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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1740 Location: Above the snow line in old Monmouthshire
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Posted: Sat May 17, 2014 2:43 pm Post subject: Poor oil pressure after oil change? |
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Hi all, I changed the oil & filter on the Herald the other week, not quite due but as it looks like I won't be getting much use out of it for a while I thought I'd do it now and avoid leaving old oil in the sump. What I'm finding now though is that the oil pressure is noticeably lower than normal. It's not too bad when starting from cold, indeed so close to normal that I only noticed it when I was actively looking out for it, but it gradually falls away as the engine gets properly hot on a longish run until it can be 15psi or so below what I'd expect.
There are no other symptoms. No unusual leaks, oil up to the top mark on the dipstick, and no sign of coolant or fuel entering the sump. No overheating or rough running. No unusual noises or vibration. It's the 1147cc engine so it has the full-flow oil filter, so even if the new filter was duff (blocked/bypassing) I wouldn't expect the pressure to be affected in this way, likewise if the pressure relief valve was stuck or otherwise defective I'd expect to see poor pressure right from a cold start.
The oil is some I bought at a show several years ago (been in stock ever since) for what seemed like a bargain price. It purports to be Duckham's Q 20/50, sealed can and the right green colour, the can and labelling are identical to some that I bought a caseload of on another occasion (and which has proved good in service). However, at this stage I'm thinking it must be a can of dodgy oil that's thinning out too much at high temperature. The first time I noticed the problem was the first time I took it out after changing the oil, a good run out to Hereford on a warm afternoon where I ended up watching the gauge like a hawk! I kept a close eye on the gauge coming back home, but the return trip was in the cool of the night and it didn't drop quite as low as it had earlier in the day.
At the moment I'm thinking that the best course of action is to treat this lot effectively as flushing oil - get it nice and hot then drain and refill with fresh, which should solve the problem. I just can't think what else could be causing it, unless anyone else has any ideas? |
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kevin2306
Joined: 01 Jul 2013 Posts: 1359 Location: nr Llangollen, north wales
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Posted: Sat May 17, 2014 3:26 pm Post subject: |
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If it was me and you have done no other engine related work, I would drop the oil and change the filter.
A fresh gallon of oil and a new filter is way cheaper than an engine rebuild.
Could be unrelated and pure co-incidence and something else is the cause though?
Kev |
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goneps
Joined: 18 Jun 2013 Posts: 601 Location: Auckland, New Zealand
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Posted: Sun May 18, 2014 12:55 am Post subject: |
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We had a 1964 Herald 1200 virtually from new. One day I made the huge mistake of buying at bargain price 4 gallons of Duckhams' green 20W/50 oil. After changing to the green stuff the oil pressure light would flash at tickover (Heralds were not originally equipped with a gauge), which it had never done before and never did again after the green garbage was replaced with proper oil.
'Nuff said.
Richard |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1740 Location: Above the snow line in old Monmouthshire
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Posted: Sun May 18, 2014 1:04 pm Post subject: |
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It hasn't been quite that low - I fitted the gauge myself, always have done with my oldies,but kept the oil pressure switch though it now works a loud buzzer. All the same, I think my next job is to drain the sump again and refill with fresh oil. It's not impossible that there's some odd, unrelated fault that's cropped up just now, but I think I'll start with the easy stuff first!
Incidentally I think some early Heralds did come with oil pressure (and water temperature) gauges as standard - the 948 twin carb models, if memory serves? |
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V8 Nutter
Joined: 27 Aug 2012 Posts: 588
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Posted: Sun May 18, 2014 7:59 pm Post subject: |
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Many years ago I owned a 1954 Oldsmobile with hydraulic tappets. 20/50 was the only grade of oil readily available at the time. I changed the oil and the car developed a misfire when starting on cold mornings. I spoke to an American car expert, he said the problem was thick oil pumping up the tappets. He recommended using Duckhams because it was thinner than anything else. I did that and it solved the problem, but it could well be the basis of your problem |
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Jim.Walker
Joined: 27 Dec 2008 Posts: 1229 Location: Chesterfield
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Posted: Mon May 19, 2014 7:48 am Post subject: |
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I could be wrong as much time has passed (and I have had a stroke which hinders re-call). But I am pretty sure that the 1147 engine had a BY-PASS FILTER , but the later FULL-FLOW filter of the 13??cc engines was/is visually identical and could be fitted in error.
Sorry if I am wrong, but check it out.
Jim. _________________ Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then! |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1740 Location: Above the snow line in old Monmouthshire
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Posted: Fri May 23, 2014 8:21 pm Post subject: |
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I had to check it out Jim, you started a doubt in my mind of the "did I lock the back door" variety... but the bypass filter was only on the 948 engines, the 1147 has the full flow filter as per the larger 4 cylinder engines. Incidentally, if anyone has any of the early type bypass filters gathering dust, I believe they're quite rare now, and well worth listing on fleabay. Anyhoo, I got it hot yesterday and left the oil to drain overnight, then refilled with fresh this morning. Didn't do the filter - thought I had several in stock but actually had none - but removed it and let it drain overnight before replacing. Went for a run today, pressure holding up a little better but still not right, could have been down to the cooler weather as much as anything else. Next step will be the filter, not sure how it could cause this problem but it's a quick and cheap job when I can get hold of one (bloody bank holidays!) and a logical first step.
There's also a question mark over the running temperature of the engine, temp gauge has been registering rather less than its usual of late (before the oil pressure problem though) and, without getting round to actually doing anything about it, I assumed the thermostat was on its way out - but it could just as easily be the gauge or sender. Really, all I know for certain about the running temperature is that it's not boiling and the heater output seems OK. In an attempt to avoid wasting £££'s on unnecessary parts, I've invested in a suitable thermometer (£5) to carry out proper testing, long thought one would be handy but always assumed they would be more expensive than they are. Anyway, between the bank holiday and the inevitable post-privatisation slowdown of the Royal Mail it looks like I won't be doing much inside of a week from now |
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Jim.Walker
Joined: 27 Dec 2008 Posts: 1229 Location: Chesterfield
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Posted: Fri May 23, 2014 9:55 pm Post subject: |
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Sorry about that Bitumen Boy.
But at 75 my recall is not what it was! I am dreading the situation when I am 76!
Jim. _________________ Quote from my late Dad:- You only need a woman and a car and you have all the problems you
are ever likely to want". Computers had not been invented then! |
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ajlelectronics
Joined: 04 Oct 2010 Posts: 168 Location: Gloucester
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Posted: Sat May 24, 2014 4:19 pm Post subject: |
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I had a similar problem on an Essex. Replaced the oil filter again and all was well again. Branded filters too! _________________ Evans Waterless Coolants
Find this and more at http://www.classicmicrocars.com
Sat TV / Aerial systems etc: http://www.ajlelectronics.co.uk |
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baconsdozen
Joined: 03 Dec 2007 Posts: 1119 Location: Under the car.
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ukdave2002
Joined: 23 Nov 2007 Posts: 4127 Location: South Cheshire
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Posted: Sat May 24, 2014 7:20 pm Post subject: |
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baconsdozen wrote: | I had a similar problem on an old land rover fitted with a oil pressure gauge. It was an air lock in the pipe to the gauge. |
How could the pressure be different either side of the airlock ?? It's not a closed system ?
Dave |
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Bitumen Boy
Joined: 26 Jan 2012 Posts: 1740 Location: Above the snow line in old Monmouthshire
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Posted: Sat May 24, 2014 7:28 pm Post subject: |
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ukdave2002 wrote: | baconsdozen wrote: | I had a similar problem on an old land rover fitted with a oil pressure gauge. It was an air lock in the pipe to the gauge. |
How could the pressure be different each side of the airlock ??
Dave |
Because the air will compress easily whereas the oil or other fluid won't - if you think about it, that's why you bleed the air out of a hydraulic braking system. It's a good suggestion, certainly something I'll check if I get no luck with the more obvious stuff.
EDIT: it looks like Dave was busy editing his post while I was replying, but I always thought an oil pressure gauge was a closed system? I remember reading somewhere or other about someone who was unlucky enough to have the pressure line to an oil pressure gauge fracture behind the dash , or maybe come adrift from the back of the gauge, while they were driving - seem to recall they got some nasty burns off the hot oil squirting about inside the car. |
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Phil - Nottingham
Joined: 01 Jan 2008 Posts: 1252 Location: Nottingham
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Posted: Sat May 24, 2014 8:54 pm Post subject: |
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I had the flexi-pipe on the Mk2 Mini oil gauge frature and it sprayed loads of hot oil all over the engine and and exhaust - plenty of smoke and 3-4 pints of oil lost in seconds _________________ Rover P2
Rover P4
Rover P5 & P5B
Land Rover S2 & S3
Morris Mini Traveller Mk2 |
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bob2
Joined: 06 Dec 2007 Posts: 1728 Location: Malta
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Posted: Mon May 26, 2014 8:42 am Post subject: |
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Just had that happen to me last week in my blue mini, changed the oil pressure rubber hose during the weekend and all looks well now. Had to clean the engine bay, the one I had restored last summer, it was a mess and the smell of burnt oil inside the car was making me dizzy almost!! |
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MikeEdwards
Joined: 25 May 2011 Posts: 2502 Location: South Cheshire
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Posted: Mon May 26, 2014 6:44 pm Post subject: |
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Bitumen Boy wrote: | I've invested in a suitable thermometer (£5) to carry out proper testing, long thought one would be handy but always assumed they would be more expensive than they are. |
Funnily enough I saw one of those probe-type digital thermometers on a food programme last week, mentioned they were under a tenner on the high street, so have one on my shopping list. I also thought they'd be more expensive - and they probably were a couple of years ago - let's hope they prove to be more lasting than my digital multimeter.
I also have heard stories of low-cost oils at shows sometimes being not quite what they appear, though mine was a warning about "Comma" 20/50 shortly after I'd just bought some. It's been fine though - apparently the Comma fakes were clearly fake - poor labelling etc. |
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