Odd cooling issue.

Well OK, I've got an '87 beater I picked up a few months ago and am doing some work to/daily driving/getting trail ready. So we're looking at the closed cooling system everyone loves so much.

But my problem isn't that the Jeep's running too hot!

Couple months ago, I blew a water pump. So I replaced that, put a new stock thermostat and serpentine belt on, and replaced some hoses. Next, I would get erratic temperatures and downright overheat when going up the 10-mile hill near my house, and the crappy stock pressure bottle/cap were spewing all over the place.

I replaced those with the fantastic Volvo 240 junkyard upgrade, and made a Home Depot Special adapter to go between the stock 5/8" upper tank hose and the 1/4" one on the Volvo tank. Flushed the radiator, jacked the rear end up, filled and burped the system through the temp sending unit, and took it for a drive.

Well, a week and a couple hundred miles later, everything's still holding well. The "problem" is, according to the dash gauge anyway, I can't get the thing to budge much over what appears to be 155 degrees, and it's under that quite a lot of the time. Why? I think the standard operating range is supposed to be closer to 190-210 degrees, no? The new thermostat is a stock 195-degree one.

So, how cool is too cool? I know a motor makes better power and gets better fuel economy when it's properly warm. What can I/should I do, short of putting a piece of cardboard in front of the radiator?

Bet all you other closed-system sufferers out there wish you had this problem. :bunny:

But..... does the underhood temp feel to you like the engine is running that cool? After that 10 mile uphill drive, does the aux. fan come on? When you turn the engine off after a drive, can you hear the coolant percolating in the block?

Every damn Renix I've had has been stupid-difficult to get the air purged out of the cooling system. Seems like you've possibly got another bubble around your temp sensor.

My $.02 anyway.

Well, I had to go and open my big piehole. This evening toward the end of my 20-mile or so freeway drive (hot out, with the a/c on) I was surprised to see the gauge sitting just PAST 210, not going any further. Rolled to a stop at the exit, temp dropped a little...drove around a little to find parking, and smelled that familiar smell! Even with the gauge still reading somewhat normal, there was the steamy spitting going on - this time at my homemade coupler mentioned above, or the 1/4 hose attached to it - hard to tell.

Hopefully I can nurse it through another day of commuting and then home for the weekend. I've got an odd situation - my girl and I drive down into town from our house in the hills (40 mi), then split up at the Jeep's parking spot for the day, meet back there in the afternoon, and go home, leaving the Jeep parked in town overnight.

So yeah, could definitely be that there are still ye olde bubbles. It was so solid for a few days though...

Methinks it's time to mosey on over to Jegs and order up some open-system conversion parts.

Drove it to work today without touching it...."155" all the way, 175 for a few minutes on the pass, back to 155, then shot to 210 quick as a blink and started spitting at the first stop light. Got back underway, back to 155...slowed to turn into work, and more 210 and spitting.

There's definitely a split in the 1/4" hose, right at the clamp. Now I wonder, when I replace that, will all be well? Or is something else going on that will cause the system to find the next weakest spot? Hmmmm.

The aux fan cycles on and off at idle, so that appears to be working. Fan clutch felt good when I took it off for the water pump and seems to push a lot of air, but I wonder if appearances are inaccurate on that one.

or.....Bubblesssssss!