L 18 Cracked Block

[dotdat]

I bought a 1974 - 620 that had Coolant in the oil. Today I removed the head and found bad news. The rear head bolt #2 that is next to Cyl. #4 was rusty around the threads. It is next to the water jacket and I would guess that the block was cracked and allowed the coolant to leak into the head bolt thread.

 

 Looks like I'm screwed. Don't know what to do. I assume that there is no fix on a cracked block. It's a nice rust free little truck. But doubt if I can find an L18 motor around here. ( So. Dakota )

 

  Your comments appreciated.

 

[datsunaholic]

Or, it simply blew the gasket and got coolant all over the threads and in the oil.  It might not be cracked, just a really warped head.

 

But, another block, or even an L20B (so long as you get the flywheel with it) is pretty much a drop in.  Might have to spend on shipping, but they're out there. 

[banzai510(hainz)]

I just gave a L18 block away to Dayton100(patrick) on here

[Guest_kamakazi620]

Or use a L16 block punch it out to l18 pistons drop in your crank and rods ....

[datzenmike]

Clean it and look at it properly. Light sand paper and wire brush. Doubtful it's cracked just needs a new gasket and check the head for warp..

[Xnke]

Like others have said, it's very unlikely the block is cracked on an L-series engine. Unless it's an L6 and the block skirt is missing around cylinder #5...

 

Then you know they still drove it till it pumped all the oil out of the crank case. Probably made it all the way back to the pits, too!

[Stoffregen Motorsports]

They don't usually crack back there. The middle bolt hole near the oil passage is where they usually crack, and even then, they're fixable. I've done it 5 or 6 times.

 

But yeah, probably a warped head/blown gasket, etc.

[banzai510(hainz)]

Stoffregen Motorsports , The middle bolt hole near the oil passage is where they usually crack.

 

yes mostly on the L20s

[Stoffregen Motorsports]

Ask 68datsun510, he has a big bore, long rod L18 (1900) that I fixed using the "Frankenblock" method. Maybe he can post a pic.

[dotdat]

Getting old and eyes not good. Another closer exam made. Looks like the PO had replaced the head gasket and did a poor cleanup job. Head is not warped but close exam looks like a leak around the H G near cyl. #4 . Will go ahead and replace it.

 

What do you guys think about some copper stuff sealer to seal the gasket? I know Datsenmike is against this, but have read posts by others saying it's OK.

 

Thanks much.

[banzai510(hainz)]

I use Permatex Coppercote on both sides and let get tacky and install head. This was a nissan gasket.

 

last one I did was a Felpro HG and I just put it on and seems fine also.

[MikeRL411]

I use Permatex Coppercote on both sides and let get tacky and install head. This was a nissan gasket.

 

last one I did was a Felpro HG and I just put it on and seems fine also.

 

 

You will find that Margarine tubs are the "right" diameter to drop on top of the pistons when you spray the Copper Cote.

[Stoffregen Motorsports]

If you use a stock type graphite coated head gasket, no additional sealant should be needed. That's assuming both surfaces are perfectly clean.

 

Coppercoat never hurts, it's just overkill. And spray the gasket, not the block and head.