Potential Oil pressure issue

Hi guys!
Had my td5 for nearly 9 years, with virtually no problems at all.
As the weather has dropped over the last couple of weeks I've noticed my oil light taking a ever so slightly longer to extinguish once the engine is turned on. Over the past week it seems to stay on about 1 second until it goes out, once warm the light goes out as usual, immediately upon engine starting.
I've ordered a new oil pump sprocket bolt, sump gasket and sealant from turner's, which will be arriving tomorrow, fingers crossed this isn't the issue as it looks like the sumps been off before, but no way of knowing until I physically do it myself.

Does oil pressure take longer to build in the cold anyway, I can't for the life of me remember if this happens every year, although I think not because I'm pretty sensitive to this type of thing. Any help or pointers would be massively appreciated.

What grade oil do you have, and how cold is it before start up?

Oil is always thicker when cold, so it can take longer to flow - hence the invention of multi-grades.

Engines don't actually need oil *pressure*, they actually require flow and the pressure is a rough indicator of flow.

If you run an oil that thickens more than others when cold and it's particularly cold weather, it make take a bit longer a push through and build pressure.

It's why a 0W-40 provides better cold start protection than a 20W-40... the 0W-40 thickens less as it cools, so is always closer to the correct operating viscosity.

Have you measured the oil pressure to confirm it's not the switch? What viscosity of oil are you using? It sounds like the parts cannon is loaded up ready but there are a few things you could check first.

Doubt it's anything to do with the oil pump sprocket bolt but it's definately worth checking it's tight. Ask me how I know

tom1979 said:

Have you measured the oil pressure to confirm it's not the switch? What viscosity of oil are you using? It sounds like the parts cannon is loaded up ready but there are a few things you could check first.

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Thank you to all for the replies.

Hi Tom, I'm using 5w-30 oil and I think I always have. I haven't measured the oil pressure, and to be quite honest I'm not sure how I'd go about doing that? Does the switch sometimes fail then? She's got 157k on the clock now so it's not untoward that some things will start to need a bit more attention I guess.
I service it every 5k and it's not due a filter change for another 2k, but I did think maybe a filter could be slightly mucky/blocked (I only use genuine makes like mahle etc) although that seems unlikely. Thanks for the help!

AllanWorms said:

What grade oil do you have, and how cold is it before start up?

Oil is always thicker when cold, so it can take longer to flow - hence the invention of multi-grades.

Engines don't actually need oil *pressure*, they actually require flow and the pressure is a rough indicator of flow.

If you run an oil that thickens more than others when cold and it's particularly cold weather, it make take a bit longer a push through and build pressure.

It's why a 0W-40 provides better cold start protection than a 20W-40... the 0W-40 thickens less as it cools, so is always closer to the correct operating viscosity.

Click to expand...

The temp dropped to -5 a few nights in a row, and down to -7 one night, but now it's been around 0 to +2 and the light is still staying g on a second longer than usual.

This is probably a stupid question but I have a lynx diagnostics and I wondered is it possible to check oil pressure with this?

Gottschalk said:

This is probably a stupid question but I have a lynx diagnostics and I wondered is it possible to check oil pressure with this?

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The only way is with an oil pressure gauge via the oil pressure switch outlet

Gottschalk said:

Thank you to all for the replies.

Hi Tom, I'm using 5w-30 oil and I think I always have. I haven't measured the oil pressure, and to be quite honest I'm not sure how I'd go about doing that? Does the switch sometimes fail then? She's got 157k on the clock now so it's not untoward that some things will start to need a bit more attention I guess.
I service it every 5k and it's not due a filter change for another 2k, but I did think maybe a filter could be slightly mucky/blocked (I only use genuine makes like mahle etc) although that seems unlikely. Thanks for the help!

Click to expand...

You shouldn't have any issues with 5w30 in this weather. I would be surprised if the filter(s) were blocked in less than 5000 miles, and 157k is not high mileage. The switches are reasonably common.

tom1979 said:

The only way is with an oil pressure gauge via the oil pressure switch outlet

You shouldn't have any issues with 5w30 in this weather. I would be surprised if the filter(s) were blocked in less than 5000 miles, and 157k is not high mileage. The switches are reasonably common.

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Brilliant, thanks mate!

Gottschalk said:

The temp dropped to -5 a few nights in a row, and down to -7 one night, but now it's been around 0 to +2 and the light is still staying g on a second longer than usual.

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IMO you worry too much for 1 second, first of all remove the switch and clean out it's little hole with carb cleaner or some other spray then with compressed air and see after that or simply buy a branded new one cos they are not expensive, you'll have to check your's before you buy cos there are two types depending on thread and there is no clear info about which one was fitted based on VIN
1. NUC000020
2. NUC10003

sierrafery said:

IMO you worry too much for 1 second, first of all remove the switch and clean out it's little hole with carb cleaner or some other spray then with compressed air and see after that or simply buy a branded new one cos they are not expensive, you'll have to check your's before you buy cos there are two types depending on thread and there is no clear info about which one was fitted based on VIN
1. NUC000020
2. NUC10003

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Thank you sierrafery! I do tend to overly worry about things, that's very true. It's mainly because its always extinguished so quickly that it's caught my attention! I will do as you say (as you replied I was looking at new oil pressure switches) and report back with results!

Gottschalk said:

Thank you sierrafery! I do tend to overly worry about things, that's very true. It's mainly because its always extinguished so quickly that it's caught my attention! I will do as you say (as you replied I was looking at new oil pressure switches) and report back with results!

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You want it to extinguish quickly as the light goes off at a very low reading of something like 0.3 bar.

Gottschalk said:

Thank you sierrafery! I do tend to overly worry about things, that's very true. It's mainly because its always extinguished so quickly that it's caught my attention! I will do as you say (as you replied I was looking at new oil pressure switches) and report back with results!

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I have had low oil pressure light on a variety of diesel engines over the last 40+ years.
Probably ten times, on one occasion, on a big marine engine, we had overheated the oil due to trying to get on too much.
All the other times, it was the oil pressure switch packing up.

I don't know much about Td5s, but @sierrafery does, and if he thinks it is the switch, it probably is.

tom1979 said:

You want it to extinguish quickly as the light goes off at a very low reading of something like 0.3 bar.

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Actually it's within a "range"

So IMO as long as it goes out even with a certain delay and stays out means that the limit was exceeded... which unfortunately doesnt mean that the pressure is rising to normal level that's why a gauge is a very good add for this

sierrafery said:

Actually it's within a "range"
View attachment 304364
So IMO as long as it goes out even with a certain delay and stays out means that the limit was exceeded... which unfortunately doesnt mean that the pressure is rising to normal level that's why a gauge is a very good add for this

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At Sea, you can't really turn the engine off safely.
Unless you were sure the oil pressure had failed, in which case you had to turn it off, and radio for a tow.
So the old method if the light came on was to remove the rocker box cap, and if there was plenty of oil spraying around inside, we reckoned the oil pressure was OK, so knock on.

Not sure if that will work on Td5, as they have a strange 2 part rocker cover, so can't remember if you can see the rocker gear through the cap.

Turboman said:

so can't remember if you can see the rocker gear through the cap.

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You can't on the Td5 cos it has an oil separator plate there between the rocker and filler hole, looks like this from inside

New genuine switch ordered and will be here tomorrow, as a process of elimination. I only thought about the sprocket bolt because if it had started to lossen then the sprocket could be rotating without drive...although I know it's more likely to just let go at once. Cheers again all!

sierrafery said:

You can't on the Td5 cos it has an oil separator plate there between the rocker and filler hole, looks like this from inside

View attachment 304370

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That's what I thought. I have actually changed the injector loom on the wife's Td5, but she sold it years ago, so couldn't really remember.

Genuine sprocket bolt has arrived, and I've noticed it has a smear of yellow (I presume) thread lock already applied to 7 or so threads, (it appears to be completely dry) do you clever chaps know if I need to add more fresh thread lock of my own or is this OK to simply fit straight out of the bag? Just want to make sure I get this 100% correct!

Pretty sure mine came with blue threadlock already applied and yes it was dry. Can't remeber if I added a bit more.