High oil pressure and oil loss - BMC 1.5

[bizzard]

There maybe some kind of severe blockage in the oil gallery somewhere behind the relief valve. It might be worth starting the engine up and slackening off the big relief valve nut to see if there's any oil under pressure there, it should ooze or squirt out from around the threads. Or perhaps someone has stretched the spring. You could even try momentarily running the engione without the relief valve spring in there or even the valve, but be careful and be ready to stop the engine immediately if there's no or little pressure shown on the gauge.

[jhodgski]

I never said I trust the gauges. I had good reason to believe the previous one may have been faulty because someone dropped the sender onto a hard floor whend it was out.

 

I had no reason not to buy another one because the previous one had been reliable for years up until that point, and I had no idea that electromechanical gauges/senders could be unreliable.

 

I'm now at the stage where Ai really.can't afford to fork out another £50 on a mechanical gauge/sender, so before doing so I am seeing if the issue may be something else.

[RLWP]

There maybe some kind of severe blockage in the oil gallery somewhere behind the relief valve. It might be worth starting the engine up and slackening off the big relief valve nut to see if there's any oil under pressure there, it should ooze or squirt out from around the threads. Or perhaps someone has stretched the spring. You could even try momentarily running the engione without the relief valve spring in there or even the valve, but be careful and be ready to stop the engine immediately if there's no or little pressure shown on the gauge.

 

It would be safer to unscrew the sender, put the wire back on, connect the body of the sender to the negative terminal by laying it on the block then turn the ignition on - don't start the engine

 

If the sender still reads 10psi the gauge set up is faulty

 

Richard

[jhodgski]

Richard, So I've just run the engine for 5 or 10 mins then stopped it. When stopped, the gauge was reading about 5 psI. (This is possibly because I unscrewed the oil filter earlier and haven't tightened it back up as tight, or maybe because the engine wasnt running for as long this time, or cos the throttle was in a different position.)

 

Anwayz I've just tried what you said and the gauge reads bang on zero when I take it right out and ground it's thread.

 

When I put it back in, it still reads bang on zero.

 

To me, that suggests pressure has built up somewhere and removing the sensor has released it.

Bizzard, I slackened off the release valve hexagon whilst the engine was running. A little oil came out, but not much. It didn't seem high pressure to me - albeit to my untrained eye.

 

I shall remove the spring now and let it run for a couple of seconds...

I don't think the spring is stretched, by the way. Its about 2 and 7/8" - and about the same length as the spring on my previous engine.

[RLWP]

I would now agree you have some residual pressure, and probably more complications

 

Well done doing that test - we can now trust the gauge

 

So, what does that leave? I wonder if we have a schematic of the oil circuit

 

Richard

 

MORE: What is the history of this engine?

Edited December 6, 2014 by RLWP

[RLWP]

I have another thought - if you remove the rocker cover, is oil getting to the rockers? It should be pretty oily up top there and if you run the engine it will splash everywhere

 

Richard

[jhodgski]

I've just run the engine with the release valve spring taken out.

 

I ran it for 2 to 3 seconds and the gauge stayed on zero the whole time.

 

For comparison, before and after that test, I ran the engine with the spring in place and it went up to 80 psi within 1 second.

 

So what could this indicate??

[RLWP]

That the spill pipe from the relief valve to the sump is clear

 

What's the story of this engine? I'm wondering about blocked oilways

 

Richard

[jhodgski]

The history of the engine is that it has always run fine according to previous owner (who I trust), but he never had an oil pressure gauge - only an oil pressure warning light.

 

He had it (fully?) serviced by Calcutt about 3 years ago.

 

Between him and me, the engine had one temporary owner who couldn't fit the engine in his tractor so sold it on (to me).

 

I'm in touch with the original owner and he's asked me to keep him updated, so I'm sure he'll help us out with any more info that may be required (?).

I've had a look at the rockers by removing the oil filler cap and there seems to be a reasonable pool of oil up there. Not splashing around, though.

[jhodgski]

I'm not 100% sure on this, but I'm pretty sure that, after stopping the engine, when I unscrewed the oil filter the reading on the gauge didn't drop (ie, it stayed at 10 or 5 psi). Hopefully this means (bearing in mind that the oil pressure did drop when I removed the nearby oil pressure sensor) if there is a blockage, it could be located somewhere around the oil filter boss - so might just be that case that it easy to access and unblock - or is that just wishful thinking?!

 

Yes, a schematic of the oil system would be VERY handy!

[jhodgski]

...just checked again, and am now 100% sure that when I remove the oil filter after stopping the engine the oil pressure reading doesn't reduce. Does this mean (regardless of which way the oil flows between them) that there is a blockage in between the filter and the oil pressure sensor - because a blockage is the only thing that could cause them to be 'disconnected' in this manner??

...if so, presumably the first suspect area would be the entrance to the oil filter?

[RLWP]

Not if the oil is sucked through the filter

 

Tony will probably know how the circuit works, let's see what he says

 

Richard

[Bod]

What make of oil filter is fitted?

Where did the filter come from?

Well known supplier, or internet supplier?

Is the correct filter fitted?

Has it been changed?

 

Lot of questions, I'm wondering if you have a sub-standard/fake oil filter.

 

Bod

[jhodgski]

Hiya Bod, I think the oil filter is a Fram. It's the screw-in type, anyway. Came from local (reputable) motor spares shop in Holmfirth, called Wheelsbrook.

 

I bought and put this new filter on, along with an oil change, soon after I bought the engine (before I first ran it).

 

I've still got the old filter knocking about somewhere, which I think was the cartridge type. I could always refit it to see if it makes any difference?

[Tony Brooks]

The 1.5 originally had a cartridge in a can type filter with the "blocked filter" pressure bypass valve as part of the filter head assembly. I have not seen a spin on filter adaptor that had the bypass valve as part, I think because most (but not all) cartridge type filters have one built in. As the bypass valve should only operate when the filter itself is blocked I do not see that being the problem, although a faulty filter could be.

 

The filter should have a large "rubber" anti-drain down valve around the holes outside the centre screw thread and if that is in some way blocked then being a full flow system it would cause excess pressure between the pump and filter. However I do not know where the sender is located relative to that pump to filter drilling. Seeing its next to the PRV I suspect it is in that drilling so the cartridge (being the only thing that has changed apparently) would be my first suspect but if it is a Fram filter its all rather odd. Is there any chance its a diesel filter? They do not have bypass valves in them.

 

I seem to remember a oil system schematic is in the on-line manual I gave you a link to some time ago. However oil should flow straight from the pump to the filter and then ALL of the flow that went to the filter should be sent around the engine. The PRV is normally (not 100% sure about this specific engine) between the oil pump and filter. The only time the full oil flow does not pass through the filter is when the PRV is operating or when the bypass valve has opened.

 

 

Is this by any chance a remote filter? If so I would say the flexible pipes may also be suspect.

[jhodgski]

Hiya Tony,

 

The sender is located between the injection pump and the flywheel.

 

The filter (not remote) is on the other side of the injection pump.

 

The PRV is on the other side of the engine, close to the flywheel.

 

Given that when the engine is turned off, the pressure reads 5 to 10 psi and it doesn't reduce when I remove the filter or the filter head - then wouldn't this rule out any issues with the filter or filter head?

 

More specifically, because the oil pressure does drop to zero when I remove the sender then doesn't this indicate there is a blockage between the sender and the filter head??

 

I will hunt for online manual / schematics now...

Edited December 7, 2014 by jhodgski

[jhodgski]

I've found the schematics. For easy reference, here they are...

https://db.tt/BoFqrVQz

https://db.tt/Rk7jJYQl

[Tony Brooks]

Hiya Tony,

 

The sender is located between the injection pump and the flywheel.

 

The filter (not remote) is on the other side of the injection pump.

 

The PRV is on the other side of the engine, close to the flywheel.

 

Given that when the engine is turned off, the pressure reads 5 to 10 psi and it doesn't reduce when I remove the filter or the filter head - then wouldn't this rule out any issues with the filter or filter head? Ie, that the issue must lie elsewhere?

 

I will hunt for online manual / schematics now...

 

I know where the PRv, sender and filter on the OUTSIDE of the engine, I am just not sure about how the drilling's run inside the engine. However now you have found the schematics they should tell you.

 

It sounds very much like a blocked internal drilling to me but how and where I have no idea. I have never come across this before. I think you said that you have checked/cleaned the injector drive skew gear oil jet and strainer, if not have a look at them, especially the strainer. It just might be between the oil pump and filter. Otherwise I am stumped and would start to force thin oil through the various drilling that you have access to when the filter, prv, sender unit, oil jet, and oil strainer (as above) are removed. That way you may find where any blockage is (if there is one). Otherwise I fear it might be an engine strip to use compressed air to blow through all the block drillings.

[RLWP]

It looks like the relief valve branches of the drillings to the filter, I cannot see where the pressure gauge tapping is unfortunately. Those really are more of a schematic than an accurate representation of the drillings

 

I'm afraid I agree with Tony. If the schematic is accurate, it is possible the injector drive filter is in line with the feed from the filter. If that isn't it I suspect a blocked drilling in the block

 

Richard

[RLWP]

I've had a go at highlighting the high pressure and filtered oil feeds to the schematics:

 

 

 

Richard

[jhodgski]

Cheers for the replies. I think the components are in this order:

 

sump > PRV > sender > filter

 

Can anyone tell me where the oil pump is located on the engine / schematic?

Great stuff, Richard. Bonus point for reading my mind, too! :-)

[RLWP]

This new crystal ball is much more reliable

 

I suspect (WARNING) that the sender is in a side branch off the main horizontal drilling. On an A series, you can see where this drilling goes as there is a half cylindrical lump along the side of the block

 

Richard

Edited December 7, 2014 by RLWP

[jhodgski]

OK, thanks - but why is that a warning / what's the danger?

[RLWP]

From a blocked drilling? Which drilling, blocked with what, what isn't getting oil that should be?

 

MORE: Oh sorry - the (WARNING) thing - it means I'm guessing rather than knowing, so check to see if I am right rather than assuming I am

 

Richard

Edited December 7, 2014 by RLWP

[jhodgski]

Correction: It's a Reisse 48140087 filter. Photo here: https://db.tt/YzkY4i1N