Any advice on how to incorporate a Lockhart oil-thermostat in the cooler lines ?

[racerrad8]

Thermostat: A device that is used to control temperature.

So, why they need for a thermostat for the FJ?

Only one reason and it is not for "additional" cooling. Additional cooling can only be done by a different oil cooler (addressed below)

The thermostat pictured is a oil cooler bypass valve to eliminate the oil passing through the cooler allowing it to come up to operating temperature sooner. The question I have first, is what is the temp the thermostat is set to open?

Now, the thermostat is going to be controlled by a heat sensing mechanism (bi-metal spring) or expansion bulb internally which can fail. When it does fail, does it fail in the open or closed position? If it fails in the open position, who cares the oil will still flow through the cooler, but if it fails closed, then you now have no cooler.

Now, the cooler I am offering has a built in "thermostat" based on oil viscosity and resistance to flow. This means the cooler has a couple of tubes that allow the flow of the thicker/colder oil while the remainder of the cooler will not flow the oil due to the thickness. Mike Ramos was the first one to bring this to my attention as he noted in his winter travels the stock cooler was allowing the oil temps to drop as the cooler was "over-cooling" the oil. The shown inline thermostat might do the same thing depending on the oil temp settings and if it allows partial bypass.

...The oil cooler itself as well as all the fittings have remained sound (after many thousands of miles) and the nice ting is that until it gets uncomfortably cold for the rider, the cooler maintains the oil temperature at 180 degrees which does not over cool the engine.

Ride safe, Mike Ramos.

Now, we had this similar discussion about the cooler design/size and such in this topic from about post 16 forward.

http://www.fjowners.com/index.php?topic=7822.0

The thermostat portion of my cooler was discussed here towards the bottom of the post;

1) Couldn't this be accomplished with a restriction on the outlet side?  I see where a small hose on the outlet side would cause back pressure, but does the inlet hose also need to be small?

A) Yes & no...The back pressure within the cooler is still going to dictate flow. If you have a large hose & cooler with a restrictor at the outlet, then you will have a back up trying to force the oil through the restrictor. That will slow the flow and fill the cooler, but then you have to control the flow to allow the cooler to work efficiently.

2) I would think the volume of oil being pumped would determine how much of the cooler gets used?  A small amount of oil supplied at high pressure is still going to run to the bottom of the cooler.  Conversely, a large amount of oil at low pressure would use the whole cooler if it is more than the cooler can flow.

A) We cannot confuse pressure & volume. They are two different things that must work together. If a small volume of oil at high pressure is put through a cooler that is restricted, pressure wise, then the cooler will fill completely, but once filled could actually raise the pressure.

And the same can happen on a low pressure/high volume, depending on the cooler, could actually raise the pressure as well.


3) Sometimes this stuff is counter intuitive.  Like a radiator.  People used to remove the thermostat in an attempt to get an engine to run cooler.  That usually causes the engine to overheat since the water flows right through the radiator and doesn't spend enough time sitting in it and shedding heat.

Exactly, that is why if you are not going to run a thermostat, you should run the appropriate restrictor. The water pump can pump the water too fast through the radiator. But if you reduce the size of the radiator and increase pressure then it will cooler better...

As far as the FJ is concerned since the cooler size is the biggest factor when mounting coolers the size really does not come into play. Now, just to throw in one more thing to make you scratch your head...

The cooler I offer for the FJ has a dual circuit built in based on the path of least resistance theory, acting as a thermostat and during the testing on the FJ is became clear how well it worked.

The coolers top two plates are a straight pass through whereas the other tubes are a cross flow-spiral tubes. When the oil is cold the path of least resistance is straight through until the oil comes up to temp. Then as the hot oil has a lower viscosity it can flow through the complete cooler. What we found when testing during the cold of winter the engine oil temp actually came to operating temp quicker and maintained in the 180* range at speed.

Check out photo #4;
RPM Oil Cooler Kit

The stock cooler would not allow the engine oil to rise above 150* on the same ride on the same day. I also note that during hot day riding the oil temp on my bike stays much more stable compared to the stock oil cooler on my wife's bike, it has a much higher fluctuation of temp.

Ultimately, back to the question at hand about hooking up that cooler on the chopper. That is a large cooler, 18 rows at 2" wide and the hoses he has a too large as well for the lower volume secondary circuit of the oil pump.

The oil pump was designed to work with a 1" wide 5 row cooler from Yamaha. I have bumped the cooler up to a 12 row, but added the additional internal restriction of the cross flow-spiral tubes and the pressure of the circuit is the same.

And finally on the subject, I am sticking with the fact he should be running synthetic oil due to the turbo. The biggest issue will be the burning of petroleum based oil at the turbo lubrication point and degradation of the bearings within, especially at shut down.

Randy - RPM

Pat, maybe a files section should be made regarding oil coolers so this information can be easily found without searching, especially since most of this information is in an "oil" post.

Randy - RPM