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Some time ago (I think it was early last year) there were some interesting posts on whether or not to fit an oil cooler thermostat.  I decided against, as I was not happy with the thought of it failing in the closed position.

Instead I have fitted an oil temperature gauge.  Lack of a suitable dash location and the preference for keeping it original pushed me into a small digital gauge which was fairly easy to fit and  to remove at a later stage if needed.  I bought a sump plug from Matt Lewis Racing (half inch BSP) that took a  one eighth npt temp. sender.   Online supplied me with a digital temp. gauge.

Fitting was OK. I made up a small bracket which slid under the dash.  Wiring needed an earth and 12v which I took from the instrument fuse 21.  Being digital I did not have to wire in a lighting feed. The twin core signal cable which plugged in at the gauge and sump plug needed extending and I ran it through under the transmission tunnel following the route of the accelerator cable.

I gave it a run today for the first time.  From cold 8*C and an outside air temp of 10*C it took a long time to warm the oil (only 40*  after 5 miles).  Even with some fairly spirited driving it only made 55*C.

I would like it to be around  80, the same as the water temp. so rather bizarrely I shall now be fitting an oil temp. thermostat as I will be able to monitor the results.

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The low temperature bothered me also: so I covered 1 oil cooler  with black tape. I now have a nice temperature of nearly 80°C (I never saw a higher temperature than 90°C - in an S4 is an oil temperature gauge), even during the long hot summer from last year.

 In winter I can even cover them both...

Karl

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I have a similar experience with both my SEs: my oil temperature rarely exceeds 60°C on normal driving. Only in traffic does it rise, because there is no airflow to the oil coolers. Max I've seen is about 90°C, stuck in traffic with high ambient temperature and coolant temperature also around 90°C. I had this discussion last weekend with a good mate who drives a C63AMG (always fun when we park up side by side, the Esprit does get the most attention. and rightfully so 😎). His oil temperature is usually 100-110°C. We expect the Esprit to run cooler as it's an older design, but the difference seems very big. Especially considering the fact the Esprit uses a much thicker oil to begin with.

Covering one cooler for day to day use seems like a very good idea! Especially with the colder weather. I am a bit weary temperature might rise too much if I do get caught in traffic. But I'll give it a try, great suggestion @Karl lambrechts!

Filip

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I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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There is nothing good to say about overly cool oil temps as the stuff is made to function correctly near 100 C. Makes a case for the use of coolant-oil heat exchangers, as commonly found on modern powerplants, in my view. These not only ensure better equilibrium temperatures but also see the oil arrive there more rapidly. All good things.

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15 hours ago, Escape said:

I have a similar experience with both my SEs: my oil temperature rarely exceeds 60°C on normal driving. Only in traffic does it rise, because there is no airflow to the oil coolers. Max I've seen is about 90°C, stuck in traffic with high ambient temperature and coolant temperature also around 90°C. I had this discussion last weekend with a good mate who drives a C63AMG (always fun when we park up side by side, the Esprit does get the most attention. and rightfully so 😎). His oil temperature is usually 100-110°C. We expect the Esprit to run cooler as it's an older design, but the difference seems very big. Especially considering the fact the Esprit uses a much thicker oil to begin with.

Covering one cooler for day to day use seems like a very good idea! Especially with the colder weather. I am a bit weary temperature might rise too much if I do get caught in traffic. But I'll give it a try, great suggestion @Karl lambrechts!

Filip

I experience the same with my '90 Esprit Turbo SE....hardly over 60 degr. C.; even with outside temp in summer of 25 degr C it is never higher than 80 degr. C.

It is a good idea to cover 1 oil cooler......even if the temp. goes up to 95 degr. C.

If the temp. raises higher in a traffic jam (105 -110 degr. C.) I would take my Esprit aside and remove the cover.

For my 231 hp Rotary Mazda RX-8 Renesis HP it is a widely adapted precaution for the winter because the oil keeps to long / to cool.........here a black "mouse pad" can easily be folded in front of the oil cooler / and behind the body and can also easily be removed from the outside of the car.

The extreme heat generating 1,3 liter 2 rotor Wankel engine needs the 2 OEM (larger) oil coolers absolutely because In summer 30 degr. still with those 2 coolers it will run at approx. 95 -97 degr.; sometimes quickly raising to 100 degr......in a traffic jam it can be even 110 degr. C.

If possible I will try to do the same solution (mouse pad) with my Esprit. 

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Edited by rudolphwolven

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Nothing at all wrong with oil temps around 100-110 C, it's designed to work at such temperatures. Use an oil cooler if running on track and seeing much above 110.

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You can always fit a fan on the oil cooler also,   i used a slighty larger oil cooler and wired a decent marine on it to cut in when the coolant fans cut in :)


A

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If the temperature got consistently too high, a fan would definitely be the way to go. Because on the SE and later the coolers are mounted on the sides, not in front of the cooling fans with the other rads like on older cars. But adding tape to one cooler and a fan to the other wouldn't be logical. And add weight. 😉

Filip

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I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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Good call Filip , sorry got my G head on  lol  :thumbup:


A

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Actually, I think an extra fan for the oil coolers would make more sense on an SE, because they don't have any forced airflow otherwise. In a G car I would think the radiator fans give sufficient airflow to keep the oil coolers working even at standstill?


I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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9 hours ago, Escape said:

Actually, I think an extra fan for the oil coolers would make more sense on an SE, because they don't have any forced airflow otherwise. In a G car I would think the radiator fans give sufficient airflow to keep the oil coolers working even at standstill?

There is a strong correlation between oil temperature and work done ( HP being used ) so it is not usually at low speeds ( low airflow through the coolers ) where the need for cooling is greatest.

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I agree there's a lot more heat being transferred to the oil at high engine loads. But high loads tend to correspond to high speeds, especially in a car like a Lotus. And at those speeds, the coolers do a good job. When stuck in traffic, coolant temperature will start rising but can be controlled by the fans providing the necessary airflow through the radiator. At the same time, oil temperature will also climb, be it slower. Without airflow, the coolers are limited in the heat they can dissipate. I find oil temperature only drops after I've been able to build some speed again, much slower than coolant temperature. So my worry is very much about low speed situations. Especially as engine oil pressure decreases with temperature, and isn't too great at idle to begin with. To be clear, I never had problems with either oil temperature or pressure, even when stuck in gridlock for some time. But I'm not too comfortable reducing the margin.

Filip


I have made many mistakes in my life. Buying a multiple Lotus is not one of them.

 

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What are the dimensions of the SE/S4/s4s (side located) coolers and their hose fittings?

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On 07/03/2019 at 09:52, drdoom said:

Nothing at all wrong with oil temps around 100-110 C, it's designed to work at such temperatures. Use an oil cooler if running on track and seeing much above 110.

Yes. Closer to 110C or up to 120C is preferable to boil off any moisture from the combustion process. After all, Lotus recommends and specifies full synthetic oil (from S3 onward???) so 120C isn't a big issue.

On 17/07/2019 at 11:59, MrDangerUS said:

What are the dimensions of the SE/S4/s4s (side located) coolers and their hose fittings?

3/8" BSP I believe. That's the reason for me purchasing a Setrab replacement cooler so I can go -AN sizes.

Edited by ekwan

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On 06/03/2019 at 12:53, drdoom said:

There is nothing good to say about overly cool oil temps as the stuff is made to function correctly near 100 C. Makes a case for the use of coolant-oil heat exchangers, as commonly found on modern powerplants, in my view. These not only ensure better equilibrium temperatures but also see the oil arrive there more rapidly. All good things.

Optimal working temperature of the oil on Esprit is 82-90 C. Controlling oil temps with tape is not a reliable method.

Install MOCAL MOCT-B3  thermostat and have one less item to worry about (fix and forget philosophy).

In addition, whilst in the area, install Ford 90 deg filter adapter for ease of changes and no more spilling oil all over the block.

Look for: OEM Ford Oil Filter Adapter F77Z6881AA For 97-04 Ford Ranger, Explorer 4.0L. Must have an offset to the right (away from the block, looking from the rear of the engine)

 

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Edited by MrDangerUS

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