Am I a little hot?

Talk about the E-Type Series 3

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TheDampMan
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#1 Am I a little hot?

Post by TheDampMan » Sun Mar 11, 2018 4:52 pm

Hi all any advice please,

First longish trip out today as the sun was shining and loved it.

Just a little concerned that after around 15 miles the temperature gauge is reading between normal and hot then reduces slightly and builds up again, I have also noticed that the rad fans start up around this temperature and don’t stay on very long.

My questions are-
Is it ok to run the car at this temperature?
Can the gauge/sender unit be giving a false reading?
Are the fans stating up at too high a temperature?
Would it be wise replacing thermostats and flushing the system?

On a completely different topic I need to purchase engine oil any recommendations ?

Any advice appreciated
Steve.
Steve
1974 S3 2+2
BMW Isetta

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JJC
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#2 Re: Am I a little hot?

Post by JJC » Sun Mar 11, 2018 6:13 pm

Well.....one mans opinion.....others will take another tact. I have had my Series 3 for 44 years. Here is what I figured out. First, I removed the thermostats. Don't feel I need them. The fans.....? I control them myself with a toggle switch next to the red idiot lights to the left (US car) of the steering wheel. Car starts to get up near the N in normal, I turn them on. I also installed a cheap, available anywhere, overflow reservoir. If the car spits out a bit of coolant, as the car cools, fluid sucked back in, keeping the cooling system virtually airless. Important , of course , to keep air out of the system. Fans last longer, car runs cooler, simple, and it keeps the owner, and the engine, very happy ! Car has never over-heated. (did run very warm one day.....fan motor did die, but replaced next day......very reliable, for the most part ).

Happy motoring !!

John

1973 Series 3 V-12, original owner 150K Miles, without overhaul (did pull heads years ago for maintenance).

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JJC
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#3 Re: Am I a little hot?

Post by JJC » Sun Mar 11, 2018 6:15 pm

Oh, and if you always run 30wt oil, cheapest you can find, and change often, your rear crank seal will not leak. For some reason, the rope seal seems to have a strange love affair with 30wt.

John

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42south
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#4 Re: Am I a little hot?

Post by 42south » Sun Mar 11, 2018 7:02 pm

Hi
My series 3 which has thermostats fitted, and a new radiator, runs with the needle on the R of normal, and never shifts much at all on the open road. If crawling in a line on a hot day it moves slightly towards the A.
The fans come on just above the R.
I did have a manual gauge fitted, and the R was 85degC.
Your fan cycles sound normal.
I also have a manual override switch fitted, but don’t need it for normal operation.
Mark Brown
1971 S3 Etype
Son: when I grow up, I want to be a pilot
Dad: You’ll have to choose.

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jagwit
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#5 Re: Am I a little hot?

Post by jagwit » Sun Mar 11, 2018 8:15 pm

JJC wrote:
Sun Mar 11, 2018 6:13 pm
I removed the thermostats.
Interesting!! Did you close off the bypass circuit John?

Mark, Steve, I recon your cars are 100%.
Best Regards
Philip
71 E-type V12 Coupe,
80 XJS (EFI by Megasquirt & EDIS-6 + 5sp manual overdrive)
73 Jensen Interceptor
74 Interceptor (EFI by Megasquirt + overdrive 4sp auto)

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#6 Re: Am I a little hot?

Post by JJC » Sun Mar 11, 2018 10:48 pm

Couldn't tell ya .....I only know what I know. Runs cool....no fuss, and never need to put much, if any, coolant in the system. 13lbs cap. Without the thermostats, of course I do let it idle for a few minutes in the winter. Of course , that's a good thing to do anytime. Let that baby warm up . Wish I could help ya.

John

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#7 Re: Am I a little hot?

Post by JJC » Mon Mar 12, 2018 1:01 am

FYI.....my car is less then 100%........there is a very small scratch under the air scoop. Can't see it, but I know its there. Also, years ago, I got rid of the silly ash tray. Covered the whole consul in leather, looks fantastic, but alas, that would make my car less then 100%.. Oh well.......

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lowact
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#8 Re: Am I a little hot?

Post by lowact » Mon Mar 12, 2018 1:13 am

Heh, heh. I’ve been waiting for this topic to come up again. First my experience and then some suggestions for Steve:
My car is now the same as Marks, temp sits in the middle of normal. Hard driving makes no difference, only in start-stop traffic with ambient temp greater than 34 degC might it move past “r”. When I first bought my car, the radiator leaked irreparably, also the water pump. New radiator was an aluminum CoolCat because it was the cheapest available, same design as the saffer one that Phil was featuring in an earlier post. Water pump leak was due to half the shaft seal not installed to make room for a larger (the later design) impeller in my original design housing! I reconditioned the waterpump back to the original design. Car ran cold, winter trips were miserable, heater didn’t work, pulled it apart to find out why, nothing wrong, just not enough heat from the engine, except in start-stop traffic gauge was always half way between zero and “n”, dropping back if a cloud passed over the sun. It was the latter that prompted me to, very belatedly, check the thermostats. I didn’t have any. Fitting thermostats got me to where I am now.
Actually, it was not just the price that attracted me to the CoolCat. It is high flow, larger tubes, better heat transfer as well as less likely to block.
Steve, your car is running hotter than it needs to or should. You have a blockage developing, most likely in your radiator, or maybe yr thermostats are a bit tired and not fully opening. Boil yr thermostats, confirm that they fully open. Go for a test drive without them fitted. Remove yr radiator and have it professionally and separately flushed, weigh it before and after. The SNGB website lists radiator weights as low as 12.81 kg, so that is the target. If yr radiator is original, expect that professional flushing will cause it to leak. If so be pleased, don't try and repair it, buy yourself a new one. Never use Bars Leak or similar. Ensure that the water you drain out of your radiator is as clean as the water that goes in.
Regards,
ColinL
'72 OTS manual V12

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jagwit
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#9 Re: Am I a little hot?

Post by jagwit » Mon Mar 12, 2018 5:32 am

JJC wrote:
Sun Mar 11, 2018 6:13 pm
I removed the thermostats.
Removing the thermostats is one thing.... (which I for one would not advise).

Removing the thermostats AND not closing the bypass circuit, would cause a substantial amount of coolant to continually bypass the radiator - hence not being cooled by radiator.

The very purpose of the coolant bypass circuit is :
1) to cause rapid warmup of the engine by having coolant flow from engine directly back to waterpump, back to engine, not going through radiator;
2) to have actual coolant flow while the thermostats are closed.

One of my challenges when fitting a new thermostat is that most new thermostats don't seem to move enough, thus the bypass port in the thermostat housing is not closed fully. This often leads to a V12 running hotter than it would if those bypass ports were closed fully.

Whilst some raise the bypass port in the thermostat housing (the most elegant solution IMHO), I added a 3mm alu washer to the bypass port plate of the thermostat to fix the thermostat-not-moving-enough problem: viewtopic.php?f=6&t=11373&hilit=bypass#p92199
Best Regards
Philip
71 E-type V12 Coupe,
80 XJS (EFI by Megasquirt & EDIS-6 + 5sp manual overdrive)
73 Jensen Interceptor
74 Interceptor (EFI by Megasquirt + overdrive 4sp auto)

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#10 Re: Am I a little hot?

Post by JJC » Mon Mar 12, 2018 10:13 am

good idea

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TheDampMan
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#11 Re: Am I a little hot?

Post by TheDampMan » Wed Mar 14, 2018 12:41 pm

Thank you all for taking time to respond.
I am going to install a manual override switch so I control the fans and monitor it from there.
Steve.
Steve
1974 S3 2+2
BMW Isetta

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#12 Re: Am I a little hot?

Post by JJC » Wed Mar 14, 2018 6:27 pm

Yea....thats the ticket !!

John

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#13 Re: Am I a little hot?

Post by lowact » Thu Mar 15, 2018 4:02 am

For the record, removing yr thermostats will make yr car run colder than it otherwise would, not hotter. And you should not alter yr thermostats to make them fully close the bypass. This is proven by both theory and practice.
The V12E cooling system is well designed and the pump is powerful. It works very well when properly maintained. If it is misbehaving it is not a design problem, it is a maintenance problem. The not-fully-closing bypass-valve provides last-ditch protection, some better-than-nothing circulation if the radiator is neglected for decades and becomes clogged.
You might imagine that, with the thermostats removed, because the bypass circuit is shorter, that the water would preferentially flow via the bypass instead of via the radiator? Not true on two accounts. Firstly, the relatively small diameter of the bypass, together with other design features, means that without thermostats it is NOT easier for water to flow via the bypass than via the radiator, unless the radiator has some blockage. Secondly and most significantly, removing the thermostats unleashes yr pump, instead of producing low flow at high pressure it produces high flow at low pressure, more than enough flow to run BOTH, bypass and radiator, at maximum capacity.
Heat transfer is proportional to flowrate. When the thermostats are removed, if the radiator is not restricted, the flowrate is so high that the at normal driving speeds the engine can’t heat up enough, which is bad. That is why you don’t run without thermostats.
This graphic shows what happens.
https://1drv.ms/b/s!AiSPBKa26IcchKUkIRyOIjPJFGxoIQ
In a nutshell yr centrifugal water pump produces pressure x flowrate. When the thermostats are closed there is a small flow thru the engine at highest pressure. When the thermostats are open there is higher flow through the engine (via the radiator) at lower pressure. With the thermostats removed here is an even higher flow through the engine (via the radiator and the bypass) at the lowest pressure.
The OEM radiator, new and clean, weighs ~12.8 kg. Remove yours, drain and weigh it. The difference is how much crud it contains, that is blockage causing overheating.
Regards,
ColinL
'72 OTS manual V12

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#14 Re: Am I a little hot?

Post by JJC » Thu Mar 15, 2018 9:04 am

Hi : When running at any speed, if I shut the fans off, eventually, perhaps on a 70 to 80 degree day, the engine will produce all the heat you desire, and the gauge will indicate accordingly. But thats just me, and my car, and 44 years of ownership. I like running without thermostats, and I like controlling the fans, but thats just my preference. I agree, Jag designed a wonderful system.....just drive and forget. But I like being more involved. Not recommended for all. Happy motoring !

John

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Ole-xke1974
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#15 Re: Am I a little hot?

Post by Ole-xke1974 » Thu Mar 15, 2018 12:45 pm

lowact wrote:
Thu Mar 15, 2018 4:02 am
For the record, removing yr thermostats will make yr car run colder than it otherwise would, not hotter. And you should not alter yr thermostats to make them fully close the bypass. This is proven by both theory and practice.
Thanks for the explanation.
On my newly restored/modified 74 S3 OTS I have run a wire to give me a control light for when the fans are on (both new VW fans), I also have installed a delay relay that keeps the fans running after turn off, if the otter switch (replaced by CoolCats modification). Next on my list is to install an override switch which I may make a two step, which will allow me to utilize the two speeds feature of the VW fans. Maybe in combination with a two speed set up where the maximum speed will kick in when both the AC and otter switch dictates fans to be on. My thermostats are new and temperature tested before fitted to the car. The radiator is a new CoolCat aluminium as well.

Now to my point of all this, your explanation reassured me that keep it all as Jaguar intended and maybe improve in areas where the technology weren't available at the time of the original design. I don't trust myself to run the fans manually, but like the option of the override as a preventive measure, if you know its going to be a hot drive at low speed, like standing in traffic.

Cheers .......... Ole
1974 SIII E-Type w. XJ S2 4sp w. O/D

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#16 Re: Am I a little hot?

Post by lowact » Fri Mar 16, 2018 1:30 am

I once owned a Ford 😊
My 1st car and I loved it, only sold it to make down-payment on a house. I’d removed the pulley driven fan and installed an electric thermostat controlled fan, with manual override switch. The thermostatic switch died but that didn’t matter, the car never overheated and if it did I still had the override… Headed off on a long drive very early one morning, ambient temp was -12degC. !5 minutes down the road there is steam from under the bonnet, my engine is boiling, the radiator had frozen solid before the thermostat had opened (no antifreeze). Stopping meant no more frigid air slamming into the front of the radiator, so 2 minutes later the engine had thawed the radiator and I’m on my way again, the thermostat modulating the temperature perfectly, I didn’t even need to use the override.
Was back in the days when Fords were Fords. This experience highlights to me the potential benefit of a manual over-ride, if the thermostatic control fails. And it will fail eventually, there is no maintenance (other than regular renewal) that can prevent this. I cannot see any outer benefit? Switching fans on early only delays the engine reaching it’s correct operating temperature, after that it cannot provide more cooling than if it is switched automatically? Also, you know your car, if it’s behavior changes under the same conditions you are alerted. Manual control could disguise this?
None of the above is technology that was not available to Jaguar 50 years ago. Imo a modern design would be as follows:
• Remove the thermostats
• Eliminate the bypass
• Fit (1 or 2) electric powered variable speed water-pumps, ie. infinitely variable flow from 0 to max (size of the electric pump)
• Wired independently of the ignition switch.
Benefits include: better efficiency and economy (pumping only what u need) faster warm-up (initially zero flow instead of bypass flow), prevents heat-soak (dangerous overheating if switched off hot). Thought I was a real clever-dick thinking of this. But then I jumped on line and found it has already been done:
http://daviescraig.com.au/blog/jaguar-1 ... r-pump-ewp
Regards,
ColinL
'72 OTS manual V12

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Ole-xke1974
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#17 Re: Am I a little hot?

Post by Ole-xke1974 » Fri Mar 16, 2018 2:27 am

lowact wrote:
Fri Mar 16, 2018 1:30 am

• Fit (1 or 2) electric powered variable speed water-pumps, ie. infinitely variable flow from 0 to max (size of the electric pump)
That would be the ideal set up. Would allow for post drive cool down as well.
1974 SIII E-Type w. XJ S2 4sp w. O/D

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