Engine flushing?

Life Cars & Motorcycles
1

While re doing the valve clearances (“hot”, like you’re supposed to) yesterday, I carelessly “parked” the two rocker-cover bolts in the wrong (air cleaner hold-down) bolt holes, which were dirty.

Didn’t realise what I’d done until after a freeway run into Tainan and back (maybe 40-ish k). Nasty streak of “silt” from the bolt holes, inside the rocker cover.

Damage limitation would suggest taking it for another run to stir up the oil (though this’ll probably cause more wear) then doing an oil and filter change, annoying because I did it very recently (Delvac MX 15-40).

Is it likely to be worth doing an engine flush as well? Don’t remember seeing flushing oil here, but then I havn’t looked.

I’ve got a lot of hydraulic oil and some 2-stroke, so perhaps I could make my own?

2

What vehicle is this?
Am I reading your post correctly? You screwed into and through the rocker cover, releasing dirt into the engine?

3

[quote=“sulavaca”]What vehicle is this?
Am I reading your post correctly? You screwed into and through the rocker cover, releasing dirt into the engine?[/quote]

Well almost that bad.

I got dirt on and in the rocker cover bolt threads, was interrupted, then, short of time, put it back together in a hurry without remembering to clean up the threads, releasing dirt into the engine.

Of course some damage will already have been done, and there’ll be some abrasive that won’t be removed by anything short of a full strip-down (embedded in the soft metal bearing shells, for example) so the best I can expect is to limit rather than eliminate it.

4

I can’t picture how bolts screwed down into the rocker cover, somehow protruded to the inner side of it. :eh:

5

Uh? How could a rocker-cover hold-down bolt do its thing if it didn’t go through?

Funnily enough I can’t actually remember the precise arrangement on all previous cars, getting old, but the Daihatsu arrangement didn’t strike me as particularly unusual.

It has 2 long bolts that go through bronze-looking washers backed by gaskets that seal the (unthreaded) entry holes in the cover, and then screw into the head. (Actually into the camshaft pedestal IIRC)

I think the Marina 1800 B series engine had a similar 2-bolt arrangement. The Lada had a lot of small bolts and washers around the perimeter of the rocker cover that were a bit of a pain but would avoid this problem (as would a modicum of care :blush: ) since they were in or outside the rocker cover gasket. Ford Pinto…um, not sure, like the Lada I think, Sierra DOHC likewise. Triumph 1300, 2-bolt, I think. No recollection at all of any of the others, but from that sample it is the less common (BL only) arrangement.

Anyway, there’s a gap between the rocker cover and the head, where the bolt threads (and any dirt they contain) are exposed to oil splash, plus the threads get scraped cleanish entering the head and the excess gunge gets deposited on the head surface, where it is also exposed to oil splash. This puts the dirt in the oil.

6

I can’t build a picture in my head of what you’re talking about I’m afraid. I know there are a host of different ways of securing a rocker cover, but I thought you were talking about air pipe/cleaner retaining bolt threads in the rocker cover, not screw threads in the head. I’m totally confused. I need a photo.

7

Cut-away schematic might be better?


rocker cover hold-down bolts by ed_lithgow, on Flickr

My recollection is that more of the bolt than is shown here (perhaps all of it) is threaded, (giving it more dirt-trapping capacity) but I might be remembering that wrong.

8

Ohhhhhh! Now I get it!

That’s a very old design indeed. Not too many rocker screws go through the open breather space in the rocker cover any more. The cover tends to flex too much with these designs, which often leads to early leakage around the rocker cover gasket area.

I wouldn’t worry too much about it though. They couldn’t have been that dirty could they?

9

[quote=“sulavaca”]Ohhhhhh! Now I get it!

That’s a very old design indeed. Not too many rocker screws go through the open breather space in the rocker cover any more. The cover tends to flex too much with these designs, which often leads to early leakage around the rocker cover gasket area.

I wouldn’t worry too much about it though. They couldn’t have been that dirty could they?[/quote]

Yeh, well, its a very old car, so it would be. Doesn’t seem to flex or leak though.

The rocker cover is cast aluminium and has a central baffle box, all of which probably makes it quite rigid, at least as compared to the pressed-steel two-bolt BL designs I mention having had, above.

I think it was pretty dirty, judging by the streak of muck from the bolt holes. :doh: :doh:

After the last freeway run the oil film on the camshaft lobes seemed to have a greyish appearance, suggestive of very rapid wear, :doh: :doh: :doh: though it could be (at least partly) imagination.

No time at the moment so I won’t drive it any more until I can attempt some damage limitation.

I’d like to fit an oil accumulator anyway so if I can get some of the fittings I might be able to use them to flush out the oilways before I start it up again.

10

Since I havn’t made any progress with the oil accumulator idea, and will be busy with a sodding summer school next month, I’m thinking I might just do a DIY engine flush to remove as much of the silt as I can.

Heres “THE PLAN” (or at least A plan)

The basic idea is to use 3 changes of 30% 2-stroke as a flush while turning the non-firing engine over with the plugs out, then, after changing the oil filter, do a couple of close-succession changes (say 100 miles or so) with Delvac 15W/40 and (very old) Mobil Special 20W/50, before resuming normal oil change intervals. I’d have to watch the very old Mobil Special for signs of short-term instability.

I’m assuming that, while 30% 2-stroke is probably a relatively poor lubricant, it won’t be too damaging in a non-firing engine, and may flush out grit that would be retained by thicker oil. 30% is still a high oil % compared to a typical 2-stroke engine running at, what, 2-5 % ?

Seals are presumably made to withstand some petrol contamination of the oil, (though of course not that much) and they won’t be exposed for long or at very high temperature.

Possibly, perhaps after filtration/settling, the 30% petroil mix could be diluted further and burned in a 2 or 4 stroke engine.

Comments? Safe-ish or guaranteed fatal?

A possible alternative would be to use a commercial engine flushing machine service, but I’m not sure what that’d cost, or that it’d necessarily be better.

11

Can anyone explain to me why one would use 2 stoke oil for flushing the engine? As I don’t even know what is in an oil flushing product, I wouldn’t know the difference between 2 stroke oil and something made to flush the engine.

12

I’d reply “why not?” (which was essentially my original question) but, on your own admission, you won’t be able to tell me.

I’d be very interested if anyone else can, though.

AFAIK flushing products are of two types. A thin (eg 0W/20 oil) OR an additive that you put in your old oil and run it a bit before draining.

Of course they don’t tell you what’s in them, (proprietary secret) but in a genuine product the oil is probably high in detergent, and the additive package is probably ditto plus fairly volatile and aggressive organic solvents designed to dissolve sludge.

Its sometimes alleged (and may sometimes be true) that the oil is mostly kerosene or diesel, and some people use these instead. I’d guess this is unkind to bearings, diesel probably less so due to its greater lubricity.

I’ve used Comma flushing oil and Wynn’s engine flush in the UK a long time ago. The former didn’t seem to do much in terms of shifting muck, (its difficult to tell if the additive does anything because the old oil is dirty anyway) but in retrospect I’d guess the engine I used it on wasn’t dirty enough to need it. I was young and a bit picky.

These products aren’t , IMO, particularly appropriate to the current situation because their primary purpose is to shift sludge, and I don’t have any. I have very fine silt accidentally introduced to the engine :doh: :doh: :doh: (see above).

The rationale for using 2-stroke oil is that, diluted with fuel, it can be used to produce very large volumes of petroil flushing lubricant at fairly low cost. I’d expect the efficiency of flushing to increase with the volume/number of changes of flush used.

If the flushing lubricant can (after settling/filtration) be burned in an engine (not of course possible with conventional flushing oil) there is no cost.

(Unless I set fire to something, of course. :ponder:)

EDIT: I THINK (hope) that the petroil lubrication wont be fatally inadequate in this role. 2-stroke engines, after all, survive worse with less, but then they are built for it, using roller bearings instead of shell bearings, for example.

I suppose its also possible that the petroil will be too thin for the pump to develop adequate oil pressure, so it won’t reach the top end.

Only gotcha’s I can think of at the moment, but I daresay there’ll be others.

ENDEDIT

13

I bit the bullet and took the sump off.

Bit of a pain in the arse, " I want to take off A, so it looks as if I have to take off B, but to do that I’ll have to take off C…and to take off G I’ll have to take off A" stylee.

Then again, I’ve only done a Marina (very easy) and a Lada (fairly easy) before, and new cars are probably even worse.

Basically, the cross-member, front and back engine mounts, anti-rollbar, gear linkage, exhaust mount and pipe, and flywheel cover plate have to come off, and its a bit tricky getting it all lined up to go back on again.

Probably worth doing though. Despite spraying the engine down with 2-stroke from the top, there was still a lot of (probably metallic) silt that hadn’t drained, and the captive nut thing for the sump plug was preventing varnish and gasket fragments from getting out.

The oil pickup strainer also had varnish and gasket fragments stuck to it. Close examination (though without a lens) showed a few of what looked like large grit/sand grains stuck in the mesh. Couldnt pull them out, so I pushed them through, then took the strainer off and squirted petrol through it. Hopefully this washed the particles out, otherwise I’ve just gone to a lot of trouble to make things a lot worse.

In the process of doing all this, I discovered that:-

(a) My girlfriends mechanic-uncle hadn’t fitted an exhaust flange gasket. No big surprise there, and it didn’t seem to have caused a problem, but hot gases squirting around the engine compartment could be a bad thing.

I made one from folded aluminium foil/pertex sandwich, burnishing it down onto the flange, then cutting an X centred in the three holes. The folded-down excess in the pipe gets burned/melted off (probably bad for a catalyst, but good if you don’t have one.) The excess in the bolt-holes perhaps helps the bolts not to seize. I’ve done this a few times before without problems, but that was with RTV silicone, so I’ll keep an eye on this Pertex version.

(b) The flywheel-plate didn’t have the specified silicone “instant” gasket along the sump join, giving another grit-path into the sump. Put some on, though this area is very difficult to see and I might not have put on enough.

(Incidentally, the sump flange studs here are recessed down a curved path which perhaps could be reached by a long socket on a flexible nut driver, which I didn’t have. No way would a UJ fit. Fortunately they were loose and I could just turn them with a 1/4 drive long 10mm socket held in my fingertips. If they were tight I think you’d have to take the engine out.

URL=http://imageshack.us/photo/my-images/411/imgsunkstud.jpg/][/URL]

That gets my Henry Ford Asiatic Automative Fiend-of-the-Week Award.)

© My front and rear rubber engine mountings are split, the front one quite badly.

I tried supergluing, though not with much optimism.

“Do you expect me to torque?”

“No, Mr Bond, I expect you to die”

I put some cable ties on to close the gap and give the glue a chance, but couldn’t keep it aligned properly, so I put a lot more cable ties on to keep it under compression. Doubt they’ll hold. I suppose I should have gone to the beach and foraged up some commercial monofilament fishing line for a lashing, but no transport.

Dunno if these mountings are still available, or at what cost.

There is quite a lot of web info on DIY engine mountings, made from eurethane casting resin or silicone, but they mostly seem to be replacing the existing bushing in a “caged” mounting. This mounting is trickier, since the rubber is loaded by engine torque (and is failing) in tension. Might still be possible to cast something if I can get the resin here in Taiwan. Front suspension strut tops look a bit dodgy too, so I could do both at the same time.

Anyone have a source of eurethane casting resin here? 3M Window Weld is apparently a slightly less professional substitute

People also apparently make engine mountings from ice hockey pucks, but I suppose they’ll be hard to find in Taiwan.

Perhaps you Canadians out there could check your pockets?

14

I’m Canadian and I checked my pockets, and damn it, didn’t find a hockey puck. Sorry about that…

15

Can’t win them all. Thanks for looking, though.

Could they be in your other (winter) jacket?

16

Since the sump was leaking at the gasket I took it off again, with the intention of trying some silicon sealant on the gasket, and maybe having a look at the crankshaft bearings/journals.

Had probably done about 50-60 miles since the last oil and filter change.

Hard to be sure but there still seems to be a lot of metal in the oil considering the low mileage. Picture below shows the result of wiping the magnetic drain plug on printer paper.

Other picture is of the sump, but its rather unclear.

next picture is of the last bit of oil from the sump drained into a bottle. Looks dark to me for such low mileage, but maybe its just a"flushing" effect.

My first suspicion was that maybe using modern “low zinc” oil (Mobil Delvac MX 15/40) had caused the cams to wear excessively, The cams don’t look too bad to me, but I’m no expert. I suppose if it wears evenly/smoothly but excessively you wouldn’t necessarily be able to tell until it rounded off.

Anyone care to comment on this cam?

Or this?

I suppose if the surface hardening has gone, they won’t last long whatever I do, but I’ve found some rather old Mobil Special 20W-50 which meets the reassuringly obsolete API SG spec, so I’ll try that next.

It’d be useful to have some way of (semi) quantifying the metal in the oil. Have some ideas on that but its a bit challenging with no lab access so I doubt they’'ll work out

Found it difficult, working under the car, to get a main bearing cap off, so I gave up. Hopefully I havn’t put it too badly out of alignment.

I could, I suppose just stop obsessing about it, but bangers, especially with manual transmission, are hard to come by here.