oil cooler replacement advice

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1of1
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oil cooler replacement advice

Post by 1of1 » Mon Apr 22, 2019 7:59 pm

Hi all !
1983 Registered series 2.

The time has come to replace radiator and oil cooler.
I have had replacements for several years but not got around to fitting.
Bought from ebay and seem to be pretty well made, can't remember from what seller or make.
Both radiators now in pretty bad shape so about time to change !
One of the brackets that hold the radiator and oil cooler together has now fell apart.
I think i have found the correct replacements from Atkins Rotary online store.

The advice from you guys is regarding the oil cooler bypass valve
as the new oil cooler comes with no bypass, also looked at other after market coolers
and none seem to come with bypass valve.
I understand the bypass valve only lets a small percentage of the oil through the cooler when first starting
which allows the engine to warm up more quickly and then as the oil reaches a temperature of 158F - 70C
it will open and let a larger amount of oil through the cooler.
But i understand it's primary function is for system safety, should the radiator become plugged for any reason.

Has anyone had experience of fitting after market cooler ?
Do you think the oil bypass valve more essential with the rotary engine ?
What are your thoughts on fitting with no bypass valve !
Anyone's advice on this would be greatly appreciated !

Car is all original but i am not averse to fitting a few after market parts.
Don't know if refurbishing is an option, as said have parts here
can always keep old parts in case ever required.

Thanks to you all !
Phil.

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gt_james
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Re: oil cooler replacement advice

Post by gt_james » Wed Apr 24, 2019 1:25 pm

I understand the original mazda ones are widely regarded as the best, I think they were originally made by calsonic.

It looks like atkins has 2 left in stock for £630 each! They also list GSL-SE and FC ones which can be fitted, and the wording sounds like these are still made, but also very expensive. I don't know if they are still made by calsonic and still made to the same high standard though.

I wouldn't want to run a used oil cooler that you didn't know the history of, and used ones will be 30+ years old.

I run a cheapy ebay one with no oil bypass. You can buy an aftermarket oil thermostat, but I don't bother. To me if you're running a new oil cooler and you don't let oil get old and sludgy, there shouldn't be any reason for the cooler to get blocked, and aside from longer oil warm up time I don't think it's a problem runnning no valve. If you do lots of short journeys, say driving to work 5 mins down the road, then a thermostat is a good idea, but you really shouldn't use these cars for short journeys. My car is always warmed up, and it doesn't take long at all for oil to get up to temp in a rotary, and the oil cooler gets pretty warm in only a few minutes. Not all the aftermarket oil coolers have a divide between inlet and outlet fittings on the end tank, I suspect mine doesn't, so circulation into the oil cooler may not be the best. I plan on getting an oil temp gauge, take some readings and then look at getting a divider welded into the end tank and seeing if there is any difference in oil temp.

1of1
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Re: oil cooler replacement advice

Post by 1of1 » Thu Apr 25, 2019 7:12 pm

Thanks for advice James !
I was thinking along the same lines but wanted to check
to make sure would be ok.
I have new water radiator and oil cooler both from ebay
as said both look pretty well made and as you say original if you can buy
are very high prices.

Thanks again !
Phil.

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