The V8 Owners Forum -

Ok
3.5 standard build ish RV8 in a Westfield with revotech adjustable fan controller. 74 degree thermostat

OK I've finally got the fan controller working (Electrical Numpty)
The fan cuts in at about 80 degrees (on the guage) however the fan does'nt seem to cool the water in fact the temp gauge continues to creep up.
Could it be that: As the temp sensor is in the manifold and the fan controller is in the top hose the thermostat isn't working correctly?

The fan is definitely not in reverse. It is drawing air through the rad and out through the top vent in the nosecone

Fan controller should be in the outlet pipe from your radiator

If it is in the top hose it will always see hot water and always run.

How high does the temp gauge go? and is there a sizable difference in the temperature between the rad inlet and rad outlet popes?

If so you could probably have a bubble of air in somewhere that needs burped out

Ian

Thanks for your swift reply Ian

So your saying the fan controller should be in the bottom hose to the rad?

I switched the engine off at about 95 so don't know if it would have gone any higher

Didn't think to feel the bottom hose but the top was hot.

First I would check you have the fan blades the correct way round?
You say the fan's drawing air through so is it fitted behind the rad?
You will find the fan blades are aerofoils the same shape as an aeroplane wing. They have TWO methods of producing lift/moving air! 1 is the angle of attack/pitch of the wing/blade and other is the shape of the wing/blade. It is possible you have the fan the wrong way round (I did this my self 5 years ago!) so the pitch of the fan is moving air in the right direction BUT the shape of the wing is lowering its efficiency! Yes the fan may be pushing or pulling the air through the rad but it won't be doing it efficiently. For a puller fan you will need the flat side of the blade away from the rad.

It's important to have the fan shroud sealed to the rad so all the air the fan moves goes through the rad and doesn't bleed around the shroud missing the rad!

Obviously you need to make sure you have no air in the system, search on here, loads of posts.

Also is your engine tune timing/fuel correct? as this also effects engine temps and needs to be correct.

I had similar symptoms to you with my old 3.5 in my Rush but now with a new supercharged 4.6 with intercooler blocking half the rad when the fan comes on it lowers the coolant temps stationary in traffic.

One more point does coolant temp stabilize when driving? I not may be more engine related?

Tom.

Simeon wrote:The fan cuts in at about 80 degrees (on the guage) however the fan does'nt seem to cool the water in fact the temp gauge continues to creep up.

Could it be that: As the temp sensor is in the manifold and the fan controller is in the top hose the thermostat isn't working correctly?

Simeon, I think Ian has called it right, you probably have air in the system, still, and the temperature gauge sensor is simply responding to the steam being generated at the system hot spots and giving you a fright.

The PDF from here explains how that happens.

http://www.vintagemodelairplane.com/pag ... ing01.html

On the other hand - if you know that all the air has been expelled then something else is in play! The fan is clearly responding to the fan stat at the top of the rad OK (or where ever it is placed) and if the fan is rotating then it must/should take heat from the radiator fins.

Consequently the temperature at the bottom hose should be noticably less than the top hose. Typically 15 to 20 degrees C. If its not then that is your next clue.

The main thermostat at 74 degrees is quite a low value so it will always be open above that temperature and only close when the temp falls again, so the stat is not obviously at fault, otherwise the fan would not cut in at 80 degrees.

The gauge sensor and the thermostat are quite close together so there should not be much difference between the two locations .

So what might prevent the fan from extracting heat from the rad fins?

Well - possibly the hot water is not flowing thro all the fins as it must but simply transferring from the LH tank to the RH tank thro the top tank, Bypassing the tubes/fins.

And that would happen if the tubes are blocked or partially blocked.

Thus whilst it appears that the rad is hot to touch and the temperature keeps on rising - cooling by the normal process would be non existent.

So, if its not air trapped in the system then its time for a forward and reverse flush of the radiator.

I think given that the fan is actually working then we can forget about the controller. It can be in the top hose by the way, it just needs to be set at a higher temp or it will as Ian said run all the time. I assume that while this is happening the radiator is actually getting hot all the way through and its not just the top hose getting hot indicating a stat problem? How big is the fan? Also as super V8 said check you have the right fan, if you have a front mount radiator on the back for example even if you spin it the other way it isn't going to move much air.

Has the radiator type and fan been proven to be adequate in another installation? I believe it to be marginal at best in a Westfield type car.

Chris.

Lots of very good information here and lots of ideas.

That said nobody has asked whay fueling system you are using, (SU, Solex, Edelbrock, Efi?)

One last thing to ask - your heater matrix inlet and outlet where are they plumbed into your system?

If plumbed incorrectly it basically allows the water an "easy route" and allows it to avoid it going through the radiator. (Radiator has more resistance to flow than heater martix so water takes the route of leas resistance)

Ian

OK Chaps

Sorry for not replying earlier but I work away all week and only see her indoors at weekends so one has to keep her happy plus it's it been absolute sports fest this weekend.

Lots of useful info here, i'll give you a little more info.

I'ts a brand new build and never been driven anywhere. The rad and fan are brand new from Westfield and designed for the V8 variant.

I'ts an old school build for simplicity case as this is unlike anything iv'e done before. Offy dual plane manifold with edelbrock 4 barrel.

I don't know about the temp on the other hoses as I never thought to try them.

I think it could very possibly be air locks. I will try and squeeze some more air out of it next week.

One thing that hasn't been covered is the efficiency of the cooling system on the go. Is the ram air effect when driving sufficient to keep the engine cool? If it is then is it not simply a case of the fan not moving enough air over the rad to dissipate the heat, ie a bigger, or more powerful, or more efficient (or all of the above) fan needed? Or the water pump not pumping the water around quickly enough at idle speed?

Just a thought

Dave