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edlithgow
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PostSubject: Deposit on dipstick.   Fri Mar 01, 2013 5:56 am

Cars was standing for a couple of months while I was away.

Checking the oil before starting I noticed that one side of the dipstick was the reassuring honey-colour of clean oil, but the other was dark grey.

The tissue I wiped the dipstick on has a faintly yellow-gold damp patch that I associate with clean oil, but also a slate-grey "skidmark",wiped off the dipstick, that looks metallic.

I guess there were fine metallic wear particles suspended in the oil, and the long stand has allowed them to settle out. Since the dipstick is at an angle, (i.e. not vertical) it can have an upper and a lower side. I wasn't paying enough attention to know if the upper side was the one with the sediment, though thats what I'd expect.

Is this normal (on a very old car)? Havn't seen it before, but I suppose this combination of circumstances might not have occured/been noticed.

I'd have thought suspended metal would visibly discolor the oil, but I suppose the oil film on a dipstick is rather thin.

I suppose I'd better drain the oil, and maybe drop the sump and look for debris. It had an oil and filter change (Mobil Delvac MX 15/40) about 6 months ago

There was an intermittant tick when I first bought the car but it went away after I pissed about with water-cleaning the cylinders, so I was tempted to call it pre-ignition. Maybe something loose just got ground away and/or lodged somewhere.
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ventorafred
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PostSubject: Re: Deposit on dipstick.   Tue Mar 12, 2013 11:10 am

Most of my motors have had a cream residue on the dip stick
because it only usually just about warms up before I get to work
its just water condensation
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edlithgow
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PostSubject: Re: Deposit on dipstick.   Wed Mar 13, 2013 1:02 am

I'm pretty sure this isn't.

There's no sign of "mayonaise", and the car is often near operating temperature before I start it. (OK, slight exaggeration, but it does get F-ing hot here in Taiwan).

Its as described. A metallic-looking deposit that settles out on long-standing. I speculate its wear metals from the cams, perhaps due to using "modern" low-zinc oil.
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edlithgow
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PostSubject: Re: Deposit on dipstick.   Fri Mar 15, 2013 5:32 am

The picture shows the result of wiping a magnetic pickup tool (that had been in the dipstick hole for 5 days) on a piece of printer paper.

The contrast between the (presumed ferrous) tip deposit and the relatively clean oil from the rest of the tool is, I think, quite clear.


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Magnetic pickup on printer paper by ed_lithgow, on Flickr
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edlithgow
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PostSubject: Re: Deposit on dipstick.   Sun Mar 17, 2013 3:17 am

The Question arises : Is this normal?

The Answer arises : I don't know.
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edlithgow
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PostSubject: Re: Deposit on dipstick.   Tue Apr 02, 2013 9:59 am

Here's what the inside of the sump looked like. Quite a lot of (presumably metallic) sludge, despite having had an oil and filter change a few hundred miles ago.

I suspect the captive nut thingy that holds the drain plug was holding back the varnish and gasket frags, and maybe stopping the sludge draining well too.

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edlithgow
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PostSubject: Re: Deposit on dipstick.   Sat Apr 13, 2013 6:28 am

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.

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

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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.

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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?

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Or this?

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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 are hard to come by here. Perhaps its the mechanical equivalent of "detailing"? Smile.
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Father Tiresias
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PostSubject: Re: Deposit on dipstick.   Sat Apr 13, 2013 9:52 am

Difficult to say without seeing the actual cams themselves but they look OK in the pictures.

As you still appear to be getting contamination in the oil I'd be inclined to do a flush out using proper flushing oil.

What car is it?
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edlithgow
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PostSubject: Re: Deposit on dipstick.   Sun Apr 14, 2013 6:15 am

Thanks for your reply. Its a 1986 Daihatsu Skywing. Never, AFAIK, seen in the UK, but mechanically like a Mk1/2 Charade (CB 22 engine), which'll be pretty rare in the Yook by now but were, I think, imported, though in fairly small numbers.

It has the advantage of a relatively small, light 3-cyl engine, if I have to take it out, but without indoor workspace that'll be difficult, and parts will be hard to find.

I thought of using flushing oil, and in fact considered "home brewing" a flushing oil with a 30-50% 2-stroke/petrol mixture, the idea being to tow the car in gear with the plugs out, for a minimum-friction flush.

I chickened out of that idea, though after removing some varnish sheets ffrom the head with forceps I did squirt some petroil in the head to wash any escapee fragments out, before a final sump cleaning. I don't think much of that will have been retained in the engine after an overnight drain-down, and it shouldn't have got into the oil galleries.

Re actual flushing oil, I've used that in the UK, (Comma brand, IIRC) but I dunno where to get it here, and in any event I'm not sure it would offer much advantage over the oil I'm using (Mobil Delvac 15/40). Since that's a diesel oil, it should be relatively high in detergent.

To me, ferrous metal in the oil implies crank or camshaft wear, (since everything else apart from the rings is aluminium or white metal) hence the wish to have a look at the main/big end bearings/journals. I got the bolts off one of the mains but I couldn't get the cap off, and now rather wish I hadn't tried.

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PostSubject: Re: Deposit on dipstick.   Sun Apr 14, 2013 11:26 am

edlithgow wrote:

To me, ferrous metal in the oil implies crank or camshaft wear, (since everything else apart from the rings is aluminium or white metal) hence the wish to have a look at the main/big end bearings/journals. I got the bolts off one of the mains but I couldn't get the cap off, and now rather wish I hadn't tried.


Could also be oil pump wear.
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edlithgow
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PostSubject: Re: Deposit on dipstick.   Sun Apr 14, 2013 3:03 pm

Yes, I was thinking I should maybe have a look at that. I suppose if the pump is badly worn low oil pressure (I don't have any special reason to suspect that, but I don't have an oil pressure guage) might also contribute to wear elsewhere.

The oil pump is chain-driven, and the chain looked a bit slack to me. If the pump is wearing badly I suppose the metal will be off the internal pump lobes rather than the drive chain (which is tiny) but if it throws or breaks the chain that'd be pretty fatal.

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PostSubject: Re: Deposit on dipstick.   Mon May 20, 2013 1:18 am

I thought the chain looked a bit loose, but this vid, apparently of a new one looks about the same, so perhaps its OK.

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I took the oil pump off and dismantled it. Since the sprocket has to come off to dismantle the pump I ended up using a gear puller on it. Seemed to be glued on with oil varnish and took quite a lot of force to shift. Dont think I bent it. but it was becoming a concern before it let go.

(I'd have put something behind the sprocket to spread the edge-load, but there wasn't clearance for anything I had to hand.)

Pump internals seem OK, from what I can see (not that I've seen one before) and measure with feeler guages.

Casting void behind the pump body was, however, full of sludge, as were the pump body bolt-holes.

Havn't taken the bypass valve apart yet because the split pin is supposed to be a non-re-usable item, and I don't have one. Wouldn't normally worry about that (not very bangernomics) but it seems oil pumps make me nervous.

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edlithgow
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PostSubject: Re: Deposit on dipstick.   Mon May 20, 2013 1:45 am

Thinking about it further I seem to recall traces of what looked like RTV silicon around the sprocket bolt, and there's also something visible in the above pictures.

Perhaps the bolt had a thread - locker on it? Which raises the question - should I put some on when I re-assemble it?

I don't remember anything about it in the manuals I have, and Loctite etc will be hard, perhaps impossible, to find here, though I have some RTV silicone.
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edlithgow
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PostSubject: Re: Deposit on dipstick.   Mon May 20, 2013 5:52 am

Bit of Googling suggests that this type of sprocket is known to come loose, at least on Porsches and Landrovers.

Description of the Landrover issue

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Dunno about Daihatsu's, but I suppose I'd better try and find some Loctite.
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