Referring to the lump idle right after start? Yeah, don't have that at all.

Out of everything that it could be, yeah, I agree with you that it's the best bet. Might be a crack or something that won't get found until I have the empty bottle out and in my hands.

Yeah I was referring to that. Once it warmed up the engine ran fine with the exception of a random misfire here and there and a high RPM dead spot every now and then if I was really rowing through the gears to redline. But I just caught mine early, had I kept driving her it would not have taken long to fail completely.

Then I caught this even earlier....



...or it's just not the same problem :lol:

Possibly but I don't think so. I think it would show in the oil because once the coolant seals go there is nothing really from stopping a bigger leak from developing. I would start replacing the small stuff and go from there. Even if you end up needing a rebuild you can still reuse all the new stuff you buy.

Right. I was resisting buying new cooling parts with the chance that it wasn't going to solve anything and I was replacing good parts. But since that chance is going to happen anyway, just starting with the most likely.

If it's not the bottle and cap, then I'm probably going to order a new radiator, hoses, and water pump all the same time and do that all at once.

That is what I would do.

I didn't read through all four pages, but you can have a coolant seal failure without noticible contamination of the oil. In fact it's usually the case. It really depends on where the failure is. Typically it's on the combusion side and the coolant is consumed in the combustion process and doesn't have a chance to get by the side seals and mix with the oil.
With a coolant seal failure, the natural vacuum that forms when your engine cools after shut down is lost. When that happens, the coolant that expanded into the overflow bottle while the engine was at temperature isn't drawn back out after shut down. In my experience this is what usually causes the overflow bottle to 'overflow'....because coolant continues to be stranded after each successive drive. Sometimes it is pressurized from combustion gases but again, at least in my experience that isn't as common.
A slightly sweet smelling exhaust on cold start, stumbling idle for a few seconds after cold start, "white smoke" (steam) on cold start, boiling sounds or air getting into the system, loss of coolant with no visible signs of leakage and coolant that is contaminated by hydrocarbons are some other signs of a coolant seal failure. NONE of these symtoms by themselves are confirmation of that failure, but the more symtoms you have in combination, the more likely that's what it is.
If it is a failure, you don't want to let it go un-repaired too long. It can errode/corrode the walls of the coolant seal grooves and turn the side plate/iron in to a big paper weight.

To be honest, this is probably where you should stop. I could have solved it and you wouldn't have noticed? :)


No, this is not what is happening. Doesn't matter if the engine is hot or cold, I get overflow from ~110F to 195F, at only a slightly increasing rate. As I've noted already.


Coolant dumping out of the overflow and apparent air in the system are my only two symptoms. I do not have a single one of the others. Again, I've noted all of this already.

Yes, entirely aware of the engine issues from coolant seal failure. I am not interested in extending or just trying to eke by. I am taking forever diagnosing this simply because I don't need to have my 8 running. It's done 80 miles or so in the past month, and almost all of those are diagnosis trying to figure this out.

Not sure how to take this. But in the possiblity that I was rude somehow, I read through the thread. Didn't see anything that I really missed. :)
I interpret that as at 110 F. the coolant, especially the water, is expanding. As it gets hotter, the rate of expansion increases and it's running out the overflow. The only other possibility that I can think of is that the line running to the overflow bottle is pinched or kinked...forming a one-way valve of sorts. Those lines are often thinned walled. Probably not common but...
Just as one or two symtoms aren't confirmation, the absence of a symtom or two doesn't confirm you have in-tact seals. Besides, I'd bet you have some of the others. That's not including one I failed to mention...a failed "Champaign bubble" test.
Corrosion of the seal grooves is a matter of time, not mileage. Especially since you're running primarily water now. Sorry if that was obvious to you, but it might not have been to others reading this who don't have a warranty and might postpone the inevitable rebuild at the cost of an iron.

Regardless good luck with it. Hopefully this thread will help someone else down the line.

Perhaps a word misinterpretation then :) I didn't take it as rude, but it is often perceived as rude and usually stuff gets missed.

Yes, the liquid is expanding, but I am more inclined to think that it is either air in the system that is expanding at a much faster rate over-pressurizing the system beyond the limits of what the cap and bottle were designed to hold, OR the expansion is entirely normal and my cooling system simply can't resist the normal pressure levels.

Agreed. Absence of symptoms doesn't mean the issue doesn't exists. At the moment I am inclined to believe that my seals are fine due to the 2 tests mentioned so far that specifically check for that: The oil analysis for coolant and the coolant test for combustion gases. With one and not the other it leaves room for error, but no theory has been put forth with coolant seal failure that would NOT show up in one or both of these. Even your theory would have shown combustion gases in the coolant.

Understood. Housings are still dry (or only oil). If I can confirm coolant seal failure then the engine gets pulled for replacement, and I had already found a replacement engine to use until I can get a solid built up one.

Coolant bottle came in, then I broke that infamous nipple on the radiator removing the old one.

Got in new hoses from BHR and a new radiator from Mazmart, will be installing everything tonight, so every part of the cooling system will be "new" (water pump has 10k on it from the reman)

See where this gets us.


As a mod I probably shouldn't be creating yet another good guy thread for BHR or Mazmart, since people are already commenting on how much cool aid I must be drinking, but they came through for me again and I can't speak too highly of them. Stellar vendors. :) :icon_tup: :icon_tup: :icon_tup: :icon_tup:

gl riwwp

Oh no!!!

Well, postponing the rest of the re-install for tomorrow morning, but my cooling system was clearly suffering, and the flushes I was doing apparently were not really flushing everything. Including my old radiator feeling noticeably heavier than the new one going in. Several of the hoses were in pretty bad shape, and got brown water out of quite a few places that I had thought were previously flushed.

If anyone has any idea of how to flush the block itself with everything disconnected, I'd rather flush any crap out before making it a complete system.

riwwp, i typed some stuff for you in b@w but dont feel like re typing it here. check it

Will this help?

From my DIY:

http://www.flickr.com/photos/9krpmrx8/5774186942/

Sounds like you need access to a flush machine. You hook it up and let the car get up to temperature so the thermostat opens properly. It has a huge built-in tank that you fill with fresh coolant and some flush chemicals that grab all the excess gunk. The pump pushes the new stuff through and the old stuff is collected in a separate tank. Everything can stay pressurized during the flush. You would be amazed at some of the stuff we would get out of cars that claimed to be hose flushed. If you don't run the fill tank completely empty the car usually finishes up with no air bubbles and only needs a top-off.

Agreed Pieper, it's largely the conclusion I came to as well. I need a more thorough flush than I can do in my driveway.

Everything is back together, just gave the 8 a shakedown of a few miles with runs up to redline and stuff, bottle holding pressure, slight coolant level drop and I can still pick up on a few bubbles here and there, so still needs to finish getting burped. Nothing dumping from the overflow.

My wife is running some errands with it right now (with strict instructions she knows to follow), and it should be burped pretty good by the time she is back and I will top off again. Tomorrow taking it to work, so ~150 miles. I'll get a shop to power flush it and replace with actual coolant, possibly Friday morning. Hose water in there right now for convenience until I'm sure the problem is fixed.


Pretty sure it was a combination of old hoses, old radiator, old bottle, all getting filthy and slowly clogged and unable to really hold pressure. Hardly surprising after 7 years and 106k.

Good luck to you. It's always nice when throwing a couple parts at your car fixes things the first try or two.

"A couple" :lol:

No, the water pump is new from the reman, the thermostat has ~400 miles on it, and every other part, including hoses, bottle, cap, and radiator, is brand new installed between last night and this morning.

I threw everything at it.


I'm just glad that the condition of everything certainly appears to justify replacing everything. Even if something I replaced wasn't the problem, I'm ok with it because it would probably become a problem in short order otherwise.


I'll give it the next few days before being at peace in my head that it's fixed. :)

When I read this thread it makes me think of some of the weird nightmare issues I came across when I was a mechanic. Round after round of throwing parts at some problem that bides its time and keeps coming back. If you ever come across a Ford with a V6 that has a lean code, then run away screaming. FWD Mercury Cougars and Windstars haunt me in my sleep.

How did this work out? I am having similar issues. The car is not overheating, but I believe too much coolant is coming out of the overflow tank. Fans come on as usual. The issue started earlier this week when the light came on indicating it was low so I filled it to full with 50/50 mix and ran it for the day...i could smell coolant every now and then at idle and when I got home I saw that it had been sprayed out making a mess. Today I added some more to the full line and some came out but didnt empty out.Maybe a notch below full when hot but still could see that some spilled hit the fans and made a bit of a mess.Now that its cooled some hours i could see its somewhere between low and full The overflow tank is new had it replaced about 2 months ago due to a break of the opening. I swapped back to the oem cap from a buddy club one today so maybe something will change... oh and i got about 30k on replacement engine from Mazda.

It's all detailed here :) All the troubleshooting steps, the tests and their results, and what ended up fixing it.

Could be several things. Read through the thread.