Help! Oil pressure!

[wilhelm116]

Help!!!

I'm having problems with low oil pressure!! I changed my oil recently (the old oil had been in there for 4 years - previous owners fault). I replaced the filter and filled with Castrol GTX, as recommended.

After a few days I noticed a drop in oil pressure. When the engine is warm (say, after 8 miles), the pressure when idling drops to around 5psi and the orange light comes on, when running at about 35mph, the pressure is 23psi. The gauge and sensor have been replaced just to make sure.

Thinking that castrol might've changed since 1965, I have just replaced the oil with Halford's 'Classic Car oil' of a different grade, only to find that the problem has worsened slightly!

There is no blue smoke from the exhaust and the car only consumes about 300miles to the pint. There are no leaks, and the radiator is clean, I have checked the pressure relief valve and that is fine.

When cold, the pressures are normal.

I have no idea what to do. Is there a thicker oil that I could use that doesn't thin so much when hot? I think this may help. I am currently at University in North Wales (Bangor) and need to get the car home to Coventry by next weekend !

Many thanks

Will

[Packedup]

When cold, the pressures are normal.

Oh dear.

When you changed the oil and filter, did you spin the engine (on the starter or with the handle) till the warning light went out, before letting it fire? Cause it sounds a bit like bottom end bearing failure to me, possibly accelerated by oil starvation at startup when you changed the oil

You might be able to get home if you stick some oil thickener (STP, Wynns and Unipart/ DX do them, called something like conditioners or stop smoke, not engine bodge as they should be known!) in, but if you have chance and a spare 30 quid or so I'd drop the sump and check the big end and mains for extreme wear. If they're through to the copper they need replacing, and will make a big difference to the oil pressure. The good news is this isn't too tricky a job, not done it on a Minor engine in situ, but it looks like there's far better access than the cars I have done it on!

Worth double checking it isn't anything else first thoguh if you don't enjoy spending a couple of hours under a car with oil dripping into your eyes...

[Willie]

What is the oil pressure at start-up from cold??

[rayofleamington]

I was thinking that it could be a blocked filter but after more thinking I'm not sure as a blocked filter is (probably) downstream of the pressure switch, therefore that wouldn't be it (although it would wreck your engine, so just hope the previous 'ok' oil pressure wasn't a result of a blocked filter!)

As a desperate measure I would also think about a blocked pick up strainer (not common on Minors as the strainer isn't small)

[bmcecosse]

The previous 'ok' oil pressure would be because the filter was blocked - it was preventing the oil running away through the worn bearings. You could try 20W50 oil - £2.74 from ASDA - but to be honest your engine is knackered - start looking for another.

[Packedup]

The previous 'ok' oil pressure would be because the filter was blocked - it was preventing the oil running away through the worn bearings. You could try 20W50 oil - £2.74 from ASDA - but to be honest your engine is knackered - start looking for another.

Surely if there's only slight crank wear new bearing shells will do the job (I've had a Triumph with dreadful pressure, put new shells on a slightly worn crank, and it was been fine for 3 or 400 hard miles, till I shunted it )? Or at least be a quick and fairly cheap fix so he can get the car back home?

They might even last a good few thousand miles if he's been really lucky

[Willie]

The fact that the old oil had been in there for four years probably
meant that it was somewhat 'gloopy' and thus giving a misleadingly
high reading. If you are dropping to such a low tickover pressure
then, as BMC says you will need a complete recon or a new engine.
My engine was dropping to 5 psi on tickover so I replaced the big
end shells (without removing the engine), and it was a complete
waste of time because the crankshaft had noticeable grooves worn
in the bearing surfaces which ruined the new shells within ten miles!!

[bmcecosse]

New shells just a waste of money when the engine is as bad as this. It will also need a new oil pump - so engine out for that. The idle pressure is not really worrying - but the low reported pressure when running definitely IS worrying. However - driven carefully it will be ok for poodling about - just don't take it on the motorway.

[wilhelm116]

Many thanks for the replies!

Oh dear, that does sound pretty serious. When I start the car from cold the pressure zooms straight to 60psi and stays there for quite a while (say 10 - 15mins of driving). Then I get normal pressures for about 20mins, and then they start to drop really low.

Just another thought, I know it's rare but could the oil pump have failed? If the oil pump was caked up with gunge from the previous (lumpy) oil, could the new oil have dislodged the rubbish sealing it?

The filter has been changed twice now and the result is the same. When I changed the oil I did crank the engine over a few times with the handle.

I'm a bit limited to what I can change while I am here. I'm staying in Halls of residence and the Uni and so the car is in their car park. I have enough tools to accomplish most tasks (i.e. nearly everything on the Haynes manual list), but only one jack and no axle stands. Also, I need to get home this Friday and any work is dependent on the weather (if you've ever lived near here you'll know what I mean!).

I've spoken to my Dad (back in Coventry), he reckons my best bet is to put some form of oil treatment/thickener and take it easy on the way home. He's started hunting for a new engine already.

If I replaced the engine I would like to restore the original and untimately reunite it with the car. If the bearings are knackered what new parts will I have to start looking for?

Many thanks for all the help!!!

Will

P.S. Does anyone have a spare 1098 engine!!!

[bmcecosse]

We don't know where 'here' is ! You will need a replacement crankshaft - or have that one re-ground plus a full set of bearing shells. Gaskets obviously - and fit a new oil pump - it will be well worn. may as well fit a new timing chain and tensioner rings (and seal) and when in there you may as well fit a new clutch plate unless you know it has been done recently.

[Willie]

The fact that you get 60 psi at start up suggests that the pump is
ok, and that the pressure relief valve is set correctly. It is interesting
that you then get fifteen minutes of normal pressure, I wonder if your
engine is seriously overheating thus losing you pressure?

[rayofleamington]

I wonder if your
engine is seriously overheating thus losing you pressure?

I just thought exactly the same thing!
An overheating engine will loose a lot of oil pressure (the pump won't work as well due to the low viscosity and it will leak out of all the bearings too quickly so it will be harder to maintain pressure.

If it's not overheating then it sounds rather serious.

Regarding the big ends, I had a problem with oil pressure on my first Minor due to very high mileage and it was showing the warning light when hot. I changed the rocker shaft (badly worn) and also the big ends. The car was transformed and managed another 40,000 miles.
By the sounds of it, I may have been lucky but other people have also managed to improve their oil pressure by changing the big ends.

I did mine outside in the rain with the car on wheel ramps (in Winter). The hardest part was getting the sump screws back in and the oval washers lined up in the dark :grrr:

[bmcecosse]

No - fraid not - ANY pump and engine will do 60 psi on cold thick oil. It's when it's hot that counts. The pump will be scored and knackered - sometimes get them on ebay for £5 - keep a search going for them. Crank regrind should be £40 - and bearings about £30 for the set. Gaskets/seals and timing chain about £10 - try BullMotif. Some Cos are doing service exchange cranks at HUGE expensive - don't encourage them !

[rayofleamington]

Or if you are feeling lucky, try a £25 to £50 second hand engine...
(I've been lucky with those!)
If you are really lucky you will be able to try the engine out before it is removed from the donor car.

[Packedup]

Regarding the big ends, I had a problem with oil pressure on my first Minor due to very high mileage and it was showing the warning light when hot. I changed the rocker shaft (badly worn) and also the big ends. The car was transformed and managed another 40,000 miles.
By the sounds of it, I may have been lucky but other people have also managed to improve their oil pressure by changing the big ends.

I've yet to have the joy of worn big ends on a Minor (I still don't own one! ) but having had a succession of Triumphs I totally agree with you. I've had 2 engines where new shells didn't really do much. One crank was very worn and chewed the bearings within 100 miles, the other wasn't as bad but still didn't hold together for long. However, one I had on the road till recently had very poor presure when hot, a new set of big ends and mains and it's the smoothest 1500 I've driven. Not a sign of low pressure even when the engine was cooking in a traffic jam. New shells in my current car (a 2000) has done wonders for the pressure too, it now sits at 60 - 80psi when cold (my tickover is a touch too high cause my carbs are shot though), and well over 30 when warm (longest run I've done is about 20 miles). This is far better than the 2 or 3psi I saw when I drove it home!

So I'd say when possible, dropping the sump and seeing just what the crank is like is well worth it. If it's only got slight grooves worn into the journals then a new set of shells is worth a risk in my opinion, given the price of them.

I did mine outside in the rain with the car on wheel ramps (in Winter). The hardest part was getting the sump screws back in and the oval washers lined up in the dark :grrr:

Sounds a bit like the first time I did the Triumph's ones... The fun was hands that were numb through cold, but still hurt like hell when the ratchet slipped...

[rayofleamington]

The fun was hands that were numb through cold, but still hurt like hell when the ratchet slipped...

yup - that's one of the many reasons that Monty was started in August and 2/3 of the work is now done

[bmcecosse]

Aye it's always worth a look - but if they have been run for any length of time with low oil pressure then sadly it will be too late - and you can't easily change the front main bearing - well you can if you pull the timing cover off too !

[Packedup]

Aye it's always worth a look - but if they have been run for any length of time with low oil pressure then sadly it will be too late - and you can't easily change the front main bearing - well you can if you pull the timing cover off too !

I honestly can't remember what access is like to the front main on the A - Is it totally impossible without removing the cover, or just very tricky? Also, does it wear as much as the others? I was told by an expert when doing my 6 pot, that the front doesn't get anything like as much wear as the others and so was safe to leave as otherwise it's a pig.

Besides, 4 big ends and 66% of the mains done should still recover a reasonable amount of lost pressure as a short term fix (providing the crank isn't toally u/s)

[Kevin]

Will your oil consuption does suggest some wear & tear but I just wondered how you checked your oil presure relief valve because a few years ago I had a moggie that was running ok but when warmed up started suffering from a flickering oil light so I changed the valve as I had a spare and it solved the problem and when I sold the car a year later it was still ok.

[wilhelm116]

Cheers,

I borrowed the ramp at a local garage and dropped the sump, it looks like the crank is pretty bad, the bearings are very poor. I can't get the spares in time to have the car repaired by friday. I know that running it with such low oil pressure isn't good and will cause huge amounts of damage, but I need to get home (be it on an RAC trailor or at 10mph).
When I eventually crawl home I will fit a new engine and work on the knackered one over the summer.

I have been offered a 948cc engine in Conwy (about 25miles from here - here being Bangor) and a friend has offered to bring it round in his land rover, but with lectures and seminars to go to, I won't be able to fit it in time (plus I'll be stuck with my original engine in the wardrobe in my flat with no way of getting it back!).

Will your oil consuption does suggest some wear & tear but I just wondered how you checked your oil presure relief valve because a few years ago I had a moggie that was running ok but when warmed up started suffering from a flickering oil light so I changed the valve as I had a spare and it solved the problem and when I sold the car a year later it was still ok.

I checked the valve to start off with but cheers!

The engine has had absolutely no work done on it since it was new (save an oil filter conversion), so I think it's about time I whipped it out and stripped it. We think the car has been three time around the clock and it's about time for something to go wrong.

Would I have to get the engine rebored? It doesn't burn oil and the pressure is good.

Many thanks
Will

P.S. I thought you might like to know a little about me, I am 18 and a first year at Bangor University studying music. I have grown up with restoring cars (my dad has two Bristols, a 410 and a 411). I have owned my '65, two dr, grey for only 3 months and I think it's fab. Not only that, nearly every one in the university know's me as 'the guy with the morris minor' and they think it's fantastic.