Coolant problems - swirl pot - cilinderblock bleeding.......

Hkondakci

Member
Hi Guys,

We got an interesting problem here. Every time after a long period of driving (high way, 200km/h+) a good level of coolant is gone. Seems that it is pushed out from the open side of the header tank (Forge), after the header tank is completely full. This line is to the open. We're thinking that because of the high pressure and possible hot spots in the cilinderhead, coolant/water gets vaporized, causes high pressure and is trown out of the cooling system. We also had on 2bar (for longer periods of boosting) on the engine dyno water temp problems, probably because of this.

Theory is to get a swirl tank with high pressure rad cap, locating this higher than the cilinderhead; swirl tank will have a bleedvalve, to get the steam and air out of the system. Possibly this swirl tank needs 2 or 3 lines from the possible hot spots from the cilinderhead, to bleed these hot spots.

I'm looking to the high powered Syklines and they all seem to use such a system; since getting serious cilinderhead problems if not using (cracking heads etc). ARC even has a complete kit for them. High powered Cosworths seem to use these kinds of systems too.

Does anyone know a GTi-R with such a system, or with only a coolant swirl pot and any pics offcourse?

rgds
habib
Any feedback to this subject is ofcourse welcome 8)
 

zia

Active Member
what kind of temp are you seeing when on 2 bar boost? what pressure does the cap open at? and have you tried removing thermostat, to see if it make a difference? by pass fan and run continously does this drop temps to acceptable level?

zia
 

Hkondakci

Member
Header tank is mounted on OEM position, so not elevated.

On the street 2bar isn't used as yet, only 1 bar still :? Got major problems with my laptop to connect to DTA, it's so deeply frustrating. The final mapping touches are still not done because of this. Probably will need to get a good old laptop with serial COM port directly on it. But these always have poor batteries, which is what I need when mapping it on the run :?
On engine dyno, with it's good cooling characteristics, water temp rose always above 85 to 90 degrees Celcius after a 10-15seconds 2bar. No not removed thermostat, but problem is not the temp when driving it. That stays cool; it has rised once, then there was not enough coolant anymore. So temp is always good, and double fans kick in after 74 degrees celcius.

Problem is water gets pushed out :shock: After a while there is lack of water then temp rises. New coolant in it, temp problem solved, but other's not.

rgds
habib
 

Fast Guy

Moderators
Staff member
I know on high powered Cossies they also used a swirl pot in the cooling system to help, I think the idea was to help remove the air from the extreme temps that the turbo was putting into the system (or something :? )

Is your turbo still water cooled?

Can you see the water leaking anywhere, or see it coming out of the expansion tank over flow?

Could you cylinder head be lifting under boost and leaking coolant?
 

Nad

Active Member
Fast Guy said:
Could you cylinder head be lifting under boost and leaking coolant?
I was just gonna say that, aka leaking head gasket, loss of coolant while presurising coolant.
 

Hkondakci

Member
Yes the Cossies use them for the coolant to be swirled (or something) from air, which is a good thing to do on our R engine I presume. I'm planning to get this one with a rad cap and put it on the highest possible position in the engine bay.

My turbo is water and oil cooled.

Power on the car seems oke (on 1bar still :oops: ) and mechnical wise there is no problem I think; there is no funny white smoke from exhaust that would reveal headgasket problems, also tips of spark plugs seem okay. Don't think that cilinderhead or headgasket is giving up now, but keep my fingers crossed :? Will put the new RNN14 super strong JUN heads Studs soon and a Nismo thermostat though.

Thanks for the link R-type, this brought me new perspectives :eek:

Looked again and indeed water is leaking elsewhere :oops: Not to much though.......Seems that the radcap or putting it better rad-neck is leaking water; the very thin aluminium sides of the rad-neck on which the rad-cap is located is continiously bend, because it's so fragile. I understand that Koyo has solved this problem by making a new style rad-neck :shock: So under high pressure it leaks and causes less pressure in the watersystem than needed. Probably the extra water in the headertank isn't sucked back because of lack of pressure, instead of to high pressure :? It keeps pushing out water and not sucking it properly back. Hmmmm...... this makes sense and could just be the solution......

Now the coolant system has to be drained again and the rad welded with a new rad-neck :x Keeping you bussy :evil: . I hope this will give the solution guys, I'll keep you guys informed after setting it up again.

Thanks for thinking with me here 8)

rgds
habib
 

GINGA

Active Member
I had this problem on mine and all it was was the rad cap was knackered :wink: it let the coolant out into the tank as it expanded with heat but wouldn't let it return causing airlocks which then made the problem even worse :roll:
swopped the caps and all was well again 8)
 

turblio

New Member
One other point that I was talking to an engine tuner about, is the coolant line that comes from the turbo he told me of a similar instance to yours,
where they could not understand where the coolant was going, after much
checking every inch of the engine, he found the turbo was producing so much heat on full boost that the coolant in the turbo exit hose was vaporising! (steam) so they now run it without water cooling and it doesn't
cause any more problems, not sure if this is your problem but its certainly
something to consider :)
Frank
 
C

Crazy

Guest
Looked again and indeed water is leaking elsewhere Not to much though.......Seems that the radcap or putting it better rad-neck is leaking water; the very thin aluminium sides of the rad-neck on which the rad-cap is located is continiously bend, because it's so fragile. I understand that Koyo has solved this problem by making a new style rad-neck So under high pressure it leaks and causes less pressure in the watersystem than needed. Probably the extra water in the headertank isn't sucked back because of lack of pressure, instead of to high pressure It keeps pushing out water and not sucking it properly back. Hmmmm......

Habib this the same problem I was having with my Koyo radiator that I purchased from you last year :( When we spoke you said that Koyo had not had this problem before but
I understand that Koyo has solved this problem by making a new style rad-neck
it seems that they knew about the problem but was not accepting my problem was genuine when I contacted you :?

Any way mate I have now sorted the problem by changing the rad-neck and it has been fine ever since :wink:
 

Nad

Active Member
turblio said:
One other point that I was talking to an engine tuner about, is the coolant line that comes from the turbo he told me of a similar instance to yours,
where they could not understand where the coolant was going, after much
checking every inch of the engine, he found the turbo was producing so much heat on full boost that the coolant in the turbo exit hose was vaporising! (steam) so they now run it without water cooling and it doesn't
cause any more problems, not sure if this is your problem but its certainly
something to consider :)
Frank
I wonder if that was why Nigel and mine's turbos had the water cooling removed??
 

Hkondakci

Member
Very interesting point you have there frank, could be something to consider in the future (near future 8) ) But could that not be a problem for the turbo when it's designed to be used with water cooling?

For now I'm getting the rad off and a new neck welded in combination with a swirl tank with rad cap in a high location (just for the sake of mind). Thinking of what brand would make such a universal swirl tank with rad cap????

I remember your issue Crazy; at that time we informed them (Koyo) and were told what I had stated to you; never had any problems :shock: . We sold quite a few of these rads, and besides yours only mine gave problems as it seems now. But recently our supplier in the States (JGY) told us that new Koyo rads were being made and the issue of fragile rad-necks would then be over for sure. That was a surprise to us too :oops: . The rad itself is super, but at that time we couldn't oversee this issue :cry:. But good to hear your fine now, since it's cooling capacities is really very good 8)

Looked again to high power SR20's in Japan and frankly can't find anything in there enine bay which looks like the Skylines swirl tank setup.... maybe our SR20 cilinderhead is not so sensitive in making hotspots and thus steam in its watercooling lines as the RB26 or the Cosworth engines.....???
 

skiddusmarkus

Active Member
Has anyone else had any problems with the large Koyo rads?Mine has been ok at low boost but hasn't really got hot yet so not been tested.

I got round the inlets and outlets being the wrong size by having the old ones cut off and buying some alluminium piping and having it welded on in their place.Much better than messing about cutting pipes/using reducers.
 
A

AndrewD

Guest
hmmm hello habib

may i propose my 2 cents ;)

ive recently been designing my own cooling system for a race engine and come across these common issues

- maybe there is a crack in the cylinder head, allowing combustion pressure to leak into the coolant jacket which in turn increases temperature and pressures of coolant forcing it into the overflow and hence when thats full, out of the system all together

- maybe your cooling system isnt capable of dissipating the required heat provided by the engine, in this case no swirl pot can help you, all that will happen is increased temperatures and pressures (also no increase rad cap here will stop this) and leaks will occur in your system

- a swirl pot is ideal for venting gasses in the cooling system, basically its a cyclonic device that diffuses air from water (as water has momentum) and then vents it from the system, still would be helpfull though as it can remove troublesome hot spots

- maybe (if there isnt a leak of combustion pressures into the water jacket) you can place a small restriction at the water outlet on the engine side to further increase water pressure and hence also increase boiling temp of the water in this section (ie potentially less boiling of water inside jacket)

- id check your cooling requirements, rough approximation is 1/3 maximum power at WOT and then see if you radiator can dissipate that much heat (if you need help here let me know i can help you) generally the limiting factor is on the air side, ie the core either isnt big enough, or your not moving enough air through the core (same goes for water side)

hope this helps mate
 

Hkondakci

Member
Hello Andrew,
Thanks for the very informative overview.
It seems that indeed combustion pressure was leaking into the cooling system, because the OEM Nissan headbolts were not into it anymore. While replacing them with the JUN head studs (without lifting the head - piece for piece unbolting the bolts and gettings the studs in) the OEM bolts were seriously streched out and were easy to unlock; it was clear that the cilinderhead wasn't clamping very much to the block anymore and the headgasket had a serious time not to get blown away.
This all made sense since the car made heavily white smoke from the exhaust after being warm-up or driven hard (for a few minutes - after cooled down it always dissapeared), and felt less powerfull on the flight.
Also it seemed that I hadn't been able to fully bleed the cooling system, which meant extra airpockets in the coolantsystem.
We are ofcourse not sure if the cilinderhead has cracked, it could be because of this lesser cooling issues. But we are still hopefull it's intacked, since I never driven it higher than 1 bar on the street yet and never driven the car with the red temp light on (on the dash).
We are also in high hope that the headgasket is still intacked. But we'll see in the near future when the engine is running again after the new manifold etc is bolted again.
We are planning to modify the inlet and outlet of the radiator, so that coolant flows out of the rad not from the bottom of it, but from the top of it, to eliminate all air-pocket eventualities. Also after the coolant is left the cilinderhead on the left of the engine it will go into the swirltank first and from there into the new bottom-side inlet of the rad, circulate in the rad and leave the rad on the top to go into the block via the new NISMO 62 degree thermostat. Also the coolantvolume will be increased a little bit more; it was increased seriously with the new alu Koyo rad before.
This swirltank will be placed high in the enginebay and has it's own high-pressure radcap.
We assume, but do not know for sure, that this system will have enough cooling capabilities for the engine when running 2bar boost with approx 550hp on the street, very soon :D :D It would be handy and very kind of you if you could calculate if this system (especially the rad) meets our requirements. Any extra info please let me know. Thanks in advance.
rgds
habib
 

zia

Active Member
We are planning to modify the inlet and outlet of the radiator, so that coolant flows out of the rad not from the bottom of it, but from the top of it, to eliminate all air-pocket eventualities. Also after the coolant is left the cilinderhead on the left of the engine it will go into the swirltank first and from there into the new bottom-side inlet of the rad, circulate in the rad and leave the rad on the top to go into the block via the new NISMO 62 degree thermostat. Also the coolantvolume will be increased a little bit more; it was increased seriously with the new alu Koyo rad before.
will this not create more problem's if cold water is going back into top left hand outlet. the water pump will not recieve cold coolant when pumping water through the engine.turbo water feed would be wrong way round.inlet manifold coolant alos would be affected.

zia
 

Hkondakci

Member
Hi Zia,
The inlet and outlet of the engine will ofcourse not be changed. The inlet and outlet of the rad will be changed. Cold water will still go into the block via the thermostat inlet and warm water will go into the rad via the cilinderhead outlet. This will not be changed. Only now warm coolant/water (probably in some cases boiling, with airpockets) is going in from the top of the rad and leaving the rad on it's bottom. You actually want warm water enter the rad at the bottom and cooled water leave at the top of the rad, so boiled water can cool down and you can vent eventual airpockets. I never actually understood the current setup made by Nissan, since it's rather contradictionary to fysics. For example when looked at the Cossie coolant system you'll see warm water gets in at the bottom and leaves at the top of the rad.
rgds
habib
 
Top