The V8 Owners Forum -

I am still having difficulty cooling the engine as it runs at 100+ with 110 often reached after a short stint in traffic (and takes ages to get back to 100 again).

Whilst I know now, I did dry store my engine for some 5 years so am wondering if there is some furring up happened. When I drain the system it is all a totally clear blue colour, though, and not a speck of dirt.

Is there a radiator flush product that will defurr things?

Yes, there are many rad flush products but I want a strong one or a specific one for this. I do have a couple of bits of copper pipe in my system for heater connections otherwise it is an ali rad.

Thanks.

I doubt if furring is the problem. What is the system / car / etc that it's in?

Chris.

I recall there was another thread....link to that with history ?

Yep, the original post I hijacked was this ...
http://www.v8forum.co.uk/forum/viewtopi ... 3&start=75

Also sorry that Photobucket does not show my car anymore- think Se7en.

Basically I've still done everything and recently removed the bypass between heater pipe circuit. In short there are no air pockets, rad is cowled at the front, two speed Kenlowe fan, calibrated temp gauge via ECU, rad is 70mm core, etc..

The rad fan does cool the water but there are side bits that the fan does not cover. However the water temp on exit from rad is 45 degrees. I think the problem is throughput. Today I have removed thermostat to see if that will give more flow and keep the engine cool - will try later this week.

I thus wondered about fglushing system in case it was all furred up. I'm also thinkinh of taking off the water pump to see if that's at fault. Trying to do easy bts first.

Problem is simple. Temp stays at 90 until oil reaches its 90 temp and / or get stuck in traffic. Then water temp goes to 100 and does not come back down. Usually goes to 110 as soon as I do a short blast or traffic again. Then will rarely goes below 100.

If throughput is not the problem, an oil cooler may be needed but that's not easy to fit.

So slow moving, low airflow it gets hotter ?

What temperature stat is fitted ?

When moving at say 50mph, does it cool to an expected level, or remain higher than expected ? ie it should have ample airflow available there.

I say expected...as cars dont always run at exactly stat setting, but they should be close and repeatable. Obviously if there are problems it can be hard to find this base level though.
If you fitted a colder stat for example...how does it behave ? Cheap and easy to try.

Thicker cores are usually less efficient than thinner...but when surface area is limited, not much else you can do there than go thicker.

Drain it and fill it with white vinegar, let it stand for a while, drain it and flush it a few times.
I did it for my Honda and it made a big difference to low speed temps.

Running above the thermostat figure is normal with the SD1. Different rad, I know. My EFI even has the centre of the dash gauge marked as 100C. On the move it will run at about 90C, but in slow traffic goes up to 100C. But never over, unless something is wrong.
Interestingly, a MegaSquirt log shows the coolant temperture being much more consistent - the injection uses a different sensor in a different place.

I'd first check your dash gauge is accurate. Put the sensor in boiling water to check. On SD1s, it's common to find the wrong sensor has been fitted. Or a badly made one.

My car has only ever had London tap water plus the correct antifreeze. Last time I changed the water pump, the inside of the water jacket looked like new. The small passages in a rad can get blocked - but you've checked that by measuring the output temperature.

Thanks guys and some more facts

My test route is a meandering A road driving 40 – 60mph. Keeps cool (90) until oil gets to (indicated) 90 degrees or I pass through a very small town (Petworth). Once hot (97+) when both fans come on, it rarely reduces below 100. Quick blast, say, and temp goes to 110 and takes time to get back to 100.

Any real fast period such as 5 miles on dual carriageway at 70 and oil goes to indicated 95. Takes a long time to reduce to 90. Water 110.
First fan speed comes on at 92 and second fan on at 97. Rarely do they both go off

First fan controlled by ECU, second fan controlled by otter switch.

Thermostat is 82 and it opens correctly.

Plenty of room for hot engine bay air to escape as I have flared side panels.

Megasquirt ECU temp sensor calibrated and located front top right in water channel. Gauge sensor is immediately next to it (don’t use normal RV8 sensor location by thermostat housing). I thus know my gauge accuracy – out by 10 degrees even though CAI matched them for me!
Water channel behind thermostat housing is clean as a whistle.

Oil gauge not calibrated.

Thanks John, may try that.

Finally, since Photobucket has stopped free photo hosting, who does everyone now use?

(Ignore Photobucket question, have looked up post.)

Testing photo upload - position of two senders and note thermostst housing now a straight one, not RV8 one.

So it would seem the natural running temperature would be around 90degC, so despite a lower stat there would be no realistic expectation to get it down to 82degC.

It does really sound like it simply needs more water cooling capacity, rather than water flow, air flow etc.

I know it's a custom rad etc etc...that doesnt mean it's enough for the setup. An oil cooler may help...but I just doubt it will do enough seeing as oil temps arent getting too far beyond that of the water.

Is there a heater core inside the car ? How does water temp respond to this running either off, or fully flat out ?

Wonder if there's an easy way of measuring the airflow through the rad?
Something like a PC cooling fan that can give an RPM readout? So if driven round by the airflow only could tell how good at was at different speeds etc?

Aerodynamics seem to be a bit of a black art - with airflow not always doing what you'd expect.

Try a short drive with the engine overs off if possible ?

richardpope50 wrote:Yep, the original post I hijacked was this ...
http://www.v8forum.co.uk/forum/viewtopi ... 3&start=75

The rad fan does cool the water but there are side bits that the fan does not cover. However the water temp on exit from rad is 45 degrees. I think the problem is throughput. Today I have removed thermostat to see if that will give more flow and keep the engine cool - will try later this week

This sounds like you have sufficient cooling in the radiator.
Have you perchance taken the reading on the water temp on the inlet to the rad?
It could be that there is a total mismatch between the temp sensor and the gauges you are using and the shown 110 degrees is actually around 90.

Perhaps use an infra red thermometer and check the actual temps in and out using the same gauge.

Ian

Are you saying that it's OK until the fans come on, then it never works OK after that?
1. Do the fans go off?
2. Are the fans pumping air the right way?
3. Does the voltage drop caused by the fans cause the temperature gauge to start to read inaccurately?
4. If you warm it up, then disconnect the fans and go for a blast, does that cool it down?

Chris.