Oil cooler issue with devastating result

[paulydee]

I have been trying to lower my coolant/oil temps for a while. I finally went to an aluminum rad with electric fan for the water temp part. For the the oil temp part I decided to build a duct which directs air from the lower chin spoiler directly to the oil cooler. The duct assembly came out fairly decent.

I remembered someone telling me that if you removed the oil cooler bypass valve that the oil would flow through the cooler full time and drop the temp 10 degrees. So I did this as well.

This past weekend at VIR I ran a light "observation" session, and the oil temp climbed immediately. I surmised that the duct was choking flow rather than aiding it, so I remove the duct and resumed stock config.

My first full on session (this was a driving school environment BTW), was the last. Within 1/2 lap the oil temp gauge was pegged. (Keep in mind the ambient temp was north of 90 degrees). The water temp was stable at about 210 so I figured things were OK. After 5 laps the motor lost power and an immediate glance to the oil pressure gauge showed 20psi. The motor was done. It runs and idles but rough as hell, obviously due to a bearing failure.

Has any of you guys heard about this oil cooler thermal bypass deal? At this point this is what I am pin pointing as the cause of the oil temp and subsequent pressure loss and engine failure. Any thoughts on this?

Pauly D in despair.....

very sorry to hear of your loss, i too lost a dear friend recently.. 12a 13b? stock 84-85 block mounted cooler along with external?

[C. Ludwig]

I've removed the bypass thermostat in both of my coolers and have had no associated issues. I'd caution anyone to use a lock nut or red loctite to prevent the bolt from coming loose. That would cause a problem. Other than that there should be no adverse effects from removing the thermostat.

Chris

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Chris Ludwig
08 ITS RX7 CenDiv

[titanium]

When you remove the thermostat from the oil cooler, it is my understanding that you need to plug the "hole" that is left. (Welding or Epoxy) Otherwise, oil will take the path of least resistance and flow from the inlet hose to the outlet hose through that hole, rather that flowing through the cooler.
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Rodney Williamson
www.titaniummotorsports.com

[AS-RACER]

Just out of curiousity, what kind of oil are you running Pauly D.? My oil temps were going crazy this weekend at Second Creek this last weekend. I was running the car at 280 oil and 220 water on Saturday. I kept coming in cause I was worried about hurting the engine with that high of oil temps. Then I talked to one of the rotor motor builders here in Colorado and he said that as long as you use good synthetic motor oil, then you should be ok at that temperature. He said that the water temperatures are what you need to worry about and that 220 was fine. So I ran the car on Sunday at 280 oil temp and 220 water temp and the engine was fine until a wire came off my fan and my water temps started to climb on the next to last lap. I haven't gotten a good chance to check the motor to make sure that it was ok after the water started over heating but, I was using mobil one super syn 15W 50 and the engine was running great. Unfortunately, the rest of the car wasn't as good. I was hit by a Z on Saturday during the race and I think it bent the shock so my car had a horrible push during Sundays race. Could not get the car to turn in. Damn Z's!!! Just kidding. I know he didn't mean to do it.

[C. Ludwig]

Maybe I didn't make myself real clear. I use a bolt to plug the hole left by the removal of the thermostat just as TITANUIM suggests welding or using epoxy. My original thought in my first post was also to suggest if that bolt comes loose not only do you bypass some of the flow around the cooler but a small nut or bolt could end up in a bad area. Seriously restricting flow

Chris



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Chris Ludwig
08 ITS RX7 CenDiv

[JeffGio]

Use a metal lock nut. They have a distorted thread and are usually identified with a rectangular depression in the middle of one side of the nut. No nylon and they will never come loose.

Cheers
Jeff

[miketrier]

After I remove the bypass valve I tap the remaining hole and put in a hex cap screw with a copper washer and lots of red loctite. If you don't plug the hole with something the oil bypasses the cooler and the engine will overheat big time.

[EP7]

Drill and tap the remaining hole for a pipe plug. It worked fine for me.