Overheating engine '73 E9

sdoyle

sdoyle

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Hi all,
I have just completed the restoration of '73 E9. The problem I'm having is that is overheating.
The engine has been fully rebuilt, rebored, pistons etc. The cylinder heat was reworked by a competent shop, it was pressure tested and resurfaced. All new gaskets seals are new.
The radiator was re-cored.
The water pump, thermostat (80 Deg C) and all hose pipes are new. All parts are from Wallothnesch.
The fan assembly is the 5 spoke with friction clutch, it seems to be ok, by that I mean it works the same as that on another E9 which I have.
The coolant is the green type 50/50 with water.
I have refurbished a reasonable number of engines, normally with no issues.
The engine has been bleed using the bled screw.
On the open road it overheats after a few miles. I am assuming that even if the fan assy. was not working properly, it should have no effect on the open road.
I have tried driving it without the thermostat, it still does the same.
Has anyone had a similar experience / suggestions. Any help would be very much appreciated.
Thank you,
Seán.
 
Simple quick test...

Does the small hose from top of radiator to expansion tank get hot?
If you disconnect from expansion does water flow through it?

Is the water in the tank getting hot?

Pro tip- never put coolant in a new engine until you KNOW the coolant system actually works....
 
Carbs? Injection? Timing? Running lean? Do you have an infrared thermometer to check hoses and exhaust outlet temps?
 
sdoyle said:
Hi all,
I have just completed the restoration of '73 E9. The problem I'm having is that is overheating.
The engine has been fully rebuilt, rebored, pistons etc. The cylinder heat was reworked by a competent shop, it was pressure tested and resurfaced. All new gaskets seals are new.
The radiator was re-cored.
The water pump, thermostat (80 Deg C) and all hose pipes are new. All parts are from Wallothnesch.
The fan assembly is the 5 spoke with friction clutch, it seems to be ok, by that I mean it works the same as that on another E9 which I have.
The coolant is the green type 50/50 with water.
I have refurbished a reasonable number of engines, normally with no issues.
The engine has been bleed using the bled screw.
On the open road it overheats after a few miles. I am assuming that even if the fan assy. was not working properly, it should have no effect on the open road.
I have tried driving it without the thermostat, it still does the same.
Has anyone had a similar experience / suggestions. Any help would be very much appreciated.
Thank you,
Seán.
Click to expand...
Please, how did you determine the overheating? Are you basing your diagnosis solely on your vehicle's temperature gauge?

https://e9coupe.com/forum/threads/mild-overheating-not-at-idle-but-at-speed.43305/

e9-overheat-temp-gauge-jpg.162134





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Last edited:
Have you bled the coolant system multiple times over several cold/hot cycles? Is the coolant level holding steady?
Check for bubbles while engine is running? Check compression? (I know this is a freshly built engine)
 
Thank you all for the feedback, I will work through all the suggestions. Busy getting ready for a show tomorrow, bringing my Lotus Esprit. :)
 

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Hi All,
Again thank you all for your inputs / suggestions. It is a '73 3.0 CSi.
Rather than try to reply to each post I will provide answers here.
Today I left it idling, the clutch fan is spinning, I think at normal speed, after approx. 10 /15 minutes, the following starts to happen.
The water in the small pipe gets hot, water is flowing through it, the water in the expansion tank gets hot. I have replaced the coolant mix with water.
Using an infra red thermometer, the thermostat housing is 92 C, top connection to the rad 95 C, the bottom connection to the rad 60 C, measured on the metal part of the rad.
The exhaust outlets on the manifold are all reading 220 C, except the front one it's reading 200C. The engine is not misfiring, I will remove the plugs to see what they are like.
The water pump, header tank, thermostat and all hoses are new. I have removed the pump, the impellor seems ok. The rad has been re-cored.
I have bleed the system many times.
I think it's overheating because I can fell the water 'gurling' in the top hose pipe and it's almost solid, if I loosen the filler cap there is very excessive pressure in the system, it will blow all the water, if I take the cap off.
I have not able to check the ignition timing yet, it's very awkward. I have find a way to do it.
it does not not have A/C, I am in Ireland.
Many thanks.
 
sdoyle said:
Hi All,
Again thank you all for your inputs / suggestions. It is a '73 3.0 CSi.
Rather than try to reply to each post I will provide answers here.
Today I left it idling, the clutch fan is spinning, I think at normal speed, after approx. 10 /15 minutes, the following starts to happen.
The water in the small pipe gets hot, water is flowing through it, the water in the expansion tank gets hot. I have replaced the coolant mix with water.
Using an infra red thermometer, the thermostat housing is 92 C, top connection to the rad 95 C, the bottom connection to the rad 60 C, measured on the metal part of the rad.
The exhaust outlets on the manifold are all reading 220 C, except the front one it's reading 200C. The engine is not misfiring, I will remove the plugs to see what they are like.
The water pump, header tank, thermostat and all hoses are new. I have removed the pump, the impellor seems ok. The rad has been re-cored.
I have bleed the system many times.
I think it's overheating because I can fell the water 'gurling' in the top hose pipe and it's almost solid, if I loosen the filler cap there is very excessive pressure in the system, it will blow all the water, if I take the cap off.
I have not able to check the ignition timing yet, it's very awkward. I have find a way to do it.
it does not not have A/C, I am in Ireland.
Many thanks.
Click to expand...
Hi Sean
This is a long shot, but is there any chance the recored rad is blocked ?
if they re- made one of the side tanks on your radiator maybe the pipe they soldered on is blocked or something.
 
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