SW Oil Temperature Gauges - Mechanical or Electrical

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Hi Guys:

My 1992 ERA #375 is equipped with Stewart Warner gauges. My particular question concerns the SW Oil Temperature Gauge.

Does anyone know if the typical "standard issue" for SW oil temp. gauges by ERA was of the mechanical or electrical type?

For some reason, the heavy wire from my oil temp sender makes me think it is mechanical. The number on the sender is sadly pointed AWAY from me towards the back of the pan. I have not ventured to see the part number on the gauge itself, as that is quite an uncomfortable position to get into to read it.

I would like to change out the gauge as my readings are always pessimistic and plan to do this at the next oil change. I figure I will start with all new components rather than try to debug these peice parts.

So, the SW catalog offers both electrical and mechanical Oil Temp gauges in the Deluxe model. Which should I go with?

[wilf leek]

Mechanical usually more accurate than electrical, plus you get the 270 degree needle sweep.

However - not 100% accurate - no auto guages are except high end race items, and far more difficult to plumb - the capillary line is relatively fragile and needs care in it's routing.

To get some idea of the gauge's (any temp guage) accuracy - put the sender (elec, or the bulb on the end of a mechanical unit capillary line) into a pan of boiling water - that is always at 100C. (or close enough to not matter).

I guess it's your choice.

[CJ428CJ]

I have the SW gauges in my ERA and the oil temperature gauge is mechanical. But my ERA is 10 years newer than yours. What do you mean when you say your readings are pessimistic? If you're running an oil cooler, it's quite likely that your gauge rarely budges off the coldest reading. Mine only bumps up a bit during long road trips on relatively warm days. For that reason, I plan on swapping out my oil cooler pancake adapter to a thermostatically regulated one during the next oil change.

[clayfoushee]

CJ,

My oil temp with SW gauge behaves exactly as you described. For the same reason, have been considering adding an oil thermostat.

What type of thermostat are you thinking about?

[Joe Prochazka]

I'm looking for an oil thermostat, too. I looked in my Canton catalog last night and found nothing. I did find one in the Jegs catalog made by Perma-Cool but it looked a little cheap. I was ging to go online today at work as time permits and see what I can come up with...........

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Yesterday, I traced the heavy line from the sender to the oil temp gauge. I found at least 2 spots (one near the headers and another under the dash) where the heavy line is crimped with a radius of about 1/4". If it is mechanical in nature, then this is NOT good, resulting in a pessimistic reading. In general, my oil temp never shows above 150*F on the gauge. Yet my water temp gauge is in the 175-185F range. To my mind, they should eventually be about equal.

I think I will order a new gauge. I do have a sandwich thermostatic adapter, which opens at about 180*F or so. My oil cooler hoses are hot to the touch after a run so it is working.

That is what I mean by a pessimistic reading on the gauge. I do not look forward to working under the dash to disconnect and insert a new gauge. It is such a Pain in the Arse to work under there behind the dash. It appears to be a simple install though, albiet uncomfortable.

The real challange is in the routing of the line. Does anyone know aprox how long a line to order. SW has these in various lengths...

[Rick Parker]

Art: When I redid my car recently, replacement of all S/W was part of the project. I chose the 2 5/8" mechanical gauges (Oil/Water) I tested them both by putting the send unit bulbs into a container of hot water from the stove. Using my wifes kitchen thermometer (thanks Honey) to monitor the water temp I determined that each of the gauges ireads almost 20 degrees low. While driving with 180 degree water thermostat veified to be functioning properly the gauge reads indicted 160 degrees. Oil gauge reads 160 degrees while running down road at 2800-3000 cruise RPM. Oil cooler has a clear 1/8 thick piece of plastic in front to prevent airflow. Running about 11 quart oil capacity with pan, cooler and lines. As far as the accuracy I was disappointed to find they were as far off as they were, I may adress this in the future but for now I just watch the gauge to be sure it is stable at an "indicated 160"!

http://www.stewartwarner.net/

Rick

[clayfoushee]

Rick,

My SW gauges also read 20 degrees too low. I've verified the temps with an IR thermometer, and also keep the indicated at 160. Initially, I thought I was running too cold. I've also used a cover on my oil cooler, which doesn't make a difference on my oil temp. gauge.

[Rick Parker]

Clay: The only time my oil temp has risen to indicated "170" was on a recent trip while accending the foothills and working the motor a little. I too thought I was running too cool but after checking thermostat recently, confired that the above was correct. I have 72" capilary tubes and realize I only need 36" for the water temp gauge. 72" for the oil is about right as the bulb goes into the bottom front of the pan. Maybe they loose accuracy through the length of the capilary tube by loosing heat used for needle movement?? With the smaller diameter S/W mechanical water temp gauge of the same style that I had before with a 36" tube it was dead on. Opinions?????

Rick

[clayfoushee]

I honestly don't know, because my SW is not accurate, but thanks for the additional info.

[TampaFla]

Just had the ERA (SW) oil temp guage installed yesterday in the oil pan of a 351W. A lot of work (cutting brazing, etc.). Not a mechanic myself but I was told placement is a key to how well it works (particularly if the pan is baffled). Try contacting GeminiMotorcars (Bruce Edward - Senior Cobra Club Member). Bruce could tell you the specifics.

[DonC]

Couple of things to keep in mind about temp guages. In general they are "wet bulb" units which means the sensor bulb has to be immersed in the fluid to give a reading. While the mechanical type of guage is generally more accurate than the electric, they are more complicated to install because of the relative rigidity of the capillary line as opposed to electrical wire. The capillary line should be free of kinks and very sharp bends. If they're there it wouldn't hurt to either straighten them out or, if the opportunity presents itself, replace it. Will a kinked tube read? In all probability yes but kinks are best avoided unless the tube is over the age of consent and no force is used.
The plus side for electrical guages is that in general wire is easier to work with than the capillary tube and, depending on the guage, they can be calibrated by a guage shop. There have been a couple of threads mentioning a gauge shop that might be worth a call to see if they can help with the accuracy.
Depending on how deep your concern goes any guage should be checked for accuracy. As Wilf mentioned the higher the quality (read costlier) the guage is the more likely it is to be accurate.
Joe - Canton makes an oil cooler thermostat that goes in the line between the cooler and the filter/adapter but it's sort of expensive but looks like a high quality piece.
Just my $0.02,
DonC

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Well I did bit the bullet today, went out to the supplier and picked up a new SW oil temp gauge with 72" of cable to the bulb. This is the mechanical Deluxe version which is part number 82327-72. The suffix 72 stands for 72" of tube length, which by the way, is perfect for the 427-8 FE engine in the ERA.

Tested the new unit in a hot cup of water with a very accurate kitchen thermometer. It read right on at 150 degrees so it is accurate for now. This unit needs no electricity to provide a reading at all. Nice.

Removal of the gauge was easy from the dashboard, simply two nuts and lockwashers and a ground wire and the bulb for nightime illumination. Basically did this by feel.

Routed the new tube to the pan. Down along the back of the engine and along the oil pan upper. Two plastic keepers attached the the oil pan nuts hold it in place. Put the front end up on jackstands and spannered out the old bulb and installed the new.

Took her out for a ride and viola' the engine achieved 150 to 180 in pulses, probably accounting for use, the cold temps outside and the gate opening and closing from the sandwich adapter oil thermostat.

Another item off the checklist.
Fun Stuff.

[NeedAntiVenom]

Joe,

Canton does make oil cooler Tstats.

http://www.cantonracingproducts.com/...ermostats.html

I was concerned about oil temp never coming up enough so I didn't connect my oil cooler - so far it hasn't gone over the water temp. Unless it really hot or you're racing you don't usually need a cooler.

[CJ428CJ]

Clay,

There was an earlier thread about an Earl's sandwich adapter with a built in t-stat. Here's the link: Oil Filter Adapter

I plan on going that route.

Chris