Possible blown head gasket?

Tiny
UDM1989
  • MEMBER
  • 1999 CHEVROLET 3500
  • 7.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 140,000 MILES
I'm pretty sure I have at least blown my head gasket, if not worse. I was pushing my engine pretty hard going 80 MPH uphill when the engine quit. I placed it in neutral and tried the restart the engine. The starter would crank, so I coasted to a stop. Lifted the hood and found milky oil all over the passenger side of the engine. It seems to have blown out of the dipstick tube. I check the radiator and it was significantly low as I expected due to the milky oil. I am guessing head gasket failed which allowed coolant into the crankcase and blowing the oil/coolant mixture to spray out of the dipstick tube. I am planning on replacing the head gaskets but wanted to see if I might be missing something in my diagnosis. How likely am I right and am I missing something else which could have happened?
Monday, October 18th, 2021 AT 12:19 PM

3 Replies

Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
Good afternoon,

Sounds like you are correct. The fact that the oil is milky tells me you need main and rod bearings as well. Once coolant hits the bearings, it damages the babbitt on the bearing and they must be replaced.

https://www.youtube.com/watch?v=8es2qK6MA_E

I attached a YouTube from our company on rebuilding the motor which is what you will be doing.

Let me know if you have any other questions.

Roy
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Monday, October 18th, 2021 AT 12:50 PM
Tiny
UDM1989
  • MEMBER
  • 2 POSTS
Hi Roy,

Thank you for the quick response! You mentioned replacing the bearings due to the coolant. I am really hoping to just replace the head gaskets. With the engine stalling
when this happened, do you still believe the bearing need to be replaced? I know you are correct that replacing the bearings would be best, but how big a risk do I run with not replacing the bearings?

Thanks,
Eric
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Monday, October 18th, 2021 AT 1:09 PM
Tiny
ASEMASTER6371
  • MECHANIC
  • 52,796 POSTS
It is a very high risk. The engine oil pressure will drop and start to knock and by then you have crank damage and more damage.

It could last for weeks or less.

Roy
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Monday, October 18th, 2021 AT 1:11 PM

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