Antifreeze in IAC =(

[SpeedToBleed]

So my P5 stopped holding it’s idle and check engine light came on with code P1504.
Code P1504 means there’s a problem with the Idle Air Control Valve.
So I got one at the junk yard today but when I pulled mine off to replace it I noticed it had antifreeze in it and in the vacuum line leading to it.
Also my antifreeze is showing low now. So I’m thinking I might have a blown gasket somewhere. (bang)
Any ideas what gasket this could be? Or could it be something else? How hard of a job is this going to be to fix? Any other ideas / tips?
I did just do a mod on my car a week before this happened but I would rather not give any details about it right now. I don’t want to be pointing fingers since I really don't know if that caused the problem or not.

 

[P-Funk!]

The throttle body has a coolant line and passage to prevent icing in winter.

Bypass the t/b with a hose connector and see if that stops the coolant on the IAC...

 

[SpeedToBleed]

Thanks for the reply. I traced the lines out, and it actually is a coolant line that goes through the IAC.
Replaced the IAC and so far so good.

 

[i12drivemyMP5]

This reminds me I need to get off my ass and do the bypass mod since I has no cold enough often enough weather reasons not to & the fact that I've had the sleeve deal to do it for over a year. Cpt Lametastico action.........

 

[P-Funk!]

Yep! I live in MD and we get 10deg below once in a while - no icing issues since i bypassed mine years ago...

 

[slavrenz]

I think you'd have to be doing nothing but very short trips, days apart from each other, in 25 degrees below 0 in order to ice over your IAC valve or throttle body.

To the OP, go rent a radiator pressure tester and pressurize your system to check for a bad head gasket. If you're not overheating though, I doubt that's it.

 

[P-Funk!]

^nope - the issue of icing comes from driving in cold (<37 deg F) drizzly (high humidity) at highway (high flow) conditions. Ice collects on the inside (flowpath) on sharp edges and builds up quickly. Micro droplets (fog with an attitude) is the worst condition for icing. Think Denver CO.

Just starting the car on a cold day - there is no ice inside the intake system. Short trips don't dwell at high flow conditions.

 

[slavrenz]

^nope - the issue of icing comes from driving in cold (<37 deg F) drizzly (high humidity) at highway (high flow) conditions. Ice collects on the inside (flowpath) on sharp edges and builds up quickly. Micro droplets (fog with an attitude) is the worst condition for icing. Think Denver CO.

Just starting the car on a cold day - there is no ice inside the intake system. Short trips don't dwell at high flow conditions.

That's a valid point, but wouldn't running the engine at highway speeds create enough heat under the hood to dissipate any ice buildup? I was thinking more along the lines of a scenario where the engine never fully warms up and has a chance to melt the ice.

 

[ganzhimself]

I bypassed the coolant line on the throttle body on my 03 P5, ran it through last winter and some very cold temps. Never had any problems. With where the TB is I don't see how the charge air wouldn't be warm enough by the time it hit the throttle body anyway. Well, on a warm engine anyway. Anyway, like I said, plenty of days below 0 and a few well under -20 with windchill and no issues.

 

[P-Funk!]

Think stock.

The cold air from in front of the engne bay is quickly sucked in and through the t/b.