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Mocal Oil Thermostat Orientation

Old 03-12-07, 12:47 AM
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Mocal Oil Thermostat Orientation

Finally have my oil cooler setup installed.

As I bought the CWC dual cooler setup used, I didn't get any instructions with it as to how the oilstat should be connected up.

The think.com website (Mocal) does not have any instructions online that I could find.

This site shows two sets of instructions for this oilstat. The orientation changed at one point, and the orientation is reversed in a later model.

http://www.xse.com/leres/ss/oilcooler.html

This website says that the side with the spring in it is where the oil from the engine should be connected. The printed instructions ( on the referenced web page) seem to indicate that while the engine output port can be one of two ports on the oilstat, the engine intake is always connected to the same port. This would indicate that the internal valve works only in one direction.

When I started my car (FD) I let the oil temp get up to ~200f. I didn't think it should get that hot between 1-2000 RPM, so I shut it off. The hoses between the coolers were cold, a pretty good indicator that no oil was flowing there. The hoses connecting the engine to the oilstat were fairly hot, as you might imagine.

I'm sure I don't have the oilstat oriented properly, but I am not really sure at this point that just flipping it around is the right way to do it. There are 4 possible ways to orient the oilstat, but the instructions indicate that only 2 of them work.

Anyone here know how to definitively determine which way to connect this thing?
Attached Thumbnails Mocal Oil Thermostat Orientation-oilstat_1_lowres.jpg  

Last edited by jkstill; 03-12-07 at 12:53 AM. Reason: spelling
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Old 03-12-07, 07:58 AM
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http://www.xse.com/leres/ss/images/mocal2.pdf

That's the sheet I had with my t-stat. Just use the "bolt heads" as your reference for the orientation.
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Old 03-12-07, 10:03 PM
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Originally Posted by Mahjik
http://www.xse.com/leres/ss/images/mocal2.pdf

That's the sheet I had with my t-stat. Just use the "bolt heads" as your reference for the orientation.

The problem with using the bolt-heads as a reference is that not all Mocal oilstats are assembled the same way.

What is important is that oil line from the front cover gets connected to a port that is on the waxstat side of the oilstat. The waxstat pushes out the rod as seen in the attached photos, closing a valve. The waxstat side can be identified by looking through the ports. The side with the big spring is the waxstat side.

The waxstat can be seen circled in one of the photos.

I took the oilstat off (which was mounted correctly BTW) and disassembled it. After putting it into some nearly boiling water, I could measure that it opened from 37.88 mm to 40.51mm.

After handling it a bit I found that the rod would pull out. Pushing it back in it seemed to be stuck. I have since put some oil in the hole in the waxstat, and worked the rod in and out a few times. It no longer binds. It now expands from 30.5 - 40.5 mm.

The car this setup came out of had some really dirty oil, and I think it caused the rod in the waxstat to bind.

I will re-install the oilstat, and see if it seems to work properly now.

If not, I guess I get new oilstat.
Attached Thumbnails Mocal Oil Thermostat Orientation-mocal_oilstat_disassembled_lowres_1.jpg   Mocal Oil Thermostat Orientation-mocal_oilstat_disassembled_lowres_2.jpg  
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mocal_thermostat_3.pdf (60.5 KB, 976 views)
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Old 03-12-07, 10:11 PM
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The way I memorized it from bat website pdf (US distributor) is Rod = Return (from cooler) and Spring = Send (to cooler)

whoops, here's the link...
http://64.202.180.37/files/thermos$.pdf?Submit1=Get+Pricing

Last edited by GoRacer; 03-12-07 at 10:20 PM.
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Old 03-12-07, 11:29 PM
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Originally Posted by GoRacer
The way I memorized it from bat website pdf (US distributor) is Rod = Return (from cooler) and Spring = Send (to cooler)

whoops, here's the link...
http://64.202.180.37/files/thermos$.pdf?Submit1=Get+Pricing
That is the document attached to my previous post.
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Old 03-12-07, 11:32 PM
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After reinstalling the oilstat, I let the car idle until warm, and then ran it at 3k RPM until the oil temp hit 210. Letting it go back down to idle the temps cooled down after a bit to 202, at which point I shut it off.

The coolant never got hot enough to turn the fans on, and I have them set to come on at 185f.

The only cooling was a box fan blowing under the car to blow exhaust out of the garage.

I could feel heat in the 2nd oil cooler, so all seems to be working now.
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Old 03-18-07, 01:22 AM
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Thumbs up Oil Temp 260F in a rotary No Problem.

I have run my 13B at the track to 210 on water and 260 on oil (Oil sending unit on out let before cooler). Ran like this for two seasons shifting at 8500 to 9000. Each year I take the engine apart and check all the clearances and bearings for damage. Nothing so far so don't panic. These motors are tough.

Good and Safe Racing.
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Old 05-17-08, 03:58 PM
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quick update on an old thread, because I forgot to do it earlier.

The tstat was replaced, as temps were getting high sooner than they should have.

New tstat fixed it.
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