No oil pressure after engine drop

[john baldwin]

Hi All,
Dropped engine & tranny (3.2 G50) to address oil leaks, replace fuel lines and replace rear wheel bearings on the bench. New oil pressure warning switch, new flex oil lines from engine and oil tank and cam oil line restrictors were also added.

After reinstallation, pulled fuel pump fuse, cranked for ~15 sec, needle came off the peg to zero to a little over 1.5 for a second or two then dropped to zero, shut it off.

Tried again...needle came off the peg to zero with the key "on" but never got above zero while cranking (30 seconds)

Have tried several times more...no difference. Normally I see 3-4 bar after 15 seconds of cranking when I take her out of winter storage.

New oil hoses were not primed with oil...everything worked fine before disassembly. Could Cam oil restrictors be a culprit?

Anything else?
Any thoughts appreciated.
Thanks,
Job

[Smoove1010]

The oiling system is pretty simple - oil flows from the tank through the s-shaped hose into the engine almost directly to the pump. If the engine is turning and oil is getting to it, the pump should be pumping.

During removal, did you stuff any openings on the oil cooler or hoses with any rags or other plugs that might've been left inside during re-assembly?

Did you remove the cooler and replace the o-rings? Perhaps one moved during assembly and caused a blockage? If so - there ought to be some serious leakage to boot;

Another post described a similar case and the solution involved factory plugs in the new pipes that weren't removed... This seems unlikely to me - IIRC, when I did my cooler lines it would've been impossible to install them with the plugs in place.

Another post on this topic suggested loosening one of the chain tensioner connectors just enough to see if oil is flowing when you crank her over.

It might also be worthwhile to see if oil is getting to the sump - just loosen the sump plug and see if any comes out.

It would seem unlikely that the pump isn't working - so that leaves:
- a blockage;
- failed sender;
- failed sender connection (easy enough to test)

You'll get this...

GK

[john baldwin]

Thanks, Smoove
On disassembly I put nitrile gloves over the open end of the S hose (@ the cooler) and another nitrile over the hard oil line at the engine and one on the tank. Easy to see when I reassembled.
Both hard pipes to the external thermostat went out for new flex hoses and were left open after I flushed them...never saw a plug.
The cooler was removed and new oil rings inserted...no evidence of leaking anywhere despite multiple attempts with the starter.
I think I'll crack a chain tensioner line....might also drain the sump and refill.
Pulled the wire on the sensor, cranked it over and the gauge pegged at 5.... So the gauge is OK. Pulled the connector to the sensor and cleaned both male and female with emery cloth/ WD.
Wish there was a way to test the sensor itself insitu....REALLY would like to avoid having to pull that out...especially since I could have done it easily with the engine just having been out!

[thumbdoctor]

Sump plate correctly oriented?

[kodioneill]

Try starting it let it run for 10 seconds just cranking may not build enough pressure.

[john baldwin]

Thumbdoc,
Don't think there IS a sump plate on a 3.2
Anyway of there is, I didn't remove it during the drop.
Kodioneill,
Never had any trouble seeing pressure seconds just cranking. Checking to see if there's oil in the sump tonight....

Thanks for your inputs.
j

[mreid]

Are you sure you put oil in it? Otherwise sounds like a bad sender.

[john baldwin]

Opened the sump plug to see if oil is making it from the tank to the engine....it is. Cracked it just enough to see oil coming out, but wondering now if I shouldn't drain it and see the quantity. If there is a rag in the lines, I'm wondering if it stayed out of the way to let some oil flow (explaining why the needle on the gauge moved initially) and then lodged itself somewhere in the line blocking further flow.
If I remove the plug and let it drain, will the external tank drain too or is that constricted by the pump? I only want to see the quantity in the tank.
Is there anyway to test the sender while it's in the car? I'd rather not go through the trouble of pulling it to find out its good....
Appreciate any thoughts.
J

[john baldwin]

Correction ....by draining the engine I only want to see the quantity in the engine sump, not the external tank....

[WERK I]

Does the oil pressure light go out after a several seconds of cranking? If it does, you can bet the oil pressure gauge isn't registering pressure because the engine's cranking speed isn't high enough.

Couple of ideas....


1.) You could take the plugs out so the engine turns over faster.
2.) Do you still have the old sender? You could put the old sender back in and see if the symptoms change.

May I ask why you put the oil restrictors in? You didn't put them in to improve your oil pressure values, did you? If that is the case, you are only masking a more serious problem of excessive clearances of the bottom-end.

[Tim L]

I would crank it longer. I just did an engine rebuild and I was suprised how long it took for the pressure to come up.

[john baldwin]

WERK I
Yes, the oil pressure light DOES go out after a few seconds of cranking which leaves me hopeful it's the sender. But what would have caused the sender to go bad while the engine was sitting is a mystery. The gauge as stated earlier checks out OK.

Can certainly pull the plugs, but haven't needed to after winter storage ever...the old sender is gone.

Restrictors went in to improve flow to the bottom end and the piston coolers...others have reported plenty of flow to the top-end with the restrictors in...Panorama's article from years ago recommended this change...I know there's a split down the middle of opinions on this board.

I was considering putting back the higher flow inserts to see if this allows for faster cranking and helps the situation....however I thought the restrictors resulted in HIGHER pressures?

Tim L,
After 4, 30-second attempts I got spooked...don't want to try cranking again without some other change just yet.

[Smoove1010]

Could it be an air bubble in the sender preventing pressure from registering at the low-rpm of startup? I recall when I installed new brake-light switches, that it was suggested to add drops of brake fluid into the sender opening before installing to prevent exactly this sort of malfunction.

[Tim L]

I think it's a bad sender or the wrong one. I would put the old one back in and test it. also I wouldn't use the restrictors. I had cam and rocker wear with the restrictors.

[john baldwin]

Tim,
Oil pressure readings were fine prior to the drop. Never touched it...addressed gaskets, fuel lines, valves. The old sender is gone (replaced ~ 4 yrs ago).

Trying to eliminate all other possibilities before pulling sender as the job's a PITA only to find out a new sender give me the same results.

[LuftWaffle]

John, Consider buying/building a mechanical gauge to verify where your pressure is. I found an old aircraft gauge and use that as a reference on a new rebuild or when I question the electrical gauge readings. You can remove the idiot light pressure switch and attach there. -John

[john baldwin]

Pulled the left chain tensioner feed line, cranked it over ~ 5 seconds and look what came out:



I guess between this and the idiot light going out (THAT has a new sender...replaced when addressing the triangle), we've got pressure....just not registering on the gauge.

I guess if the sender sits too long, it malfunctions?
Hello Pelican parts?...here I come again?

Thanks all for your input...watch this space!
John

[WERK I]

John,
It may not be a bad sender. I think the oil pressure switch trips on 5# pressure, IIRC.
The tensioner line is a high pressure, low volume line. Don't know what the correct volume would be coming out of there.
My vote goes for starting her up, but keep an eye on that pressure gauge once the engine fires. If it doesn't rise soon after starting, and I mean in a few secs., shut it down and isolate the problem. Hooking up a mechanical gauge, is a very good idea, as well.

[john baldwin]

WERK I,
Which oil pressure switch trips at 5#...the idiot light or the gauge?
And by "5#" do you mean 5-lbs. or 5 bar?
Why do you think the sender might not be bad?
If we're just trying to increase the pump speed to get the sender to register, why try starting it rather than go with your early suggestion of pulling the plugs and cranking it?
Not challenging, just trying to follow your train of thought.

The volume of oil coming out of that tensioner line wasn't much....but given that that line is deep in the lubrication circuit makes me more comfortable that oil is circulating.

Appreciate your feedback
J

[WERK I]

John,
Sorry for the much belated reply.....much, too much work going on.
Anyway, the pressure switch, I believe, trips on 5 psi.
Regarding the pressure sender, there is a lot of latency built into these units. They are relatively slow reacting which explains their steady needle during operation.

It doesn't really matter which path you take. I was merely offering some options which would give you the comfort level you desire. Myself, I turn the engine over a few seconds past the time when the oil pressure light goes out, then connect the ignition and enable the fuel pumps.