I asked once before trying again maybe someone new has joined 1990 5.8 after driving for 15 minute if i go in reverse my oil pressure goes pass low and engine light came on but its fine in drive its stays normal i still have the stock gauge.HELP?????
oil pressure
- Thread starter firstford
- Start date
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BroncoJoe19
Active member
FirstFord,
That just doesn't make any sense!
Your engine is turning in the same direction and somewhat the same RPMs in either forward or reverse.
The only thing that *I* can think of is perhaps the wire from the sending unit to the in dash guage is hitting something in your shifting linkage and that there is a partial break in the wires. When the linkage goes into reverse it stretches the wire a little so that the fibers of the wire can't carry enough current to the guage.
I Hope this makes sense.
Overall, the in dash guage is electrical and gets information from the oil sending unit in the block. They are prone to go bad (the sender). You can get a wet oil guage and thread it in to get a more accurate oil pressure reading.
You may want to read this thread, where another forum member found a solution in the use of a wet oil/mechanical oil pressure guage.
http://broncozone.com/forums/index.php?s=&...ost&p=72684
By The way,
Please consider going to the "my controls" and creating a signature file and put your truck's statistics in it, such as year, engine size stuff like that. This way we can give more specific information if it is pertanent to a particular year or engine.
joe
it has me pulling my hair out but that what its doing i promise u and its just as strange to me i've never ran across anything like it.
BroncoJoe19
Active member
Does what I suggested make any sense to you?
1. a frayed wire still inside the plastic insulation.
I'm not sure if I explained what I was thinking clearly.
2. IF you hook up a wet oil guage, I'll bet that you will see the reverse problem go away.
joe
im not sure how to install it but i'll go to autozone hopefuly it will have instruction thanks
BroncoJoe19
Active member
It should be a simple straight forward install.
Pull the sender out.
***** a new fitting in its place.
hook up the tubing (probably with a ferrule like the one you may have under your bathroom sink water supply)
run the tubing up into the cab.
hook the tubing to the guage,
finally hang the guage somewhere.
Broncobill78
New member
I believe that a mechanical gauge was suggested quite some time ago. You're *never* going to know what you're dealing with otherwise. You need reliable instrumentation and actual numbers before you can even begin to diagnose the problem.
http://broncozone.com/forums/index.php?sho...amp;#entry69756
http://broncozone.com/forums/index.php?sho...amp;#entry69756
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Thanks broncobill78 i was trying to fine that i put oil pressure loss in the search forums it didnt pull it up guess i did something wrong. Just like when i put my name on my marriage license lol
Broncobill78
New member
You should be able to pickup a decent mechanical gauge from Autozone or any other parts shop for $20 or so. There are a number of places to plumb it in. The location of the stock sending unit changes from year to year & engine to engine but the last few that I remember working on had the stock sender on the top/rear/center of the engine. Right in the middle behind the intake manifold. There's also another port on the driver's side in the front of the engine just above the oil pan where the mechanical fuel pumps used to be. This is a good port to use because it's right above the oil pump so the readings you get there will for all intents and purposes be pump pressure. You might want to leave the stock gauge connected for a bit just so that you can compare the mechanical gauge to the stocker and after watching both of them for a few weeks you'll have a pretty good idea of what the actual pressure in PSI is when you look at the stock gauge. What I do with *my* truck is to plumb in two gauges. I mount one gauge in the cab and that one gets plumbed into the port right above the oil pump (the one up front on the side) so I can always see what my pump pressure is. The second gauge gets mounted under the hood so that when I'm working on it I can see the pressure in realtime without having to keep ducking back into the cab to read it. The advantage of this is that I plumb the second gauge into the top/rear port, this one gives you a pressure reading about as far away from the pump as you can get. The oil at *this* port has gone thru most of the engine and specifically the readings here come downstream of the lifters. Being able to compare the pressure right at the pump to the pressure at the far end of the line can be useful and it can help you to spot problems before they get out of hand. just something to think about.
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I bought a sunpro gauge but im having trouble finding a adapter to fit in the oil sending port. 1 other thing if i take out the oil sending unit how would i get a true reading from the stock oil gauge.I not a true mechanic im learning as i go.
BroncoJoe19
Active member
IF you want to use both the mechanical unit, AND the original in the dash, then you will have to either get a T fitting so that you could hook up both into the engine in the same place, OR hook the mechanical into a different spot like BB78 mentioned above.
IF you want to get an accurate reading from your in dash unit, you will have to troubleshoot it and fix/replace it.
hope that helps.
Broncobill78
New member
Ahhh, so many questions & so little time
/emoticons/[email protected] 2x" width="20" height="20" />. To give you a quick baseline you should be seeing between 40-65PSI @ 2000Rpm for a 351W. Don't freak out if you're seeing less, plenty of us do but those are the *optimal* numbers and they can be changed quite a bit by varying the weight of the oil you run so we can always monkey around with them if they're not good.Now, I suspect that disconnecting the stock sending unit (if that IS indeed where you elected to plumb in the SunPro) is making the factory processor all sorts of upset but truth be told I don't have the time, inclination, or nearly enuf beer to sit here thumbing thru the manuals at 1am so you'll have to either take my word for it or figure it out yourself
/emoticons/[email protected] 2x" width="20" height="20" />Concentrate on the numbers you're getting. What are they. What is your startup Rpm & oil pressure and what are both 10 minutes later ? What is the *average* oil pressure that you're seeing when you drive ?
Joe is right in saying that a T-fitting should make everyone happy but that will mean getting yourself several new fittings and quite honestly it sounds like you had enuf to do just hooking up the one. If you CAN setup the T then go for it otherwise it's something that can be dealt with in a few days once you've sorted out the basics of what the engine is doing. It *doesn't* need to be done right now but it IS worth considering.
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BroncoJoe19
Active member
It is my understanding that if you grounded the wire, that went to the old sending unit, that the oil pressure guage would read high, and turn the light off.
IF you inserted a resistor between the wire and the ground it would read somewhere inbetween depending upon the amount of resistance. I'm guessing 15 to 30 ohms would be a good working range. You can get the resistors from RadioShack.
BroncoJoe19
Active member
I recalled Seabronc answering the same question at one time and searched back for it. Here is his response.
As a rule of thumb, 10 pounds per 1000 RPM. As long as the truck has more than 5 PSI at idle you should be OK. Don't forget the accuracy of some gauges isn't that great so if you want to really know get a good one. Check the responses above.
Interesting, Seabronc's response was to you in your first post to this forum.
http://broncozone.com/forums/index.php?s=&...ost&p=69618
While looking for this, I noted that someone else was getting 25 at idle and 65 running.
And another was getting 35 - 40 at idle and 60 running.
Dave (BroncoBill78) definitely has you in the right ball park.
good luck
joe
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Broncobill78
New member
Now just as a quick note. It's hard to say. There are SO many different pressures that are considered acceptable for an engine you almost hate to offer an opinion. At any rate, the manual says that 40-65 @ 2000Rpm is cool for a 351 & attached is a scan of that section of manual. If you'd like to see more of it or have other questions you're welcome to ask. As you can see from the responses there's NO shortage of guys willing to help out.
Thanks guys while idle im getting 50 psi at 1000 rpm i hope im reading it right and grounding the oil sending unit wire did cut the light off hopful grounding to the body of the truck is safe?And me saying psi & rpm you would think i know what im talking about this forum is a big help.I haven't driving it yet to see what psi im getting i have other things i want to do with it but again thanks for the help and im sure you all will be hearing from me again :huh:
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BroncoJoe19
Active member
Yahooo!!! I love it when a plan comes together!
I'm glad you got it working, now maybe your hair will have a chance to grow back
I noted that you have been pulling it out for a bit more than a month!OK You lucky fella... go give your wife a kiss, and hug her sister for me
And here's a beer for ya
