8V overcooling project

Beetle, out of interest, what are your sump oil temps now that you have the thermostat in place?

Brent S wrote:

Beetle, out of interest, what are your sump oil temps now that you have the thermostat in place?

Who cares? I’m only interested in the temperature of the cooling circuit oil going into the heads. That usually sits between 99-104.

beetle wrote:

Brent S wrote:

Beetle, out of interest, what are your sump oil temps now that you have the thermostat in place?

Who cares?  I’m only interested in the temperature of the cooling circuit oil going into the heads. That usually sits between  99-104.

I only asked because I'm limited to a sump oil temp dipstick, and mine routinely reads around 120-130 degrees, give or take. Assuming that this cools markedly through the oil cooler on its way to the cylinder heads etc, it then heats rapidly (maybe to 140-150 or so) before dropping back into the sump and settling back to 120-130 or thereabouts. I was thus pondering that if your oil is significantly warmer before it hits the heads (due to the thermostat effect), then maybe its getting materially warmer along the journey, maybe with a sump temp of 140, 150 or higher?

I presume those are Celsius figures Brent?

If yours is running at those sorts of Temps all the time, then you don't really need a Thermostat.

A Thermostat doesn't make the Oil run hotter, it's there to ensure it gets up to temp quickly, then keeps it within a decent range, no matter what the conditions.

As I said in my previous post, in our cooler, wetter Climate here in the UK, my Oil would rarely get above 75-80°C if the temps were around 18°C or less, lower still if it rained as well.

Having a Thermostat in the Cooling Circuit means the Oil gets up to a decent temp (100-120°C), no matter what the weather is like, and it gets there quickly.

Doc, thanks for your reply. Yes, they are Celsius. Also, I rarely ride in cold and wet conditions, so by virtue of that, my readings are likely to be higher than others.

I get the thermostat thing, but it’s probably more a question of where the thermostat is set, and what this means for oil temps as they flow through the system. Clearly, the GRiSO has a cooling system that sends (overly?) cool oil into the heads which then gets super heated and returned to the sump, in my case, sufficient to read 120-130 degrees C. I have no idea what temp the oil is after it goes through the cooler.......50, 60 or 70 degrees C? No bloody idea. Anyway, my question was that if, via a thermostat that is set to whatever, if the incoming oil temp is, say 25 degrees warmer than “normal” (say 100 degrees C for example), what does this means for the temp of the oil coming out?

Brent S wrote:

I only asked because I'm limited to a sump oil temp dipstick, and mine routinely reads around 120-130 degrees, give or take. Assuming that this cools markedly through the oil cooler on its way to the cylinder heads etc, it then heats rapidly (maybe to 140-150 or so) before dropping back into the sump and settling back to 120-130 or thereabouts. I was thus pondering that if your oil is significantly warmer before it hits the heads (due to the thermostat effect), then maybe its getting materially warmer along the journey, maybe with a sump temp of 140, 150 or higher?

There's only one way to find out. I will investigate.

Brent S wrote:

. . . it’s probably more a question of where the thermostat is set, and what this means for oil temps as they flow through the system. Clearly, the GRiSO has a cooling system that sends (overly?) cool oil into the heads which then gets super heated and returned to the sump, in my case, sufficient to read 120-130 degrees C. I have no idea what temp the oil is after it goes through the cooler.......50, 60 or 70 degrees C? No bloody idea. Anyway, my question was that if, via a thermostat that is set to whatever, if the incoming oil temp is, say 25 degrees warmer than “normal” (say 100 degrees C for example), what does this means for the temp of the oil coming out?

It doesn't really matter what the temp of the Oil leaving the Cooler is, the important thing is that the Oil gets to a decent temp before it starts it's journey through the Engine, i.e. in the Sump.

I first fitted my Temp Sensor in the Banjo where the Cooling Oil comes out of the Crankcase, now it's in the Sump.
Temps were similar at both locations, which is hardly surprising as the Cooling Oil exiting the Case has just come from the Sump.
It would be interesting to know what the temp post-Cooler is, say at 100ºC Sump temp, but as I said, it's not really important.

Thermostats are 'set' by the Waxstat, it's a small wax filled Cylinder, with a Piston and Rod that starts to move outwards when the preset temp is reached.
Mine is a 93ºC Unit, it starts to extend at that temp.

There are several different temp settings available.
It's the same unit as used in most water-cooled Engine Thermostats, but they're typically set in the mid to high 80s.

Feeling somewhat stupid...it occurs to me that I'm measuring the oil temperature from the sump to the thermostat, not the oil going into the heads.

Can you supply detail on the adaptor to fit the dipstick hole ?

The plastic original dipstick looks a bit cheap to me and I've been toying with replacing with a stainless or brass nut then silver soldering a stainless rod as a level indicator.

The gizmo you bought looks like it would work well as the basis for an upgraded dipstick.

Thanks Evans

What's this talk of silver solder? My home made jobbie works just fine with threads, loctite, and a locknut.


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beetle wrote:

...it occurs to me that I'm measuring the oil temperature from the sump to the thermostat, not the oil going into the heads.

That is correct isn't it?
When the oil from the sump does not need cooling it shortcuts straight to the heads
When the oil from the sump passes the cut off temperature it is routed through the cooler first.

Can't see how else it could be done

Yes, that's basically it Jon.
The Cooling Oil goes from the Sump, through the Cooling Circuit Pump (in the same housing as the 'pressure' Pump that feeds the Crank Bearings), to the Thermostat.
While it's warming up, the vast majority of the Oil is directed through the Thermostat Body, straight to the Heads.
When the Oil reaches the Waxstat's threshold temp, it starts to open, gradually moving the Valve against a Spring, which lets the Oil flow through the Cooler.
It modulates around the set temp, keeping the Oil in a constant range.
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That shows the two extremes of the Thermostat's Valve travel, in normal riding, the Valve will move initially from full Bypass, to full flow through the cooler, then gradually settle to somewhere in-between, moving slightly either way as the Oil Temp changes due to differing riding and weather conditions.

I added a second temperature sensor, on the oil cooler feed to the heads. As the oil temperature rose, the gauges mirrored each other until the thermostat opened. At the point, the oil temperature feed into the heads plummeted ~10 degrees. Oil coming out of the sump was reading 98 degrees when the oil going into the heads dropped to 88 degrees, quite rapidly. As the heat soaked into the engine, the temperatures stabilised at 98-99 from the sump, and 93-95 into the heads. Ambient temperature was 10 degrees. This was at a fast cruise, and an active throttle in the fast sweepers. At a slower cruise, the sump oil temperature hit 100, and the head oil temperature hit 97.  As I headed back into town, at 80 km/h, the temperature of feed into the heads rose slightly. At 50/60 km/h, they were both showing 98. I assumed the thermostat was closing up again.

I'm thinking this is a definite win.


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I'd be interested to see what temps the Oil reaches on it's drain-down from the Heads, immediately after it's done it's cooling job around the Valves.
Might be tempted to move my second Sensor (currently in the CARC Fill/Level Plug) to one of the Head Walls, if I can.

Now this is all real science - thanks guys

It will be interesting to see how the oil temperatures vary with differing ambient temperatures.

They certainly seem to suggest that the theory is correct that the oil would not be getting hot enough, without a thermostat, to vaporize any water, that presumably has got into the oil through varying temperatures and condensation.

My GRiSO should have had serious damage to the flat tappet guides at 50,000 klm.
However it was imported from Japan and from the lack of corrosion had been garaged rather than left parked on the street. The guides had some wear but not disastrous amounts and the engine seems sound. My feeling is that by garaging the bike at night the temperatures didn't vary that much preventing condensation and contamination of the oil. If the rider was taking long enough rides to get the oil properly hot would also have helped.

Before I fitted my Thermostat, my Oil would struggle to get hotter than 75°C or thereabouts, if the ambient temps were around 12°C or less.
Was worse if it rained as well.
I regularly found 'Mayo' in the Rocker Covers.

I would regularly cover the Cooler in Winter and cooler weather with a Neoprene Mouse-Mat, to keep the temps up to a decent level (110-120°C).

I have the early Stelvio, with 9-Row Cooler, and small Tank (18litre).
From 2011 onwards, the 'Big Tank' (32litre) Stelvio has a larger Cooler, with 13 Rows.
Not sure what size the GRiSO Cooler is in comparison.

Doc. wrote:

I'd be interested to see what temps the Oil reaches on it's drain-down from the Heads, immediately after it's done it's cooling job around the Valves.
Might be tempted to move my second Sensor (currently in the CARC Fill/Level Plug) to one of the Head Walls, if I can.

I’ve removed the little extension on the ETS, so it is now inserted deeper into the barrel. I believe it’s in the return path of the oil. It is less affected by air cooling. I might do another run and log the engine temp as well. The heat-soak affect will need to be considered, but it should be indicative until the engine gets really hot.

Beetle,
it looks like you have been using the thermostat unit for a couple of years now.
how is it working as far as durability?
I see they offer a rebuild kit, so was wondering if you had the need to rebuild yours or what the possible service interval would be for the GRiSO application

I don't think they have a service interval as such, they only have one moving part, two if you count the Spring.

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If it's working, and not leaking, you can leave it alone.

My home-made Unit has been in since April 2017, and apart from having to make another Gasket for it, it's not been touched.
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that's what i was hoping to hear!
everything with moving parts eventually fails and with the available rebuild kit, I had to ask if this part is offered due to frequent failure or possibly that the product has been on the market so long that when the inevitable happens, it can be rebuilt without being replaced

thanks,

The Waxstat is the only part that's likely to fail, and is readily and cheaply available.
It's the same Unit as used in gazillions of car Water-Cooling System Thermostats.

Mine is a Mishimoto item, they do three or four different temp settings, mine's set at 93°C, that's when it starts to extend.
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cycling back to this project a full four years later....!! Can't believe it's been that long and that I never finished it.

Anyway, all my tools and contents of my workshop are crated away in the process of being shipped from the UK back to the basque country (which is an unbelievable ordeal post-brexit) so for the moment I can't actually engage in any serious projects...

BUT I am back to riding the GRiSO as transport, the weather is permanently wet and between 7 and 14 degrees absolutely max and I do own a pair of scissors and some heavy duty plastic, and I'm sick of the winter mileage I'm getting so...

Am I ok to just cover the air intake for the radiator as long as the weather stays below 15c? I don't sit around in stop go traffic but I do see a few red lights.

cheers

Remind me, do you have a Temp Gauge fitted?

If so, then yes, just cover the Cooler in cooler and/or wetter Weather.
You can play around with how much of it you cover, if you have a Temp Gauge to keep an eye on the Oil.

As I recall, before I made the Thermostat, I'd typically have around 80-90% of the Cooler covered (small 9-Row Cooler remember).
I used a Neoprene Mouse-Mat, simply tucked under the top of the makeshift Engine Guard Plate I had mounted to the Sump Guard (it kept all the muck off the front of the Engine).
I could adjust it and it would stay put without any fixings.

On the GRiSO, I'd just cover the whole Inlet on the Duct thing, then cut holes as required to get the Temps you want, if necessary.
I wouldn't worry about sitting at Red Lights for a minute or two, Synthetic Oils are fine to 230°C or more.

no temp gauge,

I can't see it overheating to be honest.

Took it out for a spin on wet roads with the outside temp at 11C, was an absolute joy to get normal fuel consumption figures again, and to hear the engine make the right noise.

I'll be keeping the inlet blocked until April I think, unless someone can convince me that it's a terrible idea

And I categorically promise to finish the thermostat mod before next winter!!