This is what I would do as well. Tandem pump is not that hard to get out and makes getting at the coolant manifold below possible.
Just wanted to add a tip on this thread since I'm working on this now. Draining coolant from the reservoir and radiator still leaves coolant in the engine block. If you don't drain that, have a plan for a fair bit of coolant to drain from the hoses/flange when you remove it. (Half liter?) I had plastic under the car, but still would have easier and more Eco-friendly to collect it. If I had to do it again tomorrow I'd just pour water on flange, see where it exits below, and then put a container on the ground there to catch the coolant. Or follow the procedure to drain coolant from block.
All terrific info. Thanks! I actually replaced the tandem pump about 35k miles ago. Had I known then about the plastic coolant flange, I'd have done that at the same time. I've got a new tandem pump gasket as prep for removing it to get at the flange. Where can I find part numbers for the intake flap gasket and the seals for the charge air hoses?The coolant flange is easier to get out with the tandem pump removed. Conversely, the tandem pump is easier to get out with the coolant flange removed.
So, you *can* do either with the other in place. For me personally, I like to take the tandem pump out first. Two reasons: One, I think that is the easier route, and two, the reason the cooling flange needs to be replaced anyway is usually due to oil or fuel leaks from....the tandem pump or at least its gasket. I would try and determine which before you tear into it, if possible, since a new coolant flange will not last long if there is oil or fuel leaking.
Anymore, given the age and mileage of these cars now, I always replace the vent hose (going from the nipple on the head and wrapping around past the fuel filter to the metal pipe) as it is in the way of what you are doing and will need to come off anyway and they are 99% of the time softened on the end that goes into the head. I also find a high percentage of these cars will also need the oil cooler hose assembly in need of replacement. This is the smaller hose that goes up into the bottom of that flange. You cannot easily see its condition until you get in there and get it apart. And, occasionally, the heater/EGR cooler hoses.
Get a gasket for the intake flap, too, as this job is much easier with that removed, as well as the seals on the charge air hoses you'll be removing.
It is a fiddly job, not much room back there and difficult to see things. There is a support for the turbo oil supply pipe that fits over the stud on one of the flange's mounting bolts, too. Don't forget to get that back in place.
A ball ended long Allen bit (5mm) is needed for best access to the tandem pump's lowermost bolt. The return fuel hose on the tandem pump is also tricky to get to, usually easier to remove after you have gotten the pump loose and pulled it up a bit.
Here are some parts numbers for the coolant hoses in this thread.
Why yes, yes indeed.
I hear you there! I finally got around to replacing mine, along with the tandem pump and a bunch of other stuff. Of course after initial fill with coolant it started a slow drip so off it came without ever leaving the garage. I did manage to remove the coolant flange without removing the tandem pump. Thankfully I had also replaced the turbo oil line with a flexible model, so it wasn't giving me any problems. Put in a dealer-sourced o-ring ($1.69) and no more drip! Was also a lot more careful with torquing the flange down; finger tight each bolt, then ~50 in-lbs, then the full 84 in-lbs. Even used the torque wrench for the nut that holds on the oil line support.
No drips detected on mine yet, although the top radiator hose slipped off, and dumped coolant on the freeway the first time I drove it under load. Luckily, I had a couple liters of the stuff in the trunk, and I was able to wrestle the hose all the way back on using the coolant as a lubricant. I guess I was just tired when I was wrapping up the easy parts of the job, and didn't notice that the top radiator hose wasn't completely seated. Since that initial embarrassment, the car's operating normally.
