Cosworth Duratec coolant Pressurizing issue Revisited

[TomGaval]

I'm back again with another update to my saga.  Previously I posted that I was having pressurization of the Coolant in the expansion tank but no evidence of any exhaust gases when a chemical sniff test was performed.  I had gone to Evans coolant but was still getting pressurization.  Other attempts at resolving the issue were a new Radtec triple pass extreme radiator, Water pump, Thermostat and belt tensioner assembly.  As well as relocating the expansion tank to the highest point, a 29 psi cap and a bleed hose from the radiator back ito the expansion tank along with a couple of one way valves. 

After those mods the car ran well with water temps at 195F solid and oil temps around 210F.   The only issue was the pressurization and puking of the coolant when I ran above 5500 RPM. 

The engine is a Cosworth built 2.3L Duratec with uprated SBD cams and 13:1 compression ratio. 

I gave up this winter and pulled the head and replaced the head gasket, and while the head and block were ok, there was slight evidence of detonation according to my mechanic and the machine shop.  So after reassembling the engine, I had Steve at SBD review the current map and just last Wednesday he spent four hours doing a remote rolling road session.  

I had asked for a nice safe tune since I only do trackdays and I didn't need every last ounce of power.  He felt that he probably left 20 or more HP on the table but we were happy with the results. 

So it looks like the head gasket was breached, and the engine did lean out a bit around the 5500 rpm level.  So with that all fixed, I took it out on the track this weekend for two days of fun. 

The car ran great, however water temp did get up to 215F and Oil temp hit 220F when running hard.  When I backed off, it came back down to 200 F water and 210F oil.  I know that's not terrible, but It was running significantly cooler last year.  Steve at SBD recommended upgrading my oil cooler from the current 9 row to a 16-19 row one.   Any other thoughts or recommendations?  

Tom

[Jonathan Kay]

What coolant is in now?

Did you ever establish the target temperatures from Cosworth or elsewhere?

Are those temperatures at roughly the same ambient temperature?

Jonathan

[TomGaval]

Still using the Evans coolant.  Air temp this weekend was around 90-92F.  Last year air temps ranged from 60F to 95F.  I didn't see any varience due to the Air Temp as far as I remember.   Just took longer to heat up at the cooler temperature.   I was hoping for a temp of around 195F or 90C or so.   My 195hp RoverK runs a solid 80C all the time.  I know this Duratec at 310 or so bhp is slightly more tuned so may run a tad warmer.

This weekend, the coolant temps came up to 200F while i was running at 2000 RPM in first gear in the Paddock before my session began.  So the water temp came up pretty fast, even with a little air moving thru the radiator.  It did drop down a bit at higher speeds on track before it rose with hard acceleration.  Oil temp rose more slowly, but again under full throttle or close to it, it rose to 220F but came down when I lifted and ran at around 4500 Rpm in 6th for a lap or two.

[elie boone]

Do u use an oversize pulley on the water pump ?

[TomGaval]

Yes it does.

[John Vine]

Very interesting.  I've just read and re-read your earlier thread.  I'm sorry to hear you still have a problem with overheating.

Would it be fair to say that your earlier trials and tribulations could be laid at the door of a failing head gasket?  If so, I'm beginning to wonder whether your present overheating problems might be down to simple physics -- namely, the lower specific heat (SH) of the Evans coolant when compared to a more conventional 50/50 water/ethylene glycol (EG) mix,

Assuming that Evans is 100% propylene glycol (it's not, but it's quite close), its SH at 90C is about 0.69.

The SH of a 50/50 water/EG mix at 90C is about 0.85.  That means it will transfer 20-25% more heat than Evans.  Or, to put it another way, an engine using Evans is likely to run hotter.

Could that be the answer to your problem?

Of course, the scientific way of proving/disproving this idea would be for you to run your car under identical conditions on 50/50 water/EG and compare the running temps with Evans.  However, I doubt you would be willing to drain the Evans due to the considerable cost or prepping the cooling system should you wish to reintroduce it.

JV

 

[TomGaval]

Yes John,  Although I tried to rule out everything else before I Pulled the head, I've got to admit that the pressurization issue was most likely due to the head gasket failing as it did show evidence of a breach.

I was thinking of draining out the Evans Coolant and going back to a standard 50/50 water/coolant mix to see if that would reduce the temps as you indicated.   After all that I spent, what's another $100

I originally tried the Evans as it touted a higher boiling point and lack of pressurization, as I was trying to prevent that pressurization and puking and was still in denial on the head gasket. 

What's your thought on going to a 19 row oil cooler vs the 9 row one that's currently on the car?  The 9 row one is 3 inches high and the 19 row one is 5.75 inches high so obviously it will block a larger area of the radiator, possibly reducing the cooling capacity further. 

[Jonathan Kay]

Similar thoughts to John's, and I'd add the increased viscosity as a plausible factor.

I was thinking of draining out the Evans Coolant and going back to a standard 50/50 water/coolant mix to see if that would reduce the temps as you indicated.   After all that I spent, what's another $100

That's exactly the sort of experiment that's needed. I'm sorry if it has to be on the back of your problems, but I look forward to the results, and thanks.

Jonathan

[TomGaval]

Thanks again guys,  I just read a Red line Water Wetter report that confirms that Water or Water plus Water Wetter provides significant cooling over even a standard 50/50 mix. www.redlineoil.com/content/files/tech/WaterWetter%20Tech%20Info.pdf So I might just try the Distilled water and Water Wetter for the next track weekend which will feature our own run group of 20 plus Se7ens.  That will take place on July 2nd and 3rd.  So I'll report back after that event.  

Tom

[Jonathan Kay]

Interesting. Not convinced by water wetter.  Nearly 100% water should give you better heat transfer than 50% water and ethylene glycol, but beware the lower boiling point. And higher freezing point, which is why I've heard that the racers drain whenever the car is put away.

Jonathan

PS: I'd be happy to use deionised water rather than distilled if it saved some money. What does the manufacturer of the water wetter say on that? And I'm not convinced that either is better than most varieties of tap water.

[TomGaval]

Jonathan, it appears that Red Line says that you can use tap water as the Water Wetter does contain an anti scaling ingredients but using Distilled water or Deionized water will accomplish some scale removal in the cylinder head area.  Whatever the hell that means. 

[John Vine]

I agree with JK -- after all, water has a SH of 1.0 (obviously). 

If it was my car, I'd drain the Evans and run a test on 100% water.  If that showed a marked improvement in temp control, I'd move to a conventional  water/EG mix and test that.  I'd certainly delay experiments with increased oil cooling until I'd run those basic tests. Of course, the essence is to change just one variable at a time. 

JV

[Paul McKenzie]

Tom,

Don't use distilled or deionised water, there is no benefit in that whatsoever and in the absence of other additives will give you a corrosive environment.  Additionally you don't need anti-scaling agents even if the water you use is relatively hard; the amount of scale that will deposit will be negligible as this is not a cycling environment with steam being generated and the water being continuously replaced (as in a boiler or kettle).  Ratherthan that just use tap water and antifreeze/coolant in the normal proportions.

[Jon Stewart]

I had the same symptoms with my VX.

It would blow coolant and overheat on track with using higher revs. I replaced most of the cooling system, fitted a swirl pot, new HG and tried most of the things you've already tried. It was incredibly frustrating as it was impossible to replicate on the road but would return within 30 minutes of being on track. It displayed symptoms of HG failure but always showed clear with sniffer tests on the coolant.

This culminated in an engine failure at Spa and steam being chuffed out of the exhaust

The cause in my case was the use of the wrong head bolts/studs but i don't know if this could be an issue with the Duratec.

 

 

[ECR]

Did your wrong head bolts/studs cause head gasket failure and then overheating (I can't imagine them causing anything else ...)?

 

[Jon Stewart]

That's what was suggested Roger when it ended up at Paul Exon's for a rebuild.

A well respected 7 "specialist" had taken care of the previous build and then failed to diagnose over the couple of years it suffered with the problem but all has been fine since Paul rebuilt it (other than a broken Kent valve spring!!)

 

 

[TomGaval]

I used the Cosworth recommended ARP studs and Nuts and made sure they were torqued to the proper setting following the instructions from SBD.  Steve also provide a new and improved head gasket that he says is the latest and best one to use. So hopefully, those improvements along with a conservative tune will have finally resolved the issue once and for all.  

I'll drain out the Evans coolant and try running just water and water wetter next weekend. 

What Water and Oil temp would you guys recommend as normal running levels and max high levels for Track day conditions? 

Tom

[7 wonders of the world]

Equally other respected engine builders have encountered problems with the Duratec ARP set up on high output engines and have returned to OE tensile head bolts and have resolved the problem.

[TomGaval]

Reporting back with the results of my change over from Evans coolant to a Distilled Water and Redline Water Wetter mixture .

I drained the Evans coolant and did a very thorough flush to ensure that all if it was removed, then filled with Distilled Water and the recommended Water Wetter amount and bled the system well.

We had our annual Se7ens Track day weekend at our Local track with 20 Se7ens running in our own run group.  The Car ran well for the 20 minute sessions each day, with the water temp a steady 195F at speed and the Oil temp a steady 210-212F running hard for the 20 minute sessions.   When returning to the paddock after the checkered flag at the end of the session, temps would drop to 185F and 200F respectively.   The only time the water temp crept up to 200F was when Idling on Pit Lane after a black flag incident that pulled all the cars in while removing a vehicle off track.  I may look into making a shroud for the radiator/fan to get better airflow thru the radiator when idling.

  Ambient air temp was about 10F cooler than during the sessions before when running Evans coolant, so not exactly an exactly scientific experiment.  But I'm going to call it a success anyway. 

Coolant level stayed constant and no puking so I am optimistic that my issue has finally been resolved. It was good to be able to finally be able to run hard a full session and not fixate on the gauges constantly.

Thanks again for your help and support.

Tom

[Jonathan Kay]

Very interesting.

Congratulations on running the experiment, and thanks for the data.

What are you going to do when there's a risk of freezing?

Jonathan

[TomGaval]

Move to Florida? 

[Jonathan Kay]

:-)

Jonathan

[TomGaval]

The car is kept in an attached garage, but it is unheated, so after the last session in November, I will drain a bit of the current mixture and add a sufficent amount of traditional antifreeze to achieve a suitable mixture to prevent freezing.   The car is only tracked, so it won't be outside after the fall until it warms up in the spring.   Tom

[John Vine]

Tom, many thanks for taking the trouble to report back. Most interesting!

As you say, your test was not a fully scientific one, but I do think it adds credence to the notion that high-SH coolants work better than low-SH ones. It would be interesting to know how your car performs with a conventional 50/50 water/EG mix, if only to determine a mid-way point on the "efficiency" continuum.  I wonder if you'd be willing to try a 50/50 mix before your final pre-winter trackday?

I've no experience whatever of Water Wetter, but it appears to rely on some method of reducing surface tension, thereby increasing thermal contact. The inhibitor package is an essential feature too, given the corrosive nature of pure water.

I've just come across some Redline technical blurb here (which, I have to say, contains a deal more science-based reasoning than the Evans' promotional material I've seen so far). One of the most interesting bits for me was the chart "Removal of Heat from Aluminum".  This shows clearly the relative performance of various coolant mixes (from 100% glycol to 100% water).

JV

[TomGaval]

John, in the interest of science, I will switch over to a 50/50 mix in the fall before the last couple of trackdays.  Of course it won't be exactly the same conditions as the fall temps could be anywhere from the 70s to the high 50's, but I will be able to see what the temperature varience will be as I should have a good range of temps with just the water and water wetter during the next couple of months. 

I'll report back later.  Thanks again for all the help and suggestions given by the Blatchat contibutors.

Tom