1991 4.0 XJ6 with 40k miles. Runs really well, was leaking coolant from the coolant expansion tank seams. Replaced it with a used one from local junk yard. That one lasted a good 100 miles and then blew a leak at the seams. I JB welded the used expansion together but haven’t put the car back together yet. Now I’m thinking I might have a blown head gasket causing excessive pressure?? I could drive the car, let it sit for a week+ and then open the coolant cap and you can still hear the pressure escape.
Evidence of no head gasket failure
- Did a combustion engine block test on the coolant. The liquid did not change colors.
- Have started and let the car idle with the cap open, no gushing of water or bubbling. I do notice very tiny particles that might resemble “oil balls” might just be dirt too?
- Oil on dipstick looks fine.
- Runs really well, doesn’t overheat. Will move between Normal and Hot at idle when I’ve lost too much coolant but will move back to normal after driving. (have only ran in this state for 10-20 minutes)
Evidence of head gasket failure
- There is “milkshake” residue in the PCV pipes that connect into the Oil filler neck
- Same looking residue in one of the skinny coolant hoses that connect to the expansion tank.
- I noticed “smoking” coming from the oil filler neck with the cap open and the oil dip stick with the dip stick open
Here are some videos and pictures. Please help and advise. Its a very good condition car, does it sound/look like I will need to change the head gasket?
Please view the videos I took of the “smoking” at this link https://drive.google.com/drive/u/0/folders/1Fq0ceyPG4g8d4KSngq8Kwub11FOIEm_X