89 RCSB 5 speed, V8 swap.
I'm not sure that the oil pressure gauge on this thing has ever worked. It's always pegged, even with the battery disconnected.
I have the 2 wire sending unit and the moonie gauges.
Any suggestions what to check first?
That's easy. The 2-wire sending unit near the distributor is for the fuel pump.
The dashboard oil pressure gauge is driven by a DIFFERENT sending unit, mounted on an extension down by the oil filter. This was pictured in a recent thread on this forum.
www.gmt400.com/threads/what-the-heck-is-this.64318/
Doing an engine swap, my 93 k1500 hydro locked. I bought a 1989 k2500 with a 5.7 , the owner quit driving because the brake lines rusted out but eh engine only has 10K miles on it. I have the engine on a stand and it has an odd piece on the back I don’t know what it is, neither does the...
www.gmt400.com
In '88 and '89, maybe after that as well, the sending unit typically has a green stripe by the single-wire terminal, and a black metal heat-shield. Many parts stores list the WRONG sending unit, which is too damn big to fit the heat shield, and interferes with the engine block or the exhaust.
Correct sending unit with heat-shield, compared to Too Damn Big sending unit and box.
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Sending unit with GM extension pipe at ~80 degree angle, and Too Damn Big sending unit on cobbled-together plumbing pipe nipple and elbow which does not fit.
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Doing some more on-line research,
BWD S4320 seems to be the correct one. It has a silver case, and green paint around the end with the electrical connector.
http://weblink.carquest.com/acl/?mfg...rtNumber=S4320
The NAPA / Echlin crossover from that number is
OP6729. AutoZone sells it as
PS150.
Digging around the CarQuest web site, I stumbled upon an aftermarket version of the heat shield. CarQuest doesn't have a photo, but the description sounds good. P/N S4049S.
That number crosses to O'Reillys (Standard) P/N PS381. The O'Reillys photo shows it's very similar to the GM item except for the spring clips at the bottom (big end) that hold it in place. There's three friction tabs on the replacement shield, rather than bigger, more-involved spring clips like the OEM.
https://www.oreillyauto.com/detail/c...?q=PS381&pos=0
And then you'll probably need to hit the Treasure Yard to get that goofy ~80-degree elbow/extension. No doubt GM discontinued it two decades ago.
But here's a thought. This "green stripe" sending unit is not known for a long service life. Instead of buying the sending unit, extension, and the heat-shield, get a 3-wire sending unit from a newer GMT400 vehicle, and the matching 3-wire pigtail. Then replace your 2-wire unit with the 3-wire, and splice the 3-wire pigtail into the two-wire plus one-wire harness. This may be a longer-term solution to the crappy green-stripe sending units.