33 replies to this topic

[84sprite]

Hi all 

I’m hoping someone can help me with an issue that has come on this week with my engine.. I will try to keep it as brief as possible but give as much information as I can 

 

I have rebuilt my engine using all new internals except pistons con rods and rocker / valve setup (I did use new followers and springs etc.) 

 

before starting the engine I checked oil pressure and on starter motor was between 50-75 psi 

 

on first few starts oil pressure was good hovering around the same 50-75 psi range. While the engine was out the car I started it a few times with no issues and ran basically a float pot of fuel through maybe 10 or 15 times over the course of 4 weeks 

 

then when my body came back from paint I installed subframes, engine, front seats, brakes etc. And plumbed up a fuel bottle so I could run for longer periods - to set ignition timing and heat the new exhaust 

 

After running for 10-15 mins I noticed the oil pressure gauge was reading between 25 and 50 psi but didn’t think much of it as it was still running on idle warming up 

 

I took the car for a run up a private road to check gear changes as this was first time I could check all gears since rebuild and everything seemed sweet and all gears selected ok - I then noticed that my oil pressure was 0 - no oil pressure showing on gauge at all so I shut the engine down and pushed her home 

 

This was 4 days ago

 

just went to check oil pressure again - removed plugs and turned the engine on starter motor and there is 0 oil pressure 

 

any advice why it all was going so well and now gone so badly would be appreciated 

[nicklouse]

first thing to check if the pressure relief valve is it stuck open?

[84sprite]

Thanks nicklouse I haven’t checked it but wouldn’t this have shown up while I was doing short runs on the engine? The thimble is new by the way 

[nicklouse]

Thanks nicklouse I haven’t checked it but wouldn’t this have shown up while I was doing short runs on the engine? The thimble is new by the way 

Not always. And is an easy check or you are pulling the engine.

[84sprite]

Thanks - will check that tomorrow- is it really an engine pull if it’s not that? 

 

 

Thanks nicklouse I haven’t checked it but wouldn’t this have shown up while I was doing short runs on the engine? The thimble is new by the way 

Not always. And is an easy check or you are pulling the engine.

 

[nicklouse]

 

Thanks - will check that tomorrow- is it really an engine pull if it’s not that? 

 

 

Thanks nicklouse I haven’t checked it but wouldn’t this have shown up while I was doing short runs on the engine? The thimble is new by the way 

Not always. And is an easy check or you are pulling the engine.

 

 

Low pressure is caused by only a few things.

 

the valve stuck open.

 

the pressure gauge not reading correctly.

 

bearings failed.

 

pump failed

 

O ring missing between block and box.

 

just about everything means engine out.

[84sprite]

 

 

Thanks - will check that tomorrow- is it really an engine pull if it’s not that? 

 

 

Thanks nicklouse I haven’t checked it but wouldn’t this have shown up while I was doing short runs on the engine? The thimble is new by the way 

Not always. And is an easy check or you are pulling the engine.

 

 

Low pressure is caused by only a few things.

 

the valve stuck open.

 

the pressure gauge not reading correctly.

 

bearings failed.

 

pump failed

 

O ring missing between block and box.

 

just about everything means engine out.

 

Ok thanks 

I guess I need to hope the valve is stuck then or the gauge is knackered and just packed up 

brand new bearings and oil pump fitted during build and I know I put the o ring in between the gearbox and engine - that was in red pen on my build board ....

[nicklouse]

If you have changed anything in the gauge line check it. I did have a moment when the gauge said Zero but I had oil flow at the head. 90 degree connector I had added was blocked with “varnish” clear it put and it was fine. But I did know that the engine was giving pressure,  Not a new build.

[84sprite]

If you have changed anything in the gauge line check it. I did have a moment when the gauge said Zero but I had oil flow at the head. 90 degree connector I had added was blocked with “varnish” clear it put and it was fine. But I did know that the engine was giving pressure,  Not a new build.

I didn’t change anything on the gauge line just left it connected .. I will check for kinks though .. I did notice that there is air in the line but I think it has always had that it’s never been filled with oil ( it’s a clear plastic line I am changing to braided when I fit dash) 

[nicklouse]

 

If you have changed anything in the gauge line check it. I did have a moment when the gauge said Zero but I had oil flow at the head. 90 degree connector I had added was blocked with “varnish” clear it put and it was fine. But I did know that the engine was giving pressure,  Not a new build.

I didn’t change anything on the gauge line just left it connected .. I will check for kinks though .. I did notice that there is air in the line but I think it has always had that it’s never been filled with oil ( it’s a clear plastic line I am changing to braided when I fit dash) 

 

Air is no issue. All it does is slow the reaction of the needle a bit. You would not notice it.

[absx2]

First check the gauge and connections and undo the oil filter pipe banjo and give the motor a crank over with the plugs out.

My first guess would then be you have missed or mispositioned the gearbox O ring on installation of the gearbox and it took a drive to show itself but check the oil pressure relief valve to make sure that is seating and working correctly.

Then its time to pull the motor out and see what`s going on, did you replace the oil pump, was the gasket in the right place and was it the correct pump for your engine ??

[sledgehammer]

all the above +

 

I would change oil filter first - there are some bad ones around

 

also with oil filter off , check for flow at oil filter head - look at the oil that comes out (don't run engine , just take plugs out & turn over)

 

did engine knock at all ?

 

also as above - the oil pump gasket is critical & the correct bolts also as the wrong ones can appear tight , but bottom out early

 

this lets air into the oil pump

Edited by sledgehammer, 06 May 2021 - 09:28 AM.

[84sprite]

First check the gauge and connections and undo the oil filter pipe banjo and give the motor a crank over with the plugs out.

My first guess would then be you have missed or mispositioned the gearbox O ring on installation of the gearbox and it took a drive to show itself but check the oil pressure relief valve to make sure that is seating and working correctly.

Then its time to pull the motor out and see what`s going on, did you replace the oil pump, was the gasket in the right place and was it the correct pump for your engine ??

Thanks absx2

i know I definitely placed the gearbox o ring and checked before sealing engine to gearbox that it was seated correctly as this was a red flag on my engine build board I have marked in red pen so it was not forgotten or incorrectly placed.

the oil pump is new and correct for my engine - I also checked the gasket was fitted correctly when I replaced it 

I am hoping that it’s a pressure release valve issue or gauge issue otherwise it will have to be an engine back out exercise which I am really not looking forward to after all the work put in so far 

[84sprite]

all the above +

 

I would change oil filter first - there are some bad ones around

 

also with oil filter off , check for flow at oil filter head - look at the oil that comes out (don't run engine , just take plugs out & turn over)

 

did engine knock at all ?

Thanks Sledgehammer

i am going to change the filter again just for ruling it out 

no the engine didn’t knock at all the gauge just showed no oil pressure 

 BF715EE6-0134-4F8A-98ED-B95A2F694E44.jpeg   47.46K   1 downloads

Edited by 84sprite, 06 May 2021 - 09:40 AM.

[cal844]

If Changing the oil filter, I use Mann or Framm filters, I'd then check for flow to the head

Edited by cal844, 06 May 2021 - 09:35 AM.