coolant pressure tank/ overheat

I have an '89 Lareod XJ. Half of the time it runs at 212deg., then out of nowhere it will climb to about 230deg. It ran all day today at 212, then on my way home from work it hit 230. I shut it off when I got home and heard a hiss sound from the pressure tank cap. I sprayed water aound the cap and it sucked in the water. Would that little bit of suction cause it to overheat? I recently had new hoses put on, but before that it ran at 212. They also put in a new thermostat. Any ideas?

Closed system... I have the same thing 89 laredo. Hisses when the car warms up and I shud it off. Its air getting into the system. Not a big deal....Hasnt caused me any problems yet.

A couple things. First, does the new lower hose have the spring inside to help keep it frrom collapsing under suction? Just something to always check. And second, unless there is a lot of pressure in either direction, the cap will not let anything go past it. Any "leak" in the pressure system reduces the pressure (duh!) and lowers the boiling point of your coolant. I had the closed system on my '90 until recently, and noticed the hissing when things got nice and toasty. It kinda spooked me a bit, since I only want coolant in there, not air. Also, being an '89, is it still the stock radiator? Most folks around here give the stock unit about 10 years before it begins to struggle...or worse.

-Rich

Had the same problem with numerous caps and pressure bottles. My fix was to go to the Volvo dealers and get a replacement Volvo cap. Much higher quality and end of problem. Do a search using the word volvo for more details.

Sorry, do a search using the words Volvo cap for more details.

i had a simlier problem with my 89 limited. mine might have been a little worse, if i worked it hard i had a coolant volcano from the tank(only while in the red), however for regular driving it was fine. i thought maybe the clutch fan was not locking up. i tryed that (it was free,, worth a try) it got worse and truns out my radiator was cloged. i got it cleaned out for half the price of a replacement. i still have the minor detail of the coolant getting out, and air in. it hasn't caused a problem yet. i'am happy.

That's unusual. I think a new cap (all of about 6 bucks at the dealer) would cure that leak permanently. If you are boiling out the cap at under 240 degrees, you need a new cap or reservoir or both. If you are boiling out over 240 degrees, you have other problems. If you are sucking in, do you have enough coolant in the bottle to begin with? The coolant level should be at the notch on top of the post inside the bottle when it's cold.

ACE said:

That's unusual. I think a new cap (all of about 6 bucks at the dealer) would cure that leak permanently. If you are boiling out the cap at under 240 degrees, you need a new cap or reservoir or both. If you are boiling out over 240 degrees, you have other problems. If you are sucking in, do you have enough coolant in the bottle to begin with? The coolant level should be at the notch on top of the post inside the bottle when it's cold.

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You hit it right on the head.
Start with a new bottle and cap, make sure it has the right amount of coolant (50% and full to the cold line).

After that start looking at where the issues happen to decide if it is the rad or the pump, etc.

Michael

easiest and permanent fix is a late model MOPAR sedan pressure bottle from the junkyard. They mount on the passenger side front fender and will fit in place of your stock bottle when you remove the bracket. They are made of
very sturdy nylon and have a regular twist lock radiator cap. Mine cost me
$4.00.....good luck.