Problem with Water Temperature and Oil Pressure gauges
10-02-04, 07:20 PM
#1
Rotary Enthusiast
Thread Starter
Problem with Water Temperature and Oil Pressure gauges
Within the past week, I have been succesfully starting and running my recently rebuilt engine, rebuilt by Kevin Landers.
Please note first that our factory gauges are NOT renouned for their accuracy. Also, I rewrapped my ECU harness, and replaced every unsealed connector that was corroded or looked bad. This included the connectors for the Oil Pressure and Water temperature senders. The water temperature sender got a new bullet connector, and the oil pressure sender got a 1/4" female quick disconnect. This connector was later replaced and the new one crudely modified to slip onto the sender connecting point.
At initial startup, my oil pressure gauge didn't work due to a connector that worked it's way loose on the sender. Once connected, it was reading 60+PSI at 3000 RPM and 30 PSI at 1500 RPM.
This weekend, I've been taking care of the exhaust leaks, and the engine has gotten much easier to start and isn't flooding. But, the oil pressure gauge now reads under 30 PSI, and in some cases zero.
I've checked and rechecked the connector on the oil pressure sender. Occasionally, it goes back up to 30 PSI at 1500 RPM, but most times under 30 at the same RPM. At 3000 no change.
Ok, now onto the water temperature gauge. Since startup, with fresh antifreeze and distilled water, the temperature gauge has read at all. It responds when I ground the connector, but reads nothing. Bear in mind, I have initially ran the engine for no longer than 5 minutes, and there is the possibility of air pockets in the system, which I have, hopefully, cleared out today.
Despite having run it upward of 15 minutes, and even drove it short distances (no longer than a mile, twice); no reading.
The bullet connector may have gotten weakened and broke--so I'm going to replace that this week. I also am going to splice in a new wire using heatshrink butt connectors, but have done a temporary repair to check the gauge. I have been very careful to avoid overheating, and I've made sure not to run the engine for very long and let it cool down.
What do you think? Should I just give up the gauges as a lost cause and go with better, more accurate, aftermarket gauges?
Please note first that our factory gauges are NOT renouned for their accuracy. Also, I rewrapped my ECU harness, and replaced every unsealed connector that was corroded or looked bad. This included the connectors for the Oil Pressure and Water temperature senders. The water temperature sender got a new bullet connector, and the oil pressure sender got a 1/4" female quick disconnect. This connector was later replaced and the new one crudely modified to slip onto the sender connecting point.
At initial startup, my oil pressure gauge didn't work due to a connector that worked it's way loose on the sender. Once connected, it was reading 60+PSI at 3000 RPM and 30 PSI at 1500 RPM.
This weekend, I've been taking care of the exhaust leaks, and the engine has gotten much easier to start and isn't flooding. But, the oil pressure gauge now reads under 30 PSI, and in some cases zero.
I've checked and rechecked the connector on the oil pressure sender. Occasionally, it goes back up to 30 PSI at 1500 RPM, but most times under 30 at the same RPM. At 3000 no change.
Ok, now onto the water temperature gauge. Since startup, with fresh antifreeze and distilled water, the temperature gauge has read at all. It responds when I ground the connector, but reads nothing. Bear in mind, I have initially ran the engine for no longer than 5 minutes, and there is the possibility of air pockets in the system, which I have, hopefully, cleared out today.
Despite having run it upward of 15 minutes, and even drove it short distances (no longer than a mile, twice); no reading.
The bullet connector may have gotten weakened and broke--so I'm going to replace that this week. I also am going to splice in a new wire using heatshrink butt connectors, but have done a temporary repair to check the gauge. I have been very careful to avoid overheating, and I've made sure not to run the engine for very long and let it cool down.
What do you think? Should I just give up the gauges as a lost cause and go with better, more accurate, aftermarket gauges?
10-02-04, 08:41 PM
#3
Rotary Enthusiast
Thread Starter
Ok, the water temperature gauge is now working, and when the engine is warmed up, it's reading what it's supposed to read.
First, our gauges work by measuring the resistance from the sender. The higher the resistance, in ohms, the lower the reading. I had previously taken apart the instrument cluster to retrofit red LEDs, and the means to both mount and connect the individual gauges to the cluster is through philips screws. When I took out the instrument cluster, the screws on the temperature gauge were loose--one had backed out a little. This increases resistance. Plus, the guage itself, when grounded directly, didn't shoot to the top of the range, only a quarter from the top. So, after tightening the screws, and repositioning the needle, the gauge read correctly 1/4 of the way and no increase after the engine warmed up. The coolant buzzer and low coolant warnings have not gone off since initial startup. No coolant has been leaking or burned.
Unfortunately, the Oil pressure gauge is still not working as it should. Maybe it's the same reason as the temperature gauge--too much resistance. Connections on the cluster were ok, so I left that alone. I should also note that I am using 6 quarts of fresh Castrol GTX 10w40, a filter from Atkins, and that I did check the oil level. There are no oil leaks, and the engine isn't flooding repeatedly--in fact it's not hard to start at all.
But, better safe than sorry, I'm not going to drive the car or run the engine very long, so I'll recheck the connection on the sender again. Is there a way to measure OHMs on the sender with a multimeter? I've tried, but didn't get a proper reading in the range it should measure for.
Wednesday, or earlier, I'll do a more permanent repair on the sender wire.
First, our gauges work by measuring the resistance from the sender. The higher the resistance, in ohms, the lower the reading. I had previously taken apart the instrument cluster to retrofit red LEDs, and the means to both mount and connect the individual gauges to the cluster is through philips screws. When I took out the instrument cluster, the screws on the temperature gauge were loose--one had backed out a little. This increases resistance. Plus, the guage itself, when grounded directly, didn't shoot to the top of the range, only a quarter from the top. So, after tightening the screws, and repositioning the needle, the gauge read correctly 1/4 of the way and no increase after the engine warmed up. The coolant buzzer and low coolant warnings have not gone off since initial startup. No coolant has been leaking or burned.
Unfortunately, the Oil pressure gauge is still not working as it should. Maybe it's the same reason as the temperature gauge--too much resistance. Connections on the cluster were ok, so I left that alone. I should also note that I am using 6 quarts of fresh Castrol GTX 10w40, a filter from Atkins, and that I did check the oil level. There are no oil leaks, and the engine isn't flooding repeatedly--in fact it's not hard to start at all.
But, better safe than sorry, I'm not going to drive the car or run the engine very long, so I'll recheck the connection on the sender again. Is there a way to measure OHMs on the sender with a multimeter? I've tried, but didn't get a proper reading in the range it should measure for.
Wednesday, or earlier, I'll do a more permanent repair on the sender wire.
10-02-04, 10:52 PM
#4
24 yrs driving 2nd Gen RX
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Something else you might do, is to re-solder the connections on the PC board back of the instrument cluster. I found many cold solder joints, and got much better response out of the boost gauge, for one and more stability in the others. Also, brighter lights.
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10-02-04, 11:09 PM
#5
Lives on the Forum
Tap on the oil pressure sending unit when the gauge looks wacky- any change in reading? They seem to like to go bad during a rebuild for some reason (mine too)...
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