cooling issue....custom car
 

I have a 914 porsche with a 13b. having trouble keeping it cool. I am using a ford f-150 radiator which is mounted way up front. (engine is in the rear). You'd think that with the coolant traveling all the way to the front of the car, then going through that big radiator, then all the way back to the engine, that it would be plenty cool....but it's not. Running around 200 degrees and sometimes it tries to get up to 210 degrees, but I shut her down. Yes, I am also using a radiator cooling fan.
Do they make aftermarket water pumps to help? or different pullies for the water pump? Any ideas?

I would start with some sort of electric pump, perhaps even just a booster pump. Something like this, perhaps: http://www.jegs.com/p/Stewart-Compon...61611/10002/-1

The stock pump is certainly going to have a bit of trouble drawing water from the radiator at that distance, particularly if a large portion of the radiator is below the water pump's inlet level.

A few questions:

What fan are you using, and what type of controller?
What temp does the fan come on at?
What temperature thermostat are you using?
Is there any possibility that the belt is slipping?
When does the problem occur? At idle, only after a hard run, etc.?


:)

I was going to suggest a booster pump as well.

Or just block off the water pump and run a high volume inline water pump. You might need an alternator upgrade to run one, and you would want to make some kind of simple circuit wired to a dummy light incase the pump fails to operate.

My .02

The problem actually seems to happen more often at cruising. I like the electric pump idea, but not $400 for it.
My radiator is mounted so that it does get a good ammount of air moving through it. Right now, I am using a black magic fan that is controlled by a switch on my dash. I pretty much leave it on the whole time except for warming the car up. I am using a 185 degree thermostat. Should I possibly remove it all together?

DJMTSU- can you explain what you were talking about with blocking off the water pump and using a high volume? How does it operate? pics??

Does anyone know if they make different pullies for the stock pump to increase it's flow?

First of all, 200-210 is not that hot and isn't really a concern, I WISH my car would run that hot.

Get something to automatically control the fan. On @ 190, off @ 185 kinda thing.

Like Prophet says, a booster pump would help alot, but I don't think that's your problem, I think the radiator is. You're using a stock rad for a I6 or V8, I would call Griffen and start picking thier brains. If you've managed to get a good sized rad like that in there, than a better quality, better engineered, full alloy rad would do wonders for you.

Like I said though, 200 isn't anything to worry about.

I saw a set up on a drag FC once. Where the water pump mounts, he just had a plate bolted down. The electric pump was mounted on the fender, with the lower radiator hose going in one side, than out to the engine. It ran at a constant speed when the ignition was switched on. He said it was something he learned from Nascar school (for whatever that is worth), and the pump was available at Summit or Jegs.

But, listen to TT. He is one smart SOB. Get some serious ducting to that radiator, and upgrade to a thicker aluminum set-up.

Yeah 200-210 isnt dangerous, though it's warmer then I like to see. I like mine to be around 190. Are you running a fan shroud? Those help tremendously. Also ducting, make sure any gaps around the radiator are sealed, any air hitting the radiator needs to go through it, gaps will just allow it to escape around the sides.

yes, using a shround and have the air being guided through the fins as much as possible. Also have a heat escape scoop on my hood. You can see in my video. link is below. Money is a bit tight, so I was hoping for some "cheap answers". ha, like that is ever possible!

does anyone have any pictures of the bypass plate on the waterpump?

How confident are you that your gauge is correct?

Oh yeah, make sure your timing is correct too. If it is too retarded, it will overheat the exhaust system. Too advanced and it will overheat the motor. :)

Think of the water pump shape. and then think of a flat plate in its place....

The other option would be to get the smaller plate (water pump housing to block) and putting large -AN fittings routed to an electric pump...

if I went electric pump route, could I just leave my waterpump in place? wouldn't that be easier?

the impeller may be in the way... you may want to get ccreative on that part.

What PSI pressure cap are you running? Have you pressure tested the system and made sure absolutely no air is in there?

thats something I haven't thought of. I will fill the system from the highest point and see what happens. I have 2 radiator caps. one in the front and one on top ot the waterpump fill neck. The one up front has leaked before. maybe I need a higher pressure cap up front?

how do you perform a propper pressure test?

This may be a very dumb question, but when you first start a car and the thermostat is closed so that the engine can warm up, what happens to all the coolant that the water pump is still trying to push? Seems like it has no where to go since it is not looping through until the thermostat opens.

I always wondered that too.

I guess it just cavitates withing the water pump housing until the thermostat pops.

:dunno:

The lower the pressure in the system the better... to a certain extent based on the coolant you're using. 13psi is what I'm using.

You want to bleed the system at the highest point last. Something you might want to add to the system is an expansion tank, I swear by them now. Installed properly they will automatically and constantly bleed the system unless there is an air bubble big enough to jam up the waterpump. If that happens you're screwed and the temp will just skyrocket. With air in the waterpump, the coolant will not move at all.

With a proper pressure tester. With the car cool, hook this little tool up to the rad cap, which ever one, and pressurize the system to 110% of the cap and watch for the leaks.

it flows through the heater core (if it's open) and weeps through the t-stat.

Originally Posted by craig3x
This may be a very dumb question, but when you first start a car and the thermostat is closed so that the engine can warm up, what happens to all the coolant that the water pump is still trying to push? Seems like it has no where to go since it is not looping through until the thermostat opens.

"it flows through the heater core (if it's open) and weeps through the t-stat".

hmmm, but I don't have a heater core. And I guess my question is that if I installed one of those fancy 50gph electric pumps, what would happen when the thermostat is closed? sounds like major pressure build up???

Then you would need to route the outlet on the back of the iron (near the oil press sensor, and create a bypass after the thermostat (see the bottom of an FC radiator. The little hose is the heater return.

Or wire it so that it doesn't come on until your t-stat is open

wouldn't no water flow create weird hotspots in the engine?

I use a 16 psi cap. Coolant Pressure is related to the temperature of the coolant. As the coolant gets hotter it builds up more pressure. if your cap is old and weak or rated too low for your application the water will escape, this means it's not cooling the engine. Usually you have a water reservoir that catches the water, and when the coolant cools it sucks it back in. If you run a cap pressure too high, this puts extra pressure on the coolant hoses and seals under overheat conditions. I prefer to run a higher then stock pressure cap, this insures the coolant is still trying to cool the engine if temps ever do get high.

A system under normal operating temps will have the same pressure with a 16 psi cap as it will with a 13 psi cap. The only difference is when the temps go higher the 13 psi will boil over quicker.

hope this helps. And given your somewhat complicated system I wouldn't be surprised if you have air in your system. There is a special coolant burping funnel that is supposed to work well for this. I would try to burp your system over several days to insure no air is in there.

Also most all cooling systems that i know of have a bypass, either external or internal. Usually they are always open. this allows the coolant to still circulate around in the engine resulting in a more uniform temperature across the whole engine, which aids efficiency and reduces wear on internal parts. Otherwise you would end up with certain spots much hotter then others, and who's to say the coolant where the Tstat is located would ever get hot enough to open before damage occurs somewhere else?

Maybe but not much more than a stock system

Not really, it'll still cool the engine, it will just allow the coolant to boil at a lower temp. But a 50/50 mix under 0 pressure will boil @ ~225*, add ~15lbs to it and it rises to ~270*, roughly 3*/lb so a 13 psi cap will allow boiling to occur @ ~265* If you ever get to 265*, you have other issues. The extra 2psi on the cap really doesn't do anything for better cooling except place more stress on the hoses/seals as you pointed out.

True, but as I said above, that extra 2psi in the cap really isn't doing anything for us.

This I will disagree with, how can a system have the same pressure if it has two different psi caps? When the pressure reaches 13psi, the 13psi cap will allow fluid to escape while the 16 psi cap will hold pressure much longer. I could run a 0 psi cap if I wanted becuase my temps never get that high. However, if they did get to ~225, my coolant WOULD boil unless I had some addition pressure in the system.

I've seen that, never needed to use it, have a few friends that have but had no luck. A different approach would be to use an expansion tank. I swear by those now and will never build another car without one. It basically works as that burping funnell does constantly, every time you start and run the car.

They will have the same pressure until the lower rated cap allows coolant to boil over. The PSI rating of the cap has no effect on the pressure until the pressure overcomes the cap.

right, and the extra ~10* of cooling before the coolant starts to boil is of no need to us. Basically there is no need to run a 16psi cap if you're using a 50/50 mix. To me the extra 3psi places on the seals/hoses isn't worth it. Hell, I think we should all be running Evans, but I pull my motor too often for that :rofl:

hope this helps. And given your somewhat complicated system I wouldn't be surprised if you have air in your system. There is a special coolant burping funnel that is supposed to work well for this. I would try to burp your system over several days to insure no air is in there.[/QUOTE]

you're right. I did have air in it from a previous boil over. I filled it on the side of the road, but didn't "burp" it. Thanks. However, I still think I may have a problem by trying to use a stock waterpump to push coolant through about 12 ft of hoses

Maybe a stupid question, but have you tried Water Wetter (I think that's what its called, never used it myself) or some similar product?

some people **not rotary** have success with that as it is supposed to help with heat transfer... but he needs to make sure he's got solid (and capable) system with no air.

Redline Water Wetter.
http://ecx.images-amazon.com/images/...500_AA280_.jpg

****sidenote... There is also Heater Hotter for the winter lol***
http://www.designengineering.com/ima...cts/HH_300.jpg

Water wetter is bad, it dissolves coolant seals. DON'T use it

You could drill a small hole in the thermostat plate to allow some coolant to bypass it all the time; I've done this when not running a heater core. It's best to run the water pump all the time, so as to keep some positive pressure inside the engine (particularly important in the area around the exhaust ports and the spark plugs), and the bypass acts as a restriction to allow some flow through (preventing cavitation) while maintaining pressure.

yeah.... what he said...:leaving:

That is very good to know! Where would we be without forums? :)

great. I read this right after I just added water wetter. Time to drain!
By the way, Autozone rents cooling system pressure testers for free! just a $75 deposit

I believe you, but how do you know this?

Gotta watch out though, the other extreme are kiddies who know nothing but run around spewing crap from their mouths. I once read someone suggest using hardware store washers to space rims......:banghead:

Good friend/fellow rotary car shop owner years ago couldn't figure out why one car, flat out race car, needed rebuilds ever year from coolant seals just disolving. He found out that the owner would go home and put water wetter in the cooling system. So he went ahead and took a few coolant seals and put them in water, strait green antifreeze, dexcool antifreeze, and strait water wetter. He told me that withen 20 minutes the seals in the water wetter were disolving and turning stringy. Mystery solved.

I also bought a parts car once that was running on one rotor. Owner thought that the rear rotor was toast. Comp was fine, but the jacket rotted out a little and a section of the coolant seal was just gone. I knew the guy, knew the car, knew that he had put water wetter in the car after a mutual friend with a 500AWD eclipse used it after he started having issues. Eclipse was fine, few weeks later he thought he fragged the engine. Used iron from my collection and I had another good engine. It clicked years later when I found out about the water wetter. I always just thought that the seal broke loose but the seal itself was rubbery/stringy disolving

interesting. Thanks for the info. You'd think redline would put a disclaimer on the water wetter bottle regarding rotary engines. I wonder if they even know?