Am I overheating?

Technical advice Q&A

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paulsco
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#1 Am I overheating?

Post by paulsco » Fri Sep 11, 2020 8:13 pm

I am about to take my E-Type on its first run after a very long restoration, but I am having concerns as to whether it is overheating or not.

I have an uprated radiator with a Coolckat fan. I have a modified thermostatic otter switch as in the Coolcat/fosseway design and have fitted the ‘correct’ thermostat.
I also have an air conditioning condenser in front of the radiator.

When I run up my engine stationery in the garage the fan kicks in at 85c, but it does not go off again and the engine temperature continues to rise.

I turned the engine off before it overheated at around 95c.

I have replaced the thermostatic switch which should go off when the temperature falls to 80c, but the problem still persists.

I have not yet driven an E-Type on the road, so am not sure what normal behaviour should be, but I would not normally expect the temperature to continue to rise when the car is stationery unless there is a problem.

I have run the engine in the past and I don’t recall this being a problem. Could it be a problem with the thermostat, I vaguely remember changing from what was considered the wrong thermostat some time ago as discussed on this forum, but I can’t remember if I tested it at the time?

I am assuming that if the fan comes on the thermostat must be opening?


Thanks,

Paul
65 Series 1 FHC, 68 Jaguar 340

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mystery type
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#2 Re: Am I overheating?

Post by mystery type » Fri Sep 11, 2020 8:21 pm

If the fan kicks in, I would expect to see temperatures fall, I assume the fan is fitted the correct way around, ie.drawing air in? Failing that is the water pump working as it should?
Paul 1967 S1 2+2

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paulsco
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#3 Re: Am I overheating?

Post by paulsco » Fri Sep 11, 2020 8:58 pm

Hi Paul,

Thanks for your reply.

I have checked that the fan is pulling through the radiator into the engine bay.

As for the pump; I rebuilt it when I was building the engine, but it is not impossible that it has a problem.
There are no strange noises though and it is turning ok so nothing internal would appear to have become detached.

Paul
65 Series 1 FHC, 68 Jaguar 340

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abowie
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#4 Re: Am I overheating?

Post by abowie » Fri Sep 11, 2020 9:04 pm

Also double check your coolant level.
Andrew.
881824, 1E21538. 889457..oops. Jezza the V12 XJS race car.
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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johnetype
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#5 Re: Am I overheating?

Post by johnetype » Fri Sep 11, 2020 11:18 pm

And has the timing been set yet? If it's retarded then the engine will hotter than it should at idle.
John

1969 Series 2 FHC

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#6 Re: Am I overheating?

Post by PeterCrespin » Fri Sep 11, 2020 11:35 pm

Classic fan rotation symptom. Aftermarket fan motor is possibly permanent magnet not series-wound, so try switching wires. Lots of air movement can still be deceptive.

Use a thermometer to cross check the gauge. Feel the top hose get hot as tstat opens.
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 2001 Vanden Plas

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MSM
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#7 Re: Am I overheating?

Post by MSM » Sat Sep 12, 2020 10:18 am

PeterCrespin wrote:
Fri Sep 11, 2020 11:35 pm
Classic fan rotation symptom. Aftermarket fan motor is possibly permanent magnet not series-wound, so try switching wires. Lots of air movement can still be deceptive.

Use a thermometer to cross check the gauge. Feel the top hose get hot as tstat opens.
Paul has said that it overheats running in the garage so direction of airflow is unimportant in that particular case but of course is important when driving. A simple check on airflow direction can be done by running the fan and placing a sheet of paper in front of the radiator, if it sticks to the rad the airflow direction is correct. If it blows away the fan is rotating the wrong way.

Measurement of temperature and checking that top hose gets hot are all important.
Mike

S2 FHC

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#8 Re: Am I overheating?

Post by paulsco » Sat Sep 12, 2020 6:11 pm

Thank you all for your suggestions, I will check them all out tomorrow and feed back.

Paul
65 Series 1 FHC, 68 Jaguar 340

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Moeregaard
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#9 Re: Am I overheating?

Post by Moeregaard » Sun Sep 13, 2020 4:41 am

The Coolcat fan moves a lot of air, so I think your problem lies elsewhere. My guess is that you have a thermostat that isn't opening all the way.
Mark (Moe) Shipley
Former owner '66FHC, #1E32208
Former owner '65FHC, #1E30036

Planning on getting E-Type No. 3 as soon as possible....

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neal herridge
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#10 Re: Am I overheating?

Post by neal herridge » Sun Sep 13, 2020 5:01 pm

Do you know the actual temp. you are getting from the engine.
I have had lots of poor/incorrect reading temp senders , which make it look like its over heating when its not.
Just a thought.
Neal.

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#11 Re: Am I overheating?

Post by Mich7920 » Mon Sep 14, 2020 6:46 am

:yeahthat:
Michel
1965 E Type FHC - On the road - 1963 E Type OTS - Angus Restoration
Gran Torino Sport 1975 - Renault 4cv 1956 - CItroen 15/6 1951 - CItroen Traction 1945
Citroen Coupé docteur 5Hp 1924 - Citroen B12 1926 - Torpedo Sygma 1913
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#12 Re: Am I overheating?

Post by cactusman » Mon Sep 14, 2020 7:12 pm

Can't add anything 're the fan....I have a coolkat and it is brilliant....I'd suspect water pump or thermostat personally....
Only thing I would observe is running in a garage....even with the door open exhaust fumes may accumulate....IMO any long time (more than a minute) engine testing should be done with the car outside or with a suitable extension pipe from the exhaust to well outside the garage....carbon monoxide kills and it can be rapid.....be safe fellow e typers :bigrin:
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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#13 Re: Am I overheating?

Post by paulsco » Mon Sep 14, 2020 7:53 pm

Hi All,

I have checked again that the fan is pulling in the right direction and also the water level, which was slightly low, but not enough in my opinion to cause a problem. I did top it up though.

I haven’t yet checked the timing.

The top hose does get hot, so it would appear that the thermostat is opening, though maybe not completely.

I did have a bit of a disaster today when running up the engine to temperature. I was concentrating on waiting for the fan to kick in, which unfortunately it did not and the engine boiled over and emptied a large amount of water on to the floor!

I do have a food temperature sensor and a temperature attachment to my circuit tester, but both were giving false readings; I plan to get an infrared thermometer to have another go.

I figured that my new thermostatic otter switch must be playing up, so swapped back to the old one I had replaced.

I had checked both thermostatic switches prior to this with a circuit tester to see if they passed current when heated, which they both did and they also broke that circuit when cooled down a bit. I was unable to check the temperatures they were switching at, but they both seem to work.

I ran the car again and the fan kicked in at around 85c according to the gauge, but again the temperature continued to rise despite the fan still running and I shut off the engine at about 100c.

I should add that although I have not yet driven this car, the engine has been in for several years and I have run it many times.

This is the first time I have noticed a problem and the only thing I can recall changing is the thermostat. I may well change it back to the ‘wrong’ type to see what effect that has.

I have doors at the front and the rear of my garage, so there is a through flow of air. I also wear a resporator, although I suspect that this is a little over the top :sad:

Thanks,

Paul
65 Series 1 FHC, 68 Jaguar 340

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#14 Re: Am I overheating?

Post by mtnjag » Mon Sep 14, 2020 8:28 pm

You may have thought or tried these, just some ideas.

Careful with the IR temp sensors. They will not give an accurate reading of coolant temp.
Coolcat has temp strips that can be stuck directly on the surface and shielded from air flow which can give a fair idea of coolant temp.
Guess you ran a pot of water up to boil and checked your circuit tester temp sensor?
It will puke coolant out as it warms up if cap is off.
Pull the thermostat temporarily to see if you still have a problem. Could be sticking and only partially opening .

EDIT:
Check thermostat in a pot of water with dependable thermometer to see if it BEGINS to open at rated temp. It will be fully open 10-15 degrees above rated temp.
Last edited by mtnjag on Mon Sep 14, 2020 9:05 pm, edited 1 time in total.
Layne
Car #876005, 62 OTS

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#15 Re: Am I overheating?

Post by cactusman » Mon Sep 14, 2020 8:29 pm

Respirator is useless unless it is specifically for CO or has a fresh air feed...your average respirator mask sold at DIY stores is for removal of dust but will not remove carbon monoxide.....but through air flow will keep you safe :bigrin:
Julian the E-type man
1962 FHC
1966 MGB....fab little car too

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#16 Re: Am I overheating?

Post by PeterCrespin » Mon Sep 14, 2020 9:31 pm

“I did have a bit of a disaster today when running up the engine to temperature. I was concentrating on waiting for the fan to kick in, which unfortunately it did not and the engine boiled over and emptied a large amount of water on to the floor.”

What are your grounds for saying it boiled over?

It sounds like it threw up the extra you just topped it up with, even though you said it wasn’t very low. A small volume of water makes a big puddle on a flat floor. This is not only normal, it is only avoidable by never running the engine up to temp.
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 2001 Vanden Plas

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#17 Re: Am I overheating?

Post by mtnjag » Mon Sep 14, 2020 9:35 pm

Sorry to ask but this all with the radiator cap on right?
Layne
Car #876005, 62 OTS

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#18 Re: Am I overheating?

Post by paulsco » Mon Sep 14, 2020 10:03 pm

The respirator was a a paint spraying respirator, but as I say it was overkill, there was plenty of air flowing through :bigrin:

No it wasn’t just throwing out the excess water, there was steam poring out as well. It emptied most of the water in the header tank and the temperature gauge went off the scale.

And yes I have to admit to making the mistake of not putting the cap on tightly enough :oops:


Paul
65 Series 1 FHC, 68 Jaguar 340

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mtnjag
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#19 Re: Am I overheating?

Post by mtnjag » Mon Sep 14, 2020 10:09 pm

Well, as you know the coolant will expand when heated and overflow if the pressure cap is not tight.

But your problems in the garage have been with the cap on properly or not tight?
Layne
Car #876005, 62 OTS

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#20 Re: Am I overheating?

Post by PeterCrespin » Mon Sep 14, 2020 11:32 pm

It will overflow no matter how tight the cap is if it's topped up too high and it's purely due to expansion. It'll just burp fractionally sooner if the cap is open as the hoses won't expand. If there are air pockets it could be local boiling around the combustion chambers and that would eject even the correct level coolant PDQ. Was the heater circuit open during filling?
1E75339 UberLynx D-Type; 1R27190 70 FHC; 1E78478; 2001 Vanden Plas

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