Head gasket? WTF

[admS15]

So i had an exhaust manifold leak. I decided to change the manifold the other day and this is what i found when i removed it. Cyl 6 exh port is totally clean, 5 is partially clean also.

 

 

 

So i thought head gasket and coolant is getting into cylinder and steam cleaning everything on the way out.

 

(I did also have an episode of the overflow bottle being filled at a track day a few months back, although after changing rad cap it didn't happen again at subsequent track days).

 

Anyway i made the decision to pull the head as i also need to have a couple studs that have broken easy outs in them removed and this is a good opportunity for 2 birds with one stone.

 

 

So head was removed this morning and everything looks perfectly normal including 5 and 6. WTF is going on here, what do you guys think? What has caused the clean exhaust port? If it was running that lean to look like that, I'd think that cylinder would have been toast.

 

 

Only other thing I can think of is that the exhaust manifold leak was in that area but i cant see it causing that.

 

Can anyone make sense of or seen anything like this before?

 

Pics

 

 

 

 

 

Edit.

 

I didn't get much time to properly look everything over but just looking at the pics i was uploading, the last 2 of the head have a residue on them, not sure if that was some oil that got on there as i pulled the head. Will have to have a closer look and report back.

[GTSBoy]

Head studs back there could have been loose(r than the rest).

[admS15]

Head studs back there could have been loose(r than the rest).

I want to agree with you but they where tight as if not tighter than the rest. The passenger side wouldn't budge and rounded the hex, there was some cursing and swearing while i contemplated ringing the thread doctor, then i remembered the torx bits i bought the other day. A T55 fitted snug in the rounded head and managed to get it out. The gods where looking over me. Thanks..

 

I would have thought if water was getting in the cyl, the top of the piston would be clean too.

 

The Nissan has been let out... The magic is gone. RIP

 

New oem gasket, arp studs, timing belt kit, water pump, seals etc are on order. Will drop the head off to a head shop for a skim, extract repair 2 butchered studs and a check over the rest and follow their recommendations. Hopefully i wont have to touch it again for ages.

 

[Dose Pipe Sutututu]

Valve springs, valve stem seals too

How do the spark plugs look?

[admS15]

Valve springs, valve stem seals too [emoji4]
How do the spark plugs look?

Sparkies look good, no variance in colour. All pretty clean. I have been thinking about springs and seals. Going to get the head shop to check them and advise. Still trying to keep it budget build but if they're sketchy ill get it done.

[Dose Pipe Sutututu]

Valve stem seals at the very least!

Valve springs can wait, since you're on stock cams and not silly boost you'll be ok!

[KiwiRS4T]

Pic 1 looks like a crack - or did that clean up?

[admS15]

Pic 1 looks like a crack - or did that clean up?

Assuming you're talking about inside the exhaust port, i think that is how they are cast but i will have a better look at it again tomorrow and compare to the rest. Thanks kiwi[emoji106]

[admS15]

Valve stem seals at the very least!
Valve springs can wait, since you're on stock cams and not silly boost you'll be ok!

I happen to have a set of new valve stem seals in the shed somewhere. Will most likely get done.

[Missileman]

Broken exhaust studs are easy to remove, buy a full set studs, yokes, and washers too, and check the straightness of the exhaust manifold. 

[admS15]

Studs, yokes, washers where replaced not too long ago, except for the ones i couldn't get out. Yes it will be easier now the head is off but since its going to a shop, they can deal with it. The manifold that was on it, was warped badly. I have 2 spare straight ones to choose from.

Anyway, had a good look over everything today, dismantled the head. Cleaned the block surface. Old gasket looks to be in very good condition and there's no evidence of a path where coolant was getting in to the cylinder. Will see what the head shop says tomorrow.
@KiwiRS4T all the exhaust ports look like that, it's like the head is 2 pieces and pressed together although it's not. Lol

[admS15]

@Dose Pipe Sutututu are supertech valve stem seals better than oem. Couldn't find the ones i thought i had in the shed, i was looking for oem replacements but came across these.

[Dose Pipe Sutututu]

28 minutes ago, admS15 said:

@Dose Pipe Sutututu are supertech valve stem seals better than oem. Couldn't find the ones i thought i had in the shed, i was looking for oem replacements but came across these.

My opinion is they're the same siet, I used OEM ones that came with my gasket kit. I would also use whatever cylinder head shops use too.

[admS15]

Suppose ill just use what is easiest to get. I do prefer oem though.

[admS15]

Head went to the shop today. Guy did a pretty detailed visual inspection, commented on how everything looked pretty good and each cylinder was running real nice.

He was thinking it was water that had cleaned the ports but was surprised when he couldn't find any evidence on the gasket and when i showed him the pics of the pistons, he ruled that out.

He's pretty confident the cause is air getting sucked back in from the exhaust manifold leak. That actually makes sense because they where the cylinders where it was leaking and warped.

He reckons the valve stems looked pretty good except for 1 which looked a bit greasy. The head is going to be stripped, cleaned, new valve seals fitted and valves reseated as well as the broken bolts extracted.

In the past someone's drilled one of the studs crooked and actually taken out a fair bit of alloy. That one is going to be filled and then redrilled straight again.

I rang Nissan to try and get some valve seals quickly, they quoted me $23 each, $500 plus for a set. I lol'd hard. Ordered the supertechs, once they arrive i should have the head back within a day or two. Rest of the parts should also be here by then and i can start the shitty process of putting it all back together.

To add insult to injury, i was having a good look at my turbo and the exh housing has developed multiple cracks, so that is getting sent to hypergear tomorrow to have a good 21u housing machined to fit.

[GTSBoy]

20 minutes ago, admS15 said:

He's pretty confident the cause is air getting sucked back in from the exhaust manifold leak. That actually makes sense because they where the cylinders where it was leaking and warped.

You need to keep the foot down more.  Need boost to create +ve ex mani pressure to prevent those pesky air leaks.

[admS15]

You need to keep the foot down more.  Need boost to create +ve ex mani pressure to prevent those pesky air leaks.

My bad, advice noted. Ordering a heavier foot as we speak.

[Dose Pipe Sutututu]

10 hours ago, admS15 said:

getting sent to hypergear tomorrow to have a good 21u housing machined to fit.

.... And an external gate welded to it too

[admS15]

.... And an external gate welded to it too

Shhhh!! Thats more than i can afford pal.

[Slap]

If it isnt the leak in the zorst mani gasket doing it maybe just maybe it's clean from unburnt fuel from missfires or leaky injectors.