rallyx7

After a recent street port rebuild, my water temp runs a nice cool 150 -160 but my oil temp is shooting to 250 after just 5 miles of driving. Can this happen or ismy gauge bad?

trochoid

iTrader: (6)

Did you replace the thermostat with a new 180 deg one? Did you clean the oil cooler inside and out?

If you've done both of these, check the oil cooler thermo per the FSM and replace the coolant thermostat.

I assume you are taking your temp readings off aftermarket guages, is so, from where? If you are taking the readings from any where but the stock location, you will not get the same readings as the stock gauges.

rallyx7

The cooler has been cleaned and the thermostat tested. The gauge is an Autometer Phantom with the sender at the oil filter (racing beat oil pressure and temperature adapter part no 11802)

Wankel7

That is way to cool.....what is the ambient temps?

rallyx7

Its about 85f today. My last run the water temp got up to 180 deg. and the oil temp was pegged at somewhere over 250f

WAYNE88N/A

Do you have anything blocking the oil cooler? Bunch of dirt and crap plugging the fins?

Something's going on with the oil cooler, because if you have the sender at the oil filter, that's the first stop for the oil once it passes the cooler...

rallyx7

is it possible that I have blow by at the rotors that could be causing this?

The cooler and lines we cleaned and check prior to the motor installation.

WAYNE88N/A

Next question I guess is how do you know the gauge is calibrated?

That sender location should be about the coolest spot in the oil system- can you imagine what your temps would be in the oil pan or at the front of the e-shaft if that gauge is right?

Wankel7

Uhhhhh do you have the thermal pelet still in the E shaft? OR a bypass pellet?

rallyx7

Bypass pellet.

RETed

Put the plastic engine undertray back in?


-Ted

Wankel7

You sure you don't have the wire from the water temp sensor going to the oil temp gauge?

Froggmann

Another possibility is the oil bypass valve in the cooler itself. If that sucker is stuck on bypass then you simply aren't getting any flow through the cooler.

Innovation

iTrader: (1)

Did you do what Ted said? Is the plastic undertray on?

ddub

You still shouldn't see those kind of temps with the undertray off if the rest of the oil system is working properly. The last owner of my car took it off for god knows what reason, and I still get 150-180º oil temps measured via the RB adapter at the filter pedestal.

Sounds like the thermal valve in the oil cooler line is stuck shut and you're not getting any oil into the cooler. Try this, start the car and let it run idling in the driveway, wait until the oil temps start to get hot again and then SPRAY the oil cooler with water from a hose. If it still doesn't go down at all (when over 180º) it sounds like NOTHING is going into the cooler.

Innovation

iTrader: (1)

And if the temp goes down then what?

ddub

Then oil IS going into the oil cooler, but I'd suspect that it isn't doing its job properly.

Innovation

iTrader: (1)

Maybe the cooling fins are damaged or plugged?

ddub

Possibly, I'd try the test first, it'll at least tell you if oil is getting into the cooler, that's a start.

YearsOfDecay

Here's the best way to test this.. My oil cooler bypass pellet was shot... I foud this out just like you by retardedly high oil temps....

There are TWO things to do to test this..

1) Run the car until the oil tem gauge gets to 200..and hit the oil cooler with a lazer thermometer... if your oil temps on the gauge get to 200 degrees and the oil cooler is still down around 100.... the bypass pellet isnt closing.

2) Take the pellet out.. its attached to the bolt on the bottom of the oil cooler.. stick it in a pan of oil and SLOWLY heat the oil up.. Monitor the temp with a thermometer.. if the temperature of the oil gets to 170 and the shaft on the end of the pellet hasn't extended by at least 5mm .... its shot...

The bypass pellet is normally IN.. when the oil temps get to 160 or so, the shaft extends OUT to plug up the bypass hole in the oil cooler and send the oil through the cooler. If it remains open, the oil won't get through the cooler!

WAYNE88N/A

No need to get fancy- just put your hand on the dang cooler after about 5 minutes of cruising- if the temps aren't the same on the top portion of the cooler (in other words, if the right side of the cooler is cooler than the left), then you have a valve problem...

rallyx7

Thanks for the input but I am certain the the bypass is closed. I put a nut at the bottom of the plug that is the same thickness as the plunger that comes out of the thermostat so the thing is basically stuck in the closed position. It has a hole large enough for the plunger to come out without changing the position of the bypass value.

I have changed the cooler with a known good one. Fins are straight and clean ( I cleaned it with a pressure washer ). The bottom tray is not in place but this has never been a problem in the past with the old engine. The top and bottom of the cooler are both really hot.

Anyone got any ideas as to what it could be if it wasnt the oil cooler and the gauge was right?

here's the car:

deadRX7Conv

High oil temp can be caused by low oil level. Top off the oil. Or, overfill it a quart and see what happens.

Hows the oil pressure?
Was the oil pump or regulator replaced during the rebuild?
Who did the rebuild?

Oil viscosity can also cause oil temp swings. What brand/weight are you using?

Change the oil filter.

If the oil temp gauge/sender are working correctly, I would think that engine damage is occuring.

Even though the water temp is normal, I'd check the entire engine plumbing. Make sure water pump is pumping. Make sure all hoses are correctly hooked up. Hot oil with cool water means that the water might not be circulating well enough, leaving only the oil for heat absorbing. I'm hoping that you are using a new waterpump, thermostat, and cap with that rebuild.