Date: Wed, 2 Nov 2022 09:44:03 -0700
Reply-To: mark@MARKMCCULLEY.COM
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mark McCulley <mark@MARKMCCULLEY.COM>
Subject: Re: Oil cooler questions.
In-Reply-To: <BL0PR05MB4916EC766279CF391AA1E9B2A0349@BL0PR05MB4916.namprd05.prod.outlook.com>
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Great in-depth info, thanks Dennis.
Your assumptions are correct. I'm not sure how to answer question 4. Are you asking about the sandwich adapter or the oil cooler itself? The thermostat in the oil cooler consists of a thermistor and a potentiometer. The thermistor is mounted in the top of the oil cooler near where the oil exits and flows back to the sandwich adapter.
My original post was somewhat ambiguous about the 160F temp I measured. This was measured (with an infrared thermometer) on the oil cooler near the thermistor so it should be an approximation of the temperature of the oil as it leaves the oil cooler. The oil temp at the sump, where the sender for oil temp gauge is located, is running about 190F - 200F when engine is fully warmed up. This is at 50F ambient.
For now I have disabled the fan by removing a fuse. I'll re-enable it whenever I think I need the extra cooling.
-Mark
> On Oct 30, 2022, at 7:32 AM, Dennis Haynes <d23haynes57@HOTMAIL.COM> wrote:
>
> Mark,
>
> You have a number of things that are going on here. Again year and vehicle-engine combination is helpful. I will list some assumptions for my responses.
>
> 1) You have a 2.l based engine cooling system, with the OEM oil cooler/heater in place.
>
> 2) The oil cooler kit is using a "sandwich adapter" with internal thermostat.
>
> 3) The oil cooler is mounted in one of the pillars relying on a fan for air flow when needed.
>
> 4) The thermostat is a fixed temperature. Is it sensing the oil from the engine to the cooler or from the cooler return back to the engine? This is a huge factor for fan operation.
>
>
>
> Ok lets start with design details.
>
> 1) For the most part almost all oil control thermostats are of a bypass design. The oil flow bypasses the cooler through some port or around the thermostat disc or whatever is using for control. The sandwich adapters are often additionally limited as the pass is usually restricted. Also, the layout is usually such that the thermostat will respond to the oil temperature entering from the engine, not the return to the engine as that is through the oil filter nipple after everything. This is important, later.
>
>
>
> 2) Almost all auto based oil cooler thermostats based on some though that 160F is the minimum oil temperature will be begin to close and usually are fully closed, (oil cooler full on) by 180F. In a way this is too cold and if it can be reliably maintained changes the viscosity requirements of the oil. Ideally oil temperature should be close to coolant temperature.
>
>
>
> 3) On the Waterboxer, the oil cooler/heater is actually designed to both. It is using the coolant on the engine side of the thermostat to heat the oi quickly and then when it gets too hot removes the excess heat from t the oil. If using a stock thermostat the coolant is running at 188F or higher. The oil is leaving the engine, being heated close to this temperature and this is what the sandwich oil cooler thermostat is responding to. This is your main problem.
>
>
>
> 4) For the fan turning on, if it is sensing the oi going to the cooler it is now seeing this near 190F oil and turning on the fan even if the cooler is cold. It should be sensing the oil leaving the cooler so that it only turns on when the additional air flow is needed.
>
>
>
> For now I would begin by disabling the coolant flow to the OEM oil cooler. This will restore the add on oil cooler thermostat responding to the oil temp leaving the engine. In cold weather you may still see 160F temps but more likely you will see 160F to 180F based on load and speed. Then relocate the fan switch so that it is not needlessly running.
>
>
>
> Dennis
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