The engine block's coolant drain petcock port seems to be plugged within. Today, I replaced the radiator on my '92 245DL and followed up with the intention of draining and flushing the block and replacement radiator.

This car is new to me and I lack any past history. The old radiator had a leak and I had a spare from a '91 I previously owned. Since car was already up on ramps from changing out the engine mounts, I proceeded with the radiator changeout. While removing the old radiator, I was convinced a coolant system flush was necessary. Of course, new radiator was void of any fluids, battery was already disconnected, and I opened wide the cabin heater control. All hoses were connected and I opened the pet cock valve and had a hose attached directed to a bucket. I slowly added water from a garden hose via the expansion tank. I expected to see water exit the petcock. Nope! Water backed up from the expansion tank!

I then removed the petcock valve and still no joy. I swept the petcock port with a small screw driver and still no water. Next, I disconnected the thermostat housing and water poured out with no hint of resistance.

I could continue on with the flushing of block and radiator and refill with coolant, but I would be troubled with the non-functional coolant drain through the petcock valve.

Any suggestions to clear the drain? I had thought of applying back-pressure through the petcock valve, but I would have to juryrig a device to attach and apply that back-pressure.

Mike
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'83 245 GLT, '92 245DL, '90 760 GLT

Had the same issue with my dad's 745. Several jabs with a wire finally cleared it out and got things flowing. I don't remember if I had to completely remove the drain fitting or not to do this? I'm not sure they come completely out? Anyway, a stiff wire cleared it, I'm sure of that.
Charles

Randy has got it nailed. It takes very little to prevent flow at low pressures. Some congealed muck. This is true, in my experience, of some cylinder block drains, caliper bleed ports, and hot water radiator bleeds.

Hmmm, what do they have in common? Cast iron, small cross-sections for bleeding, and looong times between opening. Get out the coat hanger or similar. :-)

Starkie and Shadduck have it right but I'll throw in a bit more detail.

Petcock has two hexes, outer (smaller) and inner, next to the block.
Unscrew the outer till it comes out in your hand.
You may or may not get fluid flowing at that point.
If not flowing, stick an old nail or whatever into the hole where the petcock was, clean it out.

And clean up the removed petcock while you have it out. Has sort of a T-shaped hole; you'll see where you need to poke it clean.

I'm not sure how the larger inner fitting is sealed to the block so I'm not suggesting you remove it. Could be it's just brass against iron but I don't know.

My method for flushing these blocks:

Engine cold, or definitely not hot.
Remove thermostat and replace the housing with nothing inside (temporarily).
- no gasket, retaining nuts not real tight.
Top up system with water, leave cap off reservoir.
Start engine
Start it draining from petcock.
Replace water into coolant reservoir as it drains.
Keep it running, draining and topped off till you're satisfied all is clean.

To replace (most of the) tap water with distilled or purified water:

Now stop engine and drain water.
Pull lower rad hose and drain.
Tighten petcock and replace t'stat, new gasket is a good idea, reconnect all open hoses.

Add 1 qt. distilled water. Remember there's some still in system in spite of your draining efforts.
Add qty of antifreeze to achieve 50% of system volume (look it up).
Top off with distilled water.
Start it up with heater valve open, watch it warm up, top off as needed.
Close it up (reservoir cap; all else should be already closed).
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Sven: '89 245 NA, 951 ECU, expanded air dam, forward belly pan reaches oem belly pan, airbox heater upgraded, E-fan, 205/65-15 at 50 psi, IPD sways, no a/c-p/s belt, E-Codes, amber front corner reflectors, aero front face, quad horns, tach, small clock.

I have purchased cars that I found the port clogged with no coolant flowing out.

I have always been able to start the flow by probing about with a thin screwdriver. Perhaps a piece of coat hanger wire angled in for a quick reaming out?

Randy

Here is today's update. Got to get cleaned up and go to a b-b-q, but the news is positive.

With the petcock removed (13mm), I poked and prodded with a coat hanger. Thought that I might have to follow a bend in the passage and attempted weedwacker line. Moved up with a small screwdriver. Still no luck.

Next move was to remove the 19mm nut that the petcock fits in. I noted the buildup of hard crusty black crud at the bottom of that nut. It was hard to remove. Went through all the same "tools" through the larger hole. I prodded for depth of my penetration and thought something was near and in the way. Just more hard crusty crud I figured.

Moved up to #2 phillips and began more prodding. Examination of the tool tip showed lots of black wet grit. Poking wasn't the way to go. I then used the tool like a drill and felt like I was making deeper penetration and I was. Shortly, coolant was streaming out!! The entire screwdriver shaft was able to be inserted.

So, I'll be a happier person finishing this tommorrow. I'll follow "Sven's" flushing procedure. This is a graphic example of poor cooling system maintenance by previous owners.

Thanks to all of you. Take time this weekend to honor our fallen, those who are in harms way, those that wait, and those that grieve their loss.

Mike
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'83 245 GLT, '92 245DL, '90 760 GLT

Howdy,

If the car is running OK, I think I would just let it go. Maybe someone else can give us a way to clean the block passages but I cannot think of a way to do it short of a rebuild.

See this page:
http://www.woodyg.com/fairlane/finfo/coolingsystem2.html.

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Mr. Shannon DeWolfe -- I've taken to using mister because my name misleads folks on the WWW. I am a 53 year old fat man. ;-)