I posted a week or so ago about a used Odyseey the girlfriend and I were looking at. The van is a clean one owner vehicle with lots of service records noted on the Carfax. Appears to have been dealer serviced for the first 100k or so. Presently has 136k on the odo. During the test drive the vehicle performed flawlessly-- everything works right down to the power doors. Noted no oddities, leaks, strange noises or anything of the sort. Drove like a dream. Some online researched turned up lots of horror stories about the transmissions on these vehicles. This one exhibits no strange behavior from the 5 speed auto. We ended up talking the dealer down to 5k even, and had them throw in a 90 day warranty that covers major mechanical (i.e. serious internal engine defects and transmission failures). It does not cover gaskets, accessories or anything else, unfortunately. We drove the vehicle 35 miles home with no issues, but we did smell the sweet smell of coolant, which we didn't observe during the test drive. Coolant reservoir was and is still full. After arriving home, we unlocked the glove compartment only to discover a horde of recent service records that were previously unknown to us. These records go back to early 2012, and after looking through them, it's clearly why the previous owner bailed. The two shops they had been taking the van to were ripping them off left and right. They put about $6k into the van in the last couple years, some legitimate repairs, some I feel weren't. The last dealer service had a whole laundry list of repairs they wanted to do (typical dealer stuff)-- it appears they were turned off by the dealer prices and started going to indy shops. That's when the trouble seems to have begun. Complaints of overheating showed up in 2013 after they did the major 120k service which included water pump, timing belt, etc., about $1,400 all told. When overheating symptoms were brought up, the first shop did a coolant system flush (used the wrong coolant, generic green antifreeze), full tranny service, thermostat replacement, hoses, maybe some other things I can't remember. In June, 2014, the van was brought in again for overheating, the shop wrote "van has original timing belt. Timing belt stretched, not making good contact with water pump. Suggest replacement." Note that this is after they had the 120k timing belt service done. They still elected to have the water pump replaced a second time. The van went to a different shop in Sept. 2014, at which time the diagnosis was "observed external coolant leak from cylinder head. Recommend replace cylinder head gasket, mill head if warped." Each time they took it to a different mechanic, they'd suggest things that were done in the last 6 months by the other mechanic such as transmission service (claiming that the fluid is dirty), brake fluid dirty, power steering needs flushed--- when they'd already had it done recently. It was quite comical, but became clear why the PO gave up on the van. I spent quite a bit of time with the van yesterday trying to sort out what is working and what is not. I got the van *good* and hot, letting it idle and driving it around the neighborhood for awhile. No overheating, temp got as high as around 210F on the scan gauge, but would go down when the fan came on. I observed great coolant flow through the radiator, fans are coming on around 205F as they should, and come on with the A/C compressor like normal. I can see where they spotted a leak around where the front cylinder head mates with the block (rear cylinder head is squeeky clean, I could eat off the thing), but this is not a coolant leak-- it's thick slime like an oil leak. I rubbed around in the grime and smelled it, it does not smell like coolant and does not have that consistency. The amount of oily grime leads me to believe this isn't an active leak (it's not making it's way down to the oil pan, and not leaving spots in the driveway). It's more along the lines of what happens when you miss the fill hole when you add oil to your car. Here's the only two thing I observed, and both scare me, but I can't make a definitive diagnosis on these things alone: a) Bubbles in expansion tank-- not a lot, and not consistent, but I can't remember seeing this in other vehicles. Green coolant in expansion tank has a brown sheen to it-- Not the nasty mess you get when oil mixes with it, but does look like maybe combustion gases are mixing with the coolant? What I saw flowing through the radiator looked very clean, so this might just be crud that's accumulated in the overflow. Hard to tell. I swear the coolant smells like exhaust, but could just be my imagination, given that I was in the garage for 45 minutes with the engine running (with plenty of ventilation, doors open and fans going of course . b) Changed oil and saw tons of metal at the bottom of the drain pan. *But*, I had just done a transmission service on my '85 pickup, so I last had gear oil in the drain pan, so this could very possibly be left over from that. I took apart the oil filter (a generic Purolator)-- the dirty side was, ahem, dirty... black crud coating the filter material, but certainly not the amount you see when you have a spun bearing or something else nasty going on in the engine. Clean side of filter was extremely clean. I haven't cut open enough filters to determine whether the accumulated crud is normal or not. The oil was brown, not the metallic silvery or copper sheen you get when engines begin to self-destruct. I still think there was enough crud in the filter and metal in the drain pan to be a cause for concern, but still not the smoking gun I was looking for. What I think happened is that the owner drove for 15k miles with the engine hot or overheating and it took out the headgasket. Can't say that for certain, but something must have prompted the owner to take it in for overheating, and it's clearly a problem that persisted for some time. The rest of the van is in good enough shape that it wouldn't break my heart to have to do a head gasket job on it, but I still worry about the overall condition of the engine. My next step is to observe with a scan gauge the temperature during different driving conditions, and a compression check. I suspect it's not overheating because it's winter out, even though it was a solid 50+F yesterday when we drove the vehicle home. Anything else you guys would do as a test? I know absolutely nothing about these engines, and what symptoms they usually exhibit when a head gasket goes, or how common this is. I'm hoping some of you guys on this forum can help fill in these blanks for me, and help guide me toward figuring out this mess! The warranty I bought doesn't cover head gaskets, but if it were to throw a rod tomorrow, it *would* cover that, but only for 90 days, 3,000 miles. Not exactly piece of mind, but it sure is better than having nothing at all. Interested to see what you guys think, and where I should go from here!