Temperature differences

Tweety · Post by **Tweety** » Fri Dec 19, 2014 10:16 pm

Well Tweety is on the road. But there is a nagging issue and I thought I'd ask your advice. El Freddo already has seen the problem. Try to picture this.

With the previous arrangement the radiator for the ea81 was up front of the trike, with two 10 inch thermo fans both pullers. Also of course were 2x stainless steel pipes for coolant travel which also helped keep things cool. The Alfa 33 radiator facing the front, imagine you are sitting on the trike seat. The inlet on the LHS was about half way up the radiator. The exit on the RHS is at the top of the radiator. The thermo fan switch was on the RHS half way up the sides. The thermatic fan switch is a 87 on 82 degrees off brass type.

The pressurised overflow bottle was at the back off the heater hoses. Air blockages were an issue and summer time heat on my legs was unbearable.

Now imagine holding onto the radiator from the seat and spinning 180 degrees and mounting it at the rear of the engine. The radiator hoses are in effect reversed. The top hose from the SPFI thermostat housing goes through a temperature sender to the top high up radiator inlet. The thermatic fan switch is now half way down that side. The radiator exit is now half way down on the other side ideal for the route to the water pump. The coolant pressurised overflow bottle is off the top radiator hose= no air blocks. We have one 10 inch fan puller and one 12 inch fan pusher.

With the previous set up the thermatic fans would switch on at 90 degrees and off at 82. Exactly as I wanted. Even though there was a long way for the coolant to travel and that switch was on the "cool" side of the radiator. Though the digital temp sender has never moved from post thermostat housing area.

Now when running fully warmed up, the digital temp gauge, which has its sender always at the top of the thermostat housing, creeps up to 94 degrees even 98. Then the thermatic fan cuts in which is mounted now only 200mm below the digital sender. Could there be 7-9 degrees difference between those components?

So my real concern is that my digital temp gauge now reads very high. And is this a concern? Would there be 98 degrees at the location immediately post thermostat in all engines?

I am about to install a heater core with a 10 inch fan as insurance the engine remains at temps in the 80's.

Sorry for the confusion- it isnt easy explaining.

The picture depicts the top radiator hose currently. In that hose is a unit that carries- the sender for the digital temp gauge and the fitting for the coolant reservoir. You can see the thermatic fan sender further down.

steptoe · Post by **steptoe** » Sat Dec 20, 2014 6:39 am

Once read that the temperature at which an engine runs most efficiently at was 95C

Couple that with the idea of rad pressure is to increase the temp at which the water/coolant would start to boil. I have no idea if pressure helps before 100C ?

Makes me wonder if we panic unnecessarily about op temps under 105C

How does it run if you have elec fans on all the time ? Are the fans running as often as they were before? You are also running a different engine, different sort of heat pump coz it is all new.

Radiator is gonna be hotter behind the engine, rather than in front , but seems you suffer a latency issue with switch on of fans ?. I am starting to see the beauty of the Chines adjustable electronic switches rather than the tried and tested thermo switches.

Two rads, one front, one back ??

Subydoug · Post by **Subydoug** » Sat Dec 20, 2014 10:02 am

According to the FSM, 75-85degC, however, also in the FSM, thermostat starts to open at 88degC, fully open at 100degC. Thermo switch on at 95degC, off at 91degC.

Thats all with Genuine sensors and thermo. I assume the EB put a new thermostat in there for you Tweety?

My opinion would be that those temps your seeing are acceptable, If you started getting into the 105-115 region then thats probably too hot.

Also, are those temps you recorded while riding or just sitting at idle?

Regards

Doug

Tweety · Post by **Tweety** » Sat Dec 20, 2014 5:40 pm

Hi guys,

I dont think I should panic. I dont want a radiator up front, looks crap. I will have a universal hot rod heater up there though that looks good in the future.

Idle is around 98deg - 94. And the fans switch on and off at this temp. so the radiator water half way down is 82-87 deg spot on. I've made up a scoop under the sump to swing some air up there. reckon it works as didnt go over 94.

The info both you guys supplied satisfied me. The max the engine temps can be. I think with the heater core and 3rd fan it will garrantee not to overheat. That is my concern in the heat of summer.
EB didnt supply thermostat. I have always been using a large volume stat so I could push more coolant up the tubes to the front without restriction. I suppose a smaller volume one could be tried??? It would slow the coolant speed down.

Fans on all the time still gets up to 98 deg.

Anyway will fit the core when it arrives. Tony

Post by **TOONGA** » Sat Dec 20, 2014 6:05 pm

I would use the Subaru specified thermostat if you could get it.

The other thing you could try is a thermostat that opens at a lower temperature.

TOONGA

Tweety · Post by **Tweety** » Sat Dec 20, 2014 10:28 pm

good ideas Jules. thanks.

pitrack_1 · Post by **pitrack_1** » Sat Dec 20, 2014 10:40 pm

Hi,

dunno if this suggestion helps but at least the test is easy. This may apply if the digital temp sender (DTS) is a unit requring grounding, e.g. with a metal body/thread designed to be screwed in to metal.

First, we have to assume the DTS gauge accurate.

From what I read the DTS is in the middle of the radiator hose. Now if the DTS is a unit with a metal body that's meant to be grounded, then it's currently isolated from ground as it's in the middle of a pipe. In that case, the grounding takes place through the coolant, which probably adds a bit of resistance or voltage drop. This could be causing the erroneous reading if the mounting is different now to before.The reading may also change with the alternator off/on (i.e. batt 12V vs alt 13.8V) in this case

My test is to then connect an alligator clip lead from the DTS body to a good ground such as the thermostat housing. The reading should change, hopefully for the better. Although the alligator clips themselves can introduce a couple of extra points for voltage drop.

steptoe · Post by **steptoe** » Sun Dec 21, 2014 7:21 am

Was thinking along similar lines ...Tony has used this in hose adaptor for the CTS before. I have a in hose adaptor that comes with an earth screw in it. Most coolant sensors are mounted in engine manifold components and catching the innards coolant temp - not that within a hose off whoop whoop somewhere. I am certain some sort of grounding could also travel through the radiator hose.Ive used heater hose to insulate a lawnmower spark plug and killed the whole spark happening until I replaced the carbon coloured hose with silicone hose!
Tony may have killed his first thermocouple thing and blown his confidence in the new Chinese technology - but gotta try something to doubly protect the investment made in this baby!
I know I have heard my $14 temp controller simply relay click inside but not trigger my alarm - once. That could be an important fan one day ! Back up circuit is on the cards.

Tweety · Post by **Tweety** » Sun Dec 21, 2014 12:53 pm

Arhhh so that's what that tiny screw is for???

I used that to secure the wire from the sender. Yes I will ground the unit to the engine. Great idea.

There is no coolant only water in the system for a couple hundred kms then drain and add coolant then.

Jonno, you are right, am being super cautious as is a big investment. The heater core is at the PO ready for pick up, make steel frame , mount fan and seek out 2x 5/8 > 1/2" brass reducers from Enzed.

I think a lower temp thermostat is a good idea to as Tonnga advised so its fully opened at a lower temp.

Another option I have is - just prior to the thermostat housing above No 1 spark plug, is the Hudson 95 degree sender for that truck reversing alarm I have just received in the mail. If compatible I could swap the DTS for that meaning my DTS would be reading temp from prior to the thermostat, on the engine ? but I'll try the earth thing first this arvo.

Tweety · Post by **Tweety** » Sun Dec 21, 2014 9:36 pm

Googled-

radiator hose temperature sender adapter ground ....and got many posts there about grounding the sender and that small screw on my adapter is for that purpose.

Will try it soon.

Tweety · Post by **Tweety** » Tue Dec 23, 2014 9:52 pm

Lots of work done the last two days.

Wire for earth for temp sender housing done.

Change thermostat same temp 82 degrees but smaller flow. Took longer to get to 103 degrees but did still get there.

Installed heater core I got in the mail. No change in temps.

Realised the critical factor is low air flow directly into the radiator.

So I've put the bugger up the front again. lol and put the high flow stat back in to help coolant flow up to front and back

Back to where it obviously belongs- the front

Tweety · Post by **Tweety** » Wed Dec 24, 2014 8:48 pm

Radiator now at the front. Test ride. On a road a few kms from here at 90kph temp used to climb to 103 degrees. Now.....82

Engineers early in the new year, waiting for the booking soon.

Tony