Eoin
Full Member
Posts: 101
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Post by Eoin on Apr 20, 2018 18:59:14 GMT
And this is where comparing oil temps gets a bit meaningless. Yours is measured pre-cooler, mine is measured after. Sensible people seem to think 240°F is too hot for the good of the oil and would change it if it happened. By that measure, 120°C (248°F) is way too hot. Does that mean that my self imposed 120° limit is too high? Also, I’d be the first to admit that I know far more about the intricacies of the oil system in jet engines that I do about the oil system in type 4, but surely the oil in the sump will have been through the cooler first, I can’t see the point of sending oil through the cooler before it goes to the bearings, I’d have thought it would be cooled after it’s been used on its way back to the sump. Now we're into a 'what oil' thread. Semi synthetic or full synthetic will stand higher temperatures without breaking down than plain mineral. So your self imposed limit depends on the oil you're using.
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Post by sANDYbAY on Apr 20, 2018 19:29:57 GMT
Does that mean that my self imposed 120° limit is too high? Also, I’d be the first to admit that I know far more about the intricacies of the oil system in jet engines that I do about the oil system in type 4, but surely the oil in the sump will have been through the cooler first, I can’t see the point of sending oil through the cooler before it goes to the bearings, I’d have thought it would be cooled after it’s been used on its way back to the sump. Now we're into a 'what oil' thread. Semi synthetic or full synthetic will stand higher temperatures without breaking down than plain mineral. So your self imposed limit depends on the oil you're using. 15-40 mineral
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Post by Zed on Apr 20, 2018 20:05:49 GMT
From sump to pump to cooler to bearings.
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Post by Zed on Apr 20, 2018 20:19:28 GMT
Does that mean that my self imposed 120° limit is too high? Also, I’d be the first to admit that I know far more about the intricacies of the oil system in jet engines that I do about the oil system in type 4, but surely the oil in the sump will have been through the cooler first, I can’t see the point of sending oil through the cooler before it goes to the bearings, I’d have thought it would be cooled after it’s been used on its way back to the sump. Now we're into a 'what oil' thread. Semi synthetic or full synthetic will stand higher temperatures without breaking down than plain mineral. So your self imposed limit depends on the oil you're using. It's all related, or can be, because of the cooler bypass valve. When the plunger is pushed out of the way BY HIGH PRESSURE the cooler is still in the circuit, but in parallel rather than in series. The oil has no flow through the cooler because it ends up back where it started so it takes the path of least resistance through the bearings. High enough pressure could be due to Cold oil Too thick oil Too big pump. Weak spring People say fit a bigger pump if you have an outboard cooler. I didn't and I have the right pressures running and idling. The six million dollar question is how high must the pressure be to open the bypass valve. Might it be in Haynes?
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Post by Zed on Apr 21, 2018 10:52:41 GMT
With some concerted high speed driving I got my oil up to 100°C/210°F today.
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boris
New Member
Posts: 14
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Post by boris on May 29, 2018 16:41:34 GMT
With some concerted high speed driving I got my oil up to 100°C/210°F today. My cooler is only 8 row. Before cooler fitted, old loose engine. 122 deg C would be reached regularly after 20 miles thrash with 20W/50. Drove it up to 500 miles in a day running that hot. Idle oil light flicker after 60-70mph for 10 miles on M27. With cooler, old and new engine 115 deg C after monster thrash like A34 north to Oxford. 20W/50 oil 105 deg C same sort of thrash 10W/40 oil Pootling round town 80-90 deg C. Wax thermostat opens at 80 deg C in cooler circuit. The old/new engine switchover happened because it slipped the oily clutch in lane 3 on overtaking a lowered Caddy... And then it revved really high amd the flywheel went wobbly as the bodge (8 dowelling in 4 functional dowel holes) broke loose. This was a cpuple of weeks after driving it 1800 miles round France.. but sans Caddies to 'race'
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