Overheating after head rebuild?

[-bimmerboy-]

I just completely rebuilt the head, 272 degree cam, hd rockers, hd valve springs, new valve stems, new head bolts, etc. slapped the head back on last night and started it up this morning to drive to the muffler shop and after just about 5 minutes the temp gauge started going crazy then eventually went all the way to past red. After this i immediately pulled to the side of the road to find i was dumping coolant like crazy. I felt the radiator and the top hose was burning hot but the bottom hose was cold. I re tightened all the hoses and it stopped dumping the coolant but then it started seeping out of the back left corner of the head. The gasket is brand new and the bolts were torqued down exactly to what The Bentley says. Can anyone help me with this?

[Andy348]

Out of curiosity, what gasket did you use? Victor Reinz or Goetze?

Was the head planed before installation?

Hate to say it but rear left leak to me sounds like a head gasket failure. Are you certain that no other leaks could be flowing down around there?

[-bimmerboy-]

No it was just resurfaced with fine sandpaper. It did not appear to be warped when we used a straight edge and feeler gauge so could it no be warped because of the overheating? I used Fel-Pro which is the same brand that was used before with no problems

[jlevie]

Was the straightedge a machinist precision straightedge? If not, the head could have been warped and you wouldn't know it. The best way to check a head for warp is to prussian blue (or similar) on the head and rub it on a surface plate to find the high spots. Then use a precision straight edge across the high spots and feeler gauges to to measure the depth of the deviations.

The "spec" for warp is 0.006", but I think that is about twice too much, I'll surface a head if I find 0.003" deviation from flat.

That said, You might not have completely bled the cooling system. If you don't have a vacuum fill system, a reasonable substitute is to:

1) Using ramps or a jack get the front of the car 1' or more higher than
the rear. That will make the radiator and bleed screw the highest point
on the engine and facilitate removal of air.

2) With the bleed screw open, add coolant until no more air comes out of
the bleed.

3) Leave the filler cap off, or at least loose, and set the heat for max
temp and fan speed. Leaving the cap loose will prevent air that's still
in the system from causing a "coolant fountain" once the engine heats
up. Start the engine and allow it to warm up to operating temp. As it
warms up occasionally crack the bleed screw to release any air and top
up the coolant as necessary.

4) Once the engine is at temp bring it up to 2000-2500rpm for a few seconds
several times. Then crack the bleed until no more air is released. At
this point the heater should be throwing lots of hot air, which
indicates that the heater core is filled with coolant. You may have to
repeat this a few times to get all the air out.

5) Drive the car a bit, allow it to cool back down, and recheck the
bleed for air. Over the next few days you may get very small amounts (a
few bubbles) of air out of the bleed screw.

[E30_fiend]

I second the bad bleed scenario

I also think you've popped the new head gasket. If that needle went PASSED red, that's all bad news. I've never even seen the needle het half way through red before I shut the motor off. If you're leaking coolant from anywhere around the head, you've most likely popped the gasket. Time to do it again.

[MR 325]

Awesome.

[Simple_Smith]

was the coolant coming from the head itself or the coolant hose going from the throttle body that goes to the back of the block? double check the heater core hoses near there in case they were loosened during the head swap.

[e30mpg]

told u about using some RTV's