I meat to +1 on your diagnosis ideas. All good stuff everybody should know those things.


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What does this tell you?

Still short drive testing after head gasket and a went for a more spirited drive- 50mph for 10 mins or so. Temp got up too high just as I made it home.

Opened the hood and getting some coolant from the reservoir area and when I opened the bleed screw and steam was coming out. Uh oh.

Here’s the deal:

Running with no spinning fan or shroud attached.
Temp- as high as 121 degrees C engine coolant temp, on 65 degrees C radiator outlet temp. Upper radiator hose hot and tight, lower hose not hot but tight.

Must be radiator or something clogged?

Yesterday I did about half as far, temps were good, hoses both hot and full. What broke?


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Coolant Temp Warning - pegged to red. Holy crap.
 

No flow usually means t-stat not opening properly. Next bet the water pump. If outlet temp too cool means not enough flow rate.

Coolant above about 105C means you will get stream if you open the vent so that is just normal.

Coolant Temp Warning - pegged to red. Holy crap.
 

Yep, damn coincidences again? WP fails on second run? Hmmm? Wouldn’t thermostatfail open?

Got up to 90degrees yesterday on short, slow drive. Outlet was 73 and hot to touch. Frustrating.

Neighbor said go “straight to Carmax and take their off.”
Thinking he might be right.

Would the mechanical fan make that much diff in 10 mins?


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When not moving you need a fan or you'll overheat very quick but inlet and outlet temps will be almost the same.

The in/out much different means low flow. I've seen very recent thread xo that had a stuck closed t-stat they fail either way.

More likely to be an air lock, given the recent work...?

Thinking that too, just refilled the coolant let it idle up to op temp in the driveway.- scanner shows 82c engine coolant 75c radiator exit coolant. Upper and lower hoses fairly tight, hot. Squeezed on both to push any air through. Still no fan connected so it will likely not cool properly.

I assume the engine temp should read a little higher than the coolant exit temp if the radiator is cooling a little.

One odd thing. Other day I drove it a few mins up to temp and all was fine but the next AM the coolant hoses had sucked in on themselves. Some said it’s a bad rad cap. Replaced it with a different but same spec cap.

That mean anything?


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Yeah - I think it means there's air in there somewhere... :confused:

You don't mention bleeding the air using the bleed valves? I'm not familiar with the M54 - I have an M57 - but bleeding the air is a MUST do task when refilling the coolant....

Did the bleed screw prior, nothing but coolant. Can’t park at an angle with other car behind it so I’m improvising.


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Filling with ignition on but engine off (KOEO) might help - as long as the electric pump is running. You should see a small stream of coolant coming back into expansion tank.