perhaps find some Pyrex glass tubes. Or maybe just continue to use the copper and check regularly. Of course, Gano also offers solid brass housings.
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John Ashcroft says there's a coolant filter made by Tefba in Australia and available in the US from
Mussell Distributing Co.
3340 Chimney Rock
Houston, Texas 77056
+1 713 974-9022
Ashcroft provides an illustration of this filter:


"They are available in 1-1/4", 1 1/2", 1-3/4" and 2"."

Al Askevold purchased a pair of Tefba filters for his '90 convertible, and provided the following photos of the installation. "On the right side I used a hose from NAPA, PN 8303, from the t-stat housing to the filter, and a short piece of 1-1/4" hose on the other end."



Obviously these pix show a temporary fit-up; the hoses should have clamps at each end.

Askevold also has provided a cold air intake scheme on his car, so this particular arrangement of hoses was carefully selected to clear his cold air intake ductwork. Here's what it looks like with the cold air intake hose installed:



This arrangement obviously allows cleaning the Tefba filter with a minimum of fuss, since it is right there on top. In fact, it probably won't even be necessary to drain any coolant first.

Askevold tried to use the OEM hose on the left side. "The OEM hose that I cut to fit for the B bank is not the way to go! I cut 1-1/2" off the short side of the hose and 2" off the long side and installed that from t-stat to filter. After clamping everything together both inside corners on the OEM hose were bent just enough to cause a restriction, not much but not a good thing for the B bank. So back to Napa, this time I came up with a Napa hose pn 7737."



After installation, Askevold ran his car for one hour and then checked the screens.



Remarkably clean, actually; in general, owners would be well-advised to check the screens far sooner than that the first time after installation -- like after five minutes of running after the engine warms up.


Palm has the Gano filters in his car but has fondled a pair of the Tefbas. It is his opinion that the Tefbas are the better choice, despite being opaque so they must be opened to check. The screen area is much, much larger since there was no attempt to fit the screen within the cross-sectional area of the hose itself. And being able to check and clean them without having to drain coolant would be a real plus. And they're nowhere near as fragile as the clear plastic Gano filters. Either will do the job, though.


There are several issues that must be addressed regarding the Tefba filters, however. First and foremost, the diagram of the Tefba filters above shows the element itself folded into a crisp V shape with straight sides. As they come out of the package, however, they are merely bent into a gentle curve as clearly shown in Askevold's picture above. The crisp V shape is actually of considerable importance for ensuring the elements stay in place rather than getting blown against the outlet port. The elements should be removed from the housings and folded in half and then opened back into a V shape to form a sharp crease and straight sides, then reinstalled.


Second, the lift-out tray has a ledge around the edge. When the element is slid into the housing and sits on top of the tray, it contacts this ledge at three points: the two ends of the element and the point of the V. The two straight sections of the element are therefore held above the flat floor of the tray by the thickness of the ledge. The resulting gaps under the element are unacceptable, they will allow too much debris to pass through. The easiest fix here is probably to fashion a flat washer the same thickness as the ledge that will sit around the lifting post and fill in the space under the element. The better the washer fits, the less chance of debris sneaking through. Other ideas include cutting recesses in the ledge to allow the element to sit down on the flat level, or notching the element itself where it contacts the ledge.


Third, the screen ends 3/16" below the screw-on top. This is reportedly deliberate, so that coolant flow will not be obstructed in the event the screen gets totally plugged. Probably not a good idea here, though; it would be better if the coolant is obstructed and the driver learns that the screen needs cleaning via a rising temp gauge than for the crud to get past the screen and plug up the radiator.

It should be easy enough to replace the element with a homemade replacement that is 3/16" taller, provided a suitable piece of screen can be found. But that is not necessary; Ashcroft says, "On the Tefba filter the screen does end about 3/16" below the cap, but the disc is about 5/16" below the in/outlet. I just put a 3/16" thick O-ring under the disc, raises the screen to the cap."


This problem has apparently now been addressed by Tefba, and their newer models include a spring under the tray to hold it up against the lid. If you have the earlier model, you could make your own spring -- make sure to use something that won't corrode into pieces that cause more of the sort of problems that you're trying to avoid. Ideally, fashion the spring to hold the filter element just a little high so that it gets pressed down as the top is screwed onto the housing.



There have been some complaints about the Tefbas being really difficult to get open after being in the car a while. Auto parts stores sell some stuff intended to help slip hoses onto fittings, and they also offer water pump lubricants. Either substance applied to the threads and gasket of the Tefba cap may help it come off more easily. Perhaps you wanna take it easy tightening the cap when you put it on, too. Askevold reports that a strap wrench helps: "I bought an inexpensive small plastic wrench just for this job. Shortened the handle and it works verywell."


There have also been reports of the elements in Tefba filters being blown out of position and up against the outlet port when operating the Jaguar V12 in the upper regions of the tachometer. All of these reports involve Tefbas without a proper crease in the element; it is unknown if similar problems will occur with the element creased properly. If they do, ideas include using some fine stainless steel wire (such as sold for making fishing leaders) to stitch a webbing between the flat sides of the element to keep them from pulling apart. This would make an A out of the V.


If all else fails, the lift-out tray could be discarded altogether. The element itself could then be soldered to two brass discs to form a one-piece lift-out filter assembly. A couple of spars could be incorporated to hold the element's shape more securely.
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FYI, Gano coolant filters can be found here (I have no idea if this is the correct size for F-cars, or even if this is the best price): http://www.mustangpartshouse.com/products.php?scid=264&PHPSESSID=70ce7c10b2e5a0a4