There's a vent plug for MECS system high point inside the transaxle cooler.

Since you end up draining the system when you replace the pump you end up using the system fill procedure by the manual.

It tells you to loosen (I ended up removing it) the transaxle vent plug when filling. It says to fill the system until coolant comes out the vent plug hole then to tighten it (don't overtighten it, it has a rubber o-ring on the plug and you can crush that causing a leak) and then to finish filling the MECS system.

This plug is on the back (sloping & toward the firewall) side of the transaxle underneath several cable plugs going into the transaxle. It's not hard to get to, but you'll have to poke around with a flashlight to see it the first time

It takes a 12mm socket and if you remove it instead of just loosening it, you'll end up disconnecting a multi-pin electrical plug just above it to get a straight shot on the hex to re-install it.

Disconnecting & reconnecting this plug was no big deal for me. If you just loosen it, as the manual says to, you might want to use a u-joint for the socket. You'll need no more than a 1/4" drive socket.

Since the system is self venting it tells you to check the expansion tank as you run the engine to ensure it is topped up. But I did not have to add coolant after refilling it.

Remember the pump comes on when you go to the run position (KOEO) whether you start the ICE or not, this is because the HV Electrical system comes on then. You can use this for the first check of level.

I suspect that if you did not vent the transaxle you might have to add a pint or so. The air bubble in the transaxle internal cooler may be sizable.

I don't think you would get a trapped bubble here since the pump is a pressure source that can sweep any bubble out of the cooler. But you will see a drop in expansion tank level accordingly if you don't vent.

 

The pump I received was listed as an 08 pump. Do not know whether the 08s have the same problem as the earlier ones. Just have to watch as these roll up on 50k.

One quick check you could do is look at the pump and see if it is a Bosch unit. If it is I suspect you'll have the same problem. Its about 6-8 inches long. The replacement pump is about 2-3 inches long, and much smaller.

 

Thanks for the info above Bill, Nice post that I'll bookmark for later usage.

 

A photos is worth a thousand words:

 

Being the non-mechanic that I am, I wondered what MECS was?

Then I Googled it, and it's the "Motor Electronics Cooling Pump"

Hope this helps others like me who don't know all the jargon.

 

Don't know what you're pointing at in your photo (kind of looks like the A/C receiver/dryer) but it's not the MECS pump.

The MECS pump is located down in front of & underneath of the engine next to the oil filter.

 

I did goof and pointed to the wrong item. They say a photo is worth a thousand words.

 

Darn! I just replaced that thing you were pointing to.

 

Been there, done that, still living so far.

What I want to know, econoline, is how you got the pipes to mate up and without leaks?

 

PVC sprinkler fittings and duct tape. Just kidding of course, but I will take your advice and replace the MECS pump when I approach 50k miles. Did you mention a recommended place to buy the pump?