STILL with the overheating! P250

[jprestonian]

... and I think it's the head gasket (a real shame, since we just replaced this in May, 2009!).

My new gasket arrived today (ordered because I've been bartering a bit with the shop for work). It is NOT cardboard. It is black, and appears to be some type of synthetic material, or perhaps metal...! And it is two-layered, and has what appears to be two brass grommets holding the two layers together. Could they have further determined that the gasket they sent last year was also somehow inadequate, hence the change...? Or [fill in the blank]...?

Any ideers, gearheads?  How 'bout pointers on getting the chain tensioner right when I tackle this on my own, as that's what the guy last year goofed on, causing me another five weeks of downtime.
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[wordslinger]

...damn, jpress..heating again???

[jprestonian]

Yeah. If I keep it under 50mph (which is a lot of my normal riding, really), I can go two weeks between burping sessions. At that point, the gauge will read full HOT for a minute or more when idling in traffic, and I just don't wanna let it go like that very long.
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[wordslinger]

..you reckon there is a "flatness" issue with your head??

..that the gasket can only compensate for, for so long a time??

[jprestonian]

..you reckon there is a "flatness" issue with your head??

..that the gasket can only compensate for, for so long a time??

It's a thought, sure, but the mechanic said he used a feeler gauge to check it, and it was well within spec... or so he said. Of course, he didn't get the cam chain tensioner right, causing the chain to break a week later, so... 
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[wordslinger]

...i know, from your posts, that you trust your guys at the shop....

..however, if you keep blowing head gaskets, then there MUST be a flatness issue...

[wordslinger]

...considering that there isn't a temperature or coolant flow issue....

[jprestonian]

Well, this would be the second one, and the breach is on the inside (towards the water jacket), this time, as opposed to the outside (causing a massive oil leak, last time).

I'm thinking because of the changes in the gasket they supply that they may have identified a materials and/or design flaw that they're trying to correct via the "upgraded" gasket. Read my post over there, and see what you think. I'll try to get a photo of the gasket to include in the next day or two, but this new one looks a LOT more serious than the last one.
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[jprestonian]

...considering that there isn't a temperature or coolant flow issue....

Well, there is a temperature issue -- hot exhaust gases building up in the cooling system will do that.  :)  Pockets of gas get trapped near the thermosensor at times, causing the thing to go off the scale. Overall, it may not be all that hot, though. Still, you gotta get that crap out of the cooling system. Leaving it in there can cause cavitation on the pump impeller, beating it to death, over time, etc. Plus, you just don't wanna have to deal with it all the time, right?  I mean, this is a quality product, reportedly.
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[wordslinger]

..once you remove any "air" that would create cavitation in a closed loop system, then it should be gone forever..unless there was an opportunity for the introduction of more "air"..

[jprestonian]

..once you remove any "air" that would create cavitation in a closed loop system, then it should be gone forever..unless there was an opportunity for the introduction of more "air"..

Right -- and what I'm theorizing is that I'm burping most or all of it out every two weeks... but it's coming back, 'cause it isn't air. Instead, it's gases being introduced into the water jacket by a very small breach in the head gasket.
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[wordslinger]

..i agree...it's the same effect...and that leads back to craftmanship of the two surfaces...

[Hoolander2]

What happens to the level in the reserve tank, Jpres?  Does it go up, down, stay the same?  I mentioned once before I thought it COULD be just a leak in the hose that goes to the reserve tank. My theory goes like this: Engine warms up and coolant expands and sends a little overflow to the reserve tank.  Then, normally, when it cools after shut off, that same amount of fluid gets sucked back into the main system by the vacuum created when the coolant cools and shrinks.  If there's a tiny air leak in that hose, it could be sucking air back into the system instead of the fluid it sent to the reserve tank.  

It would have to be such a small leak as to allow air IN but not coolant out.  But since that tube doesn't have pressurized coolant in it, you'd never have coolant come out -- just air IN.

The possible air leak could be in the hose itself or at one of the clamps on either end.  

OR:  Same thing might be caused by a faulty radiator cap!  

I'd sure check these things before going for the gasket.
Good luckk and I sure hope it isn't the danged gasket!  

[wordslinger]

..hoolandr is right...have you replace any (all) hoses?

[jprestonian]

..hoolandr is right...have you replace any (all) hoses?

I haven't. Maybe I need to do a chemical test to detect exhaust gases before I decide to replace the head gasket, hm?
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