AlbertaBeef Posted July 8, 2018 Share Posted July 8, 2018 (edited) So yesterday my car decided to overheat ... during city stop/go driving on a 32C day while driving somewhat agressively. There was bubbling/boiling coolant in my overflow tank, and a loss (from overflow) of coolant in my system - about 2L in total that I had to refill once it cooled. Trying to diagnose the issue ... The lower rad hose starts to get fluid moving when my temp reads about 85C ... so I don't think it's the thermostat (which was replaced last summer, about 6,000km ago). The radiator fan seems to be engaging where/when you expect it to ... If I have the engine off but turn the ignition on (while hot) fan kicks in right away, so relays, etc. seem to work fine. Also, there's no leaks found under car EXCEPT that one time yesterday when it was boiling over. Here's why I'm wondering about the head gasket ... I had coolant in my overflow today after a test drive, (though not boiling in the overflow) which did NOT get sucked back in while cool. Also, my oil dipstick is pretty brown (see vid link, below), yet I only have about 500km on a fresh oil change of 5w30 Castrol Edge Extended-Performance full synthetic oil - so I find the colour suspicious. (Though truth be told, I seldom look at my dipstick within the first week or so after an oil change, so can't tell you what it normally looks like at 500km.) That being said, the coolant in my rad is PRISTINE. Not a spec of contamination in the rad, hoses or on the cap. Also, there is no white smoke whatsoever, so I am somewhat confused. Does anyone have any suggestions as what else to check? I'm going to throw a new radiator cap on and see if that makes any difference, but I'm perplexed... FYI EP82 4E-FTE, mostly stock except with WEPR manifold/downpipe and running 12psi boost. Generic 2-core honda aluminum racing rad. Edited July 8, 2018 by AlbertaBeef added video link Quote Link to post Share on other sites
lukEp Posted July 8, 2018 Share Posted July 8, 2018 Picture of the oil please. When you say brown like a milky brown or just transparent brown. Could possibly just be a failed rad cap. I've had it before on my old celica and all it does is open and dump water when giving it some beans, if I just drove normal it wouldn't loose a drop. Quote Link to post Share on other sites
AlbertaBeef Posted July 8, 2018 Author Share Posted July 8, 2018 8 hours ago, lukEp said: Picture of the oil please. When you say brown like a milky brown or just transparent brown. Could possibly just be a failed rad cap. I've had it before on my old celica and all it does is open and dump water when giving it some beans, if I just drove normal it wouldn't loose a drop. Hey there, oil is shown in the video link above ... I'm thinking it's just dirtier than I'm used to after looking at both the dipstick and the oil cap. Quote Link to post Share on other sites
lukEp Posted July 8, 2018 Share Posted July 8, 2018 Yeah that oil has not mixed with water yet. Is the heater blowing hot? I'd try rad cap first it's the Cheapest option. There should always be water in the over flow all the time, there is a max and min mark and it will transfer water from the rad to the tank- tank to rad as it gets hot and cools. Quote Link to post Share on other sites
AlbertaBeef Posted July 8, 2018 Author Share Posted July 8, 2018 44 minutes ago, lukEp said: Yeah that oil has not mixed with water yet. Is the heater blowing hot? I'd try rad cap first it's the Cheapest option. There should always be water in the over flow all the time, there is a max and min mark and it will transfer water from the rad to the tank- tank to rad as it gets hot and cools. It's hard to tell if the heater is blowing hot because it's unseasonably (30C or more) warm lately. But it *seems* to blow warm. I'm hoping it's just the rad cap. I went for a short trip again last night with no issues... here's hoping there was no damage with the previous days' overheating ... I don't plan to build/forge this thing until next year, so don't want to do a headgasket before then. Quote Link to post Share on other sites
AlbertaBeef Posted July 12, 2018 Author Share Posted July 12, 2018 Just to let folks know - it appears it was all due to a faulty rad cap. I've replaced with a newer 1.1 and it's working great. Using an infrared thermometer the temps on the rad hoses and thermostat housing after hard drive about 185-190F when I also have the A/C running. I can live with that. Quote Link to post Share on other sites
gorganl2000 Posted July 17, 2018 Share Posted July 17, 2018 i think the stock radiator cap is 0.9, but may be someone else can confirm Quote Link to post Share on other sites
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