Trojan Boat Forum

Hi all,

Just got back from the boat after my son helped me hook up the new oil pressure gage. I started the engine to see if it all worked. The gage needle did seem to move up and down as I raised and lowered the RPM. I then settled it down to around 1000 rpm and it went to 80 lbs and stayed pretty much there. As the heat started to raise I put the rpm at 2000 where the manual says it should be to check for proper pressure, and it went down to around 65 or 70. As I lowered the rpm, it went back up close to 80 lbs?

Is it normal for the oil pressure to increase at lower rpm (1000) and go down to normal at higher (2000) rpm. I think the manual states the for the 318 Chrysler, it should be between 45 to 65 lbs, which is where in read at 2000 rpm?

Any thoughts?

Thanks

Larry

PS. The engine has been recently overhauled.

Is there any air in the line?

Hi Larry,

Did you replace the sending unit as well?

Paul wrote:Hi Larry,

Did you replace the sending unit as well?

i hope it is that simple

I bought a new sender unit, but did not replace it. The unit the new gage is using is the original sender.

I guess I may as well replace it, I bought the sender and gauge at West Marine. But the sender is bear to get to.

Am I to assume that this is not how the gauge is read the oil pressure?

Thanks,

Larry

PS, this is an electric type gauge.

larglo wrote:I bought a new sender unit, but did not replace it. The unit the new gage is using is the original sender.

I guess I may as well replace it, I bought the sender and gauge at West Marine. But the sender is bear to get to.

Am I to assume that this is not how the gauge is read the oil pressure?

Thanks,

Larry

Does it have the old style with little tube that fills with oil right?

larglo wrote:I bought a new sender unit, but did not replace it. The unit the new gage is using is the original sender.

I guess I may as well replace it, I bought the sender and gauge at West Marine. But the sender is bear to get to.

Am I to assume that this is not how the gauge is read the oil pressure?

Thanks,

Larry

PS, this is an electric type gauge.

you need to replace the sender also......sorry

Oil pressure should increase with RPM and vice versa. Never seen one do the opposite. Something ain't right.

Rodman wrote:

larglo wrote:I bought a new sender unit, but did not replace it. The unit the new gage is using is the original sender.

I guess I may as well replace it, I bought the sender and gauge at West Marine. But the sender is bear to get to.

Am I to assume that this is not how the gauge is read the oil pressure?

Thanks,

Larry

Does it have the old style with little tube that fills with oil right?

no it has a sender

It's best to replace the sender and gauge together.

Sender and gauge need to be 'matched' in terms of triggering on voltage or resistance or current, and whether high or low signal means full scale or zero etc... If you got a new sender that matches the gauge, put 'em both in. If you still get this behaviour, it would suggest you might have some wiring messed up.

Yep, what Danny said....higher with increased RPM and lower with decreased RPM. Also decreases when warm. Good rule of thumb is at least 10 psi per 1000 rpm's.....

I'm going to check and see if I may have the wiring backwards, having the sender wire hooked to the grd? If not I will install the new sender I have.
i have never seen an oil gauge act this way in a car, but this being my first boat, wasn't sure about it?

It's raining and chilly today, so may take the day off and hang around the house today, but will let you all know how things go after changing sender.

Thanks for all the comments,

Larry

I believe you should have sender wire to s on guage. Ignition wire to I and ground to either of the mounting post. Hope this helps.