Bhg?

[Cressida90]

Hey, I have only owned my 90 Cressida a week and I'm loving it! But I notice that its got a funny bubbly water sound behind the dash when I run the heater in the mornings and I'm giving it some revs...
There is no wet carpet under dash and engine runs really well, also not using any water.. should I be worried its maybe the head gasket??
Its apparently had the head machined and port n polish and tripple angle valve grind, and all new gaskets 40,000ks ago, so it goes pretty hard the old 7MGE but hopefully it wont be short lived! Water in radiator is bit rusty too!?
Any advice or ideas would be appreciated cheers!

[zero_gravity]

the 'waterfall' sound from behind the dash is classic to BHG in these cars. its some air that has gotten in the lines. its not necessarily BHG but it could easily be. its not common but its possible to have a leak that sucks air in...

signs to look for:

-white exhaust. most cars start with this until warmed up but with BHG it keeps going. its coolant getting in the cylinders and getting burned.

-'milkshake' like sludge under the oil cap. this is coolant getting into your oil and causing a sludge as it mixes. btw this is VERY bad for your bearings.

-loss of coolant (self explanatory)

-overheating. beware of this, it WILL warp your head! in more extreme cases it can crack the head making it scrap

-bubbling in the coolant overflow tank. this is exhaust gasses entering the coolant system creating the bubbling/overflowing

now you also mentioned the 'rusty coolant'. that sounds like badly contaminated coolant. check that out. the antifreeze serves two purposes for the engine - 1. prevents freezing in cold weather and 2. stops galvanic corrosion between the aluminum head and the cast iron block. this is why coolant has to be flushed every now and then. after a while it loses the ability to stop the galvanic corrosion and it begins to rot out the block and head.

the next question is how much do you feel comfortable doing yourself? a simple compression test can tell you a lot here. theres enough information around to get the job done if you can take the time to learn it.

[kamesama980]

it could also be a mix of toyota red coolant and regular green coolant (bad idea). gurgling dash could also mean a coolant leak. if you want to do it yourself it isn't hard, find a very steep hill near you, park on it with the nose high and set the parking brake, pop the radiator cap (do it cold or be VERY carefull. it'll burn bad very quickly). start the car and let it run and watch for bubbles coming out. if there's a steady straem of bubbles from the start (or as soon as the thermostat opens) you have BHG. if it's intermittent and stops eventually, it's just air in the system.

[Cressida90]

Hmm ok, well I went to see the radiator man today and a mechanic. The radiator man only confirmed what I already new (air in the system) and offered to spend some time trying to get the air out, but I think i will try to do this myself the way you suggest kamesama980.
At the moment zero_gravity it doesnt display any of those signs, so I guess thats why the mechanic told me not to worry about it at all! He said that some cars do it and its not much to worry about unless any of those signs you spoke of above are apparent... could it be its just at the very very early stages of a BHG maybe?
So I will try to get the air out and replace that rusty water also... get some anti-freeze in there, which will bring out any near leaks no doubt ...that brings me on to another question.. whats the best procedure to flush the crap out then refil the radiator with the anti-freeze?
Great feed back so far! Thanks

[kamesama980]

Drain the system, pull the radiator, flip it upside down and stick a garden hose in the lower hose nipple. watch the poo come out. don't try to spray it in under pressure or you can bend the fins with the force of the water. other than that, you'll need to take it somewhere. don't forget to clean out the engine too. take out the thermostat and water neck and stick the hose in there too