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I just got burned by an electronic gauge [message #320461] Sat, 15 July 2017 04:45
Ken Burton is currently offline  Ken Burton   United States
Messages: 10030
Registered: January 2004
Location: Hebron, Indiana
Karma: 10
Senior Member
I just yesterday finished an intake manifold gasket installation on my wife's GMC Jimmy. It is a bear of a job. Everything on the top and front on the engine has to be removed. While everything was apart I cleaned and re-gasketed everything including the upper plenum and throttle body. I replaced several sensors that are almost impossible to get to with the removed items installed on the engine. When I finally go it back together I had a low oil pressure reading at all temperatures and all engine speeds indicating an major oil flow obstruction or a worn pump or bearings. It was slightly less than 20 at cold idle and a little less than 10 at hot idle. It never hit 40 cold or hot with the engine RPM up higher. I could not figure out what I had done to cause the loss of oil pressure. I finally decided to look at the old removed oil pressure sending unit since I had it out of the vehicle. I looked up the PSI vs. ohms spec and tested it at 0, 10, 20, 40, 60, and 80 PSI. It was good at all pressures.

So I broke down and removed the new one from the engine. It is not easy to get to and required removing the rear mounted distributor, among other things, and a special 1-1/16" extra deep well 3/8 drive socket to remove the sender. I tested the new, now removed, one at the same pressure readings and only 0 and 80 PSI were within specs. So in went the old original one. Upon starting the engine the cold idle was 50 PSI and the hot idle was about 40. That matches my 98 Blazer which is an identical one year older vehicle with 240,000 miles.

I guess I learned my lesson. It would not have been so bad if the sensor was easy to get to. This new (defective) one was made by Borg Warner in the USA. So much for American made parts. I'll stay with the original one that is 18 years old and has 170,000 miles on it.


Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
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