so... the line from my filler neck to the overflow blew off. after i reconnected it with zip ties, the top of the overflow tank BLEW off. the car was driving normal all day and then this time i go to drive off and failure of parts...

the second time i had to pull over because of the billowing white smoke from under the hood was because of the top of the overflow blowing off. the water on the inside was boiling. the water temp gauge i have installed was reading normal both times. the only thing i can think of is that there is excessive pressure in the coolant system. if that makes sense.

im not sure what i should do at this point... at all..not even a clue... any help is appreciated...

 

Maybe it's just your pressure cap which got stucked?
Check it in boiling water... Or just get a new one and try again...

 

its supposed to retract correct?

 

How many miles on your engine? Hate to say it, but sounds like bad coolant seals.

 

@adam

but with a bad coolant seal + engine temps in the normal range, there shouldn't be over-pressurising of the coolant sytem because the cap will vent the pressure/exhaust gases!? Or am I missing something?

 

Same thing happen to me yesterday, turned out to be because there was air bubbles in the system, I thought I made sure I got all the air out but I guess not. After it cooled down it needed about a gallon more. Is your radiator in the stock location? Mine in standing up so got to be careful not to have air pockets

 

sounds like dead coolant seals.
what happens if you start the car with the filler cap not on?
bubbles much?

 

mine is in the stock location. after i put in my new radiator and lines i bled the system very well and it drove perfect up until now. i even took a fairly decent length drive with no issues.

by pressure cap your talking about the cap on my filler next correct? if so, i boiled it in water and it did nothing. i even put it in a clear cup and poured the boiling water on it and watched to see if it would do something. i ran the cap under some cold water first to "reset" it of course. ill get another one and see what happens.

no bubbles with the cap off. all is well.

im confused about the coolant seals. if they were going bad wouldnt it cause me to lose pressure as apposed to over-pressurize? where are the coolant seals that you guys are talking about?

 

No, i don't mean the cap on the filler neck. this is only a metall piece with a rubber insert for sealing.

I mean the cap on the AST. This cap should have a spring assembly inside, so this is preloaded. when pressure rises, it pushes against the spring assembly and will "open" the flow to the overflow tank which is located in front of the wheels.

When I've got my fd, the previous owner thought it has a blown coolant seal because it pushes water always in the overflow tank and therefore was loosing coolant... came out that it was only a stucked open pressure cap... changed cap -> car works fine (good for me, it was the deal of my life )
Maybe yours just got stuck in the closed position...

This is the pressure cap on a stock ast I'm talkin about



the stock ast is located near your smic

the underside of the cap should look like this:



just to clarifiy: this is a pic of the filler neck:



The two caps will look the same from the top, but the one at the ast hast the spring assembly, the one on the filler neck only has a rubber inside for sealing

I would first change the pressure cap against a new one and try again...

also sorry buddy for confusing you up, wondering no one has corrected me... you dont have to put this cap in hot water, its just spring preloaded... (not like a thermostat) verify that you can freely compress the spring assembly and that it moves freely back into its uncompressed position...

 

I recommend borrowing the kit from Autozone or Advanced Auto that will let you pressure test each cap and then pressure test the whole system.

 

if the coolant seals are going bad, high pressure gas from the combustion process can be pushed into the coolant system- forcing coolant out various places. Overflow talk being the main one.
EDIT: oh and the coolant seals are in a groove around the outside of the housings, wedged between the housings/irons.


those hollow passages are where coolant flows through, hence if your coolant seals are screwed gasses from combustion can enter the coolant system and force it out elsewhere.

 

Got it... I don't have my ast installed. So I used the nipple off the filler neck and ran it to the overflow... now that I think about it... kind of a bar idea, also my filler neck cap has a spring on it like a normal radiator cap. Ill have to check and see what the ast has...

Ill reinstall it and report back.

One more thing... there is no advance or auto zone in Japan...

 

just remembered i cant reinstall the ast because of the radiator i have... it doesnt have a spot for the ast to connect to. im just going to try getting the fc filler neck cap and see if that works...

 

fc cap worked... problem solved.

one more thing. according to the big fat cooling thread, 150-230F is "normal" but others state 180F is the normal operating temp. at what temp is considered "overheat!!! SHUT IT DOWN"

Last time i drove, my temp got up to 233F and worked its way back down to 218F.

 

It all depends on what cooling mods you have. I don't have the numbers handy, but with the stock thermoswitch the coolant temp will go up pretty high (210f?) before the fans even kick on hard enough to bring it back down. A 2nd gen thermoswitch will at least trim that number some.

180F is a common number to see when cruising with a high capacity radiator. While it's may spend a lot of time at this temp, I wouldn't call it "normal".

After shutting down the car, always expect to see elevated temps due to heat soak. The air flow is stopped in most cases and the block still has a lot of heat to release. I've see 220, 230 after hard driving events.

IMHO, anything over 230 is getting risky hot in operation. If you do track days or get stuck in traffic in hot weather, keep an eye on this.

 

cooling mods as follows:
3 core aluminum
silicone hoses

thats it -_-*

so 230 is definitely getting close and i should be looking to shut down soon? i can live with that. im looking into vented hoods as my friend with a miata has one and i saw first hand how effective they are. so im in the market for one. also, i just picked up a 99 bumper and realized just how much bigger the openings on the front are compared to the one i have now. so hopefully those 2 things will help some. im going to try using water wetter too.

are there any other tricks? what does your car run at "normally"?

 

Do both fans work? Do you have your undertray installed and fully ducted?

 

Both fans work... there was no undertray from when I bought the car and I haven't got a chance to fab up all the ducting for all my parts yet. New intercooler, radiator, bumper, intake, things like that.

 

are they working on high speed though? seen those pos recall patch kits mess with the fan controls. turn the A/C on and see if the fan speed increases(A/C does not have to actually be functional).

 

You have a problem with the coolant system. A vented hood won't fix that problem. You probably have lots of air in the system from the screw up removing the AST and not using the FC neck until later. Go re-read the coolant system thread and get yourself a Lisle to run the car and get air bubbles out.

On a SMIC setup you should be cruising in the mid-upper 80* C on the highway @ 60+ MPH.

Air bubbles cause high coolant temps

 

im not looking to fix my high internal temp issue with a vented hood. im sure it will help a lot considering i pop my hood and take a lap around the block at low speed and watch my water temp plummet immediately upon opening the hood.

i just pulled the water pump housing and filler neck off to replace the gaskets from a leak that magically sprung up so i'll be doing a "proper" bleed/burp when its all back together.

 

If you are presently running two pressure caps you are complicating your cooling system in terms of bleeding air out. Get an under tray as soon as possible and make sure both fans are working well. The lack of under tray can cost you an engine. Some may think 230 deg is okay but long term it is very bad. It's a greater problem under load at rpm like on a race car but still not good for street driving.

Paul.

 

im not running 2 pressure caps as i have the ast deleted and an fc cap on my filler neck.

is the undertray really that important? other than the obvious what purpose does it serve?

 

The air required to cool your engine needs to be directed through your radiator and oil coolers. In order to do this effectively the flow path must be 'sealed'. You are directing the air (Telling it where to go) or else it will go where is easiest for it to go like under the car instead of through the radiators.

With the AST deleted, you will still have air bleeding issues because of engine to radiator heights.

Paul.

 

i see. ill go and find one then... how is it held on? a bunch of clips or actual bolts?