Oil Pressure Relief Valve . . . Herald 1147cc (1970 - original engine)

[Colin]

So . . . yet another of my mini sagas. New (club 20/50W) oil, new filter, engine flushed beforehand, using proprietary product.

Following the heater and engine flushes shinannigans some may remember (heat now restored and probably as good as it will get), I have been running her around town.

First couple of drives, straight after start-up, the oil pressure warning light came on. And stayed on for the 10 or so miles driven. 

Same for the next couple of drives.

On a longer, 30 mile, drive, the warning light was on initially, but went off after 4 miles or so - and stayed off.

The engine doesn't knock or rattle. It is 'tired' at 142k miles in so much as I can turn it by hand using (pulling/turning) the fan belt and fan blades, spark plugs in. But I have always made sure oil changes come far more regularly than they really needed to have been scheduled.

The car has no oil pressure gauge (something I intend to remedy at some point!).

Whislt trying to convince myself that the engine doesn't yet need a full Club rebuild, I idly wondered if the oil pressure relief valve spring may be tired. So looking at it as being a relatively quick job, replaced it. Tricky, as the filter was still on and I found the engine mount bracket getting in the way of withdrawing its cap - but it was just possible.

I admit, I didn't, "clean the seat in the crankcase with a piece of hardwood" (Autobooks Manual recommendation), presumably running some petrol in to clean any gunk at the same time. So I have no idea if that action would have made any difference and whether the seat was/still is gunked up or not.

Then, of course, I took her for a 10 mile run.

The warning light was on all the way, this time!

I don't really know what I'm asking of any of you reading this, but it'd be interesting to know of anyone else has had this experience - and if so, what their advice would be.

A Swiss chum of mine posed the thought that the oil pump may be worn - could be at 142k miles?

And that changing that could be a solution.

I'm thinking that if I have to drop the sump and replace the oil pump (and big ends at the same time??), I may as well just lift the entire thing out and send it packing for the full Monty pro Club rebuild!! (must be getting old and lazy!)

Thoughts please Gents. Back later to check on responses. Thanks.

Best,

Colin

[Clive]

So changing the oil/filter resulted in the oil light staying on?

I would put another filter on, see if that was the issue. And put the original PRV spring back in (is it longer?)

Next is a new oil pressure switch.

After that, drop the sump, a new set of big ends, and the mains that are accessable, can make a big difference and restore much of the lost oil pressure. Enough to last thpusands of miles if the engine is otherwise healthy. Likewise if the pump is outside of spec or scored etc (beware, some new pumps can be worse than the originals)

[Adrian Cooper]

Hi Colin,

While we wait for one of the wiser members to reply I'll just say that I would swap the oil pressure warning light switch before doing anything else. The way it stays on for several miles and then goes off is the opposite of what I would expect for driving until the oil warms up. I would also expect that your engine would not sound too healthy after driving for long periods with the oil pressure too low to switch off the warning light.

My 1147 engine has just passed the 200k mark since I had it rebuilt in 1985 and, like you, I have always changed the oil every 3k miles or every 6 months, whichever came sooner, so these little engines can go for long distances if looked after. Mine is a bit noisy now but it still has excellent oil pressure, uses next to no oil between changes and revs very sweetly. The 1147s are jewels.

Adrian

Ah, Clive got there first. What he said

[Iain T]

Was the oil light coming on before or has it just started? 

If the problem has just started then look to the items you've just replaced. Clive's reply is on the button. 

Iain 

[Pete Lewis]

agree start with the simple  as the pressure warning was on before you swapped the spring its more likely the pressure switch has failed 

especially as its not that consistent with what its trying to tell you

follow clives ideas , but big ends and pumps dont fail due to changing the oil 

do the simple first , as its not overly noisy and runs fairly well go for the switch 

Pete

[Colin]

Thanks to All for your thoughts:-

The Oil Pressure light coming on and staying on is a relatively new phenomenon. Prior to recent events, she would only show the dash Warning light on start-up and it would reassuringly go out very quickly after start up and often didn't even need a quick throttle blip.

This was happening before this very last and most recent oil change (so I thought I'd change the oil for new - it turns out, when I checked records later the 'old' was virtually new anyway - durr). Better safe than sorry.

My other thought about the dash OPWarning Light coming on, but then going out after 4 or so miles was that, at the high mileage and there being 142k miles of natural wear, all aspect of the car's engine components having heated up properly may have 'sealed' any 'looseness'/wear that exists in its cold state??

Thus preventing oil flowing where it shouldn't, even when thenoil was hot - so maybe the engine is in decent condition despite the high mileage? As I said, no knocks, slaps, rattles or otherwise. Nice steady tick-over etc . . . 

I have a new pressure switch and seeing as I have changed the OPValve, may as well change this, too - but in all honesty l can't see how this item, with no wear or adjustment being integral to its being (?), could affect the situation (am I wrong about this switch's lack of adjustment/performance ??!?).

Re-change of oil pump, big ends, anything I can get to renew from underneath, I know my Swiss chum has several (English) cars on stupidly high mileages, resulting from over-frequent oil changes and occasionally changing easy-to-reach main components.

If I was going down the drop-the-sump route, how can I tell if the replacement oil pump measures up to being a good one? I usually stick to parts supplied by the main suspects in the market place, so one would hope they are the real deal . . . . 

Cheers again,

C.

[Colin]

All:- Forgot to mention; the old OPRValve spring was spot on in terms of length and so hadn't weakened, or become faulty (to the eye, anyway).

 

C.

[Colin]

Pete - that's next on my list - thanks - (why could/would it 'suddenly' start to give false readings??)

[Colin]

As an aside, Clive - if you're thinking I have an oil filter with built-in pressure relief (that I think som earlier 1147's had), you'd be wrong. If so, I could see where you are coming from.

 

It's a spin-on, spin-off type.  

Cheers,

C.

[Pete Lewis]

its a simple diaphragm and spring operates like a bell push if the spring has decided to fail you get all sorts of false warnings

please do not go down the sump off for this untill you do the simple basic first 

bearings and wear and tear are a progerssive problem not an overnight experience 

do the easy   is  the  most important first line of attack

 

some spin on filters have stopped the pump from priming theres a couple of posts way back about this happening 

again filter swap is easy   ...but only change one part to identify the culprit not all the parts at once 

Pete

[Iain T]

22 minutes ago, Colin said:

? I usually stick to parts supplied by the main suspects in the market place, so one would hope they are the real deal

Colin that's an over generous assumption! Oil pump end float is the death knoll for oil pressure. Easy to check with a feeler gauge but it seems like you will hopefully have a simpler solution to your problem. 

[Colin]

Thanks again, All.

I've never heard of the oil filter stopping the pump priming . . and certainly not ever experienced it!

Does this mean the filter is faulty?

Is it like an air-lock?

Could I not release it and re-tighten?

Is the ONLY solution to change the filter?

Best,

C.

[Colin]

But I will change the switch first! 😃

[Colin]

Pete - everything's in situ, so I have no good line of sight:- could I have mis-positioned the spring & valve on replacement?

As I said, I didn't clean out the end 'cup', or whatever it sits in that I can't see . . .

Should I do that, clean it out/off, replace the valve, spring and end cap ?

Will still change the switch, too btw . . . 

Cheers,

C.

[Clive]

37 minutes ago, Colin said:

As an aside, Clive - if you're thinking I have an oil filter with built-in pressure relief (that I think som earlier 1147's had), you'd be wrong. If so, I could see where you are coming from.

 

It's a spin-on, spin-off type.  

Cheers,

C.

The cannister filters have a bypass valve built in, in case the filter gets blocked. 

My thoughts about changing teh filter is that if changing it was done and the problem occured after, the filter is a possible culprit. Especially now the only filters available are not made by a known manufacturer. 

[Colin Lindsay]

I'll agree with Pete: do the simple first. I'm not an engine expert in any sense other than a) keeping them running and b) wasting as little cash as possible on them, so a simple solution always appeals.

If changing the oil pressure relief valve has caused an issue then trying another might be a solution (especially if the new one is poorly machined and may be sticking) however I'd rather be sure especially if it was the old relief valve at fault - you need to know the actual pressure so get hold of a pressure gauge and see how it reads. I have two or three old original period gauges that I'll happily share if you need one. I don't have one fitted to the car but as spares on the shelf where they can be attached to any engine when required as a check especially after a rebuild. 

I'd also consider the pump before any more engine work - the higher output of a good one can overcome wear and give a few more miles in the life of the engine.

Simply changing the switch to get the reading you want, without any data to back it up, may lead to more problems in future.

[NonMember]

54 minutes ago, Colin said:

I have a new pressure switch and seeing as I have changed the OPValve, may as well change this, too - but in all honesty l can't see how this item, with no wear or adjustment being integral to its being (?), could affect the situation (am I wrong about this switch's lack of adjustment/performance ??!?).

Oil pressure warning switches are cheap, nasty devices and they absolutely DO fail in that way. Very common. Try changing it first, or (as Colin says) put a gauge on to see what's really happening (at least within the limits of gauge accuracy, which is pretty poor).

[Colin]

All:-

I won't try to 'engineer' the result I want (i.e. to get the warning light to go out)!

But I have no great desire to be clambering under it to change what I don't know is faulty.

I don't understand an oil filter change preventing the oil pump from priming. If it has, I've covered 50 odd miles risking wearing the engine severely!

I'll try the switch first - again, not sure why this should fail.

If not, I'll simply change the filter and hope the replacements I have are not a bad batch (Club supplied & didn't know these could fail . . )

Any answers to these , my comments are welcome!

Best,

C.

 

 

[Colin]

All - the old OPR Valve

 

Seems to have a shiny area on the bell-end (sorry!) 

Views on it welcomed!

[Pete Lewis]

the likely hood the PRV is playing up is best sent to room 101   the filter change is the last job you did before this all started 

both filter and switch are a simple swap , nothing complicated , this is the only action you should take for now , 

do not start diving after deep rooted myths and agnst   just do the simples and sleep easy 

let us know what you find when you have changed them then if needed we will all jump into  getting oily and empting your wallet ...last resort 

 

[Colin]

Pete:- Ha, ha! 

Yes - understood. 

Many thanks.

Commencing soon and will report back.

All continuing thoughts still welcomed!

Best,

C.

[Pete Lewis]

filters are a simple part full of areas that can be mis manufactured  , they are relatively cheap parts made in their thousands 

the non primeable filters were mainly alternatives with very strong anti drain , best suited to a modern pump not our 50 year old ones 

if you have driven 50 miles it would have wrecked something else by now .

the shiney area is the contact seating as the plunger is modulating to control any excess pressure  ,,,its quite normal

if you strip a LP switch its a very cheap simple bit of kit  it relies on a weady spring and small diaphragm  as i have said  more like a cheap bell push 

its very easy to fail engine vibrations will wreck the spring inside over time  and we all think this is what has failed 

you have one  ..just fit it   stop going down the impending disater route till you have swaped the cheapest fix first 

Pete

[Iain T]

Don't forget the tea and biscuits. Essential workshop accessories! 

Iain 

[68vitesse]

29 minutes ago, clive said:

Especially now the only filters available are not made by a known manufacturer. 

Recently had a delivery from one of the main suppliers, the reused box originally contained oil filters made in India.

I have an oil pressure gauge fitted to my car, I would only worry if it showed a different reading from the usual one, they are known as worry guages for a reason.

Regards.

Paul.

 

 

 

[NonMember]

1 hour ago, Colin said:

I'll try the switch first - again, not sure why this should fail.

As Pete says, cheap mechanical bit that's subjected to a lot of vibration.

Many years ago, before I'd learned my share of the wisdom Pete and others bring to us here, I had the oil warning light come on. This was my first car, a Mk1 Vitesse. I "knew" they suffered big end problems, so I jacked the engine up, dropped the sump, replaced all the bearings, reassembled with new filter and oil. It made absolutely no difference at all. Then I fitted an oil pressure gauge and discovered that the oil pressure was absolutely fine; it was just a broken switch. Members of my local group at the time then informed me that this was the first thing I should have checked because they are well known to fail that way.

We didn't have the Internet back then. With luck, we can now save you the expense and hassle of replacing things unnecessarily, before you've done all the work.