Low oil pressure after highway trip

[Viterbo]

I'm back to low oil pressure issues on my 5K.

Last saturday I went on a trip and did about 60kms on highway. It was hot outside and since I have a short diff ratio I went the whole way at around 4000rpms. When I got to the tollgate, at idle, the oil pressure light started to blink slightly. 
If I let it idle for a bit the light turns off.
I'm using a mineral 15W40 oil (Total Quartz 5000).
I assume the oil got very hot and got thin.

 

Engine background: 

1 year ago crank was machined and 0,25mm oversize bearings (NDC brand) were installed.

In january I did solid lifter conversion using the outer body of the original hydraulic lifters.

 

I don't have (yet) oil temp and pressure gauges so I'm clueless about those values.

Where can I be losing pressure?

 

[Big G]

Have you noticed if the engine gets rattley when the oil pressure light comes on coz if the oil is thining she will rattle. Have u checked the wiring connection to the sender. It could be a dodgy connection that gets worse with the increase in engine temperature. Or it could be the sender starting to fail. Years ago my girlfriends KE55 had the same issue so I teed in an oil pressure gauge and took note of when the light came on and the pressure value at the time. It was the sender. Swapped it out never a problem again.

[Viterbo]

The only noise it has it's in the valvetrain, my valve clearance keeps untuning itself hehe.

I have a kit of oil temp and pressure sensors and gauges coming but they won't be with me until 3 weeks or so.

[ke70dave]

Presumably its got enough oil in it?

[Viterbo]

Yes, not full but plenty of oil in it.

[Banjo]

As you only did the solid lifter conversion  about 4-5 months ago, & used part of the original hydraulic lifters, can you describe what that conversion entailed ?

Quote

The only noise it has it's in the valvetrain, my valve clearance keeps untuning itself hehe.

Now you mentioned that the tappet clearance is getting out of wack by itself, that is possibly indicating that there is something not right with the lifter mods.

Cheers Banjo 

Edited May 26, 2017 by Banjo

[coln72]

6 hours ago, Banjo said:

As you only did the solid lifter conversion  about 4-5 months ago, & used part of the original hydraulic lifters, can you describe what that conversion entailed ?

Now you mentioned that the tappet clearance is getting out of wack by itself, that is possibly indicating that there is something not right with the lifter mods.

Cheers Banjo 

Or you are revving the absolute crap out of it.........

[7000rpm]

Silly question, but have you thoroughly checked the electrical connection on the oil pressure switch?

[Viterbo]

19 hours ago, Banjo said:

As you only did the solid lifter conversion  about 4-5 months ago, & used part of the original hydraulic lifters, can you describe what that conversion entailed ?

Now you mentioned that the tappet clearance is getting out of wack by itself, that is possibly indicating that there is something not right with the lifter mods.

Cheers Banjo 

I got the tip here from Felix.

Outer hydro body, top nut in the bottom and short pushrods (2K engine). 

Installed 4K solid cam also.

 

 

12 hours ago, coln72 said:

Or you are revving the absolute crap out of it.........

Not going past 6000.

 

 

9 hours ago, 7000rpm said:

Silly question, but have you thoroughly checked the electrical connection on the oil pressure switch?

What kind of checking can I do besides the basic?

I think it must be working well, unless something in the switch itself.

[parrot]

I would also swap out the switch. Cheap, easy and the probable culprit. Had one fail in a mk1 Escort once. Similar to what you describe. Caused much angst for what turned out to be a $10 fix

[Clapped out]

If its not a faulty sender, my money is on the oil! Thinning out too much when hot,

 

cheers!

[7000rpm]

As in that the connection is tightly fitted, not wobbly.

ive never tested one, but imagine if you unscrewed it and connected the signal wire up with key turned to reds, you might be able to see the light turn off/on by pushing on the switch valve with something sharp?

[Viterbo]

3 hours ago, Clapped out said:

If its not a faulty sender, my money is on the oil! Thinning out too much when hot,

 

cheers!

In that case, I should go to a 20W50?

 

1 hour ago, 7000rpm said:

As in that the connection is tightly fitted, not wobbly.

ive never tested one, but imagine if you unscrewed it and connected the signal wire up with key turned to reds, you might be able to see the light turn off/on by pushing on the switch valve with something sharp?

I guess it can be tested like that.

The connection is tight, no problems there.

But the light operation seems logic and how it's supposed to be. When the engine is off the light it's on, when I crank it the light turns off and stays that way when cold at any rpm and when hot appeared in that situation (idle after some kms). I didn't have the chance to drive the car again to see what happens now.

Edited May 27, 2017 by Viterbo

[altezzaclub]

I reckon its a worn oil pump or bearings, and you've done the bearings

The red light works at 7psi in theory, an arbitrary figure that just tells you enough oil is circulationg to lubricate the motor as it idles with no load.

When the pump wears and oil leaks back past the impellors the pressure drops, but its only noticeable at idle when the pump is rotating at its slowest and the oil is thin.

Ignore it until you get the gauges...  turn the idle speed up if you don't want to chase it down with lots of money and time.

I don't know if we can get uprated K pumps with longer impellors. I know you can for Celicas, so they raise the minimum oil pressure by pumping a larger flow. The maximum stays the same as it is bled out by the ball valve.

[parrot]

Change the sender, or ideally put an oil pressure gauge in it. Otherwise there is no way of knowing.