How to verify oil pressure?
 

I recently rebuilt my 2.7. I have the engine on a test stand. I have a vdo sender and vdo oil pressure gauge. I put 12 qts in the oil tank. When I crank the engine with the ignition system off- I don't get any oil pressure readings other than 0. When I initially turn the power on- the needle on the gauge goes from below zero to zero- so I believe it is hooked up properly.

The possibilities that I can see are:

1. I didn't crank the engine long enough. I only cranked it for about 5 seconds 3 different times. I didn't want to over do it without asking first.

2. Problem with the sender.

3. Problem with the gauge.

4. Some other engine issue.

Are the spark plugs in? if so take them out so it turns over faster, I would prime it with oil right down the sender port and try it again. A mechanical gauge would be best screwed into the port to really tell.

I removed the spark plugs and cranked the engine again. The gauge did stark to go up. I was able to get it to 20 psi. Does that sound about right for this situation? Sometimes if I continued to crank the engine, the pressure would drop then go back up. I assume this is some sort of air pocket?

Also, if I stop cranking the engine, the pressure goes to zero very fast. Does that sound right?

As you can tell- I am very paranoid about oil pressure issues.

you are only cranking at about what? 200 or 300 rpm? I would say that's pretty good.

Ok. Thank you for your help!

Its not that hard to install a gauge. Here's mine
http://forums.pelicanparts.com/uploa...1462509426.jpg

this is such a cool setup !!!
can you please show another side of this pic, what harware did you use?

thank you
-Y

Mechanical pressure gauge installed.....
 

A mechanical pressure gauge could be conveniently installed either at the oil pressure switch or sender unit mounting hole. If you could generate an oil pressure at 20 psi. or more during cranking, that's a pretty good oil pressure. With the engine running, the initial pressure would go up twice to 3 times more. I get about the same pressure (20 psi.) too when just cranking.

http://forums.pelicanparts.com/uploa...1469651206.jpg

Tony

Txs Tony,
Did you threaded your own adapters? It looks like most of them US standard and those are M10x1.0 are brass made I am affrad if can snap as their necks are skinny...

It's going to take much longer then 3 x 5sec. Try 3~5 x 30sec each, letting the starter cool off a minute or so in between. Keep in mind you're having to fill the oil cooler, filter and associated lines.

I found adapter fittings. Pelican might sell them, or check one of the racing suppliers.

I have a similar setup on my racecar so I can run the oil pressure gauge sender and a 20 psi idiot light sender. I use a T fitting. The two senders plug into the T. I connect the T to the fitting on the engine via a short hose (I used a braided brake hose since that was convenient). I used the hose to isolate the T fitting and senders from vibration since otherwise the whole apparatus would be solid mounted to the engine through a skinny fitting, as 1-ev.com suggested - seems like a setup that could be ripe to break.

Scott

Metric to English adaptor......
 

The oil pressure sending unit has an 18-mm x 1.5 (thread-pitch) and so is the 'block'. The US standard pressure gauge would need an adaptor (reducer) to mount it to the 'block'. This a pretty common adaptor you could buy from your local hydraulic shop. All I did was visited the local hydraulic shop and showed him the 'block'. Ordered also a mechanical pressure gauge with the adaptor. A 0-75 psi. gauge would be ideal for testing.

Tony

What I just did with a fuel pressure related issue is took one of those mechanical gauges on a long hose and duct taped it to my rear window.
I could easily read it in my rearview mirror. Removed it when I was done.

BTW I found I had a kinked fuel hose that would fully collapse after 15-20 minutes driving, saved me from messing with the pump. :cool: