Oil cooler problems?

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Krizzie
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Oil cooler problems?

Postby Krizzie » Thu Aug 03, 2017 6:57 am

Recently I've noticed that my engine oil temp (sensor is installed as the drain plug) is quite high. Even with normal cruising it easily hits 100+ degrees Celsius. It doesn't get much hotter than 110c but still. I see other classics do less than 80c when driven normally.

I'm running Castrol Edge 10W60 oil.

Time for a bigger oil cooler or is something else wrong?
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Geoff
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Re: Oil cooler problems?

Postby Geoff » Thu Aug 03, 2017 8:02 am

Why are you running 10w60 oil?

I've never really felt too confident with those drain-plug installed oil temp senders. I forget why but I never felt that mine was reading correct. It may have been shorting against the skid plate? Then it got crunched by the skidplate...
The kind of dirty that doesn't wash off :eyebrows:

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Krizzie
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Re: Oil cooler problems?

Postby Krizzie » Thu Aug 03, 2017 9:09 am

I use 10W60 cause the engine runs much smoother with it.

My (heavyduty) skidplate is miles away from the sender. Also there would be weird signals to the gauge I guess. It just runs hot while not pushing the engine at all..

After 10 km or so the oil starts to warm up, but after 20+ kms it's above 80c and climbing to 100c+. Even when cruising at 130kmh on the highway it keeps rising.

I thought that the oil thermostat might be faulty and thus the cooler doesn't actually do anything.
My ride: MY91 Saab 900 Aero T5.5 Converted, 9000 Aero interior, Xenon projectors and many more mods/upgrades

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Geoff
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Re: Oil cooler problems?

Postby Geoff » Fri Aug 04, 2017 11:37 am

I would start with a factory-recommended oil first. One possibility is that the thick oil is clogging the oil cooler as it cools down, slowing the flow through the oil cooler, and preventing more oil from getting into the oil cooler - resulting in the remaining oil in the system getting hotter. The thin passages of the oil cooler (and other parts of the engine) are designed around 10w30. 10w60 has about 2.5 higher viscosity at the temperature you might expect oil to be at when it exits an oil cooler (~50°C?) and it only gets thicker as it cools down more (which it would do if it was stagnant in the cooler).
The kind of dirty that doesn't wash off :eyebrows:

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Krizzie
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Re: Oil cooler problems?

Postby Krizzie » Sat Aug 05, 2017 12:42 pm

Even with 5w40 which I had for 1000km to run in the new block, the temps were high.

10W40 is standard for a B202 here, 10W60 is a bit thicker at higher temperatures than 10w40, not at lower ones. Multiple Saab specialists here recommend 10W60 for tuned engines. (And since mine is tuned.. ;) )
My ride: MY91 Saab 900 Aero T5.5 Converted, 9000 Aero interior, Xenon projectors and many more mods/upgrades

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Re: Oil cooler problems?

Postby Krizzie » Thu Dec 28, 2017 9:03 am

To clear this issue, the thermostat was faulty so, the oil cooler wasn't doing anything.

After it was replaced, the temps went down to around 80c to 90c depending on how hard I've been flooring it.
My ride: MY91 Saab 900 Aero T5.5 Converted, 9000 Aero interior, Xenon projectors and many more mods/upgrades

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DrewP
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Re: Oil cooler problems?

Postby DrewP » Tue Jan 02, 2018 12:41 pm

Cool, thanks for following up. Was it just jammed shut?
"You can educate ignorance, but you can't fix stupid."

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Krizzie
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Re: Oil cooler problems?

Postby Krizzie » Fri Jan 05, 2018 12:59 pm

It was stuck or something, when it was put in hot water nothing happened. A new one was installed and the problem was gone.
My ride: MY91 Saab 900 Aero T5.5 Converted, 9000 Aero interior, Xenon projectors and many more mods/upgrades


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