fastback40 0 Report post Posted May 28, 2006 Having problem with engine gauges. The engine was pro-built with less then 500 miles on it. The oil guage starts out at 1/4 and when the engine warms it drops to just above L and sometimes will go back to 1/4. Th temp gauge get to an 1/8 inch before H and stays there. I checked everything and I can't see that its overheating. Hose's are still flexable and nothing puking out of the overflow. Its got a shroud and ground wire from motor to firewall. The Radiator been taking apart and checked for clogs. My dash circuit board protective layer is peeling badly but the solder looks solid. I've checked the water temp using a laser temp gun and it ranges from 188-196 so I don't think its overheating and I would think if it had problems it wouldn't just stay at 1/8 from hot. Wouldn't the thermostat be wide open at that poing and just go all the wall to overheating? Share this post Link to post Share on other sites
Trinitys 134 Report post Posted May 28, 2006 I'd suggest getting a accurate "test" gage and installing it. This is only tempory and you don't have it sit there for too long....just while you figuring out the issue. This would help you figure out how your factory stuff is reading. i plan on running a set of 3 gages for the first couple of months on my new motor so i can monitor it with greater accuracy the what my factory stuff does. i like the factory gages and plan on keeping them but until i'm sure my motor is in good shape, i'll rely on something a little more accurate..... in all reality....oil sounds like mine was reading...low at idle and slightly higher at midrange driving.. Share this post Link to post Share on other sites
fastback40 0 Report post Posted May 29, 2006 Well I just tested my radiator with a test gauge and its holding steady at 180-185 in 90 degree temp day. So the problem is in the gauge itself or the circuit board(Maybe). So has anyone out there tackled the gauge problem? I can buy one on ebay but it be nice to find the problem. I got my mallory coil wire tape wrapped with the sending unit wire, but everyone I talk to sez its not an issue. Can't be voltage reg since it either works or it don't. Sure wish there was a repair place out there! Share this post Link to post Share on other sites
Trinitys 134 Report post Posted May 29, 2006 to solve this issue youd need to see if you could get the gage calibrated at a gage shop.....tachman.com does it. Share this post Link to post Share on other sites
fastback40 0 Report post Posted May 29, 2006 thanks trinity yu da man!!!! Share this post Link to post Share on other sites
buening 63 Report post Posted May 30, 2006 The problems point to the constant voltage regulator on the back of the instrument cluster. This regulator affects the temp, oil, and i believe fuel gauges. It has a real small knob on it for calibration purposes. If you have spare time you can adjust that knob till you are getting correct readings. You can buy mechanical gauges at your local parts stores for cheap. Hook those up to verify readings and then calibrate your guages via CVR to match. Also be aware that the senders are self grounding and if the senders are new they could be faulty. I went through 4 new temperature senders before i got one that actually worked properly. Share this post Link to post Share on other sites
fastback40 0 Report post Posted May 30, 2006 Can I get more ino on the cvr? I bet thats the issue. The fuel gauge seems to be fine so it may not affect it. Thanks for the info really cause I wondered if there was a calibration system in place. I no the gauge is wrong and I bought a new sender and it gave me the exact same reading as the oem one. Share this post Link to post Share on other sites
buening 63 Report post Posted May 31, 2006 The CVR is attached to the printed circuit board and is located between the speedometer and the fuel/temp gauge. It has two posts that are shaped like 9V battery connections. Just below these posts is a very small post. This is the adjustment. Assuming it is just out of whack, tuning it will help. Normally when it is out of whack all guages will read high or all gauges will read low. Not a mixture of the two. You might be able to pull the dash pad off first, and then remove the cluster and then make the adjustment. Leave the cluster resting on the steering column and start the motor. Note the readings and which direction they went since the adjustment. Turn off and then readjust until happy. This way you won't have to keep installing the cluster back in its home. Hope this helps. New CVRs aren't cheap and would be a last resort (but cheaper than a printed circuit :wink: ). Let me know if i can help any further. Share this post Link to post Share on other sites
fastback40 0 Report post Posted May 31, 2006 buening, I just re-read your post. All my gauges are mixed issues. Temp reads high but oil reads low so from what your saying this can't be the cvr. So if it not the senders or cvr then the issue could be the gauge itself, but the fuel gauge seems to be fine so are the 2 the same as far as resistants? This should be simple but!!! Share this post Link to post Share on other sites
buening 63 Report post Posted May 31, 2006 Quick and simple test to eliminate the gauge or the wire from the sender to the gauge: Have someone ground the sender wire to the motor and the gauge should peg high/hot. If it pegs then the wiring and gauge should be fine. On a side note, here are my observations from what i am reading. You temp gauge is reading hot and you tested the radiator temp. The actual temp is being read at the intake for the gauge. Make sure that you have the radiator cap off, operating temps up to normal, and the thermostat opened (should see coolant flowing). Then test the water temp. I would still buy a set cheap gauges (wal-mart has tri gauge setup for $20) that are mechanical and hook them up so you know what it actually is. As for the low oil pressure readings, are these taken when the motor is hot? When the motor is cold, the reading should be mid-high but when warm and idle it should read low. At least this is what my car did. Actual pressures from my autometers are 40-50psi when cold and idle, 10-15psi when warm and idle, and around 40-45psi when driving and warm. You can see how the pressure would read low when the motor is warm and is idling. Also make sure you have the right sender wires going to the correct senders, but not sure if the temp sender wire would reach the oil pressure sender. Well if you verify the readings with a mechanical gauge and it still says the gauges are way off, then i'm leaning towards the senders. You can still try adjusting the CVR to see how it affects the gauges but make a mark so you know where to reset it back to in case it makes it worse. Share this post Link to post Share on other sites
bnickel 10,004 Report post Posted June 1, 2006 also if someone has messed the needle in the past it may not be in the correct location. these things are very easy to bend and could very well get bent and you wouldn't even know it. if the gauge seems to be working correctly other than the low reading it's very possible that the needdle somehow got bent. IIRC my gauge would read right about in the first third or so of the range when warm and at idle. so what may seem low to you might be actually be correct. Share this post Link to post Share on other sites
fastback40 0 Report post Posted June 1, 2006 OK I hooked up a mechanical temp guage and it sat at 180 for 45 minutes. The oil guage seemed fine course that was when the engine was cold. The oil guage reads bout an 1/8th from middle so I can live with that. The temp guage does peg out when grounding the wire. I don't have the old sending unit hooked up. Seems like all the other guages are fine but the temp one. I'll try another sending unit. Does everyone have 2 nuts on the sending units? Buening, you still think I should try and adjust the cvr? Share this post Link to post Share on other sites
buening 63 Report post Posted June 1, 2006 I'd leave the CVR alone if you are only 1/8 low from the midway reading of the oil pressure. Is this once the oil is hot or when cold? No the sender should thread directly into the intake. Using more fittings puts the sender above the flow of water and allows an air pocket to form, giving you higher readings than normal (steam). Try loosening the sender until coolant comes out and then retighten, hoping that is stays sealed. This will hopefully get rid of any trapped air that is under the sender. You can also figure out why there is another fitting. Is the sender too small to fit on the threaded hole in the intake? Which corner of the intake is the sender at and what intake are you running? Share this post Link to post Share on other sites
fastback40 0 Report post Posted June 1, 2006 Well good question. I'm running an edelbrock streetmaster. It dose have quite an air pocket from the sender. The sender is screwed on the intake direct. I did wonder how the sender was getting to the water. I will follow your suggestion bout releasing coolant..it dose make sense. DO yu think theres an aftermarket sender out there that has a longer probe due to different intakes? The 2 nuts I was referring to was the wire that nuts on the sender stem. Sorry for the confusion. Share this post Link to post Share on other sites
buening 63 Report post Posted June 1, 2006 Well if you are using the stock type sender without any adapters to the intake then you should be fine, just remove the air. I assume you are using the port on the front drivers corner of the intake. Yeah it doesn't matter how many nuts are on the sender stem, using two is like using a lock nut. It prevents it from rattling loose. Stock harnesses have the rubber plug that slips over the sender stem. The gauge feed harness is only around $20 from the parts venders. It is the harness that runs atop the engine that feeds the coil, oil pressure sender, and temperture sender. Good luck! Share this post Link to post Share on other sites
