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bubbling coolant bottle

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Z

zottlander

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hi all, my coolant overflow bottle is bubbling. I assume this is compression gases that are escaping via a head gasket leak. With the car ideling it's not a issue, but at speed on the highway, it sprays out the vent hole on the bottle cap. (the fan then blows it all over so it's hard to tell where it's coming from).I bought a new radiator thinking that the rad was leaking. When it happened again i had to think a outside the box. Have any of you had this particular problem? Next i am going to run a compression test to compare cylinders. (77 Spitfire) Thanks for any help.
 
Sounds like a compression test is in order.
If that is not conclusive, you may need to have a coolant-system leakdown test done.
 
Have you replaced the rad pressure cap?
 
What model? It could be a head gasket, If your engine has piston liners it could be a slipped sleeve. This happened on my '88 Range Rover & it meant a rebuild was in order.
 
I think Rick may have the answer; the coolant is under pressure in the rad, which raises the boiling point, in the overflow bottle it is not.
Check your temp gauge. If you have a new rad cap is it the same pressure as the old one, usually 4 or 7psi, or perhaps you replaced it because the old one was not holding pressure?
Simon.
 
When you get the head planed smooth, have them take off 100thou, this will raise your compression and power for next to nothing, the main cost being the shorter pushrods you will need to order.
MD(mad dog)
 
my '89 rangie did that, was a blown head gasket.
 
ok here is the results of the compression test,
cly.1 96,100
cly.3 99,100
cly.4 107,130,128
cly.2 148,136,126,110,115,120
when i had my hs4's i allways had a hard time tuning cly's 1 and three . 4 and two were easy and close to spec.I ran the test with all plugs out. i wonder if this has been a long term problem that i have worked around without solving the real problem. I hope its just the gasket, but projects for me allways tend to grow. anybody using a solid copper head gasket out there?
 
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