MrEarl Posted June 11, 2019 Share Posted June 11, 2019 (edited) Aside from when running hot, when should the water temperature idiot light come on. I read in the owners manual that it should come on when cranking the engine over. Mine does not come on with the key turned on nor when turning the engine over. Have pulled the dash and swapped bulbs with known good ones. Still nothing. What Is the likelihood of the temperature sending unit being bad. @dmfconsult Edited June 13, 2019 by MrEarl (see edit history) Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 11, 2019 Share Posted June 11, 2019 (edited) 7 minutes ago, MrEarl said: Aside from when running hot, when should the water temperature idiot light come on. I read in the owners manual that it should come on when cranking the engine over. Mine does not come on with the key turned on nor when turning the engine over. Have pulled the dash and swapped bobs was good known ones. Still nothing. What Is the likelihood of the temperature sending unit being bad. @dmfconsult The light will come on when the key is turned to start or accessory. This lets you know the bulb is working. If the new bulb is not working assure there is voltage getting to the socket. Check ground. It is a inexpensive part. Easy install. Change it out. Let's be honest about these bulbs. They illuminate just as the head is about to melt. Been there(1978 Buick Regal). I do not have much faith in the system as a result. Edited June 11, 2019 by avgwarhawk (see edit history) Link to comment Share on other sites More sharing options...
JohnD1956 Posted June 11, 2019 Share Posted June 11, 2019 @MrEarl If you pull off the connector wire, and ground the connector with a test wire, then the bulb should light. If it does, then unless the connection on the sensor is just in need of cleaning, I would replace it. Have you ever pulled a wire out of a plastic connector on this age vehicle? It's very simple. I would pull it out and clean it with some 600 or so sandpaper, or even just scrub it with some fine steel wool. Advise if you need to know how to remove the wire from the connector. 1 Link to comment Share on other sites More sharing options...
5632 Posted June 12, 2019 Share Posted June 12, 2019 My 64 Riviera has 2 connectors on the temperature secure. How do you check that? Link to comment Share on other sites More sharing options...
dmfconsult Posted June 12, 2019 Share Posted June 12, 2019 I’m with John on this, check the wiring. I’ve noticed cracked and brittle insulation around the sender so I’ve dealt with that, but no issue such as you’re reporting. @avgwarhawk is quite right, I don’t think those lights are designed to come on until extreme temps are reached (I recall reading somewhere it was 270 degrees). I haven’t installed a separate gauge but I do complete spot checks with an infrared thermometer so I know where my car typically runs (195-200 is usual temp at thermostat housing on hot days under load with my thermostat). 1 Link to comment Share on other sites More sharing options...
5632 Posted June 12, 2019 Share Posted June 12, 2019 Maybe I will learn to spell. Temperature Sensor. Link to comment Share on other sites More sharing options...
JohnD1956 Posted June 12, 2019 Share Posted June 12, 2019 27 minutes ago, 5632 said: My 64 Riviera has 2 connectors on the temperature secure. How do you check that? Does your Riviera have separate hot and cold temperature lights? Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 12, 2019 Share Posted June 12, 2019 11 hours ago, dmfconsult said: I’m with John on this, check the wiring. I’ve noticed cracked and brittle insulation around the sender so I’ve dealt with that, but no issue such as you’re reporting. @avgwarhawk is quite right, I don’t think those lights are designed to come on until extreme temps are reached (I recall reading somewhere it was 270 degrees). I haven’t installed a separate gauge but I do complete spot checks with an infrared thermometer so I know where my car typically runs (195-200 is usual temp at thermostat housing on hot days under load with my thermostat). Doug, my experience with the less than stellar idiot light involved my 78 Buick Regal 3.8. The light turned on after the radiator blew. To add insult to injury, #1 cylinder valves in the head melted. The lights warm glow is never seen until too late. Link to comment Share on other sites More sharing options...
5632 Posted June 12, 2019 Share Posted June 12, 2019 20 hours ago, JohnD1956 said: Does your Riviera have separate hot and cold temperature lights? No it does not. It has only one light bulb also. Link to comment Share on other sites More sharing options...
KongaMan Posted June 13, 2019 Share Posted June 13, 2019 2 hours ago, 5632 said: No it does not. It has only one light bulb also. A 64 Riviera has both a hot (red) and cold (green) light. Link to comment Share on other sites More sharing options...
JohnD1956 Posted June 13, 2019 Share Posted June 13, 2019 1 hour ago, KongaMan said: A 64 Riviera has both a hot (red) and cold (green) light. I thought so. I know the 65 Electra had a cold and hot temp light. I have heard that currently it is hard to find a temp sensor with both ranges. But I do not know if that is accurate. Link to comment Share on other sites More sharing options...
MrEarl Posted June 13, 2019 Author Share Posted June 13, 2019 (edited) OK guys, back at this and thanks for all the comments and suggestions so far, sorry I haven't responded sooner, life matters took precedent. On 6/11/2019 at 4:03 PM, avgwarhawk said: The light will come on when the key is turned to start or accessory. This lets you know the bulb is working. Chris, the owners manual explains it as "while the engine is cranking" but either way it's not coming on soooo.... On 6/11/2019 at 4:03 PM, avgwarhawk said: If the new bulb is not working assure there is voltage getting to the socket. Check ground. It is a inexpensive part. Easy install. Change it out. On 6/11/2019 at 4:07 PM, JohnD1956 said: If you pull off the connector wire, and ground the connector with a test wire, then the bulb should light. If it does, then unless the connection on the sensor is just in need of cleaning, I would replace it. Checked ground, cleaned all contacts. Changed out the sending unit which turned out not to be such an "easy install" I had been hitting it with PBB since the beginning when I first thought I may end up replacing it. Using a 15/16 on a 1/2" ratchet couldn't get it to budge. In frustration and desperation put an air wrench to it which only resulted in eventually spinning and rounding off the corners of the unit. Hit it with PBB and said good night. Next morning drove a 7/8" tall socket down tight over it and using a 3/4" bar she broke loose. Thank ya Jesus. Hooked the connector back up and still no dash light. Checked continuity from the sending unit connector to just before the circuit board in the dash and have continuity. Do not have continuity through the circuit board to the light socket though. On 6/11/2019 at 4:03 PM, avgwarhawk said: Let's be honest about these bulbs. They illuminate just as the head is about to melt. Been there(1978 Buick Regal). I do not have much faith in the system as a result. On 6/11/2019 at 9:10 PM, dmfconsult said: @avgwarhawk is quite right, I don’t think those lights are designed to come on until extreme temps are reached (I recall reading somewhere it was 270 degrees). I haven’t installed a separate gauge but I do complete spot checks with an infrared thermometer so I know where my car typically runs (195-200 is usual temp at thermostat housing on hot days under load with my thermostat). I'm with ya on the idiot lights, hate them. I have a full set of gauges that was on my list to install pre trip but ran out of time to do. (Actually ran out of time when trying to figure out where to hook up " ignition on" power to them) Here is what really drew my attention to this whole idiot light thing. When I took her for the 60 mile trailer attached test run through some mountain roads I checked the thermostat housing temperature with a gun. Read 265* !!!!!!! And that was on an overcast day with 88* temperature. I was not about to take off to OKC with that knowledge. Y'all keep in mind this is a 403/6.6 Olds/Pontiac engine. From my research on Olds and Pontiac sites this engine is known to be a hot running engine with up to 220 being norm and 235 not necessarily cause for alarm, but 265....scary. So I am certainly looking at a more critical issue than just the idiot light issue. Even with using gauges, because one can't keep a constant eye on a gauge I still want a warning light but may consider running one in the gauge panel vs continuing to try and diagnose the dash light problem. Also may look into a sending unit with a lower kick on temperature than 270*. This engine has already had two head jobs in its 135,000 mile life. One at around 65,000 and the last one at around 120,000, just 15,000 miles ago. From what I've read the factors contributing to the high temps and head problems seem to be "windowed main webs and siamesed cylinders." I am beginning to wonder if perhaps a head gasket may have been installed wrong or slipped and is blocking coolant flow or worse case has a blown head gasket. Maybe I'll check the radiator water for air bubbles? Passing that test I think I am looking at a new 3 core radiator, installing the 180* thermostat and high flow water pump I already have in the 70's period suit case I had ready for the trip. I already flushed the radiator and installed 60/40 water/antifreeze. Or maybe I'll just consider an LT1 swap and be done with it. Quick question, would that bolt up to my newly rebuilt 350 tranny? Geeze, i just had to sign out and sign in 4 times in order to post the pictures to help in putting pictures to words to show what I'm talking about here. @Peter Gariepy I thought you had set us up at one time to be able to upload larger files and the forum software would automatically resize to allow them to display. The current 9.7 limit is typically reached with just two cellphone sized pictures. A lot of members including myself are getting around this by signing out and back in which allows a couple more pictures but man what a pitb. Can you help with this or do we just deal with it? Edited June 13, 2019 by MrEarl (see edit history) Link to comment Share on other sites More sharing options...
5632 Posted June 13, 2019 Share Posted June 13, 2019 16 hours ago, KongaMan said: A 64 Riviera has both a hot (red) and cold (green) light. Thank you, I double check. Link to comment Share on other sites More sharing options...
JohnD1956 Posted June 13, 2019 Share Posted June 13, 2019 1 hour ago, MrEarl said: Or maybe I'll just consider an LT1 swap and be done with it. Quick question, would that bolt up to my newly rebuilt 350 tranny? I don't know for a fact but the earlier BOP trans are different bell housing bolt patterns than the Chevy engine. What you need is a 70 Olds 455. I'd say Buick 455 but then you'd be in another whole world of changes to logistics under the hood. Link to comment Share on other sites More sharing options...
dmfconsult Posted June 13, 2019 Share Posted June 13, 2019 (edited) Ok here’s the page from the chassis service manual (I didn't bother with the other page for the symptom of "Hot" indicator not lit when cranking engine, and suggesting the bulb is burnt out). Not super helpful but seems to indicate you have an open circuit (which you now know, or a defective ignition switch, and confirms the light should come on at 258 degrees. Let me know if you want some pictures of the schematic drawing for the electrical circuits around this bulb. Not likely the only issue but have you checked the fan clutch? Mine gave me a lot of issues before I replaced it. How does the t-stat look? I did install a new radiator shortly after I got my car, but not because it was overheating, it was leaking and the mounting point for the cap broke off. Edited June 13, 2019 by dmfconsult (see edit history) Link to comment Share on other sites More sharing options...
MrEarl Posted June 13, 2019 Author Share Posted June 13, 2019 Found the idiot light culprit. Gotta wonder if perhaps this tab has been bent down since factory installation and resulted in the owner being unaware of engine temps thus two sets of warped heads 2 Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 13, 2019 Share Posted June 13, 2019 Wonderful! 1 Link to comment Share on other sites More sharing options...
dmfconsult Posted June 13, 2019 Share Posted June 13, 2019 That's good news! Now to track down that temperature issue! With a temp of 265, that bulb should be on all the time! 1 Link to comment Share on other sites More sharing options...
MrEarl Posted June 13, 2019 Author Share Posted June 13, 2019 258* eh? Or did some unscrupulous mechanic press it down and claimed to have fixed her overheating problem Link to comment Share on other sites More sharing options...
KongaMan Posted June 13, 2019 Share Posted June 13, 2019 30 minutes ago, JohnD1956 said: What you need is a 70 Olds 455. I had a 70 Olds Delta 88 with a 455. Best engine I've ever had in a car. I used to haul trailers all over the country with that thing. It was nothing to go through the Appalachians with cruise set on 70 and not slow down. 1 Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 13, 2019 Share Posted June 13, 2019 5 minutes ago, MrEarl said: 258* eh? Or did some unscrupulous mechanic press it down and claimed to have fixed her overheating problem Sadly, that was my thought as well. Many attempted to remove the CEL bulb. There. Fixed. Link to comment Share on other sites More sharing options...
MrEarl Posted June 13, 2019 Author Share Posted June 13, 2019 (edited) 18 minutes ago, dmfconsult said: Ok here’s the page from the chassis service manual (I didn't bother with the other page for the symptom of "Hot" indicator not lit when cranking engine, and suggesting the bulb is burnt out). Not super helpful but seems to indicate you have an open circuit (which you now know, or a defective ignition switch, and confirms the light should come on at 258 degrees. Let me know if you want some pictures of the schematic drawing for the electrical circuits around this bulb. Not likely the only issue but have you checked the fan clutch? Mine gave me a lot of issues before I replaced it. How does the t-stat look? I did install a new radiator shortly after I got my car, but not because it was overheating, it was leaking and the mounting point for the cap broke off. Does the 258 apply to the 403? New fan clutch with new AC install. Haven’t looked at the thermostat yet. Going by the temperature gun readings on the hose at the thermostat it appears to be a 195 thermostat. Someone had suggested a 160 but from what I read the 403 needs at least a 180 for pressure to get coolant through the Siamese heads. Myth? Edited June 13, 2019 by MrEarl (see edit history) Link to comment Share on other sites More sharing options...
MrEarl Posted June 13, 2019 Author Share Posted June 13, 2019 10 minutes ago, avgwarhawk said: Sadly, that was my thought as well. Many attempted to remove the CEL bulb. There. Fixed. And they knew the owner would see the wire detached from the sending unit on the engine.And they knew the owner would see the wire detached from the sending unit on the engine. Which is probably what I am going to have to do to until the cause(s) for overheating is found to keep the light from staying on and burning up the dash.😧 Link to comment Share on other sites More sharing options...
dship Posted June 13, 2019 Share Posted June 13, 2019 Personally, I'd install both the 180 thermostat and high flow water pump first. Then just for good measure I'd install either a re-cored or new radiator second. Then, if those all fail the test look into head gasket issues. But, wouldn't a head gasket issue show currently re: coolant presenting itself in the motor oil? Link to comment Share on other sites More sharing options...
dmfconsult Posted June 13, 2019 Share Posted June 13, 2019 (edited) Yes the 258 appears to apply to all series. The discussion in other areas in this section break the issues out according to series but this section does not. Edited June 13, 2019 by dmfconsult (see edit history) 1 Link to comment Share on other sites More sharing options...
dmfconsult Posted June 13, 2019 Share Posted June 13, 2019 (edited) I’ve got a 195 degree T-stat as that is what’s recommended by the factory. On the 403, the fan clutch engagement should be at 190 Edited June 13, 2019 by dmfconsult (see edit history) Link to comment Share on other sites More sharing options...
avgwarhawk Posted June 13, 2019 Share Posted June 13, 2019 1 hour ago, MrEarl said: Does the 258 apply to the 403? New fan clutch with new AC install. Haven’t looked at the thermostat yet. Going by the temperature gun readings on the hose at the thermostat it appears to be a 195 thermostat. Someone had suggested a 160 but from what I read the 403 needs at least a 180 for pressure to get coolant through the Siamese heads. Myth? If it is 195 at the T-stat it should be good. Was the 258++ detected before the new fan clutch? The fan clutch makes a world of difference. Link to comment Share on other sites More sharing options...
dmfconsult Posted June 13, 2019 Share Posted June 13, 2019 The 258 is the factory setting for the light which should be measured close to the t-stat housing. Would be hotter at the heads. On mine with the temp reading 195-200 with an infrared thermometer at the t-stat housing, the heads are reading 220-225 if memory serves correctly. 1 Link to comment Share on other sites More sharing options...
Ronnie Posted June 14, 2019 Share Posted June 14, 2019 17 hours ago, MrEarl said: 258* eh? You might want to see if you can buy a sensor that would turn the light on at a lower temperature to give you an early warning to start watching a temperature gauge (you really should install one for towing). Good eye on finding that bent tab on the connector. It could have been that way from the factory. 1 Link to comment Share on other sites More sharing options...
MrEarl Posted June 14, 2019 Author Share Posted June 14, 2019 16 hours ago, dmfconsult said: The 258 is the factory setting for the light which should be measured close to the t-stat housing. Would be hotter at the heads. On mine with the temp reading 195-200 with an infrared thermometer at the t-stat housing, the heads are reading 220-225 if memory serves correctly. I have been shooting at the very base of the thermostat housing at the bolt flange. Shot it yesterday at the top of the housing and found it to be 7-8* cooler. I like that, I think I'll shoot it there from now on 😄 Link to comment Share on other sites More sharing options...
JohnD1956 Posted June 14, 2019 Share Posted June 14, 2019 @MrEarlDid the radiator core fins get flushed? With garden hose nozzele, from the fan side to the front end ought to do it. Link to comment Share on other sites More sharing options...
MrEarl Posted June 14, 2019 Author Share Posted June 14, 2019 Did that and with air too. The radiator was replaced at the same time as the head job so is fairly good and clean. Looking in through the filler hole it appears to only be a single core though which is surprising as I would have thought they would have replaced it in kind, which would have been at least a double core given it was a tow package car. It IS a thick 1.25" core though with wide fins. I have seen "single core - three core equivalent" advertised though, so maybe? Link to comment Share on other sites More sharing options...
JohnD1956 Posted June 14, 2019 Share Posted June 14, 2019 What about the timing and the heat riser valve? Link to comment Share on other sites More sharing options...
60FlatTop Posted June 15, 2019 Share Posted June 15, 2019 Right around the turn of the century my TEMP light started coming on right after starting the car, even before it warmed. I put on a temporary test gauge and tie wrapped it to the abandoned AC liquid line. I still open the hood an take a peek at it after driving. I gotta get a new sending unit in there before the tie wraps go bad. Oh, 41 years without an AC compressor. Maybe I will do the sending unit and the AC when Red Riviera Bob gets his air going. 1 Link to comment Share on other sites More sharing options...
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