Oil pressure dropping [solved]

[Van-Tramp]

For the past two years, the oil pressure gauge in Big Blue has been slowly dropping. I've been watching it with concern and reading up on probable causes. A few days ago, on my most recent drive, the gauge barely read any pressure at all and the big red warning light was not just blinking, but full blast. <br><br>After a few phone calls, I took the advice of a nearby garage owner and installed a mechanical oil pressure gauge... and look what it says! And this is at idle<br><br>.<img rel="lightbox" src="http://www.van-tramp.com/wp/wp-content/uploads/2013/07/oil-psi-150x150.jpg" class="bbc_img"><br><br>The problem is the simple $13 oil pressure sending unit (electronic device, as usual) which is already being shipped thanks to RockAuto.com

 

[RJCooper]

Good deal.&nbsp; I have three aftermarket gauges in my truck and always compare them to the factory.&nbsp; Way off.&nbsp;

 

[wrcsixeight]

It is not Oil PSi keeping the metal parts from touching each other, it is the film strength of the oil.<br><br>So while a minimum oil PSI is needed, more than that, is not better. &nbsp; My factory service manual says 8 PSI is minimum at 750 rpm when hot.<br><br>If more was better, then we should all dump 85w- 140 gear oil in our engines and get 100 +PSI, but start up noises and engine wear would be extreme as the oil is simply too thick to flow properly, and the oil filter would always be in bypass, filtering nothing.<br><br>There is a relief valve on the oil pump. &nbsp;Mine is 68psi when cold, 62 when hot.<br><br>Whenever I start my engine cold, it is 68 psi at any rpm.<br>When my engine is hot and the oil at full temperature, I get 18 PSI at 550 rpm, and it hits the bypass valve at 62 psi at around 2000 rpm. &nbsp;The oil takes a lot longer to reach full temperature than the coolant.<br><br>Oil pressure directly correlates with engine rpm when both are hot.<br><br>Getting a reading of ~60 at idle with a cold engine and oil is expected.<br>Getting a reading of 60 psi at idle with a hot engine means your oil is too thick, or you gauge is inaccurate.<br><br>Thicker oil generates more drag and heat. &nbsp;Thicker oil flows slower, so less oil is making it to the top of the engine, lubricating and cooling. &nbsp; At bypass pressures, much more thin oil is flowing than would a thick oil . Thick oil during cold starts, will cause more engine wear than a lighter oil. &nbsp;Thick oil, thicker than what the manual calls for, only protects better if the engine overheats while under extreme load.<br><br>Modern engines in the quest for maximum fuel economy are specifying thinner and thinner oils, but mostly in North America. &nbsp;Other countries with the same engines spec heavier oils, especially Australia<br><br>Congrats on the mechanical gauge install. Once you get used to looking at it throughout an oil change, you can notice if the oil is shearing to a lighter grade, or getting thinned from fuel dilution, and notice different behavior when you change the oil.

 

[Van-Tramp]

I plan to take it out for a drive tomorrow to make sure I still have pressure when it is hot. I know it will drop some, just hopefully not to the point of that oil warning light (triggers at 3-6psi from what I have read).<br><br>Honestly, I was just happy to see I have oil pressure at all considering the gauge on the dash barely moved the needle at idle when cold. This reading is very, very different than the dash-gauge.

 

[caseyc]

I'm glad your thing is now fixed, good to hear.&nbsp; Stupid question here...is that oil guage something you installed yourself? I don't think I have that guage on my 1995 Ford E150 conversion van.

 

[Van-Tramp]

Yea Caseyc,<br><br>You can find them on Amazon or at your local auto parts store (<span style="text-decoration: underline;"><a rel="nofollow" href="http://www.amazon.com/Sunpro-CP8216...sr=1-1&amp;keywords=sunpro+oil+pressure+gauge" target="_blank">like this one</a></span>) for under $20. It took about 15 minutes to install.

 

[caseyc]

Hi Van-Tramp,<br><br>Oh nice, thanks! &nbsp;I now have another item added on my list of things to install next time I visit my van conversion shop!&nbsp; When it comes to mechanical stuff like this, I would never trust myself to install such a thing, haha!&nbsp; <br><br>Casey

 

[MK7]

Most oil pressure gauge on cars are dummy gauges, in a sense that they only register low oil pressure or adequate oil pressure...regardless of what number the needle is on. There may be a little variation of pressure if it drops down to where it usually never have been when it was reading good. Putting on a real oil pressure gauge that's aftermarket is a good thing, so do you still need that oil pressure sending unit at all?

 

[Van-Tramp]

Woot, 20+ PSI at idle after it is all heated up. I'm so happy about this <img src="/images/boards/smilies/smile.gif" class="emoticon bbc_img"><br><br>Casey, there are so many tutorials online (YouTube) that will walk you through all these basic things. It would be sad to hear that you had paid a mechanic $50 or more to install a $17 gauge. They are actually very simple. Once you do it, you will realize how much better off you are for doing your own repairs.<br><br>If all else fails, I will do it (with you) for free... we just need to get to the same locale

 

[Van-Tramp]

@MK7 <br><br>No I guess I do not need it, but I'd like to have it operational again just for the sake of it. If I do ever sell the van, a non-function oil gauge would definitely decrease the price by more than the $13 for the new part. And heck, it is so easy to get to the spot in needs to go in the engine bay (pop hump off and it is right there) so why not.<br><br>I'm actually deciding on whether or not to keep the mechanical gauge in there as well or remove it to use at a later day on other vehicles if required. I do not care to read the gauge now that I know what it really happening, and I worry about that little tube getting caught up in the moving parts of the engine in the long run.

 

[Terry]

wups

 

[caseyc]

Hi Van-Tramp,<br><br>Thanks for the offer! I hope to reciprocate in the future.&nbsp;<br><br>Casey<br><br>

 

[wrcsixeight]

With easily available common plumbing parts one can "T" the line and use both senders.<br><br>It is what i have done. &nbsp;Both my OP gauges work, but I find the OEM gauge to be a joke. &nbsp;About 45 seconds behind the instant Mechanical gauge, and inaccurate when it does finally catch up. I keep it mainly for the idiot light to draw attention if I do lose oil pressure suddenly.<br><br>The mechanical OP gauge is probably the best gauge I have on my engine. &nbsp;From it I can infer both RPM, and temperature.<br><br>But I do have a Tach too, and a new sender for the temp gauge which restored the full swing of the gauge.<br>

<br><br>

<br>&nbsp; My old failed one wire sensor was only allowing a range between the first two hash marks from the bottom. &nbsp;If you gauge does not show the ranges above, replace the one wire sender on the intake manifold. &nbsp;It is 5$ at AZ or RockAuto<br><br>I've done what i can to make sure the hollow capillary plastic tube for the mechanical OP gauge cannot chafe or crease. &nbsp;No issues in the 7 years it has been installed. &nbsp;Many use copper instead of the provided plastic for more durability.&nbsp;