so the last week I have been waking up my FD from its winter slumber. It had last been turned on in early november or so. Last fall I had installed some gauges - autometer carbon fiber oil temp, water temp, and boost.

rather than try a pedistal, and because i didn't have the sender for the 300f sweep oil gauge, i bought a VDO oil pan drain plug with integrated temp sender. I installed that a few days ago when changing to fresh gtx 20w50 dino oil (new oem filter)

After cranking the engine a couple times with the fuel pump relays removed to pressurize the oil, adding a bottle of lucas octane booster, a couple oz. of marvel mystery oil, and a quart or so of fresh 93, and priming the fuel pump, she started up beautifully. A wisp or two of smoke from the tail for 20 seconds or so like she's always done if not started for around four days or more. (well since i bought it last august)

I drove it around my neighborhood for a few minutes until warm, then onto some side streets where I kept it to around 40mph, staying totally away from boost. It had 3/4 of a tank or so of gas in it all winter and I don't want to get into boost until it's gone, or nearly gone.

but at one point i look at the newly functional oil temp gauge, and its reading around 240f. That seemed really high to me, and after searching here, it is. I thought to myself that i must have installed a 250f sender - doing the mental math, that made sense - 240f on a 300f gauge with a 250f sender, would be around 200f in reality, which would be about right. But, it's not. Packaging says it's a 300f sender.

Regards the car - its a Pep, so only one oil cooler. Car has 35k orig miles, and is in excellent condition. Oil pressure is good, oil level shows spot on where it should be. Only real mod is 3" downpipe. Have a koyo rad and an aquamist 1s I was planning on installing after getting some use out of the car for a month or so. Water temps maxed at 205 or so. It was high 70s, low 80s, overcast, had rained all day, high humidity.

I'm hoping that the vdo sender is calibrated to run with a vdo gauge, and that the resister in there is just wrong for the autometer gauge. Or that the autometer gauge is just trash. I've actually got two boost gauges in there - a gloshift the previous owner installed, and the autometer. The gloshift was showing spikes to 12psi or so and I wanted to see if the new autometer matched that. They show different readings under both vac and boost. mityvac can't seal well enough to test either gauge for accuracy when I tried to see which is right, but the gloshift looked to be more accurate compared to the gauge on the mityvac. Anyways that suggested to me that autometer wasn't so great accuracy wise, as a brand.

So, could it be the gauge? could the oil thermostat be stuck closed? or could something else be afoot? At the temps I saw, getting on the boost would mean temps even higher. I definitely got on the boost last fall, and nothing has really been changed, so I'd think I'd have seen some damage if the temps have always been this high.

 

I think its the gauge.

 

I have the same oil pan sender. I do have a VDO gauge.

I don' think 240 is excessive (with 205 water temp), especially when you are driving at low speeds. Remember, you don't have a fan to cool the oil thru the oil cooler. Lower speeds won't generate much airflow thru the oil cooler, thus higher temps. I think the gauge is probably fine.

 

agreed, but even taking into account airflow, 240f is ridiculously high, perhaps even dangerous. I'm taking the car to work tomorrow, which is ~ten miles away, 60mph road with the odd stoplight. Still no boosting on the old gas. I'll see what it does there, but if it's hitting 240f anywhere, I've got huge concerns.

 

If it gets high on the freeway, you don't have huge concerns, you just need a new gauge

VDO gauges are very affordable. Get the 300 F gauge.

http://www.egauges.com/vdo_mult.asp?...Vision&Units=E

 

did you check if the autometer gauge is calibrated in the same range as the sender? if the ohm or volt ranges are not compatible the readings will be off. Even if both are 300F, they may have different curves.

 

good call. Both gauges read to 300, but side by side, the scale is completely different. I'm going to have to figure out the resistance difference in the senders and use resistors to get it accurate.
Good thing it was all wrong too, because at sustained 60mph I was seeing 260 registered on the gauge. Gulp.

 

or you could get a oil pan plug to 1/8 npt adapter so you can use any 1/8 npt sender. That's what I did with my new prosport oil temp gauge.

BTW, I still have my vdo sender and gauge I can sell if you need it...

 

Just wondering if you fixed the problem. I have a defi gauge and im having the same problem. gauge worked and temp was normal before the motor popped. now something is wrong

 

it sure sounds like a calibration problem.

i measure oil temp from the pan. i adapted the driver's side port that housed the oil level thingy.

cruising at 73 mph in 5th i see 150 F. i do run two mazda oil coolers.

hc

 

On my factory 2nd gen oil cooler (at least equal to two FD oil coolers) I used to see 150 F just cruising around, and 210 max during sustained hard driving.

 

Howard maybe you can help?

proper ducted duel Setrab 25 row oil coolers(new)
earls 180* thermostat(new)
Feed front bumper
temp set lower 180* on power fc

temps hit 220*-230* cruising slight hill at 70 mph water was 210*
temps hit 210* cruising slight down hill at 70 water was 190*

 

Yeah, I looked up the resistance of the sender I am using, and the sender the autometer gauge would normally be using, and the range was completely different. So there was no actual problem with my car. I can either change the sender, change the gauge, or try to get the reading close by adding resistors inline.
Your problem sounds different I am sorry to say, but try checking the sender for grounding, loose connects etc

 

The easiest way for you to do it is the resistors in a series if you haven't chosen which of your options you will go with yet, Leno.