240SX Head and Gasket replaced, still bubbling.

[macten10]

I have replaced the head and headgasket on my 1990 ka24e following all the procedures in the fsm to the tee. There is still slight bubbling thru the overflow coolant tank as soon as motor is started. I suppose this means I have a cracked block? Any opinions? Anyone used the Steel Seal or Blue Devil sealers? I hate to have to replace the engine after all that (plus new timing chain kit and oil pump)
TIA or flame away

[tyrodtom]

Did you make sure the head wasn't warped, or have it pressure tested , while it was off ?

[macten10]

I got the rebuilt head from a dealer on fleabay and only checked it with a straightedge. It looked good to me but Im not a mechanic.

[OutToWinPAHC]

1- Tightening everything.
2- "loan a tool" cooling system tester. Test system at 1.5 bar. You want to see the cooling system hold that pressure at 1.5 bar for at-least 30 minutes. If pressure does not hold pump back to 1.5 bar and listen and look for the leak. Fix that leak and move to the next step If your sure there is no external leaks, and your dropping pressure, then you need to check your oil for intermix and check compression.
3- Properly bleed the system. Use a 60/40 mix 60%water, unless you live in the arctic.

How to bleed
Jack front on the car up
Use a coolant bleeder funnel and fill it
Squeeze the hoses and burp the air out
put the heat on hot, fan off
Start car and let it run
As the engine heat up, the air will bubble out of the funnel.
Once the engine is at normal temp the bubble should stop
Then open, the bleeder screw to make sure, once coolant comes out close it. wait about 30 seconds and do it again, Keep doing this until there is no air.
At no time let the funnel go empty
Plug the funnel and put the car on with the engine running.

Take a ride make sure temps are good, run the heat, then turn the heat off and just drive. Repeat if needed.

[Fenris]

i wish i had that funky funnel when i swapped my radiator recently... i had to use a 1ltr bottle with the bottom cut off and a hole cut in the cap, leaked a bit but fit pretty snug.

[macten10]

I used the "Steel seal" and after about 20 minutes the fog disappeared from the exhaust and the bubbling stopped too. It had to be a crack in the block. The Radiator cap is also faulty as it looses pressure and causes the coolant to boil, over heating the engine after an hour or more of driving. Thanks to all who contributed.

[ron_loving]

well i was going to metion the bleeding process but OutToWinPAHC hit the nail on the head! haha