Worst AU coolant leak

[PridenJoy]

Thought i would start a thread on an issue i have dealing with on my wagon in the last few days.

On the way back from a long distance holiday, noticed the header tank was empty. Looked under the car and noticed a rapid coolant leak coming from towards the back of the motor. Credit to the car and the bullet proof AU engine, car got us home fine after a couple of water top up stops, which we would have made anyway.

Once home i thought I'd get underneath the car, hoping this leak is as simple as a hose or a water tap crack, the leak is very rapid, it drops lots of water in very short time, here is what i found.







Just in the 5 minutes i had the car up on hoist it leaked this much water.



Leak was coming from between rear of engine and transmission bellhousing, this indicated it is most likely coming from the welch plug at the back of the motor (bad spot for welch plug Ford) which can only be accessed once auto and fly wheel are removed. Bugger.

Here is the welch plug in question shown on a motor out of a car. It's hiding behind the Ford Engine operations sticker.



Car has close to 400k kms so i contemplated replacing the whole motor while I'm at it but decided to persevere with this one.

So the job was on. Tailshaft out. I marked it with a texta so i can put it on same way.







Next the exhaust needs to get out of the way to remove the auto. There is no need to remove whole exhaust, just factory Cat. Then get exhaust out of the way.

Supporting the exhaust





Cat removed





Transmission mount bolts undone. At this stage it's wise to place a jack under the auto to support it.



Transmission lines and electricals undone



Undo T bar linkage rod



Lower the jack gently to drop the rear of the auto and expose top bellhousing 19mm bolts





Also place an oil pan underneath the rear of the auto in case transmission fluid drains out of the rear once it's lowered





This is what i use to access those top 19mm bolts. The uni jointed socket is very handy.





All top bolts are out, only ones left are bottom 13mm ones which are easy to access as well as torque converter bolts. Raise the transmission so that it's level again to take the pressure off remaing bolts.



Next the torque converter to flywheel bolts. Remove inspection cover on back of engine and you're greeted with this. If not rotate the front of the engine with 22mm socket until you see one of the bolts.





There are four torque converter bolts, rotate engine to access them and undo one by one.

Next the bottom bellhousing 13mm bolts



Now all bolts securing engine to transmission are removed, it's a matter of man handling the auto to separate from the engine.



Lower the jack with the auto on it and move it to the side.


Next to remove is the flywheel, six bolts are easily undone.





And the problem is now exposed







I knew removing the plug would involve getting a shower with coolant and i didnt want to drain the whole system yet so i put a hole in it to drain first





Then hit one side of it with a hammer and pulled it out.







You can see all the pinholes in it caused by corrosion



Lots of cleaning up to do





More on next post

[gossy]

Great write up and pictorial mate.

Why on earth is that welch plug positioned there?

[Seasoned One]

Originally Posted by gossy

Great write up and pictorial mate.

Why on earth is that welch plug positioned there?

plus 1 !, did well to even find it

[XR8235]

Why on earth is that welch plug positioned there?[/QUOTE]

It's the way manufacturers cast the blocks they are all like that
Cheers

[Maka]

Thanks heaps for this awesome tech write up Sam, very much appreciated!!! It will definitely help me & others out whenever the time comes lol, big kudos to you mate!!!

cheer's, Maka

[PridenJoy]

So after copious amount of degreaser and WD40, the cleanup was complete





There was lots of metal swarf large and small inside the hole which i collected with a magnet and all was clean in there then i sanded the edges with some emery paper to make sure all is smooth



But there was still a little bit of water in there at the bottom of the hole and i wanted the sealant to be applied to surface free of water so i removed the bottom radiator hose to drain the engine



I then got the new plug (brass unlike Ford's rubbish steel) and made sure it's the same size





Best stuff to seal welch plugs



And installed



Flywheel back on, i torqued it to 85NM which seemed plenty tight.



Then put the auto back. Trick is to align it using the dowels on each side then inserting couple of 19mm bolts finger tight, then couple of 13mm bolts then torque converter bolts (all of them, tightened to spec) then the remaining bolts and then tighten the whole lot.



I refitted tailshaft and today I'll refit cat, flush the remainder of the coolant then put fresh coolant in the car and job should be done. Oh and of course re fit starter motor.

Hopefully this guide will help someone doing a search for this problem on the forums or even on Google.

[Sox]

You've probably already figured this, but it's quite likely the rest of the core plugs are just about shagged too.

[PridenJoy]

Originally Posted by Sox

You've probably already figured this, but it's quite likely the rest of the core plugs are just about shagged too.

I checked them first before i arrived at the actual source of the leak. I even removed the starter just to check the plug behind it. Looks like someone replaced all the plugs at some stage except for the one at the rear because it was too hard. Here's the one behind the starter, the rest all look in the same nick.

Originally Posted by redxm

Did you replace the rear main seal while it was apart?

I did think about that but this is one of those rare Falcons that doesn't leak from the rear main, leaks at the front of the engine instead Rear seal looked in good nick too so i didn't want to mess with it. Murphy's law it'll probably start leaking soon though

[V8falcons]

good write up and pics mate.. Ive got to pull my trans out of the fairlane soon.. not looking forwad to that..

[redxm]

Did you replace the rear main seal while it was apart?

[NCII40]

Good Write up mate
Thanks heaps for this

[billinggarry]

Thanks for the in depth repair process. It gave me the place to look for my coolant leak coming from the same area and dripping off the bell housing.
Because I have oil leaks ie sump gasket and front seal and timing cover gasket,I decided to remove the engine leaving the trans in place.
It was an effort, me with a buggered shoulder I got my son in law on the 🔧’s.
Finally got the engine out today only to find the rear welsh plug was fine!!
I have coolant seeping out from the head gasket!

Bigger job now!