Engine Temp and heater

[glynlucas]

The engine temp' on my Chim varies wildly. If the heater is turned off, the temperature rises by at least 5 degrees. I can't see how a small heater matrix could make such a difference to 12L or water!

Anyone else notice this, or is there something I should check?

Thanks

[ian8542]

You will be amazed at how much it can affect the cooling system, particularly if you have insufficient coolant in the system.
Might be a good idea to bleed the system from cold, using new coolant not just water.

[flintstone]

I remember reading an article about racing Hyundais where it said the drivers kept the foot warmers open to aid engine cooling.

What's good for them............

[GreenV8S]

When the main stat is closed or nearly closed, the only water flow through the engine is via the bypass and cabin heater. On my V8S, turning the heater to cold stops the water flow through the heater, but it may not be the same on yours. If you stop the water flow through the heater when the stat is closed, the only flow that is left is the flow through the bypass. Most RV8 powered TVRs have a bypass which is arguably too small for the engine and allegedly during the changeover to the intermediate serpentine front end some were built with no bypass at all. This can mean that during warmup and when cruising in very cold conditions the engine has insufficient water flow to remove heat from the hot spots in the heads, even though the average temperature may seem OK. This is one of the reasons why it is so important to bring the engine up to temperature before thrashing it.

When there is insufficient water flow through an engine, the temperature difference between the top and bottom increases. This can cause the temp gauge to read high, even though the average temperature may be OK. If the engine is pushed hard in these conditions you can get severe damage from localised overheating in the heads. This is one of the few cases where uprating the cooling system can do more harm than good, since a marginal cooling system will run with the stat further open than one with massive over capacity.

>> Edited by GreenV8S on Thursday 4th November 13:04

[glynlucas]

Thanks for all the replies. Very interesting reading. On my engine, the bypass appears to be an external hose - I believe some variants of this engine have an internal bypass. Is there anything that can be done to improve the operation of the bypass?

[GreenV8S]

One change TVR made was to put a 'H' connector in the supply and return to the heater matrix, increasing the flow through the 'heater' circuit but reducing the amount actually going through the heater matrix. This is sometimes called a heater bypass, not to be confused with the main bypass. I'm not aware of any bypass mods by TVR, and I don't think it would be feasible to add an 'internal' replacement to the main bypass. The obvious way to improve the bypass flow is to fit a remote stat with a decent bypass. I've got one of these on the V8S, I think the Cerbera cooling system uses this approach too.