| Slant Six Forum https://slantsix.org/forum/ |
|
| oil pressure sender behavior https://slantsix.org/forum/viewtopic.php?t=44766 |
Page 1 of 1 |
| Author: | daveca5150 [ Wed Apr 27, 2011 7:52 pm ] |
| Post subject: | oil pressure sender behavior |
Hi, 63 valiant with about 4000 miles on rebuilt engine... My oil pressure idiot light came on a few days ago while cruising on the freeway. I pulled over immediately, took off the valve cover and bumped it a few times to see if the head was getting oil, it was. So I starting it and saw decent oil flow up and over the lifters. I decided that it was probably safe to drive home. After searching the forums, I decided to try replacing the sender since it's cheap and they have been known to read faulty. At the same time, I installed a t-fitting and bought a mechanical pressure gauge with the intent of making sure the new sender was reading properly. While I was at it, I serviced my pressure relief valve as per Doc's instructions. The valve was in great shape, but needed a little deburring. It was moving well afterward. Once I put it all back together and started the engine, the gauge is showing 45 lbs of pressure at idle with very slight increase when rpms get above 2000, but never more the 50 lbs of pressure. When I shut the engine off, the pressure slowly drops, maybe 5-10 seconds to hit zero. Is all of this sounding pretty normal so far? Is my pressure relief valve not doing it's job even after cleaning? The puzzle for me is that my oil light will remain off - indicating adequate pressure - until about 35-50 seconds after engine shut-off, even though my mechanical gauge reads zero. Is this a faulty sender? Thanks, Dave |
|
| Author: | Fopar [ Wed Apr 27, 2011 8:16 pm ] |
| Post subject: | |
Some differences in sender units as to what pressure it takes to shut off light. If I recall correctly some will go off at 8 lb and some will go off at 3 lb, and how accurate does your gauge read at close to zero lb. Richard |
|
| Author: | SlantSixDan [ Wed Apr 27, 2011 10:04 pm ] |
| Post subject: | |
Is your sender threaded into the oil pump, or into the side of the block? |
|
| Author: | WagonsRcool [ Thu Apr 28, 2011 11:40 am ] |
| Post subject: | |
@ Dan, I assume that we're talking about a slant 6, was there any year block that had an external oil pressure tap? I've only seen oil switches on the pump. @ Dave. Your oil pressure sounds good. It will be highest on a cold eng above idle- the relief valve should limit it to 50-60 psi. It will be lowest at fully HOT slow idle (10-20 psi is typical for a used but good eng). Heavier weight oil can raise pressure some (but will get to eng bearings slower on startup). Thinner oil flows faster but lowers pressure. Synthetics give faster pressure buildup on start with less pressure drop when hot (but cost more $$) The oil switch has a small orfice to limit pressure changes against the internal diaphram. It's possible you have a small bit of grit inside that's restricting pressure drop when you turn the eng off. With heavy cold oil that could account for your light operation.(I assume you're turning the eng off then turning the ign switch back on to watch the oil light?) A last thought, you could have had some kind of short to ground in the oil lite circuit that would have turned the indicator on. |
|
| Author: | 1974duster kev [ Thu Apr 28, 2011 12:16 pm ] |
| Post subject: | |
my 74 duster orignal motor and the one i put in after that both had an oil passage hole on the passenger side of the block towards the rear of the motor which i hooked my gauge to, Current turbo motor this block does not have the hole so i pulled pressure from the oil pump itself. Kev |
|
| Author: | SlantSixDan [ Thu Apr 28, 2011 12:18 pm ] |
| Post subject: | |
Quote: @ Dan, I assume that we're talking about a slant 6, was there any year block that had an external oil pressure tap?
Yes. Some 1963, many 1964, and early 1965 left the factory with the sender screwed into the oil gallery at the rear of the distributor side of the block. There was a TSB released, advising dealer techs to swap the locations of the sender in the block and the plug in the pump to address customer concerns about the oil pressure warning light coming on under or after deceleration. That is why I asked. |
|
| Author: | daveca5150 [ Thu Apr 28, 2011 3:56 pm ] |
| Post subject: | |
Thanks for the replies. The sender is threaded into the oil pump, not the block like some '63s. The block does have a plug on the passenger side just above and aft of the oil pump but it looks smaller than my oil pressure sender and I think it may lead to the water jacket. Also, I'm running 10W30 (castrol GTX). Based on the replies so far, I think I feel safe enough to drive it a bit and observe what happens with a warm engine. |
|
| Author: | 1974duster kev [ Fri Apr 29, 2011 2:54 pm ] |
| Post subject: | |
Well your mech oil pressure gauge is reading good so the idiot light is being awkward toss it! Kev |
|
| Page 1 of 1 | All times are UTC-08:00 |
| Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/ |
|