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
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
