All Small Six The "Forbidden Leak"

[StarDiero75]

Howdy Everyone,

Lately I've noticed a leak under my engine... Its not oil.... Its green... Its next to the oil drip though at the back of the engine.... I checked the sending unit and she's super tight and dry, so my only guess is that its the coolant plug at the back of the motor... My question here is, I am considering yanking the motor and replacing all the freeze plugs at this point now, is this the best route? Also, if I'm replacing all the plugs, should I replace the cam plug too just for good measure? I just had this motor out to do the rear main (the rope seal ripped and refused to be pushed out) like 3 months ago, so this really sucks.

When I go to replace the plugs, should I use the brass ones or steel? I've seen both. Brass is pretty and doesn't rust out like the steel ones. Anyone know what sizes all the plugs are?

I plan on replacing the oil pan gasket too since it still leaks. I'm gonna try RTV despite how much I refuse to use it on a motor b/c I'm tired of this leaking (both my 200s do the same). Should I use the factory gasket+RTV or just RTV? While I'm in there, I kinda want to put ARP rod bolts in it since I'll be putting my aussie head on eventually (just shipped today!) and likely adding a supercharger. I know the bolts are the weak point in the motor which is why I'm considering it. Will the new ARP bolt just fit in, or will the rod need to be machined for it? If it needs to be machined, maybe its best to hold off on all this till I get the aussie and its ready to fitment.

Thanks,
Ryan

 

[B RON CO]

Hi, before pulling the engine make sure the coolant is not coming from the head gasket to water jacket seam. Good luck

 

[CNC-Dude]

Howdy Everyone,

Lately I've noticed a leak under my engine... Its not oil.... Its green... Its next to the oil drip though at the back of the engine.... I checked the sending unit and she's super tight and dry, so my only guess is that its the coolant plug at the back of the motor... My question here is, I am considering yanking the motor and replacing all the freeze plugs at this point now, is this the best route? Also, if I'm replacing all the plugs, should I replace the cam plug too just for good measure? I just had this motor out to do the rear main (the rope seal ripped and refused to be pushed out) like 3 months ago, so this really sucks.

When I go to replace the plugs, should I use the brass ones or steel? I've seen both. Brass is pretty and doesn't rust out like the steel ones. Anyone know what sizes all the plugs are?

I plan on replacing the oil pan gasket too since it still leaks. I'm gonna try RTV despite how much I refuse to use it on a motor b/c I'm tired of this leaking (both my 200s do the same). Should I use the factory gasket+RTV or just RTV? While I'm in there, I kinda want to put ARP rod bolts in it since I'll be putting my aussie head on eventually (just shipped today!) and likely adding a supercharger. I know the bolts are the weak point in the motor which is why I'm considering it. Will the new ARP bolt just fit in, or will the rod need to be machined for it? If it needs to be machined, maybe its best to hold off on all this till I get the aussie and its ready to fitment.

Thanks,
Ryan

Yes, replacing the rod bolts will require the rods to be reconditioned.

 

[bubba22349]

I like to use the Brass Freeze plugs especially in the hard to get areas of the back of the block or any of the ones in the head, but if you kept the coolant passages really clean and only used distilled water and a little anti freeze it probably won't rust out that soon. On the Cam plug they only have oil on them so they won't rust from the inside like the freeze plugs do so if I am not replacing the cam bearings I leave them alone.

I don't like using very much RTV on the oil pan gaskets or any others for that matter it will make the gaskets side right out. I always use the Permatex #2 or Gasket Snitch Aviation cemet to glue the pan gasket onto the block rails and then let it set overnight if possable with just the weight of the pan setting on it. Then I use a little RTV on the top of pan gasket and a dab in the corners, also be sure to not over tighten the pan bolts! Also before I start on it I make sure the pan rails and all the bolt holes are nice and straight again with a body hammer and a good dolly. With method I always get great results and no leaks. Best of luck

 

[StarDiero75]

Hi, before pulling the engine make sure the coolant is not coming from the head gasket to water jacket seam. Good luck

I already checked that. That's why this sucks so much lol. I would prefer a head gasket replacement over pulling the tranny or yanking the motor

 

[StarDiero75]

Yes, replacing the rod bolts will require the rods to be reconditioned.

Why is that? Why is it not just a pull the bolt out and put in a new one? Are the ARP ones slightly larger?

 

[StarDiero75]

I like to use the Brass Freeze plugs especially in the hard to get areas of the back of the block or any of the ones in the head, but if you kept the coolant passages really clean and only used distilled water and a little anti freeze it probably won't rust out that soon. On the Cam plug they only have oil on them so they won't rust from the inside like the freeze plugs do so if I am not replacing the cam bearings I leave them alone.

I don't like using very much RTV on the oil pan gaskets or any others for that matter it will make the gaskets side right out. I always use the Permatex #2 or Gasket Snitch Aviation cemet to glue the pan gasket onto the block rails and then let it set overnight if possable with just the weight of the pan setting on it. Then I use a little RTV on the top of pan gasket and a dab in the corners, also be sure to not over tighten the pan bolts! Also before I start on it I make sure the pan rails and all the bolt holes are nice and straight again with a body hammer and a good dolly. With method I always get great results and no leaks. Best of luck

Are the brass plugs easier to install or remove? I typically use a 50/50 distilled water/coolant mix, is that not great? So my concern with the cam plug is to make sure it doesn't start leaking oil. I really don't want to worry about it, unless they just don't normally leak.

I usually use the Permatex Indian Shellac and don't have problems, but this is the 1 that kicks my ass. I have the aviation one and I'll try that out next time. When you say let the weight of the pan set on it, do you mean the engine on a stand upside down, or on a bench? I will have to pick up a hammer and dolly, checking flatness is a good idea. I do however have a 2nd 200 block that I planned on making a table out of, would hammering the pan to the surface of the extra motor be a good way to flatten it? Or would it only be a good way to check for flatness?

 

[Soldmy66]

Brass freeze plugs last much longer. I will only use them. OEMs do not, I assume - because it saves them money.

+1 on aviation cement.

 

[bubba22349]

Are the brass plugs easier to install or remove? I typically use a 50/50 distilled water/coolant mix, is that not great? So my concern with the cam plug is to make sure it doesn't start leaking oil. I really don't want to worry about it, unless they just don't normally leak.

I usually use the Permatex Indian Shellac and don't have problems, but this is the 1 that kicks my ass. I have the aviation one and I'll try that out next time. When you say let the weight of the pan set on it, do you mean the engine on a stand upside down, or on a bench? I will have to pick up a hammer and dolly, checking flatness is a good idea. I do however have a 2nd 200 block that I planned on making a table out of, would hammering the pan to the surface of the extra motor be a good way to flatten it? Or would it only be a good way to check for flatness?

The Brass plugs are a bit thicker and the cup lip is a little wider than the steel plugs at least they were ones that I try to get and use. They are about the same effort on installing them I really don't know about how easy they are to take out (never had to remove one yet) but am sure they can't be that hard to do, I also tend to keep my cars and trucks a long time so that's why I like them better. That is great that you only use 50 / 50 coolant and distilled water mix.

Yes if the engines out then I will put it on my engine stand for disassembly and reassembly and yes you need it turned upside down for the best oil pan install you could also put all the bolts in loose to help keep the gasket inline and straight. Sure use that extra block to check the oil pans flatness and if you want to straighten it against it will help. I usally just use a hammer and dolly to work the area around bolt holes flat again on both oil pans and valve covers cause they can get flared out. Good luck

 

[CNC-Dude]

Why is that? Why is it not just a pull the bolt out and put in a new one? Are the ARP ones slightly larger?

The ARP bolts have a higher torque than the stock bolts and closes the housing bores up tighter. Plus removing and reinstalling the bolts distorts the housing bore also, and most any rods that have 40 or 50,000 miles or more are out of round enough to need reconditioning even if you don't change bolts. So you're just compounding problems if you do change the bolts. Also, switching from main bolts to main studs does the same thing and requires align honing of the block. It also states and advises this in their instructions. But if you're not expecting to do this, it can be a considerable extra expense.

 

[DannyG]

If the coolant leak is just "seeping" a bit, you might try some of the "pills" to stop the leaking. GM uses them in a lot of their engines. It helped me on a flat fender jeep engine also...