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oil in coolant but no coolant in oil.???!!


illestmatic

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hello Datsun fam i have an issue that i cant seem to find an answer for. Before i get started YES i have done my research but havnt found a reasonable solution. But i hope i can end this problem here. lets get to it.

 

i have a 1973 620 pickup truck w/ a L16 motor stock everything. when i first got the truck it had oil in the coolant caused by a bad headgasket which was fixed by the time it was given to me.  first thing i did was obviously flush the system and when on to drive the truck with no problem. a month later i had oil in the coolant once again. so i flushed it a second time and drove the truck the same way keeping an eye on the coolant. 3months  passes by and the coolant is oil free. when all of a sudden i wake up to radiator full of oil -____-  i suspect its a headgasket but it runs great and the tempt is constant. so at this point im stumped. i actually took off the head to find out the head gasket was fine. 

NOTE: i get oil in the coolant but NO coolant in the oil..

ive read it could be a warp head, or a cracked head, a head gasket and etc.

 

what could lead to this issue??

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Only place oil can get into the water on the head is around the oil feed hole up from the block to the cam towers.... very unlikely but I would look there for cracks.

ahhh okay and this oil feed your talking about is on the back of the block/head right.?

should i see cracks on the head or the block? 

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OK, I suspect this is a 210 head, so I will assume it is, I have not heard of other heads doing this, only the 210 head casting.

Dan Hart had a customer with this issue, and I had this issue also long after Dan figured it out, and he is how I found out what the issue was.

I found that driving around town was not an issue, I never got oil in the radiator, but when I went on the hiway for an extended period of time, I always had oil in the radiator, and this is why, your head is cracked internally near the oil jacket in the head, it is not cracked on the outside of the head anywhere, this fact drove Dan Hart crazy, he finally gave up and bought and installed a new head, and the issue went away, so after the engine was fixed and gone, he took that head and sliced it like a loaf of bread until he found the crack between the oil jacket and the water jacket.

Get another head unless you like changing headgaskets a lot, as it will never go away until the head goes away.

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OK, I suspect this is a 210 head, so I will assume it is, I have not heard of other heads doing this, only the 210 head casting.

Dan Hart had a customer with this issue, and I had this issue also long after Dan figured it out, and he is how I found out what the issue was.

I found that driving around town was not an issue, I never got oil in the radiator, but when I went on the hiway for an extended period of time, I always had oil in the radiator, and this is why, your head is cracked internally near the oil jacket in the head, it is not cracked on the outside of the head anywhere, this fact drove Dan Hart crazy, he finally gave up and bought and installed a new head, and the issue went away, so after the engine was fixed and gone, he took that head and sliced it like a loaf of bread until he found the crack between the oil jacket and the water jacket.

Get another head unless you like changing headgaskets a lot, as it will never go away until the head goes away.

i just checked what kind of head it was and it says its a "A87" idk if this still matter but i can totally relate to your story. which seem exactly what is occuring to me. can i still take my head to get it checked? and will the head shop find this crack in the water inlet? 

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I never heard of an A87 head doing this, but I have only gotten real deep into datsuns since 2010 when I joined Ratsun, before that I just modified stuff using my own brain, never really learned this kind of stuff.

I don't know if a shop can figure out an internal crack like that or not, Dan had to slice the head like a loaf of bread to find the crack, seems like he would have had it tested after the first fix didn't work, but that was a long time ago, maybe they have better ways to test them now.

 

i just checked what kind of head it was and it says its a "A87" idk if this still matter but i can totally relate to your story. which seem exactly what is occuring to me. can i still take my head to get it checked? and will the head shop find this crack in the water inlet? 

I would take it to be tested, if they say nothing is wrong with it, then I would not trust it, there has to be something wrong to get oil in your water.

Personally if they said it was good I would re-install it, if it did it again I would go get another head.

The oil jacket/galley is a long ways away from the water jacket holes on the headgasket surface of the block, if the head is good and it does it again, it's internally cracked.

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See the tiny little hole next to the center head bolt hole on the lower edge of the block is this photo, that is the oil jacket/galley hole leading into the head, this is a Z22 block photo I am using to show you where the oil jacket hole is on your engine, I believe that it is in the same place on the L16.

DSCN0455.JPG

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mhmmm interesting. ive been involved in ratsun since october of last year so i stil have alot to learn. i really hope its not an internal crack that will give me trouble again.

but ill take it to get tested tomorrow and ask the shop if an internal crack could be found.

and thank you for this picture. i actually do this oil jacket outlet. Question: is this the only hole that oil goes threw on the block to the head?

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It's the only spot oil goes up into the head.

mhmmm interesting. ive been involved in ratsun since october of last year so i stil have alot to learn. i really hope its not an internal crack that will give me trouble again.

but ill take it to get tested tomorrow and ask the shop if an internal crack could be found.

and thank you for this picture. i actually do this oil jacket outlet. Question: is this the only hole that oil goes threw on the block to the head?

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Coolant system is pressurized to ~15psi .... Oil pressure is 50-57psi.  Which way do you think the fluid will flow if there is an issue. :)

good point draker. i actually knew of this psi stuff and took apart the motor to see if i could find an crack timing cover or a busted gasket where the water inlet is on the water pump.. but i couldnt find a real obvious sign of damage. 

the real question along with the psi is "in which places do oil and coolant come close to eachother? 

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Look for corrosion on the block and head surface near the oil jet. It's unusual for oil to get onto the water but if the head and/or block material is compromised in the jet area it just might get out. Most gaskets have a copper ring to crush to seal it, but if the metal around it is bad it will leak.

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my l18 was doing this same thing, i pulled the head and found that the gasket looked fine, i measured the head and found it was quite warped, upon further inspection i found a very clean area between the oil port on the block and the closest coolant port, it looked like the gasket was not sealing in that area, i had the head machined and reinstalled it, no issues so far

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So about an hour ago I recieved some sad news. The machine shop I took my head to said it was cracked and that replacing it should be the best thing to do. Although it got me thinking ... Is there a head I could use to inhance the performance of the l16.

If not I'll just replace it with the original a87 head.

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Both closed chamber heads will lower your L16's compression from 8.58 down to 8.21. Not a huge amount but a loss just the same. Shaving about 0.5mm (0.020") off should give you back about 3cc and bring it up to the stock compression and is probably not a bad idea on an old head anyway. You want 38.5cc per chamber.

 

Both heads have larger valves than the 210 head but the same intake port size so if wanting the most for high RPM running the ports could be enlarged, but only slightly. Making the intake ports larger will lower the air speed across the mid range with some loss but give it better breathing higher up. It's a balancing act. Fastest air speed you can manage but ports not so small they restrict.

 

These heads will bolt on and both your manifolds will fit. You might want to port match the intake manifold to the larger head ports. Get a new gasket and place on the head using the studs to line it up. Spray paint the gasket and remove. Grind away any aluminum that has paint on it. Paint will only show where there is a lip. Use a burr not a stone as it will clog with the soft aluminum in seconds. Now do the same to the intake. On both, taper and blend the cut into the port walls smoothly at least an inch. Does not have to be shiny smooth, rough is fine on an intake. This will remove any lip or miss match from casting variations. Cost is almost nothing and small things like this and others, add up. They do not wear out, are permanently built in, and don't go out of adjustment. Did I mention checking the chamber cc's? The head may already have been plained and if so may be close to the 210 you are replacing.

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