SQ4 Sludge Trap enlargement

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andy.hall
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SQ4 Sludge Trap enlargement

Postby andy.hall » Sun Apr 07, 2019 2:11 am

It seems to me that if only E.T. had decided way back when to make the SQ4 crank "sludge traps" a little more capacious, there would be so many more of those engines alive and running today.
Does anyone know anything about any successful modification done to SQ4 cranks to enlarge the capacity of those "sludge traps", so as to lengthen the periods between total engine stripdown and cleaning ?
It seems reasonable to think that the current 3/16" oilway bore could be increased a little, down to a small-ish depth, and then re-threaded with a tapered pipe thread. Perhaps a small threaded brass Allen-socket plug could then be used instead of that 1/4" countersunk screw. Could something like that then triple the "sludge trap" capacity ?
The cherry on the sundae would be to be able to access the plugs without having to split the crankcases, but I think I'm going too far.

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Re: SQ4 Sludge Trap enlargement

Postby nevhunter » Sun Apr 07, 2019 8:38 am

Most engines have simple straight drillings and there's nowhere for the sludge to collect. It has to go through the bearing and just does, but slowly. When you feed two bearings from one source you get problems. If all the oil goes out the first bearing the second gets none. With a set up like the SQ4 at high revs there's a big likelihood of the first getting most of the oil especially if it's got a lot of clearance as it has to go against centrifugal force initially to get to the second bearing unless there's a stand pipe going all the way to the centre axis in the web to the second (and the first bearing at the same time. This was a problem with the late 20's racing Douglas engines withy total loss oil systems. Nev

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Re: SQ4 Sludge Trap enlargement

Postby GuyWalton » Sun Apr 07, 2019 5:35 pm

I'm just about to start an ariel square four as my next project . I have the bike its 1951 . I have refrained from starting it as I dont know the condition of these sludge traps . What I will be doing when rebuilt is upgrading the oil pump and fitting a canister oil filter . Morgo is what I normally use . Hopefully that will cure the problem .
51 mk1 Areil Square Four
55 DB 500 BSA Gold Star
55 Matchless G9
67 BSA B44
06 Ducati 999R

john.whiting
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Re: SQ4 Sludge Trap enlargement

Postby john.whiting » Mon Apr 08, 2019 12:05 am

There is no need for concern......with modern detergent oil and an effective filter,there will never be any buildup in the sludge traps.

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Re: SQ4 Sludge Trap enlargement

Postby RTichard Woolnough » Mon Apr 08, 2019 8:41 am

the P.O. of my W/ng ran the thing on diesel detergent oil fitting a spin off filter in the return, I have continued this practice and hopefully there will be no sludge build up. kind regards

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Re: SQ4 Sludge Trap enlargement

Postby david.anderson » Mon Apr 08, 2019 10:06 am

A centrifugal sludge trap will remove particles irrespective of whether there is an oil filter or not, it will fill and eventually block. The 4 sludge trap is centrifugal. The filter will just reduce the rate of filling. Detergent oils will carry deposits in suspension rather than letting them settle in obscure places, but a centrifugal trap will always remove the heavier particles.
I re built my 4 with a Morgo and I fitted an in-line oil filter (disposable cartridge from a Daihatsu Charade) before the engine was first started. I have only run my 4 on detergent oils, initially Penrite 20-50 gas then Penrite HD and now Mobil 1 V-Twin. I did about 5000miles before the AOMCC conrods became available, after which I had to strip the engine to fit them. I almost did not worry checking the sludge traps as I had done it on the initial build. I did however remove one plug to check and found the trap 1/4 - 1/3 full. The remaining sludge traps were the same. while my engine was a complete rebuild and there would clearly be a little extra due to initial engine bedding in, I was shocked at the amount of sludge. Paul Jameson stated elsewhere that the sludge traps should be cleaned every 20,000 miles. I would never exceed that mileage even when with a good filter.
David

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paul.jameson
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Re: SQ4 Sludge Trap enlargement

Postby paul.jameson » Mon Apr 08, 2019 9:25 pm

If it was relatively easy to increase the sludge trap capacity on a Square Four, the means to do so would be common knowledge by now - some 80 plus years after the pushrod Square first appeared. One problem is that Square Four crankshafts flex to a surprisingly large extent - as related by Val Page in his recorded interview by Jim Lee back in the early 1970s. The transcript of this recording exists in the Club archives. Given that the cranks flex, any reduction in cross - sectional area will reduce their life before fracture. Fracture of Square Four cranks, particularly the front crank, is not uncommon. This might be why the factory did not increase the sludge trap size over the production run of about 33 years, or about 29 years if you delete the period during WW2 when Squares were not produced. And even if you could safely enlarge the trap size, removing all 4 sludge trap plugs without dismantling the engine would remain on the somewhat impossible side of extremely difficult.
So we go back to the question of how often should you clean out the sludge traps? The Healey brothers reckoned that an engine run on non-detergent oil would throw a rod in 500 miles or less once detergent oil was used. They should have known, since they were the Square Four experts when detergent oils came into use. My own first Healey had an engine (Healey engine no 2) which had suffered a broken rod and the Healey engine I sold last year (Healey engine no 5) was the same. So we have evidence that the Healey brothers were well familiar with the sludge trap problem. One of the features of the Healey 1000/4 was the provision of an oil filter to extend the intervals between sludge trap cleaning.
Former AOMCC Square Four spares organiser David Jones threw a rod on his Mk II because of "waiting till the winter" before he cleaned out the sludge traps. Former AOMCC Chairman Lester Grant did likewise with his Mk II.
So I have never run a pushrod Square engine without cleaning out the sludge traps first and fitting an oil filter. I have subsequently stripped both my 1948 4G and my (first) Healey 1000/4 and checked the sludge traps again. Like David Anderson, I was pretty horrified to find how much sludge they had collected. The 4G had maybe done 6000 or 7000 miles when I stripped it but the sludge traps were around 1/2 full. The Healey had done about 15000 miles and the traps were around 3/4 full. Hence my recommendation that, even with a filter, cleaning the traps every 20,000 miles is necessary.
What I don't know is how quickly the traps fill over time and miles. I suspect that the first few hundred miles puts quite a deposit into the traps from the inevitable debris left in the engine when it is built, plus the particles which wear off during the running in period. I believe that my current Healey engine had done no more than 200 miles before I stripped it but there was appreciable debris already in the traps. They were perhaps 5 to 10% full. I would expect an engine in good condition to deposit relatively little once it has run in but as wear takes place the rate of deposition will increase.
Few people ride their Squares enough to exceed the 20,000 mile threshold for sludge trap cleaning. For those who do, it would be of great benefit to the other Square Four owners if they could asses how full the sludge traps were after whatever mileage they have covered - and let us have the information. Otherwise, you are all working on the data David Anderson and I have assembled - and I think that amounts to only 4 Square Fours.
Paul Jameson
36 4G, 37 VH, 53 ex ISDT KHA (project), 54 KH(A), Healey 1000/4 (project)
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.

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Re: SQ4 Sludge Trap enlargement

Postby Mike Nash » Tue Apr 09, 2019 7:57 pm

As a lowly VB owner all I know about Sq4s is what I read here, so please forgive me for suggesting the use of magnets to assist in their oil cleanliness. Their value is obvious – I’ve used them for over 50 years on a variety of engines, gearboxes, back-axles, compressors, lawn mowers etc – and for the filter in the return line of a Sq4 might not the “wrap around the spin-off filter” type (see here https://www.amazon.co.uk/SS-300-FilterM ... B001TLP6UI) complement filtering?
Ordinary motor filters capture particles down to about 20-30 microns but magnets will catch bits down to molecular level provided, of course, they’re in range to be grabbed. Fortunately, modern rare earth magnets are so powerful they'll certainly do the job – and they’re dirt cheap too! (Note, the “Filtermag” variety linked to above must be amongst the most expensive!) Most of the solids in the oil are ferrous so are obviously “catchable” but its not generally realised that light alloy materials are paramagnetic i.e. display weak magnetic properties while they're in a magnetic field, so they too are to a degree attracted to magnets.
So what I’m thinking is that with a filter and magnets in the return line, the oil feed through the Sq4 sludge trap areas will as clean as we can get it and so reduce the risk of sludge build-up as far as possible. A test of this idea would be to see if the sludge material is itself magnetic.
Regards from MikeN.

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paul.jameson
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Re: SQ4 Sludge Trap enlargement

Postby paul.jameson » Tue Apr 09, 2019 9:22 pm

The replacement sump plates supplied by Bruce Longman for the Club incorporate a magnet in the centre bolt. They also fit KH models !
Paul Jameson
36 4G, 37 VH, 53 ex ISDT KHA (project), 54 KH(A), Healey 1000/4 (project)
Former Machine Registrar & Archivist, General Secretary and Single Spares Organiser (over a 25 year period).
Now Archivist once more - but not Machine Registrar.

KevinOToole
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Re: SQ4 Sludge Trap enlargement

Postby KevinOToole » Wed Apr 10, 2019 12:35 pm

Mike Nash, just read your magnet idea for removing particles from the oil. I'm definitely going to fit some. Simple and inexpensive (cheap!), great idea.


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