TEFBA coolant filter revisited

(pknellie (aka Trev)) #1

Coming slow up the farm drive the other day after a long hard run I noted that the V12’s temp began to rise a little. 85C up to 87C on the B thermostat and 83C to 85C on the A side. No big deal on its own but idling outside the shed it reached around 92C and 89 respectively, motor still running. This is unusual. The day was about 34C so one could expect some temp increment but the real oddity was that the auxiliary fan didn’t come in. The auxiliary fan operates off the out flow temp of the radiator and is set to 80C. ??inlet coolant filters obstructed.

When I made the change from the coarse to the fine TEFBA filters (as per manufacturer’s instructions) in May this year during the initial filter clean out (TEFBA coolant filter results…. posted May 2018 ), I was concerned how restrictive the fine mesh filter might be. Considering the borderline nature of the XJS it wouldn’t take much gunk and/or silica to cause flow problems. I promised myself then, that I would check them in a couple of weeks but here we are 7 months later and I’m just doing them. My delay in checking them is that I have only travelled about 3000 kilometres.

Pic 1-3 the fine filters as removed today. Obviously a lot of the mesh is blocked.
Pic 4 the silica from the filters in May (LT) and DEC (RT)
Much of the silica etc was in the lower catchment and not in the mesh. I suspect that much of this may have been on the mesh during coolant flow.

Owing to the observation that the fine filter blocked in so few kilometres I have opted to use the coarse filters for the moment. The question that could be asked is that is this something that was going to continue (motor will eventually dissolve into the filters) or is it still the motor cleaning itself out since the flow improvement. Also, considering another block flush or even removing the heads for a gunk-out.

I would be interested in your observations.

PS we will see how she runs tomorrow.

(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #2

Some observations:

I don’t recall any fine vs. coarse discussion with Tefba filters. What I recall were screens, not perforated sheet metal. But it’s been a while, perhaps my memory is faulty.

I also recall recommending that people install these things backwards. The flow should be at the point of that arched screen so that it is pushed away from the opening on that end of the housing. With the flow into the concave side of the screen, it can be pushed against the opening and effectively reduce the active filter area by 90% since only the flow through the section of screen directly over the opening will be utilized. I also recommended folding the screen into a sharp V for the same reason.

The screen getting plugged up is no reason to switch to a coarser screen. It’s reason to check it more often.

For all those who haven’t installed coolant filters yet: See that junk in the photos? All that junk is in your radiator.

(John) #3

Hi Kirby, aren’t you describing the Gano filter and not the Tefba? sounds like it. I had Gano like you described. Had the same thing happen though… it picked up so muck junk it clogged and got hot! Only once though :slight_smile: -John

(pknellie (aka Trev)) #4

Judging by the distribution of the “gunk” in pic 1-3,
I would think all the screen is being used.

(DavetheLimey) #5

Trev, the Tefba filters have been on my car now four summers. Installed as Kirby suggested, at the same time as a new aluminum rad., new stats, hoses, fan, and clutch etc. I, too, am using the fine screens. I did my annual antifreeze “refresh” operation a week or so ago, and both filters could have been left alone. Just a couple of specks of dirt. (?) I think (hope) that your cooling system will clear up after a while. Mine did.

(pknellie (aka Trev)) #6

Thanks for that Dave. When I bought my filters about 12 months ago I found there were a couple of different Tefba ones on the market. I was told that they occasionally make improvements and one was an older model. I wonder if the mesh you have is the same as mine.

(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #7

Nope, Tefba. I dunno how you’d have a problem installing a Gano either forwards or backwards. They are much smaller than a Tefba, though, and presumably easier to plug up. But they’re transparent so you can see what’s up.

(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #8

It does appear so, yes. I’m wondering if the fact that this is a perforated sheet of metal rather than a screen may be to address the problem of the screen being pushed up against the outlet port. I don’t have that screen in my hand, so I can’t judge for myself how stiff and sturdy it is, but presumably it’s sturdier than the screen was.

(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #9

The early models I fiddled with years ago had several issues, including the fact that coolant could simply flow over the top of the screen - carrying a load of garbage with it. I came up with a way to space the lifting tray up with an O-ring or similar spacer so the top edge of the screen was firmly against the cap when closed.

With the screen folded into a crisp V shape and the housing installed backwards so the outlet becomes the inlet, I think the original woven screen would work fine – and hence I’d probably prefer it, since that perforated sheet metal looks far more restrictive to flow. Either probably works fine, though.

(DavetheLimey) #10

Not the best picture, but this is the coarse expanded metal screen I used for the first year. Sturdy? Yes. Probably same as yours.

(pknellie (aka Trev)) #11

Yes… that’s about the appearance of the coarse one. I get the feeling that there must some significant restriction with the fine one. If I had to guess I’d recon about 50% loss of area of flow.
What surprised me was the suddenness of the temp event. Good one day then significant. I suppose the drop in outflow temp might be the clue. As the volume through the radiator drops it gets a chance to cool more thus mitigating any increase in the motor. This of course has a tipping point where the restriction is great enough to cause a notable temp rise… all theory you understand.

(pknellie (aka Trev)) #12

Yes. It’s a firm SS sheet metal screen. And as I noted earlier they have made improvements to the design in recent years.

(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #13

Obviously, you could fab your own screen. Frankly, I wouldn’t be worried about flow restriction with any of them shown here as long as they are unobstructed and not pressed up against the outlet port.

(DavetheLimey) #14

I wish that the surgeon who repaired a hernia I got twelve years ago had used a better mesh/screen arrangement. Then I would not be having to go to the local hospital in about an hour and a half to fix a DOUBLE hernia I now have!
Catch you guys later…

(Kaden) #15

Why do people insist on those awful tebfa salad strainers? It does nothing except catch rocks in the coolant…ugh.

I use a spin-on bypass filtration system on my car with exceptional results - these are used on semi-trucks, diesel rigs etc and filter down to the micron level. Even after several flushes with coolant system cleaners I was still flushing silt and rust until I started using proper filtration.

If you really want a clean cooling system you’ll need a jug of Metal Rescue and a spin-on filter unit either of the two links I’ll attach here.

Premium quality metal filter unit
Basic unit

Both of which require minor modification to splice into the V12 cooling system - I used the return heater core line for mine.

Result after 1000km on new filter Note the fine silt being caught.

Metal Rescue ph neutral rust remover

(Kirbert - author of the Book, former owner of an '83 XJ-S H.E.) #16

Two issues: First, it’s not between the block and the radiator inlet, which is where a coolant filter needs to be to protect the radiator. Second, stopping fine silt is good and all, but I’m not entirely sure it’s actually necessary. Any particles small enough to pass through the tubes in the radiator shouldn’t plug it up unless they congregate for some reason. Of course, the silt probably accelerates wear on the water pump and perhaps other components.

(pknellie (aka Trev)) #17

Hi Kaden.
Could you provide pictures with this filter fitted in your XJS V12. The pics provided so far are of other vehicles. It would be good to see it in situ.

(Kaden) #18

Yes, those two pics are from the diesel trucks - my other vehicle is a 600hp diesel pickup which is where I get much of my inspiration from regarding aftermarket products.

I would note that my first few flushes with the garden hose and shop vac removed a disgusting amount of crap, metal flakes rubber bits horrific discoloured coolant etc. I only used the filter unit after the 5th flush. I’ve been chasing an over-heat problem for years…I could just recore the rad but that is alot of effort considering I drive the car every day, biggest benefits I’ve seen are with Metal Rescue and a standard coolant filter with the filter hole opened up abit for a larger flow rate.

I currently have the basic spin-on filter installed, and have removed the carbon canister to make way for the compact metal/magnetic filtration unit I linked to which will be mounted and connected in that front wheel well area which is now dead space.

From the link and pictures you can see the smaller metal filter unit is compact enough to mount anywhere in the engine, the spin-on filter was a temporary measure but it has done me well over the past 3 years I’ve had no reason to move it…eventually I’ll buy another unit from IPR and mount with pictures for everyone to see.

(JLo) #19

I have never used a coolant filter however after all the RTV I have been using lately I may try it out. Attached is picture of just some of the sediment last time I back flowed the heater core.

(pknellie (aka Trev)) #20

My “awful Tefba salad strainers” managed to filter all the rocks (silica or remanent casting sand) from blocking up my newly cleaned radiator. This is why we use two Tefba filters to clean up in both radiator inlet hoses. These grains of silica come directly from the block to the radiator and each grain is capable of blocking a radiator flute. As for finer particles, the Tefba also filters particulate rust using a magnet in the base. Any remaining fine particulate material I don’t see as a problem.
Whilst I can’t see how your filter in the heater hose could have prevented those “rocks” reaching my radiator I respect your choice to use it.
Trev_emphasized text_