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Help with D100 oil relief valve! Or sending unit?
https://www.slantsix.org/forum/viewtopic.php?t=52773		 Page 1 of 1
Author:  dc [ Wed Jul 17, 2013 5:25 pm ]
Post subject:  Help with D100 oil relief valve! Or sending unit?
I searched and found the oil relief threads, but I've got a problem.

Image

The oil relief valve on my D100 backs right up to an engine mount! Anyone know what the easiest way to check it is?

I had run some marvel mystery oil in my oil, and did an oil change. Everything was fine, but now the truck has sit for 2 weeks, and I fired it up to find the low oil pressure light comes on about 20 seconds after I start the truck. My mechanical gauge that is hooked to the filter take-off location reads 40-45psi.

The oil dummy light was flickering on and off repeatedly, so I changed the oil again with a new filter, and after 20-30 seconds, it started flickering again. If I turn the truck off and turn it back on, I have another 20-30 seconds before the light comes on. The light is on (or flickering... it can't decide whether or not it wants to go on and off or stay on solid) regardless of if I'm in gear, neutral, idling, reving, etc.

Does that sound like the relief valve? Could it be anything else? I'm supposed to drive the truck over to get the clutch replaced tomorrow, I'm guessing I should hold off until I fix this issue.

Please help?

EDIT: Also, I had bled the air out of the oil pressure gauge line, but I'm seeing air pockets in it again. Would this indicate an air leak? Or is this normal?
Author:  dc [ Wed Jul 17, 2013 6:28 pm ]
Post subject: 
I also can't find the oil pressure sending unit. I even have an fsm. I don't see anywhere where it says where it actially is. Please help me, I'm obviously new at this..lol.
Author:  Fopar [ Wed Jul 17, 2013 7:05 pm ]
Post subject: 
Look at the end of the pump below the filter, you should find it there.

Richard
Author:  Sprag [ Wed Jul 17, 2013 8:43 pm ]
Post subject: 
The oil sender on mine was covered with so much filth I wouldn't have found it if it weren't for the wire dangling from it!

Image
Author:  dc [ Thu Jul 18, 2013 3:50 am ]
Post subject: 
Thanks for the picture! I don't have an oil sending unit. The previous owner replaced it with the mechanical connection (I see the 3 adaptors he used to get the right size..lol). I didn't see one anywhere else either. No other wires coming from the block over there.

So I don't know where the wire that is supposed to go to the unit is.. I'm guessing the heat is increasing the resistance in one of the wires and making the light turn on? Unless anyone has any othee bright ideas on locating the connection, I guess I will just pay attention to the mechanical gauge

.I think the air got in the line because I just replaced the filter. Any recommendations on that? Does it matter if air is in the oil gauge line?
Author:  Sprag [ Thu Jul 18, 2013 6:55 am ]
Post subject: 
No worries about air in the gauge line, it should work fine.

In your shoes, I'd want to find the sender wire which I'd guess was tucked back in/around the harness and now it's somehow contacting ground intermittently. But first I'd just make sure the gauge responds to up/down pressure changes with engine RPM and carry on.
Author:  dc [ Thu Jul 18, 2013 7:37 am ]
Post subject: 
It is doing what it has always done. It shows 40ish psi with small increases when revving for about 10-15 minutes, then it drops to about 10-15psi @ idle, and follows throttle inputs much more immediately after that. I'm assuming once the motor warms up the relief valve takes effect? I dunno. I've read that other peoples slants read like this too.

That sound normal?
Author:  Fopar [ Thu Jul 18, 2013 8:39 am ]
Post subject: 
Yes you might use a 3 way fitting with pressure switch so as to use the Idiot light as a way of not having to look at the gauge if your pressure drops the light will come on.

Richard
Author:  Ssg Pohlman [ Fri Jul 19, 2013 7:56 am ]
Post subject: 
Not sure what year D100 or makes a difference but my 84 has 40lbs at start and makes maybe 50lbs w rpms. Though I've never had it drop below that even after warm and idle :?:
(Well I did one time but it was the junk fram someone left in my garage. Missing the O ring when it was spun on the truck, pumped about 2.5 Qts on the floor when it fired up after oil change :evil: :oops: )
Pohlman
Author:  dc [ Fri Jul 19, 2013 4:22 pm ]
Post subject: 
Mine is an 85. I payed close attention last drive and it starts around 40-45, tops out around 50 like yours, but then drops to 20psi at warm idle.

She is having a new clutch put in as we speak. There was a broken trans mount... and the pressure plate was bad. Should be better than new by tomorrow!

Next up is finding the darn wires that go to the oil light. I'd prefer it not to be illuminated all the time. I also have an MSD I'm putting in after I change the plug wires to a stranded set. Maybe next weekend!
Author:  Ssg Pohlman [ Fri Jul 19, 2013 5:54 pm ]
Post subject: 
I'm sure the gurus will chime in but mines never dropped below 40 even today while doing a goo thrashing and carb adjusting. Who knows, mine may be the one that's odd.

As for the plug, mine was a round black plug w I believe 3 wires (idiot light) and it was zip tied up w the rest by the fire wall. There will be a connector by the fire wall w it, and other connections right by the valve cover. Start there and see if you can find it then. If not its liable to be clipped off etc. To get an idea of plug prong orientation just look up the sending unit via autozone etc and it will show a pic.

An 85, does yours still have that nasty lean burn system etc on it as well?
Author:  dc [ Fri Jul 19, 2013 7:21 pm ]
Post subject: 
It did have the lean burn.. and actually the computer is still physically there, but the previous owner disabled all that stuff. It is a good old dumb carb now.
Author:  Ssg Pohlman [ Sat Jul 20, 2013 8:39 pm ]
Post subject: 
If that's the case I'd look to see if you have a diff dizzy. If the PO didn't change it out then you have no timing advance. The lean burn ones are locked so they can be controlled by the ECU. I'd look for a vacuum line running to it.
Pohlman
Author:  wjajr [ Sun Jul 21, 2013 2:53 pm ]
Post subject: 
Find that loose wire that once connected to oil pressure sensor, and keep it from grounding out. The way idiot light works is when oil pressure is too low it grounds circuit to make light come on; not unlike a dome light door switch circuit would function.
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