So a strange thing happend today...

wengejor · 10-03-09, 04:44 PM

I got up early this morning to go cycling and warmed up the truck for about 10 minutes or so in the driveway. I drove about 3 miles to the highway and after a few miles at speed I looked down and my oil pressure gage slowly moved down to the first line. I thought, man, something bad is about to happen. Usually it's right over the second line on the gage. So I pushed in the clutch and cycled the throttle a few times and it went back up to the second line. Just a minute later it went back down again, this time half way between the two lines...cycled the throttle again and it went back up...

The rest of the trip was fine with no issues and the ride home was fine as well.

I know the PO put in an aftermarket oil pump just before I bought it and it has always had good oil pressure, but this is a first for me.

I was thinking that maybe it had an air bubble stuck at the pump and that it just needed to get pushed out...any other ideas?

No power loss, no wierd sounds...

Jace · 10-03-09, 05:00 PM

Only other thing I could think of is your oil level. I've had pressure fluctuations because I was low. Just a thought.

seanzy1105 · 10-03-09, 05:27 PM

i would say hook up an aftermarket pressure guage just to see if you have oil pressure, if you do its the pressure sender, if you don't its either the oil pump or something else

wengejor · 10-03-09, 05:49 PM

Oil level is good. I checked it last weekend and it was full.

sirenmoses · 10-03-09, 07:11 PM

your rig has the oil galley plug fix done?

wengejor · 10-03-09, 09:04 PM

Yup, oil galley has a set screw threaded in.

REKCUT · 10-03-09, 09:33 PM

Put in a real gauge. The factory ones are crap and prone to ground problems.

wengejor · 10-04-09, 09:34 AM

Yeah, I had an aftermarket gauge on there, but I didn't like it so I bought a new stock sending unit and hooked it up to the stock gauge.

alaska60 · 10-04-09, 11:19 AM

check for clean connections at the gauge. My guess is the pressure sender.

wengejor · 11-06-09, 12:32 PM

Man, this happened again today. Was driving on the highway with around 3k rpm and the oil pressure drops and stays down for awhile until I push the clutch in and let it idle then the oil pressure comes back up. I'm going out to check the connections and put some dielectric grease on it.

Maybe I'm running into high pressure relieve? Could it be an air pocket?

With the mechanical gage I was reading something like 60 psi.

austinmark · 11-06-09, 12:35 PM

Quote:

Originally Posted by wengejor

I got up early this morning to go cycling...

this just goes to show that the cycling adage is right, "ride to the ride." sounds like that would have fixed your problem.

wengejor · 11-07-09, 12:31 PM

haha, yup, I was contemplating riding to the ride this morning. It would have been a 70 mile day on the bike then!!

rchalmers3 · 11-07-09, 01:18 PM

A big no to there being air pockets causing the symptom. The motor is not designed with any significant dead end galleys.

Pump cavitation would be a possibility. If there is a leak between the pump and pickup, it is conceivable the pump could lift oil through the pickup at low speed, but create cavitation on the air leakage at higher operational speeds.

Time to perform oil pressure testing using a known good gauge. A sender or connection fault may be the cause, but I'd error on the side of caution.

Rick

cruiser88 · 11-07-09, 02:45 PM

Quote:

Originally Posted by REKCUT

Put in a real gauge. The factory ones are crap and prone to ground problems.

wengejor · 11-07-09, 05:44 PM

Yeah, I need to get a different gauge. The aftermarket one I have seems to be pretty insensitive to quick changes in pressure. I would like to stick to the stock gauge as well as put another gauge on someplace else.

I'm thinking it could be cavitation. Seems like it only happens when the engine is cold and starting to warm up. It'll go down, then I usually let off the gas, then the oil pressure comes right back. After that, it won't do it again for the rest of the trip.

wengejor · 11-10-09, 04:20 PM

Ok, so update on this.

I have been watching my oil pressure gauge closely. I don't think it's an issue with the connection.

It's now happening at pretty much the same part of my daily commute.

At the beginning of the commute, the needle is slightly below the second line on the gage. At about 5 miles into my drive on the highway, the oil pressure goes quickly down to as low as the first black line. If I continue to run at 3K rpm, then it will stay down. If I let it idle, then it abruptly goes back up.

After this, the pressure is pretty much steady right over the second black line for the rest of the commute.

This has happened now for 4 commutes in a row.

I checked the level and it's fine. I noticed that the oil is coming up on the dipstick and there are some very small bubbles.

chesshircat · 11-10-09, 05:38 PM

you need to quite screwing around with the stock guage and sender and get a mechanical guage. thats the only way to know for sure

wengejor · 11-10-09, 06:30 PM

You're probably right. I drove around for more than a year with a crappy aftermarket oil pressure gauge and there were no issues other than the fittings leaking all over the place with the oil filled tubing coming into the cab.

Now, I put a new OEM sender in over the summer and hooked up the stock gauge I get some funny stuff happening.

Anyone know of a good gauge and sender that is wired rather than the tubing that most use?

alaska60 · 11-10-09, 08:11 PM

Hey bro...........
I have had an "autoguage" oil pressure guage with the tube style for 6 years and no issues other than it tells me the exact oil pressure to the pound every second I am running.

Dont worry bout that tube.....when installed correctly, they work very well.

chesshircat · 11-11-09, 07:00 AM

The tube style is what you want, that is a mechanical guage.