Overheating

[Black Sunshine]

Today I finally got around to changing my valve cover gaskets and spark plugs and wires.

When I finished I was in a hurry and I screwed up some stuff. First I left the MAF disconnected. It wouldn't run right. I thought that I screwed up the order of the plug wires. Before I did anything drastic I checked the intake and saw the MAF plug.

The really dumb thing that I did was I forgot to position the clamps on the hot coolant hose. So when I drove it down the road on a three mile trip it over heated. It seemed to have emptied itself. I filled the motor and then the reservoir. It heated right back up. I let it cool down. It drank all of the coolant from the reservoir. I filled it up again. I ran it and it was ok for about ten minutes.

This time I had it parked. It started going hotter and hotter. I turned on the AC to see if the fans would turn on. No fans. I don't know why the fans aren't turning on. I don't know if it's just low still or there is something wrong with the thermostat.

It didn't have any cooling problems before this incident. I've topped off the coolant about once a year since I got it. It seems to evaporate the coolant a little. I've never had a leak or an overheating problem.

[Black Sunshine]

I straightened it out. First I let it cool down again. Then I topped it off again and let it warm up with the fill cap off. Then when the coolant started welling up from the cap I replaced the cap. I think these essentially bled the system.

Once it got warm I looked for the fans to turn on. They didn't seem to be turning on. I disconnected both of the connectors on the thermostat housing. Nothing happened. I thought one being disconnected should turn the fan on. I opened the fuse box and tapped all of the relays on the top.

Then I looked at the diagram. I was surprised to see that there are three fan relays. I don't which fan is considered fan No. 3. The driver side radiator fan is No.1 and the passenger side is No.2. They are labeled too. When I touched the No. 1 relay to pull it out the fans both started. Maybe it was a coincidence. I don't know. They weren't running before when the van was over heating.

Nevertheless I took it for a test drive to the drive thru liquor store. It performed without fail.

Strange stuff.

[wiswind]

They can overheat when there is air in the system......and it can be a challenge to burp all the air out of the system.

[Black Sunshine]

This seemed to be the problem. The coolant expanding and contracting with the reservoir full seemed to help it get the air out. My repair manual says to bleed it but doesn't offer a method. The cap is pretty high on it so I ran it with the cap off until the expanding coolant decided it wouldn't fit anymore.

[lfootmatt]

Those fan relays are pretty notorious for going out at its age. I lost the A/C relay a while back causing the A/C system to over pressurize and it blew out an o-ring.

Local shop knew exactly what it was. $64 relay, $2.30 o-ring, and $120 to evac and service the A/C system. The guy was a disgruntled Lexus Master Tech who got pissed and quit because the stealership wanted him to be unethical and overcharge/overstates needed repairs. He could have told me I needed an entire system and I wouldn't have argued it.

An ethical and competent mechanic. I've only ever known a handfull of those! No offense to any mechanics here, I just don't know you.

You might kep an eye on the fans.

Later,

Matt

[Black Sunshine]

Interesting. . . .

I definitely don't want the AC to go out.