Complex Overheating Issue

[nisskid]

first things first, the car is an RB20 track car, it's been having heating issues for a while, i wasnt running a aftermarket water temp gauge for a while, i just noticed it was losing power. after shit came to a head at winton drift matsuri, and i was bursting hoses left right and centre, while overheating my engine to the point of steaming, we thought we'd solved the problem on the 2nd day after noticing the hose wasnt pressurising, thinking the thermostat was spent, we replaced it. unfortunately it kept having the issue the next day, until finally bursting some more hoses and ending my day. i came to the conclusion that this was probably the reason i was losing power for the last how ever many days out at the track.

so after replacing all the heater hoses, thermostat, flush/recon the radiator, i did a leak down test which showed decent low leak on all cylinders, which i wasnt expecting thinking the head gasket was gone. i was confident it would be ok, my old man installed an autometer water temp gauge while i was overseas as he was going to use the car, but he installed it in the lower hose, which is obviously in the wrong spot. he noticed on the day that although the temp was reading quite low, steam was coming out of the overflow, so he took it easy. next prac day both of us were driving it, and it was overheating badly, steam was coming out of the overflow at such a rate it was whistling through the exit. once again, reading f**k all temps at the bottom hose. worth noting possibly that i was getting temps of 110-120 for the oil. i run a pretty huge oil cooler which i some times think is doing all the work.

my theory was lack of flow, that it was simply not cycling water through the system, no hot water was getting through down to the bottom of the radiator, it was just cooking up top and pushing out the overflow.

i could only think of 3 things which could cause this, buggered water pump, huge blockage in the system, or thermostat not opening. after talking to a radiator place, they told me that very rarely do they get complete blockages which stem flow to a still, so after checking thermostat, and it being fine, i pulled out the water pump, which also looks fine. there is a decent amount of corrosion however.

there's the other issue of bleeding, i cant open the bleed valve on the manifold as it's seized, so ive been using a big bottle cut in half sealed on the radiator's top to bleed the system.

so now im really at a loss, things checked:

- hoses replaced and strong, no leaks

- radiator flushed/recon'd

- thermostat checked and is ok (only seen a few days of track anyway)

- water pump looks to be ok, spins free and blades are in tact

- head gasket checked via leakdown test, appears to be fine.

- radiator cap is fine

my main issue is there are things which could cause general overheating, what's getting me is the lack of heat in the bottom hose which indicates lack of flow, even if for example head gasket was spent, the overheating would still send hot water all around the cycle, and at most you'd get a reading in the lower hose 20 degrees less than whats going into the radiator, which would be 110+ if it's steaming like it is, but im getting more like 50-60 degrees.

[battery]

have you been running anti rust coolant or just water?

Have you done a pressure test on the entire system?

I once had bad overheating due to the 2 heater hoses that run into the cabin, got a new peice and looped at the block all good

oh and as for the bleeding i found parking on a hill to work well!

[nisskid]

i think i did, but tbh i may have drained it at some stage, just put water back in for a bit, and forgot to put coolant back in.

what do you mean by pressure test? i havent pressure flushed it yet, that's next but requires a lot of work to get it down to rad place, and they talked me out of it so going to see them tomorrow.

[battery]

same as pressure testing cooler piping... cap off the overflow put fitting on rad hook up compressor load up to 10psi then see if it holds..

also should be able to check for blockage if you take thermostat out and put a hose in..

I ran water in my last rb20 for years and even though the radiator was %80 blocked the galleries were fine...

[nisskid]

we quickly chucked a scope up the port and the galleries look okish. there's no water coming out though that's the only thing, so not heaps worried about leaks, just flow is worrying me.

it's doing my head in lol

[battery]

if you have an air leak you wont get flow!!!!

i have been down this road before and its amazing what an air leak can do!

PS whats going on with the lack of blog posts lol

[nisskid]

haha, been real busy trying to sort my car out, will try and get some stuff sorted asap

[DVS JEZ]

Did u replace the water pump when u took it off?

Have u tried running coolant? Try a new radiator cap too. Try one with a slightly higher pressure. Higher pressure systems help prevent water boiling.

Have u had the tune checked. It is VERY possible ur fuel pump or system is leaning the engine out causing extremely hot cylinder pressures which is boiling the fluid in the head near the combustion chamber.

[zebra]

Are you running the factory clutch fan?

Is it a standard radiator?

do you have an oil cooler?

on top of what Jez said, are you running overly retarded ingnition timing?

not much airflow gets to the radiator when drifting, if it were me I would get the biggest radiator I could find and stick it in the car and make sure the factory clutch fan is 100% perfect (after checking the already mentioned potential problems)

[Room42]

Mate it sounds to me like you are mostly on top of it so based on what you wrote I'll just say a few things. Never use water in your cooling system. It will always boil. Only use one type of coolant in your system. Using 2 types can cause a reaction with the alloys and corrode stuff quicker. A simple one but check that your thermostat is in the right way. Check that you radiator hose isn't getting sucked shut when you floor it. It happens. You said that you cant open your bleed bolt. Get it sorted, also check the little hoses around it etc for blockages. A radiator cap with a couple of psi more will suppress boiling however isn't usually needed. Check your viscous coupling in your fan. It should have a little resistance when you try to turn it. If there is a little oil leak on it then get it replaced. It has already been said but check that you aren't running too lean for your application. Anyway just a few ideas to help you on your way.

[eightsixboy]

One thing is the bleed screw, you have to be able to bleed it from there, everytime I have bled mine there has been a crap load of air from that bleed screw.

What did you do to reco the radiator? Sounds like it could either be a blockage or even a massive air lock.

[femno]

- head gasket checked via leakdown test, appears to be fine.

No. There are so many other conditions the HG is under during running: Heat, Boost, Expansion etc etc that could cause it to leak.

Chances are that because its been running so hot so much the head could be warped and HG cooked. Have you put the head check chemical on it? I would do that before anything else. It will tell you if EX gasses are in the cooling system and if so, HG or head gone.

Does it heat really quickly? or does it slowly rise in temp?

Agreed need to sort the bleeder out.

[battery]

If he's not getting flow then it's got nothing to do with the tune....

Edited June 6, 2011 by battery

[nisskid]

thanks for the help guys

If he's not getting flow then it's got nothing to do with the tune....

this is what's puzzling me, there is no reason for the gauge to read wrong, so regardless of everything, the lack of flow is what's making it so difficult to figure out, otherwise id just get a big f**k off radiator if i was just trying to get rid of excess heat, unfortunately i dont think that's going to do anything if the water isnt flowing around.

[nisskid]

Are you running the factory clutch fan?

Is it a standard radiator?

do you have an oil cooler?

on top of what Jez said, are you running overly retarded ingnition timing?

not much airflow gets to the radiator when drifting, if it were me I would get the biggest radiator I could find and stick it in the car and make sure the factory clutch fan is 100% perfect (after checking the already mentioned potential problems)

yes yes and yes (big one too), timing i dont know, but it hasnt changed since it was first tuned, and the problem has come in.

it looked like i was burning plugs last day out, but ive been having this overheating issue since before then.

[battery]

If you take the thermostat out and rev the engine cold you should be able to see serious water movement through the rad cap hole... If it's just sitting there and your water pump is fine my money is on a leak for sure... Have seen this so many times with all my cars...

[Duncan]

...Never use water in your cooling system. It will always boil. ......

Sorry but that is not right. In fact water is one of the best coolants you can run for ability to absorb energy/heat without boiling.

You said that you cant open your bleed bolt. Get it sorted.....

A radiator cap with a couple of psi more will suppress boiling however isn't usually needed.......

Check your viscous coupling in your fan.....

Totally agree with all those....simple things and any of them could cause a problem.

I had a problem with overheating for months and tried literally everything except the obvious....a pressure test would have showed that it had a leak and was loosing water, then overheating. Took 8-10 minutes at full noise to go from dead cold to boiling hot.

[zebra]

Sorry but that is not right. In fact water is one of the best coolants you can run for ability to absorb energy/heat without boiling.

Its true

Many many race cars run pure water for its heat dissapating awesomness

[1400r]

bleed screw

end thread

gorilla grips or smash a undersize socket onto it

[Room42]

say what you like but... I have personally seen water in heat exchanging systems run hot and boil. Coolant doesn't do that. Lol whatever gets you off tho. I guess we are all qualified mechanics here aye?!