Cylinder Head Advice

[Katana]

I've started pulling the cylinder head off a 306 S16 (XU10J4) to replace the head gasket and was hoping for some advice from the engine builders and guru's on this forum.
I've rebuilt many a 2 stroke motorcycle but this is my first time tackling a cylinder head, so please go easy and forgive any bone head questions. :joker:


What do you guys make out of this lifter bore damage? The damage is on the exhaust side lifter bores only (adjacent each head bolt hole) and to me at least, seems to be from someone previously having a socket hang up underneath the bore when removing the head bolts?
I've also attached a couple pictures of general bore wear for your thoughts.

One of the hydraulic lifters has damage and I'm guessing most likely due to the damaged bores. Perhaps a piece of metal being dislodged? Is this lifter still serviceable or replace? A couple of other lifters have minor marks (attached).

The 8 exhaust valve guides have obviously been replaced at some point but 2 of the 8 exhaust valves and seats are now very worn on one side. Can these out-of-round seats be re-cut correctly or will new seats need to be installed first? (The worn valves/seats are already sitting a lot lower in the head compared to the others.)

I would also like to get your opinions of whether it's worth having this head repaired or to find another in better condition before handing over to the machinist for refurb?
I will be dropping by the machinist next week for a chat but would like to get fellow forum members thoughts too.

Any advice appreciated and thanks in advance.
Cheers

 

[driven]

3 of 8 is shot.
Depends upon what you are doing with car.
Keeper or Seller?

Seller just put it all together, it will work

 

[PeterT]

I think you should cut your losses and throw it all in the bin. Whilst the head is repairable, it is really not worth the money to replace the guides and poorly cut seats, in addition to the cracks and broken lifters. I'm not trying to sell you one of my spare heads either, as you're in WA. It's just the reality of the situation.

Guides are always the starting point when cutting seats. If they aren't round and on size, the seats will never be concentric. Maybe the spring has been coming up at a strange angle due to the weird seat angle and that's what damaged the lifter bore?

 

[Katana]

3 of 8 is shot.
Depends upon what you are doing with car.
Keeper or Seller?

Seller just put it all together, it will work

Thanks Driven. Yes definitely a keeper, just weighing up my options for now.

I think you should cut your losses and throw it all in the bin. Whilst the head is repairable, it is really not worth the money to replace the guides and poorly cut seats, in addition to the cracks and broken lifters. I'm not trying to sell you one of my spare heads either, as you're in WA. It's just the reality of the situation.

Guides are always the starting point when cutting seats. If they aren't round and on size, the seats will never be concentric. Maybe the spring has been coming up at a strange angle due to the weird seat angle and that's what damaged the lifter bore?

Thanks PeterT. I was thinking along the same lines once I dismantled the head but I thought I'd ask the forum first.

There is no spring damage or marking either which had me baffled. It's a damn tight fit for a T55 torx in there, which had me believing poor prior cylinder head removal tools/technique.

If you had a spare head available that would be a huge help. While I'm expecting the same verdict, I'll have a chat to my machinist in the coming days and get back to you. Cheers

 

[jaahn]

Hi Katana
Its hard to say from here but it looks like that head has had a catastropy of some sort. Perhaps overheated or dropped a timing belt or something. Those wear marks are not normal wear and tear, nor is that 'chipped' lifter. I have never seen that !!
As the others have said bin it now and start with a good one with no obvious problems. Then it is worth doing up for your long term use.
I would be looking at the pistons and down the bores to see what is down there too ! And checking the block deck for flatness. :nownow:
Jaahn

 

[robmac]

I'll stand be corrected, but the scoring and galling on the lifter bores, for want of a better explanation may have been caused by contaminated oil.

What does the engine oil look like ?

edit: My theory is not entirely at odds with the head being overheated. Oil loses it lubricating properties when overheated.

 

[schlitzaugen]

Geez. Talk to your machinist, but I don't think anyone would want the hassle of repairing those bores. Not even sure how you'd do it. The rest is doable, you can replace everything with a lot of money but that one alone is the killer.

 

[Katana]

Hi Katana
Its hard to say from here but it looks like that head has had a catastropy of some sort. Perhaps overheated or dropped a timing belt or something. Those wear marks are not normal wear and tear, nor is that 'chipped' lifter. I have never seen that !!
As the others have said bin it now and start with a good one with no obvious problems. Then it is worth doing up for your long term use.
I would be looking at the pistons and down the bores to see what is down there too ! And checking the block deck for flatness. :nownow:
Jaahn

G'day Jaahn,
It certainly looks that way. It did overheat before the head gasket went (split radiator hose) but I don't think it got anywhere near hot enough for that sort of damage to occur. As soon as I noticed the temp gauge, it was shut down.

Pistons are in good condition for what I can tell and bores are what you'd expect for the age and km's of the car. Deck is flat.

I'll stand be corrected, but the scoring and galling on the lifter bores, for want of a better explanation may have been caused by contaminated oil.

What does the engine oil look like ?

edit: My theory is not entirely at odds with the head being overheated. Oil loses it lubricating properties when overheated.

Engine oil is good Robmac and has been changed religiously during my ownership. Full synth + genuine filters.
The head has been apart before though and something tells me the head was put back together by an amateur in a sandpit.

Geez. Talk to your machinist, but I don't think anyone would want the hassle of repairing those bores. Not even sure how you'd do it. The rest is doable, you can replace everything with a lot of money but that one alone is the killer.

I'm betting the machinist will be saying the same thing.

 

[schlitzaugen]

Yep, that's what I think.

All the best oils and the utmost attention are worth naught if the engine has been monkeyed with by a, err - monkey.