I'm only here looking for a bit of diagnostic help, because the vendors here are scratching their heads and seem a bit baffled.

I was hitting twistys a bit approaching Fontana, when I see the temp light pop. Pulled over immediately and shut her down. (I have an '06 R53 with only 20k) thermostat was replaced only a few months ago. When I popped the hood the coolant overflow tank hose was off (I'm guessing a pressure event as I checked very carefully before coming out + 400 miles motored before the problem) and she was pretty empty of coolant.

Compression is testing 120 in #1 and 2, 140 in 3 and 4... Plugs are white (lean with no tune) and the seems to be nothing mixing with the oil.

Pressure builds even at idle, pushing water/steam out of the cap.

For real.... Any ideas, questions, help would be seriously appreciated.

 

I don't see a question. clogged cooling system. What does the oil look like?

Vendors like Way Motorworks, M7 etc... are baffled?
Compression seems low IMO. Have a leakdown test done if you are that concerned. You might have a blown head gasket now or a warped head and depending on how long it overheated.

 

Oil looks good... I'll ask around about leak down tester. I'm concerned because I can't drive her for sure!

 

You have cylinder pressure bleeding on to your cooling system which mean you have a busted head gasket that separates the cooling system and the cylinder pressure. Another test that can be done also is to pressure check the cooling system.

 

Miles... Is that a "leak down" tester?

 

In very basic terms, a compression test tells you about your engine's ability to generate cylinder pressure, and a leak down test tells you about it's ability to hold pressure. Another way to think of it is that with a compression test you are seeing how much pressure the engine creates, and with a leak-down test you are seeing how much pressure it loses.

 

1. Air whistling out of the intake filter, at the intake manifold, or through the intake piping - probable leak at the intake valve
2. Air heard hissing out of the tailpipe, turbocharger, or exhaust manifold - Probable exhaust valve leak
3. Whistling or hissing out of the PCV valve, oil filler cap hole, or dipstick tube - Worn piston rings or cylinder wall.
4. Air bubbles in engine coolant at the radiator cap or in the coolant overflow - Possible blown head gasket. May also indicate a crack in the cylinder head or cylinder wall.
5. Air escaping from the spark plug hole of an adjacent cylinder - Likely a blown head gasket between cylinders.

 

Thanks guys... I think I'm going to have Eric pull the head to take a peek. I'll keep ya posted.

 

No. A leakdown test is done with compressed air. Once for each cylinder. A cooling system test is usually a tight-fitting rad cap replacement with a little pump and guage.

Keith

 

Don't pull the head until you do a leak down test.

 

A word of caution about pressurizing the cooling system...Take the spark plugs out first, if you push coolant into a cylinder and then turn it over it won`t be pretty!

 

^^^+1

 

^^^^+2

 

^^^^+3

 

If you have a bad cylinder head gasket somewhere in between the cylinder and coolant jacket you will push pressure in the cylinder to the coolant side. Sometimes it will bring coolant into the cylinder side once the pistons compress down and it becomes a cycle vice versa. You did said you have white spark plug tip?

All the above advice are great but dont pull head w/out 100 percent sure.

 

^^^^^+1

 

 

Update: No one has a leak-down or coolant tester here at all. Eric is going to rule out the thermostat this morning (the motor runs beautifully still) but if that's ok he doesn't have time for more until evening. I'm debating two courses of action... 1. Renting a tow dolly and taking her to closest dealership, or 2. Renting tow dolly and just taking her home Sunday so I can enjoy at least some "vacation".

You guys seem to think it would be bad to pull the head without prior testing, but I want to ask why. Would it be wasteful in time/effort/money to do so from a diagnostic basis? Is there a risk involved?

I guess what I'm saying is, is there a reasonable shot the gasket could be replaced and that'll sort me out?

 

Yes this is wasteful especially if you don't have the right tools like the Camshaft timing tool.
IMO rent the dolly, hang out until dragon is over then tow it to the dealer.

 

It's the expense of labor and parts to change a head gasket, if the solution is something "simple". Do MINIs throw a CEL (misfire) when a headgasket leaks?

If you want to ride-along for any drives, catch me on the FRS.

Keith

 

I once used a combustion leak tester on another car and worked great.
Here is the video explaining what it is.

 

Nice Miles, I appreciate the informative video. Car is going to be towed to Helix starting tomorrow. (Hopefully early!) should have a diagnoses next week.

 

 

I saw Eric & Mike scratching their heads about your MINI while at the dragon. To be fair to them being in a tent at the dragon is far from being in their home shop. I'm sure they will diagnose & fix your MINI just fine. They are very good at what they do.

 

What was the damage to this car?