Oil Pressure issues

[Billman]

Different oil squirters have different flow and pressure ratings, depending on internal spring and spout diameters. If they are different part numbers it could very likely be a starting point to look at. I'be also come across faulty ones that are stuck open which would cause a drop in pressure too. I've got both AAT squirters and AAN ones on the shelf. I'll see if there is a way of rigging something up to test them tomorrow.

Interesting aspect I didn't thought till now....

[JP]

OK sorry for the late reply but had to finish an engine of to get to the area where the AAN block was being stored. After removal of the oil squirter and thoroughly cleaning it I proceeded with a simple test to check spring strength.

I took an air blower with a narrow blow nozzle on it and regulated the compressor pressure to 60psi on a constant flow hydrovane compressor. I then clamped the air blower to the workbench permanently blowing with a ruler next to it. I then proceeded to bring the oil squirtes ball bearing end closer and closer to the air jet until I could hear it opening. I'd move it back and forth between open and closed a couple of times until I found the point on the ruler where I felt it opened at. Wrote down the distance and repeated the test with the second oil squirter.

Crude and simple test but effective and it showed both opened at identical distances indicating identical spring strength.

Next I did a full visual inspection of dimensions and spotted the next factor which would determine oil pressure which is the size of the nozzle/outlet of the squirter. Visually there was a significant enough difference that you could see the AAT one was larger. Although the outer dimension was almost identical the inner dimension on the AAN has a small chamfer tapering down to a smaller internal bore. Some quick measurements followed to find the AAN internal dia was 1.08mm and the internal dia of the AAT squirter was 1.68mm.

Which means the Diesel AAT oil squirter has a cross sectional dimension 240% larger than that of the Petrol AAN squirter.

I would say it is a safe bet that if you were to change the oil squirters your oil pressure issue will be resolved.

Regards JP

[Billman]

Nice aspect but can we somehow cheat and have both! Much oil for pistons and bores + higher pressure?

When I let the throttle and watch the oil pressure I see that it does not settle lower smoothly apparently because of the spring pressure.

Maybe a softer spring could send more oil to the head.

[newsh]

Er, yeah I guess that translates as "thanks JP"

[JP]

The valve you are referring to that feeds the head is not a pressure valve. It is a one way check valve to prevent oil draining back to the sump whilst the engine is of. If the valve goes faulty all the oil galleries in the head will drain empty when the engine is not running and then on startup it will sound tappety until these oil galleries have been filled again.

As for more lubrication to the bottom of the pistons and bores, I rather have a high pressure narrow stream that splashes everywhere on impact than one that is wider with lower pressure that just saturates the contact points.

Think of a garden hose vs a pressure washer, the garden hose shifts higher volumes of water at lower pressure on impact with the surface it is aimed at it splashes a little and runs of. Take a pressure washer which emits a much higher pressure concentrated beam of water not only does it use less water when it impacts with the taret surface mist spray goes of in all directions with such force it saturates the whole surrounding area. Same principal applies to the oil squirter, the only reason the diesel will have a larger opening is because the oil will be much thicker during operation which automaticaly creates a higher pressure. You will probably find if you fit the AAN squirter to a diesel the pressure will be too high on cold start.

[s2_wot]

Subscribed to this thread to see if this change is the solution. In your experience JP would there be any upgrade that could be done to the AAN nozzle?

[Billman]

Nice, thanks JP! Once again top!

Can I Simply remove the squirters from an old AAN block and use them in mine?

[JP]

Yes they are a direct swap. Before fitting old ones just blow them through with an airline and make sure they are all functioning. As I've seen them with stuck open ball bearings before because of silicone that someone may have used sealing a sump at one time or just rust from sitting about dry in storage.

[Billman]

Ok, I am gonna make the swap when the gaskets arrive.

[JP]

Cool let us know if it resolves the issue as it is the only thing left that would make an obvious difference as I remember in the old days when we were still trying to get 500-600hp out the cossie lumps we used to play with the squirters to adjust oil pressure

[Jonnybravo]

Cool let us know if it resolves the issue as it is the only thing left that would make an obvious difference as I remember in the old days when we were still trying to get 500-600hp out the cossie lumps we used to play with the squirters to adjust oil pressure

Didn't know you were into the old boat anchors, oil pressure can be a big issue on the old yb though.

[AndyP]

Thank JP, great information as always.

I already have the gaskets, just got to get hold of some squirters now. I'll let you know if it resolves the issue.

[Thuppu]

Yes, I had this made at the local hydraulics place



It only confirmed what the gauge in car was reading.

What is the oil pressure sensor thread size? Need also to check the pressure with a gauge.


Edit.

Seems to be M10x1.

[Billman]

doesn't M10 mean 10x1,5?

[AndyP]

What is the oil pressure sensor thread size? Need also to check the pressure with a gauge.


Edit.

Seems to be M10x1.

I think it is M10x1 and it's not tapered like most fittings. I could not get a fitting for the gauge so I cut the end off an old pressure sender and TIG welded it on.