so i've got a little problem with overheating. It just started within these last two weeks (see post about low/even compression), but lately it's been doing it without the a/c on. If i drive normally, under 70mph-ish, it's okay. But if i boost or go above 80mph for a period, the needle starts to rise above half. I've got my a/c low pressure switch d/c so that i can turn my a/c on to use the fan, but not heat the condensor, and that seems to help a bunch. I'm wondering if maybe the radiator isn't flowing up to par, and the head gasket is still okay. Thermostat is opening fine, waterpump is flowing. Along those lines, is the atx radiator core any larger than the manual - should i need a new one i was wondering if that may be a sort of cheap extra-cooling help. I missed out on the fluidyne multi-buy, dammit! But yeah, any insight would be appreciated.

You may be getting heat soak from the turbo.

through the manifold? or emitting to the radiator? And it just started, continues now even if I get on it on a rather cool evening... I'm sort of inclined to think it's the head gasket, as I'm hoping it's not a small crack in the head that's passing exhaust gas under high cyl. pressures. May have to do a dye test on that one

Originally posted by justins71
Along those lines, is the atx radiator core any larger than the manual -

It is a bit larger. By how much IDK :shrug

Originally posted by cs82685

Originally posted by justins71 Along those lines, is the atx radiator core any larger than the manual -

It is a bit larger. By how much IDK :shrug

It's larger, but that extra space is for the integrated oil cooler, you're not getting any extra cooling.

so the extra size is only the endtanks... dammit. Oh well

So I think I found the gremlin - radiator cap. It was holding pressure, enough to harden the upper hose, but when I tested the cap up to 16psi it immediately fell down to about 4. Had some issues with tester tool before on overflow tanks so I did about a dozen tries - all consistent. Got a new cap and it held perfectly, so I think I was in the wonderful world of vapor lock and boil-over, then low coolant, vapor lock, boil over, that whole vicious cycle. We'll see how it goes during rush hour traffic heading home tonight!

glad to see you found it!

well unless there's still air pockets it was doin fine most the way home, but towards the end it started to spike up again... maybe i'll see about havin the radiator rodded out or something. looked for the dye kit the other day at parts store but they were out, or i'd have checked that yesterday to rule out head gasket - so i'll still have to get to that.

So it was the radiator after all. Pulled it last night, and looked into the tank openings and could see a one (which by the way the core is twice as thick, and it's OEM replacement...sweeeet) and a thermostat while I was at it just to be on the safe side, then once I had it I took off the endtanks of the old one. I swear, of the 40 or so tubes only about 4 or 5 were NOT blocked off! I have no idea how it made it this long - unless when it got pretty hot some deposits became dislodged and made it worse. Anywho, I beat the crap out of it on the way home last night, and the needle never budged above the half-mark. Problem solved, and no head gasket issues as far as I know!