'04 Odyssey Purchase - Might have been taken...

92saturnsl2

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A million thanks for all the responses so far. The compression test results are in, and while they look promising, they do more to cloud the issue than they do to solve it. I don't know how the cylinders are numbered on these engines, so I'll list the values from left to right, standing at the FRONT of the van, facing the engine. Rear Bank = 195 ~ 200 ~ 199 PSI Front Bank = 208 ~ 201x ~ 200x PSI I put an "x" where the suspected cylinders would be. This is where the oily mess appears where the cylinder head mates with the engine block. Again, I don't know the origin of the oily grime, but it does not appear to be coolant. The plugs looked fair, they seem to be the original NGKs that came from the factory. Idiot had no problem dumping $4,000 on new brakes, shocks, struts, motor mounts, any everything else the mechanic wanted to sell him, but he declined spark plugs when the dealer suggested them. Strangely, the two plugs where I noted the "x" (suspected bad cylinders) appeared to be cleaner than the rest, and the one at the end of the block had rust on the threads and smelled of coolant. While this isn't proof that the head gasket is bad, it's not a comforting observation either. Is it possible that there would be a bad head gasket, but not show up in a compression test? I should note that we are at 6,500 feet elevation here, so the compression values are a fair bit lower than what would be measured at sea level.
 
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Originally Posted By: 92saturnsl2
Timing belt stretched, not making good contact with water pump. Suggest replacement
Wow!! This is classic. Like others mentioned, check for gas in the AF. The old lady's civic had similar issues and it was the HG. It drove fine most of the time, but would randomly run hot, and smell of AF at times.
 
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Yes it is possible. I had a friend with a HG leak that was tiny, only showed up after we did a double-length exhaust gas test. Was hard to detect even once the head was off but it was definitely present. Caused long highway runs to end with a bubbling overflow tank and cursing. Passed every pressure test performed, only reared it's head when fully up to temperature and fully hot and then slowing to speeds requiring the fan.
 
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Originally Posted By: 92saturnsl2
A million thanks for all the responses so far. The compression test results are in, and while they look promising, they do more to cloud the issue than they do to solve it. I don't know how the cylinders are numbered on these engines, so I'll list the values from left to right, standing at the FRONT of the van, facing the engine. Rear Bank = 195 ~ 200 ~ 199 PSI Front Bank = 208 ~ 201x ~ 200x PSI
1 - 195 2 - 200 3 - 199 4 - 208 5 - 201 6 - 200 Do you have an air compressor? Does your compression tester have a removable hose with an air fitting on the end? You can put each cylinder at TDC and inject 50 psi of air pressure into them with the engine hot and radiator cap off. If you see bubbles, a head gasket is bad, or a head is cracked. No bubbles, high probability heads and gaskets are good. This will also locate the bad cylinder/s.
 
An easy way to check if cylinder gasses are getting into coolant, without using all sorts of tools, is to start a cold engine (preferable that sat overnight), rev it to about 3k RPM and hold it there for about a minute. Shut the engine off and remove the radiator cap. If you hear pressure being released, you have a head gasket leak. Also a note, usually the cylinders that have the coolant leaking into them will be extremely clean and carbon free, including the spark plugs. What's done is done, the car is purchased, but I would take it for an hour or so drive (idling and driving around the block is not enough), possibly do some higher rev accelerations to see how everything behaves and get on that warranty if you notice anything.
 
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Iowa
Originally Posted By: KrisZ
An easy way to check if cylinder gasses are getting into coolant, without using all sorts of tools, is to start a cold engine (preferable that sat overnight), rev it to about 3k RPM and hold it there for about a minute. Shut the engine off and remove the radiator cap. If you hear pressure being released, you have a head gasket leak. Also a note, usually the cylinders that have the coolant leaking into them will be extremely clean and carbon free, including the spark plugs. What's done is done, the car is purchased, but I would take it for an hour or so drive (idling and driving around the block is not enough), possibly do some higher rev accelerations to see how everything behaves and get on that warranty if you notice anything.
Yes, a good, quick test. Passing doesn't clear the engine, but failing generally means you're hosed- but make sure to follow up with something more definitive like the combustion gas chemical test. A pass there still doesn't clear you, but a fail means that you're hosed for sure. I've had two do this in the last 2 weeks... Including my own.
 
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Hello, MAY THANKS to exranger06 for posting the video of the exhaust gas leak detector. I had never heard of that before. But man, even though I learned something I'll always wonder why these super helpful people make a 6 minute video when 1 was all that was needed. Kira
 
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first, let me say this is a great vehicle. I watched as a durango plowed into the back left door, full T-bone, at 35 mph, no brakes. I watched my wife and kids in front of me get knocked across the intersection in our '02 ody. They all walked away from it with only bumps and bruises. both vehicles were totalled. The Ody, while mangled down the left side, still drove straight as an arrow until it got turned in to insurance. So--- to me it's worth your effort to go through this stuff. A small HG leak will not show on a compression test. IMO, your best bet is to use the exhaust gas sniffer, or really to pay a mechanic to do the sniffer to verify if there is a problem. If so, do you have any of the 90 days left to go claim warranty? I've driven vehicles for a long time with HG leaks. Until fluids start mixing, I found I could reliably do all my around town drives without issue. So, depending on your use pattern, if it has a problem you could live with it for a while. I've known two of those V6s. Neither has given me a lick of trouble, and neither have the 5spd transaxles bolted to them. Both trans get amsoil ATF and an auxiliary in-line ATF filter and knock-on-wood have been fine.
 
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texas
Originally Posted By: 92saturnsl2
A million thanks for all the responses so far. The compression test results are in, and while they look promising, they do more to cloud the issue than they do to solve it. I don't know how the cylinders are numbered on these engines, so I'll list the values from left to right, standing at the FRONT of the van, facing the engine. Rear Bank = 195 ~ 200 ~ 199 PSI Front Bank = 208 ~ 201x ~ 200x PSI I put an "x" where the suspected cylinders would be. This is where the oily mess appears where the cylinder head mates with the engine block. Again, I don't know the origin of the oily grime, but it does not appear to be coolant. The plugs looked fair, they seem to be the original NGKs that came from the factory. Idiot had no problem dumping $4,000 on new brakes, shocks, struts, motor mounts, any everything else the mechanic wanted to sell him, but he declined spark plugs when the dealer suggested them. Strangely, the two plugs where I noted the "x" (suspected bad cylinders) appeared to be cleaner than the rest, and the one at the end of the block had rust on the threads and smelled of coolant. While this isn't proof that the head gasket is bad, it's not a comforting observation either. Is it possible that there would be a bad head gasket, but not show up in a compression test? I should note that we are at 6,500 feet elevation here, so the compression values are a fair bit lower than what would be measured at sea level.
pictures of oily mess please, i think your worrying alot over something simple like a leaking valve cover.
 

92saturnsl2

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Originally Posted By: cptbarkey
pictures of oily mess please, i think your worrying alot over something simple like a leaking valve cover.
I will try to post pics when I get home. The more time I spend with this vehicle, the more I'm inclined to fix whatever is wrong with it. It drives like a brand new car and is in such great shape for an older vehicle. Plus, the owner has dumped tons of money in new parts over the last couple years (brakes, suspension, cooling system, etc.) All signs point to the engine being in good shape mechanically, but there's still the possibility of a very minor head gasket leak-- I only say this because the plugs I pulled out of those cylinders were noticeably cleaner than the rest. They were plugs with 140k miles, so the difference was very evident. I believe this engine has an open-deck block, so compression gases entering the coolant in one (or more) cylinders is a very viable mode of failure. The compression test results, lack of overheating (at present), and engine performance all tell me that the leak (if there is one) is very small / minor. I do agree I need to check the coolant for exhaust gases. I know there's the test strips you can buy, and I intend to do that. I will definitely post the results when I do this, but it might take a couple days to get ahold of the strips. I drove the van into town yesterday (about 35 miles each way) and it performed flawlessly. The sweet smell of coolant is very evident, however, once the van warms up. The coolant level in the overflow tank hasn't moved noticeably. When I got home, I spotted a small amount coolant collecting on top of the splash guard (the plastic thing under the radiator that keeps water and stuff from getting in the engine). It can't be 100% sure this isn't from me opening the radiator cap and having coolant drip down there, but it was far enough away from that, that I think the radiator or something down there is leaking. Coolant temp was a consistent 180F as measured on the scan gauge while driving. In traffic it would creep up to 190-195F, but never above that. Here is my hypothesis, given all my tests and observations: a) van overheated from a leak in radiator (or elsewhere). Leak origin still yet to be determined. b) owner overheated van c) shop starts throwing parts at it (hoses, thermostat, radiator cap, water pump) d) numerous overheats (severity unknown) in between repairs leading to a small leak in the headgasket and/or warped head. It is known that the van first had signs of overheating from at least June, 2014, and these went unrepaired for at least three months while the two shops spent time and money throwing parts at it, and repeating repairs the other had done. I don't think the owner was negligent or that the van had poor maintenance or was abused in any way. I just think he was rather clueless, and brought the van to incompetent mechanics who did not take the time to diagnose the problem accurately. That may have caused him not just a ton of money, but a head gasket as well. Time and more diagnosis will tell... we are taking the van up to Denver this evening to the Avalanche game. It will spend a fair bit of time in traffic I'm sure, maneuvering through the parking lots and such. Fortunately I like turning wrenches as a hobby; this has been a neat little journey learning about this Honda. I'll be happy with my purchase so long as I'm not replacing an engine or having to dump tons of money into it.
 
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For minor head gasket issues, sometimes just re-torquing the head bolts will fix it, at least for a while. This worked for my brother on an entirely different V6 engine (Vulcan). He found one head bolt to be loose (as in could turn it with finger tips). Tightened it up, no more problems. For some engines this is a trivial job. It's a bit more work to tear down to the valve covers on a Honda 3.5L V6 compared to a pushrod engine, and with the SOHC, the cam shaft or rockers might be in the way of some bolts. Still it's something a home mechanic can do and if you're willing to experiment before committing to a head gasket job, might be worth a try. There are some good photo guides on Honda specific web forums. One more thing... have a backup plan in case you find something horrible in there. smile
 

92saturnsl2

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Van drove to Denver just fine and performed beautifully. Spent about 20 minutes in heavy traffic navigating our way out of the Pepsi Center parking lot after the game, stop and go the whole time. Never overheated, never gave any inclination that there was anything wrong. Oil is fine, coolant level is fine, though the sweet coolant smell has persisted. I am going to try the combustion gas in coolant reservoir test this weekend, along with pulling the new plugs in the suspect cylinders to see what they look like.
 
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It's possible it might just have a leak, the PO never checked the level and it would start overheating (or the gauge would show it was getting hot) whenever it was low.
 
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It's possible that there's an external head gasket leak. My college roommate had this with a 305 in his Monte Carlo SS. It would seep coolant down the side of the block, but the cylinders themselves were okay. This could be related to the rusty fasteners I think I remember you pointing out. I wouldn't normally draw a correlation with rusty fasteners on the outside of the block and a head gasket or coolant leak internal to the block, but I'm sure that stranger things have happened. You might consider dropping in some cooling system tablets marketed by General Motors and (I think) Subaru. These are organic-based pellets designed to seal very small leaks or block porosity. They usually can't hurt anything. I'm also not sure I've seen it mentioned yet -- the coolant overflow tank is just that: an unpressurized overflow tank. It's not a pressurized expansion tank. Oh -- I also second the notion that if the system is not properly bled, there could be residual air in it from a previous drain. There's a detailed 30 minute procedure in the service manual for bleeding these (vehicles with rear HVAC).
 
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Originally Posted By: Hokiefyd
It's possible that there's an external head gasket leak. My college roommate had this with a 305 in his Monte Carlo SS. It would seep coolant down the side of the block, but the cylinders themselves were okay. This could be related to the rusty fasteners I think I remember you pointing out. I wouldn't normally draw a correlation with rusty fasteners on the outside of the block and a head gasket or coolant leak internal to the block, but I'm sure that stranger things have happened. You might consider dropping in some cooling system tablets marketed by General Motors and (I think) Subaru. These are organic-based pellets designed to seal very small leaks or block porosity. They usually can't hurt anything. I'm also not sure I've seen it mentioned yet -- the coolant overflow tank is just that: an unpressurized overflow tank. It's not a pressurized expansion tank. Oh -- I also second the notion that if the system is not properly bled, there could be residual air in it from a previous drain. There's a detailed 30 minute procedure in the service manual for bleeding these (vehicles with rear HVAC).
Good catch Expansion tank and overflow tank are different. One is pressurized, one is not. Former includes the radiator cap, latter has a tank cap and a traditional radiator cap. Former you'd put the tester into the expansion tank, latter you'd do it on the radiator cap.
 
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Are you checking the coolant level the same every day when the engine is stone cold and level? That is the best way to check it; mark the overflow with a sharpie when it's stone cold. Also check the level in the radiator; if there is a leak somewhere that breaks the vacuum created when the engine cools down, it won't suck the coolant from the overflow back into the radiator.
 

92saturnsl2

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The final verdict is head gasket failure on the front driver's side cylinder. I discovered this when I pulled the plugs while the engine was warm (yes, I know not to install plugs when the engine is warm because of the aluminum head/threads). On that cylinder, there was visible steam escaping through the spark plug hole, and it covered the spark plug tube in condensation in a very short time. There's definitely coolant getting into that cylinder. Last time we drove it to Denver it started overheating-- temp would go up to 240F or so on the scan gauge, but only when it was under heavy load like going up a hill. Downshifting (increasing RPM) would bring the temp back down. When I got home, this is when I discovered the radiator was about a gallon low on coolant, even though the overflow is full. So the van is losing coolant with no visible leaks; I'm having to top off the radiator every few drives. As the above poster mentioned, it's not pulling in coolant from the overflow, presumably because there's a leak into the cylinder, so that breaks the vacuum required to pull the coolant in. Not exactly good news, but at least I have some closure to this and can plan a repair that will make this thing reliable. Has anyone tackled a head gasket job on this engine (J35A4)? Does it make sense to do the rear head gasket since it is not exhibiting any problems?
 
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Head gaskets are not that big a deal on this engine. Do both at the same time and put this thing to bed. You have to remove the timing belt and LIM anyway so its not a big deal to grab the rear head. Have the heads done at a machine shop, have them dye or vacuum/pressure inspected for cracks especially around the valve seats and pockets and on the outside behind the exhaust manifold region. Do not skip this step! Nothing like doing the gasket only to find out there is crack in the head and it was all for nothing. Have them planed flat and check the block with machinist a straight edge and feeler gauges. Use OE gaskets only on this engine. IIRC Honda revised a few of the gaskets, if they did a revision on the HG the aftermarket might not be current. If i can help you just PM me i have all the FSM for these on DVD and the actual books for every part of the vehicle. These are just some thoughts, i have not looked at the books just general info. I have the exact procedures if you need them.
 
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