... or worse.

In my experience, it's not just as simple as a gasket issue when they start the internal water leak.

Don't stroke out if you're observing, Joe. Too preliminary to make this conclusion in your situation.

 

Yes Joe. Sorry. Didn't mean to gather the clouds. Is to preliminary at this point.
Fill as discussed. Heater valve open. Squeeze/purge radiator outlet hose. Check oil.

 

OP based on the info provided you have a failed water pump impeller
NOTE if the engine runs for less than 5 mins and goes to overheating then coolant is not being pumped.
NOTE dont keep trying this experiment as head gasket damage or warped heads will result.

Now to fill the 928 cooling system, with all of the hoses connected,
it is a self bleeding system,

That means you fill it from the coolant tank till the tank is filled to just above the seam.

NOTE sometimes it takes a little while for the level to drop when your filling it,
but patience is required.

You do not have to do any thing like jacking the car up,
or removing hoses or back filling the heater core.

The coolant quantity is about 4 gallons,
the block holds about 2.3 gallons,
this means that to drain the block the block drains or the water pump must be removed to drain the block.
the rest is in the radiator, coolant tank, and heater core.

NOTE when filling the system, turn the heater to full hot,
then run the engine till the fans come on,
or it reaches operating temperature,
NOTE this is done with the cap off the coolant tank.

Once the fans come on,
then install the cap, and drive with the heat on for about 5 miles,
then park the car let it cool, this will level the coolant.

When cool, top up as necessary to just above the tank seam.

NOTE you can find leaking head gaskets with the block tester found at NAPA.

OR by letting the engine run and observing the coolant tank with the cap off,
if you see a steady stream of bubbles then the HG is leaking into the coolant/

 

where did you get the new thermostat ?? and on which side did you install the seal ?

 

That line implies to me that you're at least a couple gallons shy in the block, did not top it up via the hoses, and are attempting to add only via the reservoir? This seems like a recipe for an impossibly large bubble. Top it up via the hose first and see if that doesn't get you fixed. Your test runs would effectively be dry of coolant. The water pump can't cycle air very well.

But, I'm no expert. Maybe these cars can be filled only/primarily via the reservoir.

Edit to add: After careful re-reading Merlin's post... apparently via the reservoir only is fine. It seems odd to my shade-tree mind, and every time I've opened my cooling system I've filled via the hoses, never had an issue. But... like I said, I'm no expert. I'd still wager $1 you've just got a huge air bubble.

 

I drained a couple of months back and refilled through the reservoir.

Took it slow, was patient and got all 4 gallons in.

 

This comment with your avatar.

 

For the OP--

Your statements about changing because the old colant was sitting in there so long. and then changing less than half the coolant are in conflict for me. Go ahead and drain the block and the radiator completely, flush with clean water, and refill per the instructions shared.

Several times I've had symptoms similar to yours, where the car got hot pretty quickly immediately following a coolant change. It took a combination of radiator hose squeezing and engine reving to clear the air bubble that forms in the water bridge. Once that bubble was pushed through, the thermostat opened and all was normal again.

When filling initially, I pull the vent hose from the top of the radiator, and verify that the raditor is filled until a little liquid comes out. Put the hose back on and continue filling. The vent hose from the coolant crossover and the thermostat area to the reservoir is too low to do any serious vapor venting, at least the way it's all installed in the car. In a perfect world, thoe two vent hoses would slope up continuously towards the reservoir so air/vapor could move up through them directly to the reservoir. But they don't. I've tried filling with nose up, nose down, car level, and no one position seems more effective than others. Best procedure so far includes keeping the reservoir completely full while initially running the engine.

Remember too that there is a seal in the water bridge directly behind the thermostat. It's rubber and metal, cheap, and should probably be replaced every time the thermostat is changed. That disk on the back of the thermostat extends when the coolant gets hot, blocking the bypass loop around the radiator and forcing all the coolant flow through the radiator. This function is opposite the method used in most other cars, where there's a fixed bypass path that's always open, and the thermostat regulates only the coolant flow through the radiator. Anyway, that disk has to seal against the bypass port if you want full flow through the radiator. Having the corect thermostat is important too. IIRC, Behr and Walpro brands are the original fitment. Other parts-store pieces may work, but why not get the right one from one of our vendors?

 

no rear seal on the early cars.....

 

I got the thermostat from a European auto shop in the city I work in. The gasket was placed facing the fan.

 

I know it's been a couple of days since I've posted on this trainwreck, so here goes...

I don't see any white smoke coming from the exhaust. Maybe some when I first got it running again. The dipstick doesn't look like it's gummy like oil and coolant are present. I've seen that before on my old vw gti.

The broken climate control slider was all the way to the right. The fan control doesn't work at all, no blower in any position. I've been looking for the replacement part number for the old relay. Looks original. So until that's sorted out, no power there, although the clock runs.



Trainwreck. No pictured on the right side of that unit, all the vacuum lines have been unplugged. Damn the PO!




More good news. These connectors were behind the climate control unit. Note the snipped and missing wires. FML.

I went ahead and pulled one side of the upper radiator hose and managed to pour maybe a quart or so of coolant in there before it wouldn't take anymore. I fired her up again and right away checked lower driver side hose, it felt hard enough to squeeze, like there was coolant in there. I thought I heard/felt an air gush once, but none after.

I was only down there a minute or two before I checked the temp gauge and it was about to hit the red line. So I shut it down. I'm being vary wary of overheating the block and warping the head.

I've mentioned my concern about the gauge being wonky already... here's what I mean:



Key on running lights off. (I only put 5 gallons of gas in the tank I replaced recently, worthy of note)

Key on, running lights on. Note this is after I ran the car and shut it down as before, maybe 45 minutes later.

So what do you guys think of my pretty little mess now?

 

I didn't clarify if the hose ever got hot. That's tricky, on the one side I can let run it until it gets hot - providing it does actually get hot, but on the other hand, the way the gauge shoots up so fast, I am worried about letting it run too long and do some real damage. But while squeezing it, I noticed it didn't get warm at all.

Is there a definitive method of ensuring that the water pump is working without squeeze checks or eyeballing things?

 

First of all, congrats again on getting this jewel running. If this were my project, I would consider this 4th down and 3 to go. I'd definitively go one of two directions; punt it down the road or it's time for a parts order.

How well does it run? Does the transmission engage? Does it shift? You've verified that there are no mixing fluids. Do compression and leakdown checks, too. This would be next on my agenda. Determine whether this vehicle is worth the effort, time, and money. If your conclusion is 'yes' then I would get a new timing belt and water pump on order. Drain ALL of the old coolant.

While you're working on the top side of the engine, I would go ahead and replace all of the rubber fuel hoses, vac hoses and large o-ring from the AFM to the throttle housing, and refresh the ignition system. Replace everything from the coil to each plug and the green wire, too. Make sure that the capped vac ports on the throttle housing are in fact capped. Replace anything questionable.

You've already replaced the t-stat. New hoses might not be a bad idea. Transmission cooler hoses, too. They are usually hardened and they'll probably come apart when you pull the radiator to the TB/WP.

Doing the above should have you running well and the cooling system functioning as it should.

 

A nickel says this is the win. I think Mr Bailey is alluding to improper installation, perhaps the thermostat is in backwards. https://rennlist.com/forums/928-foru...hermostat.html

 

Re: your trainwreck under the console -

Yes...PITA but a very, very doable clean-up project. The wiring diagrams along with a Voltmeter are amazingly helpful, and with some patience and good crimp work you should be able to get it nice and clean.

I moved away from using the crimp joints you are using to a combination of splicing the wires and a few layers of heat shrink. Combine that with labeling on the heatshrink (you can get writable ones) and you go from a mess of spaghetti wires to something that's organized and easy to work with in the future.

I'm going to be doing the same thing with my wiring under/in the pod in the fall/winter. A lot of piece of mind that all wires are accounted for, that there are no burnt lines and that all the splices are solid & sound.