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My new 521


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Not a champion. Fully half of the owners on here have leaking issues. Fix it, get a different OE unit, or go premium like koyo. All the inexpensive aluminum radiator companies seen to have about a 50% fail rate.

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be honest my OPL Champion clone had a slight leak in the vains is what I could tell. just install maybe 2months ago


I fucking did it  last week. Prestone seal. Seems to be working.  But I didn't like doing this.  But since its new I said fuck it. when that glob came out of that bottle I was like  WTF  am I doing!!!!!!!!!!!  but theres not wet spot on ground . Might still be wet on frame.



Knowing what I know now.  Get a KOYO  or see if a rad shop can fix this.   one shop did my stock 521 to a 3 core but he had to see if the top and bottoms are still good. I had another bad spare and he got one of the top or bottom to make one good 3 core. But this was like 15years ago.  plus its a perfect fit unlike the spacers needed for the Champions and even the KOYO and maybe wire rerouted as I did in my 521.

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I'll check into the Koyo. It doesn't leak regularly but only when I drive for about 45 minutes pushing the motor going up a hill. Once I park it'll start leaking for a couple minutes and then it stops. So lately when I drive it I just pop the radiator cap once I park to relieve some of the pressure and hasn't leaked since. But there is still a leak and I'd like to fix it because having water is a pretty important thing to have in your radiator

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I have a small coolant leak between the head and block?!! Will post a pic when I get home. I'm hoping it is just leaking out as opposed to leaking somewhere in cylinder 3. No smoke and runs strong. Not overheating but I can foresee bigger problems if I don't fix it soon

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What is the red looking stuff?


Was the head and block surfaces checked for flatness?


Were all threds in block and head bolts cleaned before assembly?


Was head milled?  if so how much?


Was block decked?  if so how much?


What brand of head gasket did you use?


Did you check head gasket to head and block to make sure all water ports had holes in the head gasket?


Please put head gasket on dry!  The only place it is suggessted to use sealer is where the timing cover and block meat and then if you use sealer in this area it is used very sparingly.

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I have a friend Mark (Pacific Coast Datsun) He called me todayon his 620,  A few months ago He was on the highway and his 620 all of a sudden was extremely hot and he was looking for a safe place to pull over when he heard a loud bang and the engine died and would not restart after cooling down and adding coolant.  He finally had time today to pull the head after running a dry compression test.  Test showed 90 on #1, 30 on #2 & 3, and 170 on #4.  He has had al kinds of problems since he purchased it as a rebuilt engine ffrom Al, Datsun Parts LLC, has new business name now.


Any way after pulling the head he foung the head gasket was fine and the wear no noticible cracks in the head or block.  I told him he needed to tear the engine down completely.  He has a spare L20B so he will install it in time.  I am going to try and get up to Bull head City to help him tear down the bad engine to find out what happend.


Sometimes with engines it is a crap shoot as to what caused a problem.


I would check the head and the block on your engine to be sure the surfaces are flat.

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It is also possible for an oil passage inside the cylinder head to get a leak into the water jacket.  When that happens, whatever fluid is at a higher pressure leaks into the wrong place, putting oil in the coolant, and coolant into the oil.

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