Rixio_Scon

A little background first...this a quick spec list, it was all carried out last year at the cost of £8k total!

Street Portes Engine 6k miles ago
Recond twins
Power FC
Feed Rad
New HKS Filters
New Larger Downpipe
KSP full exhaust system no cats no silencers
New Exedy twin clutch
New Plugs
New Leads
HKS FMIC
Running 316rwp on stock injectors @ 98% duty

Iv had an overheating problem for the last 4 months now. The car can get to 115'c! The filler neck to rad hose pressurises. It spews out coolant from the expansion grommet. The car has not been driven unless to test if it does overheat, which is only up and down the road 1/4 of a mile...
...this is what has been done to try and solve it...

1. All the coolant pipes in the engine bar the turbo hard pipes have been replaced.
2. All the AST pipes have been replaced
3. Some of the vacuum hoses have been replaced
4. Air pump has been removed
5. A/C pump has been removed
6. Fans have been replaced
7. Fan wiring has been replaced
8. Water pump has been replaced
9. Water pump housing has been replaced
10. Therostat has been replaced
11. Thermostat housing has been replaced
12. AST has been tested & replaced with stock & Pettit Racing
13. Compression check has been carried out, all ok
14. Combustion check has been carried out, all ok
15. Radiator has been flushed with caustic soda twice
16. Filler Cap has been replaced
17. All the clamps/jubilee clips have been replaced
18. Radiator has been replaced from Feed to stock
19. The Heater Matrix has been disconnected & bypassed


& yet today it still overheated after being off the road for the last month having all that work done to it! Today was when the rad was changed, it overheated after 2 minutes compared to 40+mins with the Feed rad...?!?!

I spent all my time and energy trying to get it fixed but its still happening & nobody can understand why!!!!!!!!

PLEASE HELP!!!!!

gafu mazda

this might sound stupid but do you have a separate temp gauge on the car?

Rixio_Scon

I have a power fc commander yeh

Svelte_7

iTrader: (4)

It's possible that with the air pump removed, that the belt on the water pump is not making good contact and is slipping at speed.

Just my .02 quid.

And with the new radiator installed, it's quite possible there's still a bunch of air in the cooling system. Do a search on "burping."

Good luck.

PhDMDRX7

Get yourself a radiator cap funnel: https://www.rx7club.com/3rd-generation-specific-1993-2002-16/radiator-cap-funnel-eliminate-air-bubbles-342309/ and check for "champagne" when the engine is running. This sounds like a coolent leak to me. Does the engine give off whie smoke and does it smell sweet?

Rixio_Scon

Im so used to bleeding the system after having this problem for so long, i can 110% do it in my sleep...no chance theres still air in it...

Belts are all in line and all ok...

I wish it was that simple though

Absolutley 110% no smoke, no problems starting either hot or cold & no champagne bubbles at idle...

Will try & sort out a funnel though, but doubt they ship to here! THX

jkstill

iTrader: (11)

What Svelte_7 was asking about was not the condition of the belt, but does the belt have enough contact with the pulley to spin the water pump?

Without and airpump the routing of the belt will leave a very small contact patch for the belt. You could tighten the belt, but that isn't a good idea.

If you don't have something like this:
3rd Gen Airpump Elimination Pulley then there is not enough contact to drive the water pump.

Rixio_Scon

Thats the first thing iv ever heard of using an extra pulley for the air pump removal. I doubt it could be that because it was overheating before the air pump and ac were removed. Thats why i removed them in the first place 1) so i could get some space in the engine bay and 2) so it removes unwanted pulleys

The belt does have lower contact but it does turn the pulley as it would before...so not sure on that front...

jpandes

clogged? If you just had your motor rebuilt, there's a chance that all the excess sealant used to assemble your motor made it's way to you radiator and partially clogged the passages.

It happened to me. I had just gotten my new ported motor installed from Pineapple Racing and my temps got upto 122C! I ended up installing a new Koyo radiator and the problem was solved.

good luck

Rixio_Scon

Iv changed the rad twice now...i have a Feed racing rad which i flushed and refit but didnt make a difference still overheated after 40-90mins (It would take alot of **** to block a 3" Feed rad)...then today i fitted the stock rad and it overheats almost instantly now -5mins

Everyone was betting on the rad from the beginning but thats not the cause of it...

Rixio_Scon

........i know there are some mega guru's on here & some1 must have an idea of whats going on...

tphan

From a cold start up (car sat over nite)

1. How long does it take to reach 85*C

2. How long does it take to reach 115*C from 85*C

Cooling system presurized has been carry out?
Any changes in pulley size?

adam c

iTrader: (2)

Sounds like a bad thermostat to me. Did you buy OEM, or some aftermarket piece of junk?

Rixio_Scon

1. 6-8 mins

2. It can vary between 3mins & 2 hours

With the stock rad it doesnt take long to overheat. Even if the temp is 85'c it starts spewing out of the expansion!

The thermostat has been changed twice. Once the day after this started and 2nd a few weeks ago. Both are from engine builders so aint shitty ones...(i dont think)

car hugger

iTrader: (1)

Couple things to check.

Make sure your fans are operating at all speeds. Fans should automatically come on when you turn your parking lights on.

Have you changed your thermosensor and thermoswitch? If not, do it and get the FC thermoswitch instead of the FD, that will turn your fans on sooner.

Get the OEM thermostat and make sure the jiggle pin is at the top.

Replace the filler cap, if it's not sealing right pressure will build and escape.

Get a hydrocarbon test done on the coolant.

Something else is your injector duty cycle is way to high. You need bigger injectors at least 850's in the primary and you should consider a bigger fuel pump.

RE-Amemiya7

Since all of the coolant issues have been covered, i go a different direction. Have you checked your Oil lately? when was the last time the fliter and oil were changed? If your oil level is fine i would check the guage itself.

Are both temp guages, i.e the stock and PFC ones showing overheating, or just one? With the mods you have done, overheating shouldent be an issue. If you are running both guages off the same sensor, i would try running another guage using a different sensor. I believe you can put another in by taping into the fill neck, or even some radiator hoses allow for a temp sensor to be run from there.


I had a similar prolbem on my old Chevelle, it turned out the the car wasent overheating, the sensor/guage was just bad.

jacobcartmill

iTrader: (6)

maybe this has been overlooked, but check to see if you have a bad water seal...

no smoke?

dgeesaman

iTrader: (7)

I think this covered it:

adam c

iTrader: (2)

Good advice Except........

Turning on the parking lights will trigger the fans to come on at a lower temp than with them off. It won't turn them on automatically.

ttmott

iTrader: (1)

Careful with this one, the FC thermoswitch will not turn the fans on earlier. It will, however turn the fans to the next higher speed at the FC switch temperature provided the ECM and / or the AC requires the fans to be on. Only the ECM via the thermosensor or the AC can turn the fans on. Check your electrical schematics; the thermoswitch simply adds another ground leg to the fan motors for higher amperage draw and consequently higher speed. The parking light thing is a new one to me and does not work on my car.

I just went through this whole mess on overheating and solved it.... Four things contributed to the problem that you should check.

1. Verify the fan safety modification is working properly which is to ground the test lead by the ECM using the procedure as posted in this forum's FAQ's.

2. Verify the both fans are operational - I had one that was burned out but couldn't see it as it's under the IC inlet duct.

3. Check to make sure (this is a no brainer) the rad caps are on the correct neck otherwise it will blow the coolant every time. Also I put a 13 psig cap on.

4. Remove the coolant hose from the throttle body and then fill the coolant. This will vent the trapped air from the engine block that typically causes overheating. Make sure the coolant is between 40:60 and 50:50 otherwise either it will boil at a higher system pressure or will not transfer heat adeqately.

Hopefully this helps...

Rixio_Scon

Everything covered by you guys has been carried out already...

The fans are on constantly from when the ignition is on & are new fans (tried 3 sets now)
A coolant pressure test has been done yesterday with no leaks
A radiator pressure test was done yesterday on the Feed one with no leaks
A coolant combustion check was done again and was negative
The stock temp gauge doesnt move until 120'c+ which it used to get to before i got the PFC Commander that i now read off
The oil is ok and at normal level
The thermostat has been changed to OEM once (The first one was OEM the 2nd was low temp)
The system is bleed properly because i was taught by an engine builder...i.e the throttle, filler neck & burped
The pressure caps have been changed


Is there anything else

adam c

iTrader: (2)

You must ask the question: What cools the engine?

Coolant must flow thru the radiator, be cooled, and flow thru the engine. If your fans are working, then the coolant will be cooled. That leaves flow. If coolant is not flowing, what will stop it? A blockage, or a bad water pump. Most likely a blockage. The most likely blockage is the thermostat not opening. I suspect that is the problem. Either it is installed wrong, or it is defective. Get a new OEM t-stat, and make sure it is installed right. You could even remove it completely, just to see if that was the problem.

ptrhahn

iTrader: (9)

You've got a blockage someplace (either coolant flow, or air flow to radiator), or a misinstalled part. There's no way around it. Coolant systems are relatively simple. If water is moving, and air is flowing, you wouldn't have a problem.

Str8Down

Blockage or Faulty waterpump.

scotty305

iTrader: (2)

Two years ago, I was at a friend's repair shop changing my radiator fluid. I did everything possible to remove air bubbles from my cooling system after a flush & fill. I removed that TB line, poured very slowly, and squeezed the radiator hoses. One of the mechanics saw me trying to burp my system, and let me use his coolant funnel. I put it on, started the car, and the funnel removed at least 200mL of air from the system, even though I had already done everything possible to burp it.


Another thing, I've heard of some people having troubles after installing an aftermarket radiator: the non-OEM fitment was causing the radiator hoses to be kinked or squeezed, which didn't let enough coolant flow through the radiator. You might want to check for that.


Good Luck,
-s-