RX7 2nd Gen Over heating

[Lynn77]

I need some help sorting out my 13B engine over heating. It started this spring at CMP where I over heated and lost a engine, since then I have rebuilt the engine, but I still have a heat problem at high rpm's. I originally thought it was my water cooling system, but everything there appears okay. I am now wondering if it's not the oil cooler and the water temp can't cool the engine as fast as the oil temp increases. Normally water temp was running at 160 to 170 degrees, now it will go over 200 if I don't shut down and oil temp will run 20 degrees hotter than water temp.

In addition oil pressure was over 100psi at high rpms but latest attemp to run this engine the best I can get is 40psi and at idle maybe 15psi. can the heat cause problems with the pressure relief valve?

What else should I check that could be causing over heating?

[MaxEnergy]

possible that your front cover lost its oring allowing the oil pressure to bypass into the front cover. In any event that low of oil pressure means you will have to take the engine apart to some extent. Either the oil pump is bad (unlikely)or the oil is bypassing the front cover oring or the rotor bearings. Given that it is overheating it sounds like the latter and a bearing is about to go.

[bldn10]

"now it will go over 200 if I don't shut down and oil temp will run 20 degrees hotter than water temp."

If you are talking 200-210 on water and 220-230 oil, you are NOT overheating! I used to shut down when my oil got over 230 but I got this SpeedSource car and they recommended setting the Pi oil temp. alarm at 250. I think people are routinely running these engines at up to 250 oil and 200+ water. I don't know if you'd want to do a 3-hour enduro like that but sprint races are apparently not a real problem. My 26-event engine was recently rebuilt due to bad oil seals and there was no other damage - the housings, rotors, etc, were all fine.

On the oil pressure, that IS cause for concern. But before you tear that thing down you might check the gauge and make sure it is OK.

[wrankin]

When you say "oil temps" where are you sampling the temps? I have a oil pedistal sensor, but it's catching the temps when they return from the coolers so I am never seeing above 180 (w/ dual coolers). What's view as "accemptable"?

Thanks,

-bill

[mustanghammer]

When you say "oil temps" where are you sampling the temps? I have a oil pedistal sensor, but it's catching the temps when they return from the coolers so I am never seeing above 180 (w/ dual coolers). What's view as "accemptable"?

Thanks,

-bill
[/b]

Sorry to hijack but how are your dual coolers plumbed? Are they in series or in parallel?

I am contemplating the addition of a second cooler to my IT7 car.

Thanks

[Jim Susko]

When you lost your original engine you may have sent some debris through your oil cooler, causing the thermostatic bypass to stick open and reducing the cooling available. It would also lower your oil pressure when the engine is warm. I'd reverse flush the cooler at high pressure or try another cooler. On my first gen, I replaced the thermostatic element with a pencil-shaped piece of aluminum that I jam into the bypass hole with the cap. You don't really need the thermostat on a race car.

[seckerich]

Sorry to hijack but how are your dual coolers plumbed? Are they in series or in parallel?

I am contemplating the addition of a second cooler to my IT7 car.

Thanks
[/b]

Plumb the coolers parallel or you will lose too much pressure.

[mustanghammer]

Plumb the coolers parallel or you will lose too much pressure.
[/b]

Thanks, will do!