NC98Z

iTrader: (1)

Join Date: Sep 2003
Posts: 356
Trader Rating: (1)

Guages Question.

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Is there anything ya'll can think of that would make your water temp and your oil pressure gauges read low. I've already got a new oil pressure sending unit to replace mine with but I've also got low readings on my water temp guage and I'm wondering if I'm looking the wrong way for the trouble. This is after a new shortblock installation. oil pressure reads 19#s at idle and water temp guage never gets over 160,even in this summer heat and I don't have a 160 thermostat mines stock.
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Look guys I can't get an answer from the external engine section. And I would appreciate if you would respond. I ain't no newbie but I just paid over $3000 to have a new motor tranny install not even counting what I paid for the tranny less than 1500 miles ago. And there has to be an answer for this. There are some top notch people on here if I can get a response from something you or your buddies might have run into it will keep me from burning another day of vacation so I can run the car up 100 miles from here where it was installed.

staringback05

iTrader: (8)

maybe a voltage issue somewhere...have you tested load? or ground?...have you hooked it up with software and seen what its reading then?

NC98Z

iTrader: (1)

So far I've bought a new 98 oil pressure sending unit ( different years different resistance scales ) and I'm going to get up in the morning and change it out . If it reads the same they are going to tap out the tap above the oil filter and stick a mechanical gauge on it. For a truer reading. If its bad too the people who installed it for me are going to have to take over. I don't have a lift available that I can use so I'm kinda stuck between a rock and low oil pressure readings. If its not the sending unit or the dash gauge bad (and 98s have the only true factory gauges I know of) its got to be a o-ring or a bad pump. I've been a member of this forum since 2003 and I don't ever remember a problem quite like this one. My engine temp never get above 160. Even in this heat wave after is been ran and sits a while its too low.

staringback05

iTrader: (8)

id still really like to see what all of it would read on efi live...

DJ_951

just an extra $.02. The gauges are electric and sensitive to current flow. With a new engine I would check the ground strap from the engine to the body. (there maybe two) They could have used (lots) of teflon tape to install the gauges which also does't promote a good ground. Grounds are a pain.

intense3123

+1 for checking the grounds and the wiring. I know that the temp sensors are a negative temp coefficient type. Meaning that as temperature rises the resistance goes down. If your already starting with more resistance than normal then your readings will be lower than actual.

NC98Z

iTrader: (1)

Actually the guys that work on my car hooked up a tech tool to the diagnostic port and the temp sending unit thought it was 35 degrees all the time. And that information is used by your CPU for A/F computations and lord knows what else. Funny thing about something that important is it won't throw a code but that car sure ran alot better when the new water temp sensor was installed. As far as the oil pressure the 98 guage again is telling the truth. When the shop put a mechanical oil pressure guage on the engine it was also reading about 15#s at idle. I'm gonna take it back to the shop in a couple of weeks and the guys there will fix for me. I'll ask them what they did
to correct it and post it up for the forum. Looks like what I've been told is true 98 guages are accurate.