XC 90 Low coolant message

I have started getting repeated "low coolant, stop safely" messages. Every week or so, car loses coolant from maximum to minimum markers in
reservoir. I see little or no coolant on garage floor. Car does not run hot. Qualified Volvo mechanic cannot find where coolant is going. Has run pressure tests, checked for leaks, replaced reservoir, etc. No luck. Suggestions appreciated. Thanks. Don
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On 01/11/2013 23:21, Don Tuttle wrote:

Have you checked the 'oil' level?
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Cheers,
Roger
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I check oil regularly because car has used some oil for a long time. I add some (not much) between regular maintenance check-ups. Car runs slightly rough for a few seconds first thing in the morning, if that might be a clue. All 5 ignition coils recently replaced. Thanks for help. Don
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On 03/11/2013 13:17, Don Tuttle wrote:

I suggested checking the oil level in case it was going *up* - i.e. coolant somehow getting into the oil sump, which might have explained the loss of coolant.
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Roger
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On 11/3/13, 9:31 AM, Roger Mills wrote:

Also, if coolant was getting into oil, the oil would likely have the color and consistency of a chocolate milkshake. BTDT.
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But a very MINOR headgasket leak may leave absolutely no visible trace in the crankcase - yet would cause a limp on startup - and COULD put enough glycol into the oil to damage the engine, even without enough water to emulsify the oil.
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wrote:

The rough start points me to a slight head gasket leak How many miles on this beast, how old, and what overall condition?? If otherwise in good shape replace the head gasket. If it is getting a bit sketchy and /or you want to stretch it's life for a year or so, get a good cooling system sealer and follow the directions. Knights Alumaseal has alwoys worked well for me, or for a "last ditch" repair use "irontite" boiler sealer. I say last ditch because it CAN be a bit of a mess if/when you go to do a full repair later - but the stuff REALLY works.
I'd try the knights to see if it solves the rough start and the slow leak at the same time. If it does, you KNOW it's a headgasket and you can decide to live with the "fix" or do a full repair.
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Oil level does not seem to be going up. Oil on stick seems to be of normal look and consistency.
Re mileage, age, condition: 158,000 miles, 9 years old, overall condition excellent. After I started measuring mileage following reservoir fill-up, first reading 178 miles, second reading 145 miles.
I took this group's ideas to Volvo mechanics (independent shop doing Volvos exclusively). They recommend against putting any sealers, additives, etc. like Alumaseal into engine, but will do so if I want. They are preparing a head gasket estimate. They have suspected that was the problem but have been unable to confirm and did not want to recommend major repair without more evidence. Sounds like trying Alumaseal would be a good indicator. Thanks for all help. Don
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wrote:

Another test is with the engine hot, remove the plugs and put a pressure tester on the rad. Keep the pressure pumped up as the engine cools - maintaining pressure untill the engine is fully cooled. C check for moisture in each cyl when you crank it over prior to replacing plugs and restarting the engine. MIGHT find where the leak is.
Also check the colour of the plugs for any difference between cyls. If one is whiter or cleaner than the rest, suspect that cyl.
Often a retorque of the head bolts will also solve a minor leak (at least for a while)
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Alumaseal instructions say pour contents directly into radiator. OK to pour Alumaseal into the reservoir? Thanks, Don
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wrote:

No - that won't do any good - it needs to circulate through the system. If you cannot put it directly into the radiator, pull the top rad hose and dump it in, or a heater hose high up in the system. Then close it up and run it as per instructions. Top up the system through the reservoir.
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I did that. Before Alumaseal, I was getting "Low Coolant" message at 150-175 miles after reservoir fill-up. Since Alumaseal, I have gone 475 miles and although coolant is slowly dropping, it is not down to Minimum level yet, and I have received no "Low Coolant" message. Start-up is also not nearly as rough. Will live with the Alumafix until I can budget full repair. Thanks for all help. Don
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