The mystery of the disappearing coolant!

[izzo]

Micromachinery is a mechanic and into Datsuns. He gave me a tip I'll pass along. It works great, too. Once the old rear main seal is out. Get some Napa auto parts store brand Syl-Glide. Put some on your finger and rub it around on the rear main inner surface where the crank will be spinning in it. Never had one leak or fail. Keeps the seal from going in dry etc.

 

I use a little piece of 1x1 soft wood and a hammer to tap it back in place. Tho some one on the forum custom made a tool to install these also for around 20 bucks.

[datzenmike]

Tim's right. Lips should always be lubed before sliding it in.

[distributorguy]

 

They are not really 'freeze plugs' but core plugs. 

 Says the man who doesn't live in MN.   Lol.  

I've never seen a cracked block from freezing.  Even the two I rescued from their outdoor parking spots after 25 years of retirement in Northern MN.  

[datzenmike]

I have. Block deck between cylinders and coolant holes in wrecking yard and the core plugs were popped also. Usually from rain flushing the coolant out then freezing later. Admit, not that common but I wouldn't want it to happen to a good engine..

 

MN? fawk it's the coldest place in America.

[Stoffregen Motorsports]

Use regular oil on the inside diameter of the seal, but for the outside I use Gasgacinch - https://www.google.com/#q=gascacinch

 

It lubricates and dries to form a light glue which helps keep the seal from leaking where the cap meets the block.

 

 

The day we moved from MN, it was 40 below with a 75 below wind chill. It was so cold, the Peterbilt hauling our stuff had gelled diesel and wouldn't start. They had to heat up the fuel tanks to get it flowing again.

[distributorguy]

And we don't even have frost in the ground yet this year - MUCH warmer than usual.  I do recall being out in -70 wind chills and as cold as -58 not factoring in wind.  And you hear stories about how the folks from the Titanic were cold in the water...

 

I once had a car shipped here from San Diego, not thinking that it likely had no anti-freeze in it.  February through the Rockies had its way with all the core plugs.  Every last one.  The block was fine, albeit an MG not a Datsun.  Very similar however.  

 

To the original poster: if your rear main is not leaking bad, I'd leave it alone.  Otherwise plan on installing a speedy-sleeve and make darn sure the seal is installed square to the block and not bent in the installation process.  Tapping opposite sides while installing WILL bend the metal structure and it won't seal well.  That's why making a tool that applies even pressure all the way around is important.  

[5t341tH]

Well I started the car up and it looks like it still leaks coolant. It is much more visible now. I see drips coming out from between the transmission and engine. But I believe it is leaking from higher up. I see coolant puddle on top of the transmission right behind the head. Is there a place for coolant to leak from behind the head? Is there a "core plug" there?

Also. I see that oil still leaks we well. I saw that it was oily around the oil pan gasket towards the rear of the engine. I even replaced the oil pan gasket with an OE one. It still appears to be leaking from there. Anything I can do to prevent oil leaks? I hate oil spots and coolant in my garage...

[Draker]

With the oil pan gasket, you should try to find a rubber one. Or, mostly rubber. If you can't find one, no big deal. You have to be very careful how tight you tighten the pan bolts. The bolt holes in the pan will 'cone' in over time. When you over tighten the bolts, it will just split that cork gasket right down the middle. I had this happen to me. 

 

Regarding the coolant, there are only a few places on an L motor where coolant can leak. Take a good look around. It's possible for a freeze plug to leak, but I'd be more suspect of somewhere else. If it's the back of the head, it's going to be a heater hose, a freeze plug, or the head gasket at the rear or the motor. 

 

I'm pretty sure you can rent coolant system pressure testers from a parts store. Just pump it up to 15 and poke around until you find the leak.

[DanielC]

Go under the car, and try to tighten the oil pan bolts gently, and evenly.

 

It is a little late now, but when the engine is out of the car, and the oil pan is off the engine, take a small ball pien hammer and hold the ball end on the oil pan bolt holes.  Then hit the other end of the ball pien hammer with another light hammer, just hard enough to flatten or very slightly concave the metal around the bolt hole.  Check the flatness of the bolt hole area with a straight edge on the sealing surface.

 

If you use a cork gasket, you have to very careful to tighten all the bolts evenly, in several steps.   You do not need a large 3/8 ratchet, a 1/4 ratchet will do fine for final tightening.   You can even use a 10 MM socket nut driver, or socket on a screwdriver type handle.  

 

 

For coolant leaks. look for some corrosion on the outer sealing surface of the fitting on the engine that attach the radiator and heater hoses.  any roughness or other defects can affect the ability of the hose inside surface to seal to the fitting.

[datzenmike]

There is a core plug hidden in front of the flywheel. Make sure it isn't dripping from a heater hose to the fire wall or from the head gasket first

 

[distributorguy]

Someone on FB doesn't know their ass from a drain plug...

 

But my ass is a drain plug... :angel: