Low oil pressure 13/60

[Antonnick]

So much helpful advice! Very grateful. I also had a look on U tube where there are some iformative videos on what to do.

[Antonnick]

I checked the movement of the crank as suggested by pulling on the wheel at the front by hand. Could detect only a slight movement, so this is Ok and a good sign I would think. The oil pump has been removed and dismantled and checked for clearances. Again ok - it looks quite new but probably because it is in an oily environment.

I am therefore sticking to the original plan of Mann Filter, LiqiMoly 20/ 50 oil and new spring for pressure relief valve and leaving the main and big end bearings alone. Whilst waiting for the bits, cleaning up the sump and painting the outside BMC green.

If there is no improvement on the oil pressure after a test run then will drain the oil out again for re-use, put in new bearings as recommended and see what happens then.

[glang]

good news so far but while you have the sump off waiting I really would open at least the big ends to look at the bearings. These are easier to do than the mains and wear out first so if good should mean the mains are also ok. As long as you keep everything very clean, dont force anything and retighten the bolts correctly you'll have no problem.

[RobPearce]

If you're following glang's advice, check no. 3 first - in my experience it's nearly always the worst - and make sure you put things back exactly as found. In particular, swapping caps between con-rods, or turning them round when re-fitting, will both wreck your bearings.

[PeteStupps]

I would be enormously tempted to remove the rear main-bearing cap as well, so you can properly check the thrust bearing clearance with a feeler gauge and also inspect one of the main bearings. Wouldn't have to remove the bearing from the cap, it's quite simple now you've got the sump off!

[Antonnick]

 

So, I have removed no 3 Bigend and here is the picture. This seems to show pitting, but which I cannot really feel at the finger. What I can feel is some very slight longitudinal scoring. This is also faintly seeable in the picture.

I suppose this means new bearings definitely now?

[glang]

hmmmm to me that doesnt look that worn as at the end of the shell you can see what looks like the original surface of the white metal and I take it you cant see any trace of copper in the scoring or pitting even with a magnifying glass? However the pitting, if thats what it is, I dont like and its definitely not what you normally see - how does the crank journal look and feel?

[Antonnick]

The crank looks quite shiny with some pitting but not like it is on the bearing shown. I will see if I can take a picture and post it in a minute.

[Antonnick]

Here is the picture. The picture surprises me as it looks more alarming than what I actually can see.

And there is no trace of any copper on the bearing.

 

[glang]

Difficult to judge from a photo but it doesnt look bad. I would try to have a look at the other half of the bearing to compare it but dont think the bigends are the cause of your low oil pressure. Are you going to take off a main bearing cap while youre there to discount them? If you do and find nothing and no expert on here really dislikes your photos I personally would put it back together and continue with your original plan. Is it possible that the engine has been worked on recently and someone has changed the bigends without doing the mains?

In any case you must really clean well that bearing cap and shell (especially the mating surfaces and of course sliding ones) before reassembly and retighten up the bolts correctly.

[JumpingFrog]

 

Quoted from Antonnick-

Here is the picture. The picture surprises me as it looks more alarming than what I actually can see.

And there is no trace of any copper on the bearing.

I'd say the bearing isn't the original tri-metal type from the colour (too light/shiny) so there is no copper. Looks to be a bi-metal bearing, IMO hard to gauge wear and more prone to damaging the crank.

The photo is a little small, so can't tell much. But by the sounds of it a regrind is required long term, new shells might help as a stop-gap measure.

[glang]

A possible cause for that pitting might be electrical. Apparently if the engine is not correctly earthed via the main earth strap current can flow in other routes even through the crank bearings which would explain why the pitting is spread around rather than being concentrated just in the area of highest load......

[glang]

Just thought, look on the back of a shell to see if its oversize and the crank has been reground.

[Antonnick]

Here is a picture og the backside - I have no idea what the symbols mean.

Electrical pitting  - when I took the sump off, the manual said that one of the bolts held an earthing strap. It did not. The strap is there but wedged between the sump flange and the block ( I assume it is the block) However it is very loose but even so I cannot free it. I bet that has intermittant contakt. Also when I got the car it was positively earther which I assume was on account of the installed radio - ( I took this out and restored the negative earth resetting the coil and Dynamo )

[Antonnick]

I have made a bigger picture

[RobPearce]

I can't really read the lettering on that bearing well enough but I don't see an undersize marking. The first photo does look like a bi-metal rather than the preferred tri-metal bearing but, despite the odd speckling, it's got no signs of localised wear - the whole surface looks to be in the same state. It's exceedingly rare for a big-end to show completely even wear across the whole surface, so this suggests there's actually no visible wear at all.

I'm leaning towards the theory that somebody has replaced the bearings, probably quite recently, but didn't have the crank re-ground. That would be an entirely reasonable course of action for a bit of light wear evident on the bearings, except that, if the wear was light enough to not raise any concern, the original part-worn bearings would probably have been better than the cheap bi-metal replacements.

[Antonnick]

Ok, I will clean it, oil it, put it back, torque it up and then try and then remove a main bearing - probably the middle one, and have a look at that. If that is also reasonable, then back on with the sump cover , oil and filter and see what happens to the oil pressure.

[nang]

I can read 'STD' stamped on shell which I imagine means standard, original size crank. Really think you need to measure accurately the shaft journal. Otherwise we're only guessing. Can you borrow a micrometer ? 

Tony.

[glang]

I believe the thinking is that if the PRV wasnt seating properly oil could leak past constantly which isnt a problem with cold oil or high revs but could result in a low system pressure with hot oil at tick over......

[Antonnick]

If it does leak past the valve, where does it go then? Certainly it does not leak out in mine anyway. I have general low pressure anyway with ca. 25 PSI @ 80km/hr.

I have also measured the shiny shaft before replacing the bearing (where the bearing was attached to - is that the "journal"?) not with a micrometer but with digital calipers @ 41,29 mm so this may not be too accurate. Having now looked this up in the manual which says 49,92, I must have measured it wrongly. 😭

Next step is main bearing removal  to check, hopefully later today.

[glang]

The excess oil is dumped back to the engine sump so externally you wouldnt know it was happening. However in your case this seems unlikely but is something worth looking at....

Using calipers it isnt really possible to get an accurate enough measurement of the journal dimensions (were talking thousandths of a milimeter here) and anyway as said previously the wear on the shell doesnt seem to show that kind of issue.

Keep up the good work, sure you'll sort the problem out. My Vitesse was similar until I changed the main bearings (big ends had been done quite a while previously) and installed a new larger capacity oil pump.

[RobPearce]

Quoted from Antonnick-

I have also measured the shiny shaft before replacing the bearing (where the bearing was attached to - is that the "journal"?) not with a micrometer but with digital calipers @ 41,29 mm so this may not be too accurate. Having now looked this up in the manual which says 49,92, I must have measured it wrongly.

Which manual did you look in? The official Leyland/Triumph manual (part #511243) gives the "crank pin diameter" as 41.27 to 41.28 for a GE-prefix engine.

Anyway, as glang said, you can't measure it accurately enough with callipers.

[Antonnick]

Quoted from RobPearce-

Which manual did you look in? The official Leyland/Triumph manual (part #511243) gives the "crank pin diameter" as 41.27 to 41.28 for a GE-prefix engine.

Anyway, as glang said, you can't measure it accurately enough with callipers.

The informations I got from the Workshop manual, Camshaft journal dia. Dimensions. It gives 1,9654 " and 49,92 mm for the 13/60........?????????? But despite the innacuracy of the calipers, it would seem the crank has not been reground.

[glang]

Antonia are we talking about the same things here? You have written 'camshaft journal' while the dimension we need is for the crankshaft pin journal. Anyway as you say I think we can take it that the crank is standard - if it had been reground and standard bearings used it would have run for about 5 minutes and sounded horrible

A micrometer is useful not just to check whether the crank has been reground but also, by taking numerous measurements, if the journals have worn oval. However in your case thats not something to worry about at the moment😆 

[Antonnick]

That would explain the very different measurements. Journal and pin journal. so the pin Journal is the shiny bit but what then is the journal - I had to look the word up in the dictionary which at first insisted it was a "newspaper" until the technical section was shown (www.leo.org)

Anyway next step is to look at a main bearing and if this is OK as well, then what else can cause my low Oil pressure? The question is perhaps premature because if the bearing is ok, then I need to first test with the new Mann filter ( it is quite heavy when compared to the old one) new PRV spring and above all, the Liqui Moly 20/50.