New engine. High oil pressure.

[subcrx]

Just took my boat out today after installing new 5.7 350 with a rochester carb. cooling system is closed. Oil pressure gauge maxes out at cruising speeds and when at idle drops to 80psi. It has never done that before, before it would read 40 when cruising and 0 at idle. Anyone seen such a difference?

 

[bomar76]

Re: New engine. High oil pressure.

wrong sending unit would do it in a heartbeat....show oil pressure way off.
I'd install a TEMPORARY mechanical gauge to verify pressure, if it's actually normal you new engine has the wrong sender.

 

[Coors]

Re: New engine. High oil pressure.

What Bomar said.

 

[subcrx]

Re: New engine. High oil pressure.

how would i know which sender to get, I used the one off the old engine. Which was a different year

 

[Coors]

Re: New engine. High oil pressure.

Old year sender, don't use teflon tape.

 

[subcrx]

Re: New engine. High oil pressure.

all the senders on Iboats have the same part number. for all inboards.

 

[bomar76]

Re: New engine. High oil pressure.

I just reread your original post and saw where you said gauge w/ old engine would read 40 at cruise (dunno what RPM that is for you, but guessing somewhere between 750 and 6500) and ZERO at idle.
If it truly was zero, you had some serious issues.
That thing should have been rattling and ticking like hell at idle.
You replaced the engine...why? Did the old engine suffer an oil related failure? Or was it freeze damage? What?
Perhaps you gauge is FUBAR....
Again, buy a mechaincal gauge and temporarily hook it up and see just waht is going on.
I doubt your oil pressure is really that high, that will blow the seals out.

 

[Coors]

Re: New engine. High oil pressure.

There are plugs that get the oil pressure, only the oil filter seal and rear main get pressure, all else is splashed.

 

[fishrdan]

Re: New engine. High oil pressure.

Oil pressure gauge maxes out at cruising speeds and when at idle drops to 80psi.

Is this a factory engine or home built engine? The high oil pressure could be caused by a high pressure oil pump or a high volume oil pump with the high pressure spring installed. Either way it's not a good situation.

Sounds like you need to confirm with a mechanical gauge,,, and/or replace the sender as suggested earlier.

 

[bomar76]

Re: New engine. High oil pressure.

There are plugs that get the oil pressure, only the oil filter seal and rear main get pressure, all else is splashed.

What part of it will blow the seals out (and you even listed them) do you not understand?

 

[subcrx]

Re: New engine. High oil pressure.

I replaced the engine because of water ingestion, blew a piston apart and damaged the crank and rod. This new engine is a fresh rebuild with 0 hours from a very reputable shop near me. this is them http://www.partsandpeople.com/NorthCalifornia/article/1293/ The old engine ran fine when it read 0. could never figure it out. When I installed the send i have now on the old engine it read 40psi at higher rpms and 0 at idle. With this same sender on the new engine it maxes out the gauge and drops to 80 at idle. Runs perfectly fine. This sender came with a gauge from gaffrig, I never installed the gauge. Is that gauge considered a mechanical one?

 

[fishrdan]

Re: New engine. High oil pressure.

This sender came with a gauge from gaffrig, I never installed the gauge. Is that gauge considered a mechanical one?

gaffrig? don't understand???
Is this a new gauge/sender? If so, try hooking up the new gauge temporarily to see if the oil pressure looks OK on the new gauge.

A mechanical gauge connects to the engine with a small nylon tube, oil pressure pushes directly on the gauge. If in doubt, drop $25 at the auto parts store for a mechanical gauge for troubleshooting.

If the old engine was running fine while the gauge was reading 0 psi at idle something does not sound right. As bomar76 said you should have heard the engine complaining of low oil pressure, tick, knock, rattle.

Even though the engine was built by a reputable shop, the engine could still have a high pressure oil pump installed. Oil pump mis-boxed and they installed it not knowing or maybe they just slipped up and installed a high pressure oil pump? Things happen...

 

[subcrx]

Re: New engine. High oil pressure.

yes Gaffrig gauge and sending unit. just wires, no tubes. Its fairly new. Ill try the gauge it came with then try a mechanical one. Ohh and if it were truly high how long would it take to blow the seals out, cuz we cruised on plane for about an hour today

 

[bhammer]

Re: New engine. High oil pressure.

Is it a high volume oil pump with a small oil pan? Seen that issue posted here before.

 

[fishrdan]

Re: New engine. High oil pressure.

Ahhh Gaffrig (just googled them up )

Yes, try their gauge with their sender as they could be using a different value of sender than came with the boat.

 

[bomar76]

Re: New engine. High oil pressure.

Is it a high volume oil pump with a small oil pan? Seen that issue posted here before.

That will produce NO oil pressure as a small pan can be sucked dry.
Opposite of what he has.

 

[Coors]

Re: New engine. High oil pressure.

What part of it will blow the seals out (and you even listed them) do you not understand?

I understood it, your majesty.

 

[bhammer]

Re: New engine. High oil pressure.

That will produce NO oil pressure as a small pan can be sucked dry.
Opposite of what he has.

Ahh, okay. I thought I had read that the OP, in the other thread, had excessivley high oil pressure. I can see how if you pump too much oil up and it can't recover in time, you would then have no pressure.

 

[buggiedad_67]

Re: New engine. High oil pressure.

There are plugs that get the oil pressure, only the oil filter seal and rear main get pressure, all else is splashed.

dont know what plugs are getting oil pressure, no seals get direct pressure on them, all on crankshaft, camshaft, lifters, push rods up to rockers gets pressure, but dont know of any plugs in there

 

[bomar76]

Re: New engine. High oil pressure.

Ahh, okay. I thought I had read that the OP, in the other thread, had excessivley high oil pressure. I can see how if you pump too much oil up and it can't recover in time, you would then have no pressure.

That's a relatively common problem on marine engines built by auto mechanics...they think high volume is good.....NOT good in an engine that runs at high RPM for extended periods.