Cooling system advice please

[AussieJohn]

When I rebuilt my current engine the block was filled with rubbish to above the core plugs. It took a lot of work to remove this and the engine ran cooler afterwards. PS I bought my first Elan in 1969 and had no problem with overheating; this was in Sydney. I had no trouble with 3 more Elans regarding overheating [ and this comprised 2 which were modified and used for hillclimbs and lapdashes ] I have a sneaking suspicion that rubbish in the block can be the cause of problems. cheers, John.

[mbell]

I'd 2nd what John said. I needed to replace the core plugs on my engine while i had it out to look at a gearbox issue. I removed a lot sand and junk from within the block as part of that and now seeing lower temperatures but temps weren't an issue before. Well worth doing if you have the engine out for any reason.

Your suggestion seem a bit over the top to me. If its getting too hot at idle there two likely issues:
1) The heat isn't been removed from the engine
2) The heat isn't being dissipated by the radiator

Causes of:
1) is likely low coolant flow due to pump (idle speed?), general junk in engine, thermostat not fully opening etc
2) Is most likely not enough airflow through the radiator to remove the heat but could also be blockages or radiator not up to the job.

If I was chasing this I would:
1) Clean/flush radiator
2) Back flush engine block
3) Remove thermostat and make sure it opens fully in pan of boiling water
4) Use IR thermometer to test the temp of coolant in lower coolant hose (radiator outlet)
- If it increase roughly inline with engine temp, radiator isn't removing the heat so look at better fan or radiater
- If engine temp increases quick than lower hose temp, it is likely a flow issue

On the thermostat personally I think you shouldn't be fitting a lower temperature one unless you want the engine to run at that temp.

[englishmaninwales]

The issue of accumulated material at the back of the block seems to be a common theme. I removed loads when the core plugs were replaced at engine rebuild.

[rgh0]

I you have room behind the rad, a sucker fan avoids blocking free air flow the way a pusher does.

John

I dont believe it makes any significant difference to air flow through the radiator whether the fan is in front or behind the radiator. However same fans will block more air flow than others depending on the diameter of the motor hub and the shape of the cowling. You do however need to ensure the fan blades are designed for sucking rather than blowing if mounting it behind the radiator

cheers
Rohan

[TBG]

All you need to do.......

[MrBonus]

I have what I believe to be the original S3 radiator and a single 10" electric fan (with a manual override under the dash), 74 degree thermostat, and I've yet to see the car climb meaningfully above 80 at prolonged idle in summer heat.

My engine was rebuilt in the mid-'90s and the specs of that rebuild are unknown to me.