Bouncing temperature on 85' K5

Seeing as how you just had slush/air in the system, I'd bet it's just some air in the system. Burp her for 10-15 minutes and see if that helps. A venting rad cap makes this process MUCH easier and MUCH less messy! Well worth the $5.

Doc

It was actually happening before.

How do I "burp" her. Do you mean running it with the cap off?

Also, I have the small hole on the radiator that the previous owner fixed with JB Weldbond. It is weeping slightly. Could this be attributing to it? If so I'll have to chip it off and braze it.

~KJ~

Yep, If that hole weeps a bit when the engine starts to cool down instead of drawing coolant back into the radiator from the overflow tank it draws air through that hole. Presto air pocket...

What reservoir? Never had a cap for it....

~KJ~

I wouldn't suspect the fan at those speeds. The fan can hardly pull air as fast as 35 MPH. It is actually in the way at speeds much beyond idle.

-- Gordie

'A Lawyer from Genoa, a cousin of Doctor Festa of Rome persuaded that his cousin was in a state of exaltation, decided to go incognito to Padre Pio.

As soon as the Father laid eyes on him he exclaimed: "What are you doing here? You are a Mason!" This was followed by verbal blows and counter-blows which all ended in the lawyer kneeling down in front of the humble friar who had converted him.'

Booklet - Who is Padre Pio?, page 18 - Published 1974 Tan Books and Publishers, Inc.P.O. Box 424 Rockford, Illinois 61105

I know that it's supposed to 'go away' but if at idle it bounces, I thought it might not be working....

~KJ~

KJ,

When the coolant cools down after the engine is shut off, it contracts and sucks in extra coolant from the expansion tank (aka reservoir) to keep the system full of fluid. If you have a hole ANYWHERE in the system, it will suck air into the system as it cools, hence you end up with an air pocket.

Go and buy a $5 Stant Lev-R cap for your rad. It has a little red lever on it that you can use to purge the system while it's running and nice and hot to get all the air out. This will make little difference until you fix the rad leak though.

Doc

But that air bubble would rise to the top of the radiator, not the head. It wouldn't cause the problems noted. So the best guess for this problem is the thermostat or a collapsing lower hose. He should still fix the hole properly, though.

============================= What exactly do you mean by "bounces"? Bounces as fast as a ball would bounce or a more slowley up and then down kind of thing? If it actually jumps up and down -jerky kinda fast I'll vote on the gauge or sensor.

Slowly climbs up, and drops rather suddenly, over and over. If I had to say it stops after a LONG ride (1+ hours).

~KJ~

======================= If after it is cool, you pull the rad cap and it is full of coolant: I would guess the t-stat is sticking. It gets hot then pops open, then cools off, closes and does it again..........Besides, the things only cost like 5 bucks. The cheapest first try :)

I agree, cheap thermostats often don't work right from the start. The hole MUST be fixed and the overflow tank must be operational. B

I'll vote for a bad intake gasket. Run a pressure test to check for leaks.

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