so the other day my check engine light comes on and the truck starts over heating.. ..ok. no big deal. just have someone pull the code.. ..well.. they say low flow on the EGR (i think that's the abbreviation). they tell me the thermostat was installed backwards.. ..of course they had already done the work not reading the note saying I just wanted the code. (could have saved myself $100) ..but. anyway. so i think after i drive away "backwards for the 3 years since i've owned it and *now* it starts having problems? maybe...." ..20 miles down the road the check engine light comes on and the temp needle starts heading up. ..so now I think the egr valve just needs to be replaced.. ..maybe? maybe.. ..but what about the fluid level that seems to drop ever so slightly inside the radiator even tho I haven't driven it in a couple of days??? ..so out of curiosity I pull the dip sticks for the oil and trans.. ..it was early. the light wasn't good, but did I just see a haze of green fluid on my trans dip stick??? ...what's this? head gasket or just something easy to fix. Would this bring about the "low EGR flow"? any ideas? ..don't tell me cracked block. ..i don't think I could handle that right now.. a head gasket it bad enough. there are a few too many bolts and crap to pull out for me to do it on a weekend never had done it before... but how does this get to the trans if that's really what i saw?

 

It sounds like you have an automatic. If so, then it has a cooler that lives inside the radiator. It is possible to develop a leak between the coolant and ATF systems. The fix is a new radiator.

 

Double check and if coolant is in trans, replace/repair radiator AND change trans fluid and filter. Until you said that about the trans, I was thinking water pump seeping or there are several coolant hoses that could leak.