Coolants

John Hugh

16 February 2013 at 19:30 #50011

Having suffered extensive (and expensive) cracks on head and block of the two 2 Litres I have owned, I’ve been wondering whether local hotspots due to vapour blanketing may be an issue. I think we mostly use ethylene glycol (EG)/water mixes with (we are urged) inorganic additives. But it would seem that 100% propylene glycol (PG) coolants (Evans?) should have advantages, particularly in their high boiling point which should eliminate vapour hot spots. However PG has little more than half the thermal capacity of water so coolant temperatures should be higher which doesn’t sound good given that my 14/60 already likes to boil if shown a hill on a hot day. And that’s after re-coring the radiator. Has anyone any views on or experience of these PG coolants? Also, I read that France has banned EG in view of its lethality to animals so what is used over there?

John

Peter S30

19 February 2013 at 11:13 #50019

Dear John,

I also often had local evaporation in the cylinder heads in my V12 after longer uphill driving but with overall water temperature still acceptably low. Solution is better water circulation and I think this is more important than differences between coolants and additives.

In my case the best would be to completely clean the heads and blocks from corrosion and limestone. I only removed the waterplates and the sludge behind. I tried to clean the engine with pumping acidic cleaner around (with an external pump) but with limited success.

Also my water pump has probably corroded blades with low pumping efficiency so boiling occurs at low revs after forced driving when I switch to a higher gear after reaching the hill top.

The solution for the moment (since a few years..) is an electrical water pump in series with the normal one.

In general the solution is a clean block and head and an efficient water pump.

ray sherratt

19 February 2013 at 15:47 #50020

I would be looking at water temp in and out of the rad, if the water is running through the rad to quickly, then there is insurfeit time to dissipate.You mention cracking in the head
is combustion leaking under load? You could try a local rolling
to test, by putting the engine under load and using the 4 gas placed close to the rad cap. If there is a leak it will pick it up more or loss straihgt away.
Ray.

Peter S30

19 February 2013 at 16:21 #50021

faster circulation gives always better heat transfer, has no negative effect. If going more quickly through the radiator (difference in and out will be smaller but more than compensated by more frequent exchange).
I agree with other tests (gas leak, crack, head gasket..)

ray sherratt

19 February 2013 at 16:49 #50022

I beg to differ Petter,extsive tests with race cars with stats removed allways shoad higher temps. If a flow restictor was introduced the temp droped. Its the same with oil unless a form turbulance is introduced the outer layer of fluid reduces the inner layers abillity to remove heat.
Ray.