Seized engine block drain plug. Danger removing it?

[gr_diver]

Hello friends once again!!!

Summer approaches, and during first days of June I ought to flush/refill the cooling system.

The problem is that the drain plug is SO seized in place, even after a week of daily spraying WD40 on it it still refuses to work loose...

I am close to giving up, but my question is, if I somehow manage to remove it, is it possible that threads and local area inside could be rusted/corroded to the extend that it would not seal again? The system must be pretty clean because after 2 years the fluid still looks "relatively" clean...

The flushing is not much of a problem. I will bypass the heater core, remove thermostat (will be done anyway, I always replace it every 2 years just in case), and fill/empty twice with clean water, running the engine between to circulate the water... Replace thermostat afterwards and fill with coolant solution...

[tomking]

Impact wrench.

[gr_diver]

tomking: good idea, I will try to borrow one if I locate.


Main question though is: could the corrosion be such that removing the plug will make it impossible to seal afterwards, and thus I should avoid it? Has anybody experienced such a condition?

[deaner]

Originally Posted by gr_diver Hello friends once again!!! Summer approaches, and during first days of June I ought to flush/refill the cooling system. The problem is that the drain plug is SO seized in place, even after a week of daily spraying WD40 on it it still refuses to work loose...

WD40 is not a good penetrant. Any penetrating oil but WD40. I like to use, GM Heat valve and penetrating spray. Available at any GM Dealer. Some swear by PB Blaster. Also you can soak it and then tap it lightly with a hammer. This should help.

[baz]

PB products might not have made it to greece they have only just got to the uk
i like heat and a hammer but im a blacksmith

[Opelkurt]

Originally Posted by gr_diver tomking: good idea, I will try to borrow one if I locate. Main question though is: could the corrosion be such that removing the plug will make it impossible to seal afterwards, and thus I should avoid it? Has anybody experienced such a condition?

Anything is possible, but I've never had any problems after removing a stuck drain plug. Anti-seize paste and / or teflon tape on the plug threads should seal things up and prevent trouble next time.

-Kurt

[namba209]

Originally Posted by gr_diver I will bypass the heater core,

Why do that? The heater core is nothing more than a small radiator and it could probably use some flushing also. If you don't wish to use a chemical flush in the heater, what I've done, with good success, is use an adapter on my water hose, disconnect both heater hoses and force water in one heater hose, then the other. The reverse flushing cleans out a lot of junk from the heater core. If the threads on your drain plug are eroded away in the block, there are a couple of ways to fix it. A heli-coil is one or just tap it out to the next larger size and wrap the new plug threads with "teflon tape". HTH.

[gr_diver]

Thanks everybody for your responses!!!!

I failed to mention that I do flush the heater core at the same time, but seperately. So there goes one...

I will try the suggestions for the stuck drain plug... The biggest problem is the location, that makes certain tools (like extensions and such) useless, and applying effort difficult...

[gr_diver]

Phew, I just finished the cooling system!

I did it early, cause early came the summer heat. It was 35*C today, and during city driving after highway the engine was not happy at all, temp went a tad over the middle when I idled it for 5 mins, but during driving everything was fine... So when I came home I immediately opened the rad cap (no I did not get burned, I was carefull ;-) ) and a nice brown rusty crust was floating... ooops!!! Propably checking the rad when cold was letting this filth settle and made coolant look crystal clear...

So the tools and buckets came out. I finally did it the very-old-fashioned way... [Warmed engine to circulate water, emptied from bottom radiator hose, flushed radiator, replaced hose, refilled]x4. I also had the cap off during the procedure to observate what filth came out of the enngine during circulation.

The first two times an oh-my-god solution came out. Clean water within 15 minutes was turned to brown "filthy brake fluid" looking condition. Third time only a bit of foam, and finally the fourth clean sparkling water came out. Four flushes took about 1+1/2 hours, cause I let it get hot and circulate a lot each time...

In went a nice new coolant solution, and that's all about it for another two years (at least I hope so!!! )

So I didn't need to remove the drain plug after all!!!!

Thank you all for every single reply!

[Cherrybomb]

I can't find that damn drain plug! the manual tells me it exists, and yet I cannot seem to see it. The A/C covers the whole right side of the engine, and I've tried the oil sending unit to see if that could be it (ya, I know). Still, where the hell is this mystic plug?

[jeff denton]

From the oil sender go up two inches and aft an inch and a half.

[newman27]

So I over tightened my fan belt and destroyed my water pump (new one arrives tomorrow - this will be Sunday's little project). Do I have to mess with this drain plug when flushing the cooling system? I don't recall reading in the FSM that you have to remove it. Also, is the 1/2" down / 1/2" up flex test the best method to make sure your fan belt is adjusted properly? I had a squeal and got carried away on tightening it up ...

Thanks,

Matt

[BQS4]

Matt, when the pump comes off, you're going to lose a LOT of antifreeze, in that you have to drain the radiator.

[newman27]

Originally Posted by BQS4 Matt, when the pump comes off, you're going to lose a LOT of antifreeze, in that you have to drain the radiator.

OK but I was wondering specifically about the need to remove the drain plug from the side of the engine in the process. The water pump replacement instructions from the FSM does not mention needing to remove this plug in the process. I just went back and checked the FSM and notice that the coolant system flush service does mention removing this drain plug. So, maybe my real question is, while changing out the water pump, should I bother with the cooling system flush service too including draining from this plug? Maybe this is a good time to do it (even though the car has only been on the road 10 months).

Thanks,

Matt

[namba209]

Matt, the squeal from the belt was probably caused by and old belt that was glazed on the contact surfaces. If it was a fairly new belt, then probably the pump was giving up the ghost. The 1/2" deflection is probably the best way to adjust the belts, although there is a device that measures belt tension, but is rather expensive for the average mech and isn't used that much anyway. HTH.

[2 Fast 4 U]

I always see if I can move the logest part of the belt up & down 1 cm both ways

[BQS4]

Originally Posted by newman27 OK but I was wondering specifically about the need to remove the drain plug from the side of the engine in the process. The water pump replacement instructions from the FSM does not mention needing to remove this plug in the process. I just went back and checked the FSM and notice that the coolant system flush service does mention removing this drain plug. So, maybe my real question is, while changing out the water pump, should I bother with the cooling system flush service too including draining from this plug? Maybe this is a good time to do it (even though the car has only been on the road 10 months). Thanks, Matt

Matt;
You don't need to remove this drain, but, in the need to flush out your system, there is a better way. Prestone has a "back flush" system that has an attachment to one of your heater hoses and you can hook your garden hose to this, open the heater valve on your heater core and back flush all the old coolant out of the heater core, head/block and radiator in one shot. This system will also allow you to remove all the air out of your cooling system, much like bleeding your brakes, to make your cooling system more efficient.