Coolant Overflow Bottle Hose Routing...Engine Overheating

Hello all,

Just joined your wonderful forum and have already found a wealth of knowledge.

I'm the proud owner of a '76 Riviera (basically a Westy) that I just finished dropping a Toyota 3TC engine into (see my website here).

I have tried several different radiator configurations before settling on my most recent one which has one radiator mounted vertically in the left side of the engine compt, and another radiator mounted in series horizontally to the belly of the bus. Both radiators are shrouded to force air through them (the engine compartment rad draws air from the left air vent, and the belly rad draws air from above and blows it out below).

Here's my problem...upon the initial test drive, I foolishly forgot to connect my radiator overflow bottles. While driving, the temp climbed to 190F (88C) and stayed there for several minutes until the system built up enough pressure to allow the coolant to escape through the coolant overflow nipples below the radiator caps. It then proceeded to spew coolant all over the road until the engine was cool enough to allow me to refill and drive home.

Since this time, I have mounted overflow bottles to catch the coolant, but the engine is running HOT....240F (116C). I purged all air from the system upon refill and have ensured that coolant is circulating properly through the radiators. I have noticed, however, that the fluid level in the overflow reservoirs never seems to increase as the engine gets hot....would trapped air in the overflow lines cause this to happen?

Any help would be greatly appreciated.

thanks,
Jeff

Shot in the wind --have you tried running with the centre cut out of the / or no thermostat ?--or as a thought have you checked the thermostat ? maybe a thermo that opens sooner ?
Can your water pump keep up with the twin radiator system you seem to have?

definitely trapped air, most likely in the lines going to the bottom radiator. easiest way to cure is to try disconnecting the hoses going to the bottom rad at their highest point and pour water down them until they fill up, make sure you give them a good jiggle underneath too, maybe even a squeeze as any saggy bits could hold air, the only other thing then is to make sure that there is no blockages in the lines going to the overflow tanks or the tanks themselves that would block the water. I had an undercar setup, filled it up as described and didnt have any trouble.

Yeah, sounds like trapped air, i had similar issues in a 2lt cortina-powered kombi once. 😀

It might not be trapped air.....
Water will start to vaporise before 100°C, also in engines you can get hot spots on the cylinder walls, causing localised vaporisation even boiling.
Don't drill your stat.

Can you make a flow through header tank, even if it's only a partial flow through it? (See Helbus' tank on here for ideas)

I had this sort of problem with my Subie lump before the stat opened fully. A flow through tank sorted it

HTH