Head Gasket Oil Leak

[Steve49841]

My car has developed an oil leak between the block and head directly above the oil filter. I'm guessing it's coming from the cam shaft oil supply galley/line. Has anyone else had this problem and how did you fix it. I'm going to re-torque the head bolts but other then that I'm probably headed for a new head gasket....oh goodie.

[Chickenman]

Fairly common problem on L-series engines. Re-torquing head gasket may be all it needs. If not..you know what you have to do. Don't forget to check head for straightness.

[djwarner]

I had this problem with Felpro head gaskets. They put a simple flat rubber ring around the hole for oil port. This perhaps 1.5 thousandths thick. Better head gaskets have a brass ferrule there that is many times thicker and is crushed when the the head is torqued down.

[rossiz]

if your head bolts are original (or older than a few years) i would strongly urge replacing vs. torquing or you are very likely to snap one. they get corroded into the head and after the repeated heat cycle stressing they get brittle. head bolt sets are available for ~$60 from courtesy nissan (i got the turbo ones, which are rated for a bit more torque).

if you snap a head bolt it will turn a 1 hr. job into an afternoon (at best) if it snaps flush and you don't have enough left sticking out of the block to grab w/vice grips you will be very, very unhappy.

[Steve49841]

Guess I got lucky...I managed to re-torque the old head bolts without breaking anything. The oil leak is stopped for now but I know if it starts again I will be looking at a new head gasket. Thanks for all the input

[Chickenman]

That's why I always like to use a bending beam or dial indicator Torque wrench on critical fasteners such as head bolts.

 

With those, if a bolt is close or past it's yield point, the Torque reading will stop going up as you turn the wrench. At that point you IMMEDIATELY stop, remove and replace the fastener because the bolt is stretched too far and is about to snap.

 

Click style Torque wrenches will give you no such warning. 

[nbenning]

Hello .... Along the same topic of tightening head bolts ... I can use some guidance.

I removed my '72 240z head a couple months ago and had it refurbished at a local machine shop.  It was  re-installed a few weeks later and torqued to 47 ft-lbs using the inside-to-outside alternating bolt grouped method outlined in various service manuals.  In the meantime, we finished completing the rest of the engine build over the course of 6-8 weeks.  Yesterday, fluids (water, oil, a/t fluid) were put into the engine and the engine was cranked a few times (~ 30 sec). I noticed antifreeze leaking from the head/block separation just a few inches to the left of the oil filter on passenger side.  We immediately drained the antifreeze to prevent any water getting into cylinders.

Upon research of my engine serial number (#60040) , I found it should have had a final round of torquing to ~61 ft-lbs.  We increased the bolt torque, but realized the torque wrench used was not behaving properly and now we are not sure where the bolts really stand.  So I've retrieved another torque wrench  ... Therefore should I:

• Loosen and tighten each bolt individually back to a torque of 61 ft-lbs? or
• Loosen all bolts using the outside-to-inside method and then re-torque them inside-to-outside with the recommended sequence of 29->40->61 ft-lbs? (if I go this second route, I can put a small amount of oil on the head bolt threads, which I neglected to do when putting the head on the first time)

and hope this solves my head gasket leak ...

Thoughts/recommendations?

Thanks, Nick

[Chickenman]

Remove all the head bolts. Apply a proper thread lubricant to the threads ( ARP and Clevite make thread lubricant ). Also put some lubricant between the head bolt and the head bolt washer. Installing the head bolts dry will not allow the bolts to stretch properly. You will get a false ( High ) Torque reading on your gauge. I trust you were using new head bolts the first time? If so you can re-torque them again. Especially as they were not stretched  to their Plasticity value. 

If you were trying to re-use old head bolts.  Get some new ones. 

BTW, what Head Gasket were you using? Some aftermarket ones have incorrect water passage positioning.

[gwri8]

Ditto on Chickenmans' recommendation. Better safe than sorry when it comes to head bolts.  The good news is that you probably won't snap any when removing them.  Stock head bolts are not re-useable. ARP bolts are, but they are more expensive.

[nbenning]

Hello ... Thanks for the feedback.

To answer your questions ... Yes, I installed new OEM head bolts purchased from ZCarDepot.  I'll take your advice and remove the bolts, apply the ARP lubricant on threads and bolt/washer surface area as well and re-torque in three steps to 61 ft-lbs.  When I removed the original 40+ year bolts at the beginning of the project, we sheared a head bolt and to make matters worse, break an "easy out" trying to extract the original bolt.  Don't want to go through that mess again!

Also, the gasket I used was part of a complete engine gasket set by Stone (Part no. A101-P142H) see attached pic ... Is this one of the gaskets giving other Z owners problems with coolant leaks in to the oil?

Thanks, Nick

[Chickenman]

Stone is a brand that I've never heard of before, so I can't really tell you if it's good or bad. 

 You should always match the head gasket to the block and head visually before installing. Any gasket should be checked for that matter.

L28's were the models that had different shaped upper block surfaces throughout their manufacturing years, and there were different versions of head gasket available.  Installing the wrong head gasket would leave certain water passages on the block uncovered and they would naturally leak... ( Like a sieve ).

Nissan eventually superseded ( revised ) the gasket so that one Part Number worked on both types of L28 block. Problem is that some of the aftermarket manufacturers still had two different Part numbers. 

 

[Zed Head]

On 9/10/2017 at 11:58 AM, nbenning said:

 Yesterday, fluids (water, oil, a/t fluid) were put into the engine and the engine was cranked a few times (~ 30 sec). I noticed antifreeze leaking from the head/block separation just a few inches to the left of the oil filter on passenger side.

Thoughts/recommendations?

Seems like you have a bigger issue than just bolt torque.  You haven't even generated pressure in the coolant passages and it leaks already?  Not right.  

When you say cranked a few times do you mean it ran for 30 seconds or somebody held the key at Start for 30 seconds?  Doesn't really matter much, just wondering.  

I'd refill it with coolant after confirming that you didn't do something weird like set your wrench to inch-pounds, or have a broken torque wrench, and see if it still leaks.  A little coolant in the cylinders will be easy to clean out, since you'll be removing the head anyway if it still leaks.