Duratec Coolant issue Resolved!!!!

[Rob Walker]

Remove the thermostat and see it it still overheats

[TomGaval]

Rob, I did pull out the thermosat and temps still got up to 220F+ after several hard laps even in 30F air temp last week.  I let the car warm up prior to going on track, by running around in First gear in the paddock and took it easy on track for several laps prior to opening it up.  Tom

[Rob Walker]

Still overtemp with no stat can only be:-

Reduced or lack of coolant flow/ airlocked

Radiator fans running in wrong direction ie in opposition to incoming air flow.

Too small a radiator or restricted airflow.

I have built several duratec cars and never had any issues with high water temps quite the reverse, I have seen high oil temps using the wet sump but in general the main problem is getting the engine to hold 80C and above even with one third of the rad blanked off and the oil cooler blanked off on road use.  There should be no need to consider a swirl pot , Something is wrong with your installation.  I agree 104C is getting a bit too high for the coolant I would want to see around 95C coolant and upto 105C bulk oil on track

[TomGaval]

Ok, it warmed up enough for me to venture back out into the garage for a few minutes.  Car was idle since last trackday. I opened the bleed bolt on top of the radiator and no coolant came out so again, obviously airlocked again.  Unbolted the expansion tank and put it up on top of the dry sump tank and opened the cap. Coolant/air sputtered out for a bit.  Replaced bolt, and started car with the expansion tank open and held on top of the dry sump tank. Watched air bubbles rise into the expansion tank for a full 5 minutes before stopping.  Radiator got progressively warm and at 195F the Fan kicked on.  Temp gauge dropped to 185-190F and radiator cooled off so that it was actually cool on top and on the front.  Hot air was being pulled out the back.  The top right where the top hose entered was hot and the Bottom left where the bottom hose exited was hot as well.  Does that sound right?  I thought it would have been a bit cooler at the bottom.  

No more bubbles rose, and after a full 30 minutes idling, the water temp was 200F and the oil temp was 175F.  When I revved the engine a bit, the water temp did drop back under 200F for a bit then came back up.

So Where the heck is the Air coming from?  Obvioulsy it only occurs at sustained high revs.  I'm definately going to relocate the expansion tank to a higher point.   It definately seems that the car runs well for 15-20 minutes at moderate revs but once It is pushed the pressure/air builds up and cooling is impaired.   Once again, your thoughts are appreciated.   Tom

[Pendennis]

Sounds right Tom, you won't be able to determine a temperature difference with your hand between top and bottom inlet and outlet hoses.

The air is coming from your expansion tank, it MUST be above the engine so you maintain a fully flooded state reservoir above any coolant part of the engine. If it is not you cannot possibly prevent any ingress of air into the coolant circuit.

Tom, with the inlet pipe below the water table of the head this means coolant cannot flow under gravity to maintain a fully flooded engine circuit, so it can easily airlock. In addition, despite your tank being half full of coolant that content of water would get thrown around the tank during cornering so the inlet hose would very easily allow the air in the tank to ingress into the inlet pipe. This is why expansion tanks if used on track cars must be as high as possible. However, this is also why many track orientated cars bin the tanks and go for a sealed circuit with the swirl pot arrangement.

So get the tank as high as possible, but if the inlet pipe from the tank is below the outlet of the engine you still have a potential air locking scenario which ultimately only a swirl pot would solve.

[7 wonders of the world]

Hi Tom,

Wether your using the sperical bottle on the front cruciform in fornt of the engine or the suarer Rover bulkhead mounted bottle you should be able to maintain water level as both are higher than the engine water level.

Are you using the OE water outlet form the rear of the head (the one that has a monting point for a single coil pack) or a pipe over the exhaust primaries?

Where is you bleed feed taken from?

Where does your 16mm lower bottle hose feed into on your system?

 

It should feed into the thermostat housing either directly or T into the heater return - do you have a constant heater flow circuit ie is the heater vlave in the right way / working it should be full flow in either open or closed position.

If your system has this blanked off on the stat housing then you can feed into the top or bottom hose.

Once the rad is bled thro either bleed plug or via a hose the rad should remain so.

Are you running with the OE bypass hose form the rear of the ylinder head to the 90 degree gold colour metail pipe that feeds inot the block directly obve the stat housing?.

It sounds, as you say you fill the bottle, that the bleed line is exessive. Many bottles have a restrictor in the inlet pipe on the bottle some in the form of a simple roll pin pushed into the plastic neck to reduce pressure/flow. This would still allow an air bleed but wold prevent excessive discharge to the bottle - hence keeping the coolant and expansion volume in their correct respective places as it apears they are currently trading places.

I would look to restict this line to something line 2mm diameter and retest.  

[7 wonders of the world]

Hi Tom,

Wether your using the sperical bottle on the front cruciform in fornt of the engine or the suarer Rover bulkhead mounted bottle you should be able to maintain water level as both are higher than the engine water level.

Are you using the OE water outlet form the rear of the head (the one that has a monting point for a single coil pack) or a pipe over the exhaust primaries?

Where is you bleed feed taken from?

Where does your 16mm lower bottle hose feed into on your system?

 

It should feed into the thermostat housing either directly or T into the heater return - do you have a constant heater flow circuit ie is the heater vlave in the right way / working it should be full flow in either open or closed position.

If your system has this blanked off on the stat housing then you can feed into the top or bottom hose.

Once the rad is bled thro either bleed plug or via a hose the rad should remain so.

Are you running with the OE bypass hose form the rear of the ylinder head to the 90 degree gold colour metail pipe that feeds inot the block directly obve the stat housing?.

It sounds, as you say you fill the bottle, that the bleed line is exessive. Many bottles have a restrictor in the inlet pipe on the bottle some in the form of a simple roll pin pushed into the plastic neck to reduce pressure/flow. This would still allow an air bleed but wold prevent excessive discharge to the bottle - hence keeping the coolant and expansion volume in their correct respective places as it apears they are currently trading places.

I would look to restict this line to something line 2mm diameter and retest.  

[elie boone]

Can't see why the header tank must be higher than the highest coolant level of the engine. As long as it's higher when you fill the coolant to the engine, then you put the cap on and now you can place it a few inches lower than the coolant level in the engine. I ditched the bleed on the rad and put a banjo in place, this is then connected to the top of the header tank. but you defo need the bigger pulley.

[Jonathan Kay]

From the information available I'm with Pendennis.

Could you do a sketch with altitude of the key bits measured and marked up?

Jonathan

[Pendennis]

Good idea, however all Tom has to do is put a level on the top of the water outlet back of head and see where it lies in relation to top of the crucifix platform. Yesterday I put my 2L Duratec back in my S3, so the bay is bare. I have laid a level as described herein and confirm the top of the coolant outlet port is approximately 30mm higher than the crucifix platform. So if I used any expansion tank with the outlet on the bottom, mounted as described above it cannot possibly be filled and vented free via that arrangement. Yes of course you can fill and vent initially whilst manually holding the tank higher in the air but when re secured what happens when your pushing the car hard around a corner just as it needs to draw some coolant back in after it has spat some out during expansion?

My 2L Duratec uses the Raceline engine mounts, Tom's set up may allow the engine to sit lower but the 2.3L Duratec is about 13mm taller and as far as I know they all sit slightly higher in the chassis making this scenario worse. Also bear in mind the engine sits 1 degree nose down as well.

I wonder why Raceline water rail steps up as it leaves the engine with the swirl pot even higher*wavey*

[elie boone]

Pendennis, the Raceline system with tower is a open system,  a closed system can be mounted lower and use the air in the header tank to pressurise the system when warm, there is no spilage of coolant.

[TomGaval]

Just checked out the routing of the hoses.

1) The rear outlet appears to be the standard one with the large hose exiting on the left and running below the Roller Barrels and into the top left of the Radiator.

2) The bleed hose originates from the right side of the rear outlet and runs to the top of the expansion tank. It is a 1/4 inch ID hose.

3) The lower hose on the bottom of the expansion tank feeds into a tee that comes off the thermostat housing the other side of the tee connects to a hose that I added in place of some blanking plugs and replicates the heater hose. (no heater) and connects on the right side of the rear water outlet on the head. 

4) Yes the OE bypass hose is connected as stated.

5) I eyeballed the level of the tank bottom hose outlet vs the height of the rear water outlet on the head and it is close but appears that the bottom hose is slightly below the level of the water outlet on the head. Not much but a litlle.

6) I've measured and it looks like I have room for a small expansion tank on the left side of the bulkhead. I'll start looking for one that fits now.  I will also look into the smaller pulley for the water pump.

Thanks Guys!

Tom

[Pendennis]

Hi Elie, yes granted although not sure I would describe my Raceline system as an open circuit.

I have seen many a closed circuit spit out coolant. The Raceline system collects that coolant and maintains a reservoir which in theory prevents air being pulled in.

But not sure why you think that is relevant, just because its pressurised do you believe it cannot pull air in?

[6speedmanual]

Blown head gasket?

[7 wonders of the world]

Make yourself a restrictor up for the bleed hose to prevent excess coolant being dumped inot the tank which inturn pushes the air volume back inot the cooling system.

1/4" is too big.

Let us know how you get on.

[7 wonders of the world]

Make yourself a restrictor up for the bleed hose to prevent excess coolant being dumped inot the tank which inturn pushes the air volume back inot the cooling system.

1/4" is too big.

Let us know how you get on.

[elie boone]

With a closed system you have only a limited flow in the header tank and this mostly when the engine is cold. the return of the radiator 6mm tube can't produce enough bubbles so that air is drawn in trough the bypass hose and in the engine. Another factor is that the flow from the small radiator return doen't flow direct into the coolant, there is a sort of deairation box inside the header tank. BTW i use a Renault header rather than the Rover item.

[TomGaval]

6speedmanual, as a result of your comment, I did another test of the coolant for the presence ofexhaust gases.  I used a new kit with fresh fluid and after letting the car warm up to 195F and reving it to 5000 rpm a few times, I conducted the test as per the instructions and the results were again negative.

So hopefully the head gasket is not the issue.  I did notice today that the coolant level which started just below the min line on the bottle really does not leave much coolant in the tank.  The bottom hose is covered but the far side and middle are barely covered at that starting point.  That leads me to believe Pendennis's conclusion that the fluid sloshing in the tank could cause air to introduced into the system.

However, while letting the coolant warm up before testing, with the cap removed, the level of fluid in the tank did rise to just ove the Max line on the tank, which was about an inch or more above where it started.

Temp here in Philly was 70F yesterday, 55F today and we are expecting 1-3 inches of Snow tomorrow.  That's probably it for the garage other than Shovelling.     Tom

[Simon.Rogers]

Tom.

be aware that the Evans coolant does expand quite considerably.

i hàve had to change my Busa system which ran with no header tank just a rad cap to one with a true expansion tank.

it does nothing to the circuit other than allow space for the Evans to expand.

 

Doesnt solve the problèm though!

[TomGaval]

Noted.  Thanks Simon!

[Jonathan Kay]

Did you ever sort this out?

Some interesting data on Duratec cooling has just appeared in this thread.

Jonathan

 

[TomGaval]

Well, not quite.  I've had the car on track 3 times so far this year and the first time out I still experienced some pressurization of the coolant in the expansion tank which resulted in some slight puking of coolant after 20 minutes at speed on track.  I received some info from Cosworth USA on the engine which stated that they recommended a 21 to 25 PSI cap for the expansion tank.  I was using the stock 16 psi one.  So I found a 20 psi one and while I still had some pressure build up, I did not have any puking.  Water temp on track running hard stayed pretty much around 210F and Oil temp around 220F.

Last time out 2 weeks ago I switched to a 29 PSI cap that I found at a Range Rover dealer, and  again, no puking.  However, the pressure that had built up after a day on track was still there two days later while the car sat in the garage.  When I went to open the cap, coolant started filling the tank rapidly and when I replaced the cap and then undid the bleed bolt on the radiator some air bled out and then the coolant dropped out of the expansion tank and started to come out of the radiator bleed hole. 

 l just finished relocating the expansion tank from the front cruicform up onto the highest point on the scuttle/bulkhead.  It definitely self bleeds now, and I have another track day scheduled for this coming Thursday to test it again.  The only other step left if this doesn't work is to switch to an electric water pump system as recommended by SBD.    While it could still be a head gasket, my mechanic still doesn't think so based on the lack of oil/coolant contamination and the fact that it's only high rpm related.     I'll update again after Thursday's track workout.   Tom       

[TomGaval]

Took the car to the track on Thursday.  First session went well. Made the whole 25 minutes session. and ran it hard once the oil temp came up.  Coolant temp stayed rock steady at 190-195F Oil temp 210F.  No puking and the level in the tank rose about 1 1/2 inches to mid tank level.  I was cautiously optomistic. 

Coolant level in the tank dropped back to the Max line on the tank, which was still well above the original level that I started it at, in the hour or so between sessions.  Ran for just about 20 minutes and the coolant temp rose to 220F, oil about the same.  Once I backed off, the temp came down. Coolant had risen to about 3/4 level of the tank and a slight bit of coolant had burped from the cap.

Prior to the third session after lunch, after the system had cooled off, I opened the cap and the coolant rose slighly but no real pressure build up.  I then opened the radiator bleed bolt and got a slight bit of air and then coolant.  Level in the tank had dropped back to just below the max line level.  Third session, the car ran well, Coolant level did not exceed 200F. Oil 210F.  Coolant level rose a bit and there was again just a few drops that burped from the tank/cap. 

So I'm really confused now.   Car runs great, but this is now very annoying.   I'm thinking of changing out the water pump with a new mechanical one for now. Then doing the SBD Electric one over the winter.  Also thinking of moving the 10 row oil cooler from the front of the radiator to behind it and replacing it with a 16 or 19 row one.  Any other thoughts/suggestions???   Tom

[Jonathan Kay]

Thanks for the update. I'm sorry you've still got problems.

More tonight, but in advance of that:

1. What coolant are you now using?
2. What's your target maximum coolant temperature?

Jonathan

[ECR]

I've been chasing a water "burping" problem on my 2.0 VX for some time. The problem appeared gradually, so at first I wasn't concerned. I changed header tank cap/thermostat (still the same) I "sniffed" the coolant using a sensitive fluid (all ok). The problem stayed with me, so as I was doing almost all of my track driving in higher ambient temperatures (having moved to SW France) I concluded that although my (scuttle mounted) coolant layout had worked well in the UK it had been perhaps a little marginal. I then replumbed the coolant system, doing away with the header tank and fitting a swirlpot between the engine and the top radiator connection. A test at Chateau Mornay showed the same problem (worse if anything).

I then re sniffed the coolant and had an immediate indication of head gasket failure (which it proved to be). Why didn't the first sniff test find it ?

1, the original test was done when the test point was on the scuttle some way from the engine and perhaps problem was so small that the test couldn't see it....

2, The second sniff test was done at the new swirl pot which is directly at the exit from the thermostat on the head. Could it be that the proximity to the head allowed the test to work that much better ? I have no proof of this, but it was one of the most positive results I have seen using this equipment.

If there's any way you can sniff the coolant very close to the water exit from the head, then I suggest you try it. Your problem is looking increasingly like a head gasket to me ....