[MLB]

A week ago I drove the car out of town, 250 miles each way, drove it around over weekend and drove it back to Madison with not a single problem or drop of coolant that I noticed. But the moment i pulled up into the driveway at home there was a flood of coolant , at least several hundred ml or so, that appeared to be coming from the expansion tank.


After washing the car I pulled into the garage where it has sat for over a week now. Just this morning I checked the expansion tank and it seemed almost full. When I unscrewed the cap there was enough pressure to raise the level up and overflow around the cap.


Got to be lots of air getting in the system somehow, right?

Oil level on the dipstick is perfect and where i left it. Oil looks fine, not milky or anything like that but I'm concerned.

Is there supposed to be a O ring or gasket around the bleeder screw?


Earlier this summer I took great pains to bleed the system with the front of the car slightly higher than the rear, engine running at a high idle, bleeder screw removed and a small recirculation hose fitted that transferred the escaping bubbles and coolant back into the expansion tank. Ran the car this way for over 20 minutes on the driveway. Maybe that trick didn't work?


Any ideas?

Thanks

--Michael

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[flash]

thermostat is likely sticking.

 

when you bled the system, did you make sure the fan was on high, and the heater was set to its highest temp?

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[MLB]

Yep, both fans confirmed, heater was on high/max. Thermostat was replaced with new OEM last fall,same part number as the original.

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[vliegwielolaf1234]

I would Check the coolant for  exhaust gasses , to rule out the headgasket .

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[MLB]

Vliegwielolaf - thats my thinking too.

Been wondering how long I would get away with not having to replace the HG.

Car is now @ 100k miles...

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[JWahlsten]

Michael,

 

I wouldn't worry about mileage at this point for the headgasket, I'd worry about age... Mine was in bad shape with just under 120k on the clock when I pulled it.  These things have been bathed in coolant and water for the last 20+ years, it's likely time for a change.

 

Look on the bright side, you already know how to time the cams...

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[chuaed]

I believe there is a drain plug somewhere near the left underside of the engine (quite possibly the bleeder screw you mentioned above), check that it is secure.  I was experiencing the same exact symptom where there wasn't any obvious coolant leaks but would always find a puddle of coolant on the garage floor after driving.  Pressure tested the cooling system and all seemed fine.  Noticed bubbling one time in the expansion tank and assumed it had to be the head gasket giving way.  Ended up buying a new head gasket but before any work was done, it became more obvious that the leak was coming from the drain plug and this took several months to manifest.  As it turned out, it was a simple tightening of the plug and no leaks nor drop in coolant level ever since.

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[MLB]

Thanks for the replies everyone,I plan to do a leak down test tomorrow night. But afterI got home tonight I removed the expansion tank cap, there was more overflow (150 ml?), and finally bubbles percolating up through the hose connected to the side of the tank until the reservoir was nearly empty. :0/

@ chuaed - do you mean a plug on the engine, and not the drain valve on the bottom of the radiator (driver side)? The bleeder screw I was referring to was the one at the top of the engine next to the front of the fuel rail cover,used for bleeding air out of the coolant system. My indie Porsche mechanic gave me one of the aluminum sealing rings (washer) for that bleeder screw so now at least that part is right.

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[chuaed]

I was told by my mechanic the coolant leakage was near the water pump. It was actually an outlet to the heating system, not quite a drain plug. Thats as much detail as I have actually. I should have probed..

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[vliegwielolaf1234]

i would stop driving until the problem is fixed , you do not want to heat it up to often and warp the head  , there is a limit to shaving the head to get it straight .

A new one used if availble could be costly .

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[flash]

check the upper and lower radiator hose temps after it has warmed up.  they should be different, but not one hot and one cold.  if they are, then you either have a stuck thermostat or a non-functional waterpump

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[MLB]

Ah yes, flash, i did check that using an IR thermometer gun, when i was bleeding the air before. Have notes somewhere but recollection was about 195-200 max temp with only about 5-10 degrees max difference between upper and lower when fans were running.

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[flash]

hmmm - it should be more like 20-30 degrees, but still, it means that things are flowing.

 

that then may mean a leak from a cylinder into a water jacket.

 

pull the spark plugs and sniff for coolant

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[MCL968]

With that number of miles and an original gasket, it would not surprise me a bit to find exhaust gasses in the coolant or coolant gasses in the cylinder. When I had mine done at 110k it was ready to go.

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[MLB]

OK leakdown test results are in. Now, I did this test on a cold engine which some might say invalidates the test, let me know, experts. But all cylinders passed with almost exactly the same leakage value, all in the "green zone" on the gauge. Thats good news, but now I still don't have an explanation about the coolant overflow issue.I think I'll order a test kit for detecting exhaust gases in the coolant since my local auto parts store doesn't stock them, but I've also heard of a "shadetree mechanic" test where you run the engine with a balloon sealed in place of the coolant filler cap, and if the balloon inflates before the coolant has time to warm up there's a problem.

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[flash]

what i think is happening is that when the engine warms up, the metal expands. when that happens, the head "lifts" and then the opportunity for slippage is there, and you could get chamber air into the coolant system.  high pressure air would pass before low pressure coolant.

 

however, there may be slight evidence of coolant on the spark plugs, which is why i said to remove and smell them.

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[MLB]

I forgot to mention that, I didn't notice any coolant smell from the cylinders or on the spark plugs. but it had also been a while since the engine was running so I suppose it could've dissipated?

While replacing the head gasket as a preventive measure seems extreme, I'm kind of thinking that's where it stands.besides I have a cross country trip in mind for next year not to mention trying a DE event at Road America. Better to replace it before it totally fails rather than after...

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[flash]

yup - logical thinking

 

so, as long as you are pulling the head, do a valve job and variocam/timing chain.  it's only a few hundred bucks, and will buy you more power and better fuel economy

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[MCL968]

That was my thinking, and by looking at the pads you can see how the engine was maintained before you purchased the car. I was impressed with how little wear my pads had. Given the repair and maintenance records that came with the car, it made sense that the pads would be in pretty good shape after 110k.

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[flash]

remember that whatever wear you see on the top pad, double it for the bottom one.  it can lull you into a false sense of security if you don't know that.

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