260Z Head Gasket

[Sprocket]

G'day

 

I'm a new owner of a 260Z, having only picked it up yesterday. On the run home (some 500km) the car ran beautifully right up until the last few km, when it blew a head gasket. We were able to limp those last few km home OK without the temperature gauge going too berserk.

 

Once home, I did a compression test while the engine was still warm and got 160 psi on all cylinders except #1, which was well over 200 psi. Cylinder 1 also had coolant spurting out of the plug hole when I cranked the engine, so I figured the high compression reading was because the cylinder is partially filled with coolant. Anyway, it's obvious that coolant is leaking into cylinder 1, and possibly oil as well (bowing smoke). So the head has to come off to check it for flatness, shave it if necessary, and fit a new gasket.

 

I have a Datsun Service Manual for S30 models and I'm OK working on engines in general, including OHC. But being a new Z owner and not familiar with these engines in particular, I'm on a steep learning curve, so I have a bunch of questions before I get the spanners out ...

1 Are the gaskets the same for 240Z, 260Z, etc.?

2. Is there a recommended brand of head gasket to use? (basically stock engine - not high compression)

3. Who/where is the best source of parts for these old engines in Australia? (with particular reference to head and manifold gaskets)

4. Are the head bolts re-useable (ie. not the stretch to yield type)?

5. The engine looks pretty basic SOHC, but are there any esoteric traps for a newbie doing a head-off job?

 

Sorry about the dub questions. I'm sure  won't be asking so many when I get to know the car better.

 

Cheers,

Cam

(Tasmania)

[Clockwork]

Hey, I just bought a VRS gasket set from sparco near KnD in Hobart. Price was reasonable enough I thought. Dunno about quality tho, but they are reputable enough so I'm satisfied

[Riceburner]

Best to get some ARP head studs, they are reusable. I've used genuine Nissan head gaskets available from Stuart Wilkins Motorsport in Sydney, just use a healthy coating either side of Hylomar before fitting.

 

If your going that far, would it be too much of a stretch to pull the engine and check bearings and rings? You'll need to check the block deck anyway for straightness and issues too.

[dat2kman]

If its lost water, and may have gotten hot, head may have a bit of warp.

A 4-6 thou clean up cut to a surface finish f Ra40 gives a nce surface for gasket mating.

Scrape top f blck, take care not to blck oil feed hole to head,

Follw instructions.

A head gasket from lcal Repco should be fine.

Follow torque instructions, it is always an unknown as to how stretched the old stock headbolts are, the ARP stud kt, ften is about same price as new Nissan head bolt set!

ARP market a specific kit for L6 engine, available from lcal performance type shops near you!

[Sprocket]

Head is now off and with Reggie (the cylinder head man) in Moonah. He'll give it condition check, replace anything that needs replacing (hopefully only valve guide seals) and shave as necessary to flatten it. He also said he'd source the gasket kit (incl manifold, thermostat and fuel pump gaskets) for me at trade price - probably from Repco, around the corner from his shop.

 

I've had heads done by Reggie before and he does a good job. As I walked into his workshop carrying the head, he said "That looks like a bit of ancient history - an L26". The fact that he could recognise it at a glance gives me some confidence that he knows his stuff.

 

Cylinder block face is already cleaned up and waiting for the reconditioned head. I was careful to avoid cap getting in any of the oil galleries, and I gave all the holes a suck out afterwards with my compressed air suction doohickey, just to be sure.

 

As for head bolts, I've found out that they're not torque to yield type, so are OK to re-use.

 

 

PS: Hey Clockwork (Joel?) I think we may have met. Are you a mate of Alex R, the bloke with the Alfa GTV?

Edited October 17, 2015 by Sprocket

[Clockwork]

Nah I don't think I know anyone with an Alfa. I'm in Hobart itself, not sure where u are? I was going to take my head in to Phil Young in norchy but your guy sounds pretty good too.

 

If u haven't come across him and aren't going to do any tuning yourself, damian dransfield on gormanston ct is the goto imo. He is the most recommended person I've come across I think. Will probably try and talk u into putting on webers or something tho

 

Also, with your road worthy, if you find it hard to get parts or are a bit worried about something not passing, talk to mick Williams down at the dover bp, he races zeds (business partner rod races escorts and both are into a few other cool rides) and does road worthies too.

 

Actually, another guy on here - wogsrus, may b the person u are thinking of. I remember he mentioned alfas to me once.

[Sprocket]

Thanks for those contacts. I've heard of Mick Williams but have never met him.

 

I've had work done by Phil Young in the past. He did the head on my Volvo Penta Diesel boat engine and a couple of motorcycle engines. Seems to do a good job. Only reason I go to Reggie now is that he was recommended to me by Rob Warren (Red) at Red's Motorcycles next door. Also, Reggie is closer when I'm coming from Bellerive, and I used to work in Moonah myself.

[1600dave]

 are there any esoteric traps for a newbie doing a head-off job?

 

 

 

Yeah, don't let the timing chain tensioner pop out.

[Sprocket]

Thanks Dave.

 

Yes, I did a bit of homework before disassembly, so was aware of that little trap. I jammed a wooden wedge down there. I must remember to take it out again!

 

Actually, it's the first time I've worked on an engine with a hydraulic tensioner. As I mentioned earlier, most of my engine work has been on motorcycles, all of which use spring-loaded tensioners that can be backed off. When I first took the rocker cover off the Datsun I thought the chain was a bit slack. That was before I sussed that it's a hydraulic tensioner. Presumably the slack disappears when the oil pressure gets up a bit.

 

@ Gareth - Sorry, I didn't respond to your suggestion to pull the engine to check rings and bearings. I'd rather not yank out the engine at this stage for a couple of reasons.

Firstly, I have no reason to suspect there's any issues in there - oil pressure is good, as is compression, and apart from losing coolant, the engine was running well. I've checked the gasket face on the block with a straight-edge and feeler gauges, and can't detect any non-flatness.

Secondly, my workshop isn't set up for working on cars so I don't have an engine hoist. I do have a 1 ton chain block, but where the car is parked, there's only light tin roof purlins above it to hang the hoist from. I reckon the roof would cave in if I were to hang that lump of Datsun cast iron from it!  One of he things on the wish list is to install an overhead beam the length of the workshop on which I can run a trolley car to hang the chain block from.

Thirdly, with a whole stack of motorcycles, storage shelves, tool cabinets, benches, lathe and various other crap in there, there's not a lot of room to work. I need a bigger workshop!

 

Cam

[Sprocket]

Well, the head is back on. Car was very reluctant to start. Took a lot of cranking, but I suspect I may have flooded it in my enthusiasm to get it going.

 

Anyway, it eventually coughed and spluttered into life on what seemed like one cylinder at a time until all 6 were working. It then smoothed out and sounded OK. Took it for a short test drive to get it up to operating temperature and everything seems to be working normally. Temp didn't go over about 80 deg C (measured at the top radiator tank with an infra-red thermometer).

 

I'll let it cool down and re-torque the head bolts. I'll also drain the coolant (only water at this stage after a cooling system flush) and replace with proper corrosion inhibited green stuff. Will check torque again after a few more heat cycles. Hopefully I won't be looking at the pistons again for quite a while!

 

Thanks for the advice.

 

Cam